typescript-mode.el

;;; typescript-mode.el --- Major mode for editing typescript  -*- lexical-binding: t -*-

;; -----------------------------------------------------------------------------------
;;     TypeScript support for Emacs
;;     Unmodified original sourve available at http://www.karllandstrom.se/downloads/emacs/javascript.el
;;     Copyright (c) 2008-2025 Free Software Foundation
;;     Portions Copyright (C) Microsoft Open Technologies, Inc. All rights reserved.
;;
;;     This program is free software: you can redistribute it and/or modify
;;     it under the terms of the GNU General Public License as published by
;;     the Free Software Foundation, either version 3 of the License, or
;;     (at your option) any later version.
;;
;;     This program is distributed in the hope that it will be useful,
;;     but WITHOUT ANY WARRANTY; without even the implied warranty of
;;     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;;     GNU General Public License for more details.
;;
;;     You should have received a copy of the GNU General Public License
;;     along with this program.  If not, see <http://www.gnu.org/licenses/>.
;; -------------------------------------------------------------------------------------------

;; URL: http://github.com/ananthakumaran/typescript.el
;; Version: 0.4
;; Keywords: typescript languages
;; Package-Requires: ((emacs "24.3"))

;; This file is not part of GNU Emacs.

;;; Commentary:

;; This is based on Karl Landstrom's barebones typescript-mode.  This
;; is much more robust and works with cc-mode's comment filling
;; (mostly).
;; The modifications to the original javascript.el mode mainly consisted in
;; replacing "javascript" with "typescript"
;;
;; The main features of this typescript mode are syntactic
;; highlighting (enabled with `font-lock-mode' or
;; `global-font-lock-mode'), automatic indentation and filling of
;; comments.
;;
;;
;; General Remarks:
;;
;; XXX: This mode assumes that block comments are not nested inside block
;; XXX: comments
;;
;; Exported names start with "typescript-"; private names start with
;; "typescript--".

;;; Code:

(eval-and-compile
  (require 'compile)
  (require 'cc-mode)
  (require 'font-lock)
  (require 'rx)
  (require 'newcomment))

(eval-when-compile
  (require 'cl-lib))

;;; Constants

(defconst typescript--type-name-re "\\(?:[A-Z][A-Za-z0-9]+\\.\\)\\{0,\\}\\(?:[A-Z][A-Za-z0-9]+\\)"
  "Regexp matching a conventional TypeScript type-name.  Must start with upper-case letter!")

(defconst typescript--name-start-re "[a-zA-Z_$]"
  "Regexp matching the start of a typescript identifier, without grouping.")

(defconst typescript--name-re (concat typescript--name-start-re
                              "\\(?:\\s_\\|\\sw\\)*")
  "Regexp matching a typescript identifier, without grouping.")

(defconst typescript--objfield-re (concat typescript--name-re ":")
  "Regexp matching the start of a typescript object field.")

(defconst typescript--dotted-name-re
  (concat typescript--name-re "\\(?:\\." typescript--name-re "\\)*")
  "Regexp matching a dot-separated sequence of typescript names.")

(defconst typescript--plain-method-re
  (concat "^\\s-*?\\(" typescript--dotted-name-re "\\)\\.prototype"
          "\\.\\(" typescript--name-re "\\)\\s-*?=\\s-*?\\(function\\)\\_>")
  "Regexp matching an explicit typescript prototype \"method\" declaration.
Group 1 is a (possibly-dotted) class name, group 2 is a method name,
and group 3 is the 'function' keyword.")

(defconst typescript--plain-class-re
  (concat "^\\s-*\\(" typescript--dotted-name-re "\\)\\.prototype"
          "\\s-*=\\s-*{")
  "Regexp matching a typescript explicit prototype \"class\" declaration.
An example of this is \"Class.prototype = { method1: ...}\".")

(defconst typescript--module-declaration-re
  "^\\s-*\\(?:declare\\|\\(?:export\\(?:\\s-+default\\)?\\)\\)?"
  "Regexp matching ambient declaration modifier or export declaration.")

;; var NewClass = BaseClass.extend(
(defconst typescript--mp-class-decl-re
  (concat "^\\s-*var\\s-+"
          "\\(" typescript--name-re "\\)"
          "\\s-*=\\s-*"
          "\\(" typescript--dotted-name-re
          "\\)\\.extend\\(?:Final\\)?\\s-*(\\s-*{?\\s-*$"))

;; var NewClass = Class.create()
(defconst typescript--prototype-obsolete-class-decl-re
  (concat "^\\s-*\\(?:var\\s-+\\)?"
          "\\(" typescript--dotted-name-re "\\)"
          "\\s-*=\\s-*Class\\.create()"))

(defconst typescript--prototype-objextend-class-decl-re-1
  (concat "^\\s-*Object\\.extend\\s-*("
          "\\(" typescript--dotted-name-re "\\)"
          "\\s-*,\\s-*{"))

(defconst typescript--prototype-objextend-class-decl-re-2
  (concat "^\\s-*\\(?:var\\s-+\\)?"
          "\\(" typescript--dotted-name-re "\\)"
          "\\s-*=\\s-*Object\\.extend\\s-*\("))

;; var NewClass = Class.create({
(defconst typescript--prototype-class-decl-re
  (concat "^\\s-*\\(?:var\\s-+\\)?"
          "\\(" typescript--name-re "\\)"
          "\\s-*=\\s-*Class\\.create\\s-*(\\s-*"
          "\\(?:\\(" typescript--dotted-name-re "\\)\\s-*,\\s-*\\)?{?"))

;; Parent class name(s) (yes, multiple inheritance in typescript) are
;; matched with dedicated font-lock matchers
(defconst typescript--dojo-class-decl-re
  (concat "^\\s-*dojo\\.declare\\s-*(\"\\(" typescript--dotted-name-re "\\)"))

(defconst typescript--exttypescript-class-decl-re-1
  (concat "^\\s-*Ext\\.extend\\s-*("
          "\\s-*\\(" typescript--dotted-name-re "\\)"
          "\\s-*,\\s-*\\(" typescript--dotted-name-re "\\)")
  "Regexp matching an ExtTYPESCRIPT class declaration (style 1).")

(defconst typescript--exttypescript-class-decl-re-2
  (concat "^\\s-*\\(?:var\\s-+\\)?"
          "\\(" typescript--name-re "\\)"
          "\\s-*=\\s-*Ext\\.extend\\s-*(\\s-*"
          "\\(" typescript--dotted-name-re "\\)")
  "Regexp matching an ExtTYPESCRIPT class declaration (style 2).")

(defconst typescript--mochikit-class-re
  (concat "^\\s-*MochiKit\\.Base\\.update\\s-*(\\s-*"
          "\\(" typescript--dotted-name-re "\\)")
  "Regexp matching a MochiKit class declaration.")

(defconst typescript--dummy-class-style
  '(:name "[Automatically Generated Class]"))

(defconst typescript--class-styles
  `((:name            "Plain"
     :class-decl      ,typescript--plain-class-re
     :prototype       t
     :contexts        (toplevel)
     :framework       typescript)

    (:name            "MochiKit"
     :class-decl      ,typescript--mochikit-class-re
     :prototype       t
     :contexts        (toplevel)
     :framework       mochikit)

    (:name            "Prototype (Obsolete)"
     :class-decl      ,typescript--prototype-obsolete-class-decl-re
     :contexts        (toplevel)
     :framework       prototype)

    (:name            "Prototype (Modern)"
     :class-decl      ,typescript--prototype-class-decl-re
     :contexts        (toplevel)
     :framework       prototype)

    (:name            "Prototype (Object.extend)"
     :class-decl      ,typescript--prototype-objextend-class-decl-re-1
     :prototype       t
     :contexts        (toplevel)
     :framework       prototype)

    (:name            "Prototype (Object.extend) 2"
     :class-decl      ,typescript--prototype-objextend-class-decl-re-2
     :prototype       t
     :contexts        (toplevel)
     :framework       prototype)

    (:name            "Dojo"
     :class-decl      ,typescript--dojo-class-decl-re
     :contexts        (toplevel)
     :framework       dojo)

    (:name            "ExtTYPESCRIPT (style 1)"
     :class-decl      ,typescript--exttypescript-class-decl-re-1
     :prototype       t
     :contexts        (toplevel)
     :framework       exttypescript)

    (:name            "ExtTYPESCRIPT (style 2)"
     :class-decl      ,typescript--exttypescript-class-decl-re-2
     :contexts        (toplevel)
     :framework       exttypescript)

    (:name            "Merrill Press"
     :class-decl      ,typescript--mp-class-decl-re
     :contexts        (toplevel)
     :framework       merrillpress))

  "List of typescript class definition styles.

A class definition style is a plist with the following keys:

:name is a human-readable name of the class type

:class-decl is a regular expression giving the start of the
class.  Its first group must match the name of its class.  If there
is a parent class, the second group should match, and it should be
the name of the class.

If :prototype is present and non-nil, the parser will merge
declarations for this constructs with others at the same lexical
level that have the same name.  Otherwise, multiple definitions
will create multiple top-level entries.  Don't use :prototype
unnecessarily: it has an associated cost in performance.

If :strip-prototype is present and non-nil, then if the class
name as matched contains")

(defconst typescript--available-frameworks
  (cl-loop with available-frameworks
        for style in typescript--class-styles
        for framework = (plist-get style :framework)
        unless (memq framework available-frameworks)
        collect framework into available-frameworks
        finally return available-frameworks)
  "List of available typescript frameworks symbols.")

(defconst typescript--function-heading-1-re
  (concat
   typescript--module-declaration-re
   "\\s-*function\\s-+\\(" typescript--name-re "\\)")
  "Regexp matching the start of a typescript function header.
Match group 1 is the name of the function.")

(defconst typescript--function-heading-2-re
  (concat
   "^\\s-*\\(" typescript--name-re "\\)\\s-*:\\s-*function\\_>")
  "Regexp matching the start of a function entry in an associative array.
Match group 1 is the name of the function.")

(defconst typescript--function-heading-3-re
  (concat
   "^\\s-*\\(?:var\\s-+\\)?\\(" typescript--dotted-name-re "\\)"
   "\\s-*=\\s-*function\\_>")
  "Regexp matching a line in the typescript form \"var MUMBLE = function\".
Match group 1 is MUMBLE.")

(defun typescript--regexp-opt-symbol (list)
  "Like `regexp-opt', but surround the result with `\\\\_<' and `\\\\_>'."
  (concat "\\_<" (regexp-opt list t) "\\_>"))

(defconst typescript--keyword-re
  (typescript--regexp-opt-symbol
   '("abstract" "any" "as" "async" "await" "boolean" "bigint" "break" "case" "catch" "class" "const"
     "constructor" "continue" "debugger" "declare" "default" "delete" "do" "else"
     "enum" "export" "extends" "extern" "false" "finally" "for"
     "function" "from" "get" "goto" "if" "implements" "import" "in" "infer" "instanceof"
     "interface" "keyof" "let" "module" "namespace" "never" "new" "null" "number" "object" "of"
     "override" "private" "protected" "public" "readonly" "return" "satisfies" "set" "static"
     "string" "super" "switch" "this" "throw" "true"
     "try" "type" "typeof" "unknown" "var" "void"
     "while")) ; yield is handled separately
  "Regexp matching any typescript keyword.")

(defconst typescript--basic-type-re
  (typescript--regexp-opt-symbol
   '("any" "bool" "boolean" "bigint" "never" "number" "string" "unknown" "void"))
  "Regular expression matching any predefined type in typescript.")

(defconst typescript--access-modifier-re
  (typescript--regexp-opt-symbol
   '("private" "protected" "public" "readonly" "static" "extends" "implements"))
  "Regular expression matching access modifiers.")

(defconst typescript--decorator-re
  (concat "\\(@" typescript--name-re "\\)"))

(defconst typescript--constant-re
  (typescript--regexp-opt-symbol '("false" "null" "undefined"
                                 "Infinity" "NaN"
                                 "true" "arguments" "this"))
  "Regular expression matching any future reserved words in typescript.")

(defconst typescript--builtin-re
  (typescript--regexp-opt-symbol
   '("console"))
  "Regular expression matching builtins.")

(defconst typescript--function-call-re "\\(\\(?:\\w\\|\\s_\\)+\\)\\(<.+>\\)?\s*("
  "Regular expression matching function calls.")

(defconst typescript--font-lock-keywords-1
  (list
   "\\_<import\\_>"
   (list typescript--function-heading-1-re 1 font-lock-function-name-face)
   (list typescript--function-heading-2-re 1 font-lock-function-name-face))
  "Level one font lock keywords for `typescript-mode'.")

(defconst typescript--font-lock-keywords-2
  (append typescript--font-lock-keywords-1
          `((,typescript--constant-re (0 'font-lock-constant-face))
            (,typescript--basic-type-re (0 'font-lock-type-face))
            (,typescript--keyword-re (1 'font-lock-keyword-face))
            ("\\_<for\\_>"
             ("\\s-+\\(each\\)\\_>" nil nil
              (1 'font-lock-keyword-face)))
            ("\\_<yield\\(\\*\\|\\_>\\)" (0 'font-lock-keyword-face))))
  "Level two font lock keywords for `typescript-mode'.")

;; typescript--pitem is the basic building block of the lexical
;; database. When one refers to a real part of the buffer, the region
;; of text to which it refers is split into a conceptual header and
;; body. Consider the (very short) block described by a hypothetical
;; typescript--pitem:
;;
;;   function foo(a,b,c) { return 42; }
;;   ^                    ^            ^
;;   |                    |            |
;;   +- h-begin           +- h-end     +- b-end
;;
;; (Remember that these are buffer positions, and therefore point
;; between characters, not at them. An arrow drawn to a character
;; indicates the corresponding position is between that character and
;; the one immediately preceding it.)
;;
;; The header is the region of text [h-begin, h-end], and is
;; the text needed to unambiguously recognize the start of the
;; construct. If the entire header is not present, the construct is
;; not recognized at all. No other pitems may be nested inside the
;; header.
;;
;; The body is the region [h-end, b-end]. It may contain nested
;; typescript--pitem instances. The body of a pitem may be empty: in
;; that case, b-end is equal to header-end.
;;
;; The three points obey the following relationship:
;;
;;   h-begin < h-end <= b-end
;;
;; We put a text property in the buffer on the character *before*
;; h-end, and if we see it, on the character *before* b-end.
;;
;; The text property for h-end, typescript--pstate, is actually a list
;; of all typescript--pitem instances open after the marked character.
;;
;; The text property for b-end, typescript--pend, is simply the
;; typescript--pitem that ends after the marked character. (Because
;; pitems always end when the paren-depth drops below a critical
;; value, and because we can only drop one level per character, only
;; one pitem may end at a given character.)
;;
;; In the structure below, we only store h-begin and (sometimes)
;; b-end. We can trivially and quickly find h-end by going to h-begin
;; and searching for an typescript--pstate text property. Since no other
;; typescript--pitem instances can be nested inside the header of a
;; pitem, the location after the character with this text property
;; must be h-end.
;;
;; typescript--pitem instances are never modified (with the exception
;; of the b-end field). Instead, modified copies are added at subseqnce parse points.
;; (The exception for b-end and its caveats is described below.)
;;

(cl-defstruct (typescript--pitem (:type list))
  ;; IMPORTANT: Do not alter the position of fields within the list.
  ;; Various bits of code depend on their positions, particularly
  ;; anything that manipulates the list of children.

  ;; List of children inside this pitem's body
  (children nil :read-only t)

  ;; When we reach this paren depth after h-end, the pitem ends
  (paren-depth nil :read-only t)

  ;; Symbol or class-style plist if this is a class
  (type nil :read-only t)

  ;; See above
  (h-begin nil :read-only t)

  ;; List of strings giving the parts of the name of this pitem (e.g.,
  ;; '("MyClass" "myMethod"), or t if this pitem is anonymous
  (name nil :read-only t)

  ;; THIS FIELD IS MUTATED, and its value is shared by all copies of
  ;; this pitem: when we copy-and-modify pitem instances, we share
  ;; their tail structures, so all the copies actually have the same
  ;; terminating cons cell. We modify that shared cons cell directly.
  ;;
  ;; The field value is either a number (buffer location) or nil if
  ;; unknown.
  ;;
  ;; If the field's value is greater than `typescript--cache-end', the
  ;; value is stale and must be treated as if it were nil. Conversely,
  ;; if this field is nil, it is guaranteed that this pitem is open up
  ;; to at least `typescript--cache-end'. (This property is handy when
  ;; computing whether we're inside a given pitem.)
  ;;
  (b-end nil))

;; The pitem we start parsing with.
(defconst typescript--initial-pitem
  (make-typescript--pitem
   :paren-depth most-negative-fixnum
   :type 'toplevel))

;; When we say "jsdoc" here, we mean "jsdoc 3". There exist multiple dialects of
;; "jsdoc documentation".

;; Note that all typedoc/jsdoc regexp by themselves would match occurrences that appear outside
;; documentation comments. The logic that uses these regexps must guard against it.
(defconst typescript-typedoc-link-tag-regexp
  "\\[\\[.*?\\]\\]"
  "Matches a typedoc link.")

(defconst typescript-typedoc-literal-markup-regexp
  "\\(`+\\).*?\\1"
  "Matches a typedoc keyword markup.")

(defconst typescript-jsdoc-before-tag-regexp
  "\\(?:^\\s-*\\*+\\|/\\*\\*\\)\\s-*"
  "Matches everything we allow before the @ of a jsdoc tag.")

;; This was taken from js2-mode.
(defconst typescript-jsdoc-param-tag-regexp
  (concat typescript-jsdoc-before-tag-regexp
          "\\(@"
          (regexp-opt
           '("arg"
             "argument"
             "param"
             "prop"
             "property"
             "typedef"))
          "\\)"
          "\\s-*\\({[^}]+}\\)?"         ; optional type
          "\\s-*\\[?\\([[:alnum:]_$\.]+\\)?\\]?"  ; name
          "\\_>")
  "Matches jsdoc tags with optional type and optional param name.")

;; This was taken from js2-mode.
;; and extended with tags in http://usejsdoc.org/
(defconst typescript-jsdoc-typed-tag-regexp
  (concat typescript-jsdoc-before-tag-regexp
          "\\(@"
          (regexp-opt
           '("enum"
             "extends"
             "field"
             "id"
             "implements"
             "lends"
             "mods"
             "requires"
             "return"
             "returns"
             "throw"
             "throws"
             "type"
             "yield"
             "yields"))
          "\\)\\s-*\\({[^}]+}\\)?")
  "Matches jsdoc tags with optional type.")

;; This was taken from js2-mode.
;; and extended with tags in http://usejsdoc.org/
(defconst typescript-jsdoc-arg-tag-regexp
  (concat typescript-jsdoc-before-tag-regexp
          "\\(@"
          (regexp-opt
           '("access"
             "alias"
             "augments"
             "base"
             "borrows"
             "bug"
             "callback"
             "config"
             "default"
             "define"
             "emits"
             "exception"
             "extends"
             "external"
             "fires"
             "func"
             "function"
             "host"
             "kind"
             "listens"
             "member"
             "memberof"
             "method"
             "mixes"
             "module"
             "name"
             "namespace"
             "requires"
             "since"
             "suppress"
             "this"
             "throws"
             "var"
             "variation"
             "version"))
          "\\)\\s-+\\([^ \t]+\\)")
  "Matches jsdoc tags with a single argument.")

;; This was taken from js2-mode
;; and extended with tags in http://usejsdoc.org/
(defconst typescript-jsdoc-empty-tag-regexp
  (concat typescript-jsdoc-before-tag-regexp
          "\\(@"
          (regexp-opt
           '("abstract"
             "addon"
             "async"
             "author"
             "class"
             "classdesc"
             "const"
             "constant"
             "constructor"
             "constructs"
             "copyright"
             "default"
             "defaultvalue"
             "deprecated"
             "desc"
             "description"
             "event"
             "example"
             "exec"
             "export"
             "exports"
             "file"
             "fileoverview"
             "final"
             "func"
             "function"
             "generator"
             "global"
             "hidden"
             "hideconstructor"
             "ignore"
             "implicitcast"
             "inheritdoc"
             "inner"
             "instance"
             "interface"
             "license"
             "method"
             "mixin"
             "noalias"
             "noshadow"
             "notypecheck"
             "override"
             "overview"
             "owner"
             "package"
             "preserve"
             "preservetry"
             "private"
             "protected"
             "public"
             "readonly"
             "static"
             "summary"
             "supported"
             "todo"
             "tutorial"
             "virtual"))
          "\\)\\s-*")
  "Matches empty jsdoc tags.")

;; Note that this regexp by itself would match tslint flags that appear inside
;; strings. The logic using this regexp must guard against it.
(defconst typescript-tslint-flag-regexp
  "\\(?://\\|/\\*\\)\\s-*\\(tslint:.*?\\)\\(?:\\*/\\|$\\)"
  "Matches tslint flags.")

;;; Faces

(defface typescript-jsdoc-tag
  '((t :foreground "SlateGray"))
  "Face used to highlight @whatever tags in jsdoc comments."
  :group 'typescript)

(defface typescript-jsdoc-type
  '((t :foreground "SteelBlue"))
  "Face used to highlight {FooBar} types in jsdoc comments."
  :group 'typescript)

(defface typescript-jsdoc-value
  '((t :foreground "gold4"))
  "Face used to highlight tag values in jsdoc comments."
  :group 'typescript)

(defface typescript-access-modifier-face
  '((t (:inherit font-lock-keyword-face)))
  "Face used to highlight access modifiers."
  :group 'typescript)

(defface typescript-this-face
  '((t (:inherit font-lock-keyword-face)))
  "Face used to highlight 'this' keyword."
  :group 'typescript)

(defface typescript-primitive-face
  '((t (:inherit font-lock-keyword-face)))
  "Face used to highlight builtin types."
  :group 'typescript)

;;; User Customization

(defgroup typescript nil
  "Customization variables for typescript mode."
  :tag "typescript"
  :group 'languages)

(defcustom typescript-indent-level 4
  "Number of spaces for each indentation step in `typescript-mode'."
  :type 'integer
  :safe 'integerp
  :group 'typescript)
;;;###autoload(put 'typescript-indent-level 'safe-local-variable #'integerp)

(defcustom typescript-expr-indent-offset 0
  "Number of additional spaces used for indentation of continued expressions.
The value must be no less than minus `typescript-indent-level'."
  :type 'integer
  :safe 'integerp
  :group 'typescript)

(defcustom typescript-indent-switch-clauses t
  "Enable indenting of switch case and default clauses to
replicate tsserver behaviour. Indent level is taken to be
`typescript-indent-level'."
  :type 'boolean
  :group 'typescript)

(defcustom typescript-indent-list-items t
  "Enable indenting of list items, useful for certain code styles."
  :type 'boolean
  :group 'typescript)

(defcustom typescript-auto-indent-flag t
  "Whether to automatically indent when typing punctuation characters.
If non-nil, the characters {}();,: also indent the current line
in typescript mode."
  :type 'boolean
  :group 'typescript)

(defcustom typescript-flat-functions nil
  "Treat nested functions as top-level functions in `typescript-mode'.
This applies to function movement, marking, and so on."
  :type 'boolean
  :group 'typescript)

(defcustom typescript-comment-lineup-func #'c-lineup-C-comments
  "Lineup function for `cc-mode-style', for C comments in `typescript-mode'."
  :type 'function
  :group 'typescript)

(defcustom typescript-enabled-frameworks typescript--available-frameworks
  "Frameworks recognized by `typescript-mode'.
To improve performance, you may turn off some frameworks you
seldom use, either globally or on a per-buffer basis."
  :type (cons 'set (mapcar (lambda (x)
                             (list 'const x))
                           typescript--available-frameworks))
  :group 'typescript)

(defcustom typescript-mode-hook nil
  "*Hook called by `typescript-mode'."
  :type 'hook
  :group 'typescript)

(defcustom typescript-autoconvert-to-template-flag nil
  "Non-nil means automatically convert plain strings to templates.

When the flag is non-nil the `typescript-autoconvert-to-template'
is called whenever a plain string delimiter is typed in the buffer."
  :type 'boolean
  :group 'typescript)

;;; Public utilities

(defun typescript-convert-to-template ()
  "Convert the string at point to a template string."
  (interactive)
  (save-restriction
    (widen)
    (save-excursion
      (let* ((syntax (syntax-ppss))
             (str-terminator (nth 3 syntax))
             (string-start (or (and str-terminator (nth 8 syntax))
                               ;; We have to consider the case that we're on the start delimiter of a string.
                               ;; We tentatively take (point) as string-start. If it turns out we're
                               ;; wrong, then typescript--move-to-end-of-plain-string will fail anyway,
                               ;; and we won't use the bogus value.
                               (progn
                                 (forward-char)
                                 (point)))))
        (when (typescript--move-to-end-of-plain-string)
          (let ((end-start (or (nth 8 (syntax-ppss)) -1)))
            (undo-boundary)
            (when (=  end-start string-start)
              (delete-char 1)
              (insert "`")))
          (goto-char string-start)
          (delete-char 1)
          (insert "`"))))))

(defun typescript-autoconvert-to-template ()
  "Automatically convert a plain string to a teplate string, if needed.

This function is meant to be automatically invoked when the user
enters plain string delimiters.  It checks whether the character
before point is the end of a string.  If it is, then it checks
whether the string contains ${...}.  If it does, then it converts
the string from a plain string to a template."
  (interactive)
  (save-restriction
    (widen)
    (save-excursion
      (backward-char)
      (when (and (memq (char-after) '(?' ?\"))
                 (not (eq (char-before) ?\\)))
        (let* ((string-start (nth 8 (syntax-ppss))))
          (when (and string-start
                     (save-excursion
                       (re-search-backward "\\${.*?}" string-start t)))
            (typescript-convert-to-template)))))))

;;; KeyMap

(defvar typescript-mode-map
  (let ((keymap (make-sparse-keymap)))
    (define-key keymap (kbd "C-c '") #'typescript-convert-to-template)
    keymap)
  "Keymap for `typescript-mode'.")

(defun typescript--post-self-insert-function ()
  (when (and (derived-mode-p 'typescript-mode)
             typescript-autoconvert-to-template-flag
             (or (eq last-command-event ?\')
                 (eq last-command-event ?\")))
    (typescript-autoconvert-to-template)))

;;; Syntax table and parsing

(defvar typescript-mode-syntax-table
  (let ((table (make-syntax-table)))
    (c-populate-syntax-table table)
    (modify-syntax-entry ?$ "_" table)
    (modify-syntax-entry ?` "\"" table)
    table)
  "Syntax table for `typescript-mode'.")

(defvar typescript--quick-match-re nil
  "Autogenerated regexp used by `typescript-mode' to match buffer constructs.")

(defvar typescript--quick-match-re-func nil
  "Autogenerated regexp used by `typescript-mode' to match constructs and functions.")

(make-variable-buffer-local 'typescript--quick-match-re)
(make-variable-buffer-local 'typescript--quick-match-re-func)

(defvar typescript--cache-end 1
  "Last valid buffer position for the `typescript-mode' function cache.")
(make-variable-buffer-local 'typescript--cache-end)

(defvar typescript--last-parse-pos nil
  "Latest parse position reached by `typescript--ensure-cache'.")
(make-variable-buffer-local 'typescript--last-parse-pos)

(defvar typescript--state-at-last-parse-pos nil
  "Parse state at `typescript--last-parse-pos'.")
(make-variable-buffer-local 'typescript--state-at-last-parse-pos)

(defun typescript--flatten-list (list)
  (cl-loop for item in list
        nconc (cond ((consp item)
                     (typescript--flatten-list item))
                    (item (list item)))))

(defun typescript--maybe-join (prefix separator suffix &rest list)
  "Helper function for `typescript--update-quick-match-re'.
If LIST contains any element that is not nil, return its non-nil
elements, separated by SEPARATOR, prefixed by PREFIX, and ended
with SUFFIX as with `concat'.  Otherwise, if LIST is empty, return
nil.  If any element in LIST is itself a list, flatten that
element."
  (setq list (typescript--flatten-list list))
  (when list
    (concat prefix (mapconcat #'identity list separator) suffix)))

(defun typescript--update-quick-match-re ()
  "Internal function used by `typescript-mode' for caching buffer constructs.
This updates `typescript--quick-match-re', based on the current set of
enabled frameworks."
  (setq typescript--quick-match-re
        (typescript--maybe-join
         "^[ \t]*\\(?:" "\\|" "\\)"

         ;; #define mumble
         "#define[ \t]+[a-zA-Z_]"

         (when (memq 'exttypescript typescript-enabled-frameworks)
           "Ext\\.extend")

         (when (memq 'prototype typescript-enabled-frameworks)
           "Object\\.extend")

          ;; var mumble = THING (
         (typescript--maybe-join
          "\\(?:var[ \t]+\\)?[a-zA-Z_$0-9.]+[ \t]*=[ \t]*\\(?:"
          "\\|"
          "\\)[ \t]*\("

          (when (memq 'prototype typescript-enabled-frameworks)
                    "Class\\.create")

          (when (memq 'exttypescript typescript-enabled-frameworks)
            "Ext\\.extend")

          (when (memq 'merrillpress typescript-enabled-frameworks)
            "[a-zA-Z_$0-9]+\\.extend\\(?:Final\\)?"))

         (when (memq 'dojo typescript-enabled-frameworks)
           "dojo\\.declare[ \t]*\(")

         (when (memq 'mochikit typescript-enabled-frameworks)
           "MochiKit\\.Base\\.update[ \t]*\(")

         ;; mumble.prototypeTHING
         (typescript--maybe-join
          "[a-zA-Z_$0-9.]+\\.prototype\\(?:" "\\|" "\\)"

          (when (memq 'typescript typescript-enabled-frameworks)
            '( ;; foo.prototype.bar = function(
              "\\.[a-zA-Z_$0-9]+[ \t]*=[ \t]*function[ \t]*\("

              ;; mumble.prototype = {
              "[ \t]*=[ \t]*{")))))

  (setq typescript--quick-match-re-func
        (concat "function\\|" typescript--quick-match-re)))

(defun typescript--forward-text-property (propname)
  "Move over the next value of PROPNAME in the buffer.
If found, return that value and leave point after the character
having that value; otherwise, return nil and leave point at EOB."
  (let ((next-value (get-text-property (point) propname)))
    (if next-value
        (forward-char)

      (goto-char (next-single-property-change
                  (point) propname nil (point-max)))
      (unless (eobp)
        (setq next-value (get-text-property (point) propname))
        (forward-char)))

    next-value))

(defun typescript--backward-text-property (propname)
  "Move over the previous value of PROPNAME in the buffer.
If found, return that value and leave point just before the
character that has that value, otherwise return nil and leave
point at BOB."
    (unless (bobp)
      (let ((prev-value (get-text-property (1- (point)) propname)))
        (if prev-value
            (backward-char)

          (goto-char (previous-single-property-change
                      (point) propname nil (point-min)))

          (unless (bobp)
            (backward-char)
            (setq prev-value (get-text-property (point) propname))))

        prev-value)))

(defsubst typescript--forward-pstate ()
  (typescript--forward-text-property 'typescript--pstate))

(defsubst typescript--backward-pstate ()
  (typescript--backward-text-property 'typescript--pstate))

(defun typescript--pitem-goto-h-end (pitem)
  (goto-char (typescript--pitem-h-begin pitem))
  (typescript--forward-pstate))

(defun typescript--re-search-forward-inner (regexp &optional bound count)
  "Helper function for `typescript--re-search-forward'."
  (let ((parse)
        str-terminator)
    (while (> count 0)
      (re-search-forward regexp bound)
      (setq parse (syntax-ppss))
      (cond ((setq str-terminator (nth 3 parse))
             (when (eq str-terminator t)
               (setq str-terminator ?/))
             (re-search-forward
              (concat "\\([^\\]\\|^\\)" (string str-terminator))
              (save-excursion (end-of-line) (point)) t))
            ((nth 7 parse)
             (forward-line))
            ((or (nth 4 parse)
                 (and (eq (char-before) ?\/) (eq (char-after) ?\*)))
             (re-search-forward "\\*/"))
            (t
             (setq count (1- count))))))
  (point))


(defun typescript--re-search-forward (regexp &optional bound noerror count)
  "Search forward, ignoring strings and comments.
This function invokes `re-search-forward', but treats the buffer
as if strings and comments have been removed."
  (let ((saved-point (point))
        (search-fun
         (cond ((null count)
                (lambda () (typescript--re-search-forward-inner regexp bound 1)))
               ((< count 0)
                (lambda () (typescript--re-search-backward-inner regexp bound (- count))))
               ((> count 0)
                (lambda () (typescript--re-search-forward-inner regexp bound count)))
               (t #'ignore))))
    (condition-case err
        (funcall search-fun)
      (search-failed
       (goto-char saved-point)
       (unless noerror
         (error (error-message-string err)))))))


(defun typescript--re-search-backward-inner (regexp &optional bound count)
  "Auxiliary function for `typescript--re-search-backward'."
  (let ((parse))
    (while (> count 0)
      (re-search-backward regexp bound)
      (when (and (> (point) (point-min))
                 (save-excursion (backward-char) (looking-at "/[/*]")))
        (forward-char))
      (setq parse (syntax-ppss))
      (cond
       ;; If we are in a comment or a string, jump back to the start
       ;; of the comment or string.
       ((nth 8 parse)
        (goto-char (nth 8 parse)))
       ((and (eq (char-before) ?/) (eq (char-after) ?*))
        (re-search-backward "/\\*"))
       (t
        (setq count (1- count))))))
  (point))


(defun typescript--re-search-backward (regexp &optional bound noerror count)
  "Search backward, ignoring strings, and comments.

This function invokes `re-search-backward' but treats the buffer
as if strings and comments have been removed.

IMPORTANT NOTE: searching for \"\\n\" with this function to find
line breaks will generally not work, because the final newline of
a one-line comment is considered to be part of the comment and
will be skipped.  Take the following code:

  let a = 1;
  let b = 2; // Foo
  let c = 3;

If the point is in the last line, searching back for \"\\n\" will
skip over the line with \"let b\". The newline found will be the
one at the end of the line with \"let a\"."
  (let ((saved-point (point))
        (search-fun
         (cond ((null count)
                (lambda () (typescript--re-search-backward-inner regexp bound 1)))
               ((< count 0)
                (lambda () (typescript--re-search-forward-inner regexp bound (- count))))
               ((> count 0)
                (lambda () (typescript--re-search-backward-inner regexp bound count)))
               (t #'ignore))))
    (condition-case err
        (funcall search-fun)
      (search-failed
       (goto-char saved-point)
       (unless noerror
         (error (error-message-string err)))))))

(defun typescript--forward-expression ()
  "Move forward over a whole typescript expression.
This function doesn't move over expressions continued across
lines."
  (cl-loop
   do (progn
        (forward-comment most-positive-fixnum)
        (cl-loop until (or (eolp)
                        (progn
                          (forward-comment most-positive-fixnum)
                          (memq (char-after) '(?\, ?\; ?\] ?\) ?\}))))
                 do (forward-sexp)))
   while (and (eq (char-after) ?\n)
              (save-excursion
                (forward-char)
                (typescript--continued-expression-p)))))

(defun typescript--forward-function-decl ()
  "Move forward over a typescript function declaration.
This puts point at the 'function' keyword.

If this is a syntactically-correct non-expression function,
return the name of the function, or t if the name could not be
determined.  Otherwise, return nil."
  (cl-assert (looking-at "\\_<function\\_>"))
  (let ((name t))
    (forward-word)
    (forward-comment most-positive-fixnum)
    (when (looking-at typescript--name-re)
      (setq name (match-string-no-properties 0))
      (goto-char (match-end 0)))
    (forward-comment most-positive-fixnum)
    (and (eq (char-after) ?\( )
         (ignore-errors (forward-list) t)
         (progn (forward-comment most-positive-fixnum)
                (and (eq (char-after) ?{)
                     name)))))

(defun typescript--function-prologue-beginning (&optional pos)
  "Return the start of the typescript function prologue containing POS.
A function prologue is everything from start of the definition up
to and including the opening brace.  POS defaults to point.
If POS is not in a function prologue, return nil."
  (let (prologue-begin)
    (save-excursion
      (if pos
          (goto-char pos)
        (setq pos (point)))

      (when (save-excursion
              (forward-line 0)
              (or (looking-at typescript--function-heading-2-re)
                  (looking-at typescript--function-heading-3-re)))

        (setq prologue-begin (match-beginning 1))
        (when (<= prologue-begin pos)
          (goto-char (match-end 0))))

      (skip-syntax-backward "w_")
      (and (or (looking-at "\\_<function\\_>")
               (typescript--re-search-backward "\\_<function\\_>" nil t))

           (save-match-data (goto-char (match-beginning 0))
                            (typescript--forward-function-decl))

           (<= pos (point))
           (or prologue-begin (match-beginning 0))))))

(defun typescript--beginning-of-defun-raw ()
  "Helper function for `typescript-beginning-of-defun'.
Go to previous defun-beginning and return the parse state for it,
or nil if we went all the way back to bob and don't find
anything."
  (typescript--ensure-cache)
  (let (pstate)
    (while (and (setq pstate (typescript--backward-pstate))
                (not (eq 'function (typescript--pitem-type (car pstate))))))
    (and (not (bobp)) pstate)))

(defun typescript--pstate-is-toplevel-defun (pstate)
  "Helper function for `typescript--beginning-of-defun-nested'.
If PSTATE represents a non-empty top-level defun, return the
top-most pitem.  Otherwise, return nil."
  (cl-loop for pitem in pstate
        with func-depth = 0
        with func-pitem
        if (eq 'function (typescript--pitem-type pitem))
        do (cl-incf func-depth)
        and do (setq func-pitem pitem)
        finally return (if (eq func-depth 1) func-pitem)))

(defun typescript--beginning-of-defun-nested ()
  "Helper function for `typescript--beginning-of-defun'.
Return the pitem of the function we went to the beginning of."
  (or
   ;; Look for the smallest function that encloses point...
   (cl-loop for pitem in (typescript--parse-state-at-point)
         if (and (eq 'function (typescript--pitem-type pitem))
                 (typescript--inside-pitem-p pitem))
         do (goto-char (typescript--pitem-h-begin pitem))
         and return pitem)

   ;; ...and if that isn't found, look for the previous top-level
   ;; defun
   (cl-loop for pstate = (typescript--backward-pstate)
         while pstate
         if (typescript--pstate-is-toplevel-defun pstate)
         do (goto-char (typescript--pitem-h-begin it))
         and return it)))

(defun typescript--beginning-of-defun-flat ()
  "Helper function for `typescript-beginning-of-defun'."
  (let ((pstate (typescript--beginning-of-defun-raw)))
    (when pstate
      (goto-char (typescript--pitem-h-begin (car pstate))))))

(defun typescript-beginning-of-defun (&optional arg)
  "Value of `beginning-of-defun-function' for `typescript-mode'."
  (setq arg (or arg 1))
  (while (and (not (eobp)) (< arg 0))
    (cl-incf arg)
    (when (and (not typescript-flat-functions)
               (or (eq (typescript-syntactic-context) 'function)
                   (typescript--function-prologue-beginning)))
      (typescript-end-of-defun))

    (if (typescript--re-search-forward
         "\\_<function\\_>" nil t)
        (goto-char (typescript--function-prologue-beginning))
      (goto-char (point-max))))

  (while (> arg 0)
    (cl-decf arg)
    ;; If we're just past the end of a function, the user probably wants
    ;; to go to the beginning of *that* function
    (when (eq (char-before) ?})
      (backward-char))

    (let ((prologue-begin (typescript--function-prologue-beginning)))
      (cond ((and prologue-begin (< prologue-begin (point)))
             (goto-char prologue-begin))

            (typescript-flat-functions
             (typescript--beginning-of-defun-flat))
            (t
             (typescript--beginning-of-defun-nested))))))

(defun typescript--flush-caches (&optional beg ignored)
  "Flush the `typescript-mode' syntax cache after position BEG.
BEG defaults to `point-min', meaning to flush the entire cache."
  (interactive)
  (setq beg (or beg (save-restriction (widen) (point-min))))
  (setq typescript--cache-end (min typescript--cache-end beg)))

(defmacro typescript--debug (&rest arguments)
  ;; `(message ,@arguments)
  )

(defun typescript--ensure-cache--pop-if-ended (open-items paren-depth)
  (let ((top-item (car open-items)))
    (when (<= paren-depth (typescript--pitem-paren-depth top-item))
      (cl-assert (not (get-text-property (1- (point)) 'typescript-pend)))
      (put-text-property (1- (point)) (point) 'typescript--pend top-item)
      (setf (typescript--pitem-b-end top-item) (point))
      (setq open-items
            ;; open-items must contain at least two items for this to
            ;; work, but because we push a dummy item to start with,
            ;; that assumption holds.
            (cons (typescript--pitem-add-child (cl-second open-items) top-item)
                  (cddr open-items)))))
  open-items)

(defmacro typescript--ensure-cache--update-parse ()
  "Helper function for `typescript--ensure-cache'.
Update parsing information up to point, referring to parse,
prev-parse-point, goal-point, and open-items bound lexically in
the body of `typescript--ensure-cache'."
  `(progn
     (setq goal-point (point))
     (goto-char prev-parse-point)
     (while (progn
              (setq open-items (typescript--ensure-cache--pop-if-ended
                                open-items (car parse)))
              ;; Make sure parse-partial-sexp doesn't stop because we *entered*
              ;; the given depth -- i.e., make sure we're deeper than the target
              ;; depth.
              (cl-assert (> (nth 0 parse)
                         (typescript--pitem-paren-depth (car open-items))))
              (setq parse (parse-partial-sexp
                           prev-parse-point goal-point
                           (typescript--pitem-paren-depth (car open-items))
                           nil parse))

;;              (let ((overlay (make-overlay prev-parse-point (point))))
;;                (overlay-put overlay 'face '(:background "red"))
;;                (unwind-protect
;;                     (progn
;;                       (typescript--debug "parsed: %S" parse)
;;                       (sit-for 1))
;;                  (delete-overlay overlay)))

              (setq prev-parse-point (point))
              (< (point) goal-point)))

     (setq open-items (typescript--ensure-cache--pop-if-ended
                       open-items (car parse)))))

(defun typescript--show-cache-at-point ()
  (interactive)
  (require 'pp)
  (let ((prop (get-text-property (point) 'typescript--pstate)))
    (with-output-to-temp-buffer "*Help*"
      (pp prop))))

(defun typescript--split-name (string)
  "Split a typescript name into its dot-separated parts.
This also removes any prototype parts from the split name
\(unless the name is just \"prototype\" to start with)."
  (let ((name (save-match-data
                (split-string string "\\." t))))
    (unless (and (= (length name) 1)
                 (equal (car name) "prototype"))

      (setq name (remove "prototype" name)))))

(defvar typescript--guess-function-name-start nil)

(defun typescript--guess-function-name (position)
  "Guess the name of the typescript function at POSITION.
POSITION should be just after the end of the word \"function\".
Return the name of the function, or nil if the name could not be
guessed.

This function clobbers match data.  If we find the preamble
begins earlier than expected while guessing the function name,
set `typescript--guess-function-name-start' to that position; otherwise,
set that variable to nil."
  (setq typescript--guess-function-name-start nil)
  (save-excursion
    (goto-char position)
    (forward-line 0)
    (cond
     ((looking-at typescript--function-heading-3-re)
      (and (eq (match-end 0) position)
           (setq typescript--guess-function-name-start (match-beginning 1))
           (match-string-no-properties 1)))

     ((looking-at typescript--function-heading-2-re)
      (and (eq (match-end 0) position)
           (setq typescript--guess-function-name-start (match-beginning 1))
           (match-string-no-properties 1))))))

(defun typescript--clear-stale-cache ()
  ;; Clear any endings that occur after point
  (let (end-prop)
    (save-excursion
      (while (setq end-prop (typescript--forward-text-property
                             'typescript--pend))
        (setf (typescript--pitem-b-end end-prop) nil))))

  ;; Remove any cache properties after this point
  (remove-text-properties (point) (point-max)
                          '(typescript--pstate t typescript--pend t)))

(defun typescript--ensure-cache (&optional limit)
  "Ensures brace cache is valid up to the character before LIMIT.
LIMIT defaults to point."
  (setq limit (or limit (point)))
  (when (< typescript--cache-end limit)

    (c-save-buffer-state
        (open-items
         orig-match-start
         orig-match-end
         orig-depth
         parse
         prev-parse-point
         name
         case-fold-search
         filtered-class-styles
         new-item
         goal-point
         end-prop)

      ;; Figure out which class styles we need to look for
      (setq filtered-class-styles
            (cl-loop for style in typescript--class-styles
                  if (memq (plist-get style :framework)
                           typescript-enabled-frameworks)
                  collect style))

      (save-excursion
        (save-restriction
          (widen)

          ;; Find last known good position
          (goto-char typescript--cache-end)
          (unless (bobp)
            (setq open-items (get-text-property
                              (1- (point)) 'typescript--pstate))

            (unless open-items
              (goto-char (previous-single-property-change
                          (point) 'typescript--pstate nil (point-min)))

              (unless (bobp)
                (setq open-items (get-text-property (1- (point))
                                                    'typescript--pstate))
                (cl-assert open-items))))

          (unless open-items
            ;; Make a placeholder for the top-level definition
            (setq open-items (list typescript--initial-pitem)))

          (setq parse (syntax-ppss))
          (setq prev-parse-point (point))

          (typescript--clear-stale-cache)

          (narrow-to-region (point-min) limit)

          (cl-loop while (re-search-forward typescript--quick-match-re-func nil t)
                for orig-match-start = (goto-char (match-beginning 0))
                for orig-match-end = (match-end 0)
                do (typescript--ensure-cache--update-parse)
                for orig-depth = (nth 0 parse)

                ;; Each of these conditions should return non-nil if
                ;; we should add a new item and leave point at the end
                ;; of the new item's header (h-end in the
                ;; typescript--pitem diagram). This point is the one
                ;; after the last character we need to unambiguously
                ;; detect this construct. If one of these evaluates to
                ;; nil, the location of the point is ignored.
                if (cond
                    ;; In comment or string
                    ((nth 8 parse) nil)

                    ;; Regular function declaration
                    ((and (looking-at "\\_<function\\_>")
                          (setq name (typescript--forward-function-decl)))

                     (when (eq name t)
                       (setq name (typescript--guess-function-name orig-match-end))
                       (if name
                           (when typescript--guess-function-name-start
                             (setq orig-match-start
                                   typescript--guess-function-name-start))

                         (setq name t)))

                     (cl-assert (eq (char-after) ?{))
                     (forward-char)
                     (make-typescript--pitem
                      :paren-depth orig-depth
                      :h-begin orig-match-start
                      :type 'function
                      :name (if (eq name t)
                                name
                              (typescript--split-name name))))

                    ;; "Prototype function" declaration
                    ((looking-at typescript--plain-method-re)
                     (goto-char (match-beginning 3))
                     (when (save-match-data
                             (typescript--forward-function-decl))
                       (forward-char)
                       (make-typescript--pitem
                        :paren-depth orig-depth
                        :h-begin orig-match-start
                        :type 'function
                        :name (nconc (typescript--split-name
                                      (match-string-no-properties 1))
                                     (list (match-string-no-properties 2))))))

                    ;; Class definition
                    ((cl-loop with syntactic-context =
                           (typescript--syntactic-context-from-pstate open-items)
                           for class-style in filtered-class-styles
                           if (and (memq syntactic-context
                                         (plist-get class-style :contexts))
                                   (looking-at (plist-get class-style
                                                          :class-decl)))
                           do (goto-char (match-end 0))
                           and return
                           (make-typescript--pitem
                            :paren-depth orig-depth
                            :h-begin orig-match-start
                            :type class-style
                            :name (typescript--split-name
                                   (match-string-no-properties 1))))))

                do (typescript--ensure-cache--update-parse)
                and do (push it open-items)
                and do (put-text-property
                        (1- (point)) (point) 'typescript--pstate open-items)
                else do (goto-char orig-match-end))

          (goto-char limit)
          (typescript--ensure-cache--update-parse)
          (setq typescript--cache-end limit)
          (setq typescript--last-parse-pos limit)
          (setq typescript--state-at-last-parse-pos open-items))))))

(defun typescript--end-of-defun-flat ()
  "Helper function for `typescript-end-of-defun'."
  (cl-loop while (typescript--re-search-forward "}" nil t)
        do (typescript--ensure-cache)
        if (get-text-property (1- (point)) 'typescript--pend)
        if (eq 'function (typescript--pitem-type it))
        return t
        finally do (goto-char (point-max))))

(defun typescript--end-of-defun-nested ()
  "Helper function for `typescript-end-of-defun'."
  (let* (pitem
         (this-end (save-excursion
                     (and (setq pitem (typescript--beginning-of-defun-nested))
                          (typescript--pitem-goto-h-end pitem)
                          (progn (backward-char)
                                 (forward-list)
                                 (point)))))
         found)

    (if (and this-end (< (point) this-end))
        ;; We're already inside a function; just go to its end.
        (goto-char this-end)

      ;; Otherwise, go to the end of the next function...
      (while (and (typescript--re-search-forward "\\_<function\\_>" nil t)
                  (not (setq found (progn
                                     (goto-char (match-beginning 0))
                                     (typescript--forward-function-decl))))))

      (if found (forward-list)
        ;; ... or eob.
        (goto-char (point-max))))))

(defun typescript-end-of-defun (&optional arg)
  "Value of `end-of-defun-function' for `typescript-mode'."
  (setq arg (or arg 1))
  (while (and (not (bobp)) (< arg 0))
    (cl-incf arg)
    (typescript-beginning-of-defun)
    (typescript-beginning-of-defun)
    (unless (bobp)
      (typescript-end-of-defun)))

  (while (> arg 0)
    (cl-decf arg)
    ;; look for function backward. if we're inside it, go to that
    ;; function's end. otherwise, search for the next function's end and
    ;; go there
    (if typescript-flat-functions
        (typescript--end-of-defun-flat)

      ;; if we're doing nested functions, see whether we're in the
      ;; prologue. If we are, go to the end of the function; otherwise,
      ;; call typescript--end-of-defun-nested to do the real work
      (let ((prologue-begin (typescript--function-prologue-beginning)))
        (cond ((and prologue-begin (<= prologue-begin (point)))
               (goto-char prologue-begin)
               (re-search-forward "\\_<function")
               (goto-char (match-beginning 0))
               (typescript--forward-function-decl)
               (forward-list))

              (t (typescript--end-of-defun-nested)))))))

(defun typescript--backward-syntactic-ws (&optional lim)
  "Simple implementation of `c-backward-syntactic-ws' for `typescript-mode'."
  (save-restriction
    (when lim (narrow-to-region lim (point-max)))

    (let ((pos (point)))
      (while (progn (forward-comment most-negative-fixnum)
                    (/= (point)
                        (prog1
                            pos
                          (setq pos (point)))))))))

(defun typescript--forward-syntactic-ws (&optional lim)
  "Simple implementation of `c-forward-syntactic-ws' for `typescript-mode'."
  (save-restriction
    (when lim (narrow-to-region (point-min) lim))
    (let ((pos (point)))
      (while (progn
               (forward-comment most-positive-fixnum)
               (/= (point)
                   (prog1
                       pos
                     (setq pos (point)))))))))

;; Like (up-list -1), but only considers lists that end nearby"
(defun typescript--up-nearby-list ()
  (save-restriction
    ;; Look at a very small region so our computation time doesn't
    ;; explode in pathological cases.
    (narrow-to-region (max (point-min) (- (point) 500)) (point))
    (up-list -1)))

(defun typescript--inside-param-list-p ()
  "Return non-nil iff point is in a function parameter list."
  (ignore-errors
    (save-excursion
      (typescript--up-nearby-list)
      (and (looking-at "(")
           (progn (forward-symbol -1)
                  (or (looking-at "function")
                      (progn (forward-symbol -1)
                             (looking-at "function"))))))))

(defun typescript--inside-dojo-class-list-p ()
  "Return non-nil iff point is in a Dojo multiple-inheritance class block."
  (ignore-errors
    (save-excursion
      (typescript--up-nearby-list)
      (let ((list-begin (point)))
        (forward-line 0)
        (and (looking-at typescript--dojo-class-decl-re)
             (goto-char (match-end 0))
             (looking-at "\"\\s-*,\\s-*\\[")
             (eq (match-end 0) (1+ list-begin)))))))

(defun typescript--syntax-begin-function ()
  (when (< typescript--cache-end (point))
    (goto-char (max (point-min) typescript--cache-end)))

  (let ((pitem))
    (while (and (setq pitem (car (typescript--backward-pstate)))
                (not (eq 0 (typescript--pitem-paren-depth pitem)))))

    (when pitem
      (goto-char (typescript--pitem-h-begin pitem )))))

(defun typescript--move-to-end-of-plain-string ()
  "If the point is in a plain string, move to the end of it.

Otherwise, don't move.  A plain string is a string which is not a
template string.  The point is considered to be \"in\" a string if
it is on the delimiters of the string, or any point inside.

Returns point if the end of the string was found, or nil if the
end of the string was not found."
  (let ((end-position
         (save-excursion
           (let* ((syntax (syntax-ppss))
                  (str-terminator (nth 3 syntax))
                  ;; The 8th element will also be set if we are in a comment. So we
                  ;; check str-terminator to protect against that.
                  (string-start (and str-terminator
                                     (nth 8 syntax))))
             (if (and string-start
                      (not (eq str-terminator ?`)))
                 ;; We may already be at the end of the string.
                 (if (and (eq (char-after) str-terminator)
                          (not (eq (char-before) ?\\)))
                     (point)
                   ;; We just search forward and then check if the hit we get has a
                   ;; string-start equal to ours.
                   (cl-loop while (re-search-forward
                                (concat "\\(?:[^\\]\\|^\\)\\(" (string str-terminator) "\\)")
                                nil t)
                         if (eq string-start
                                (save-excursion (nth 8 (syntax-ppss (match-beginning 1)))))
                         return (match-beginning 1)))
               ;; If we are on the start delimiter then the value of syntax-ppss will look
               ;; like we're not in a string at all, but this function considers the
               ;; start delimiter to be "in" the string. We take care of this here.
               (when (memq (char-after) '(?' ?\"))
                 (forward-char)
                 (typescript--move-to-end-of-plain-string)))))))
    (when end-position
      (goto-char end-position))))

;;; Font Lock
(defun typescript--make-framework-matcher (framework &rest regexps)
  "Helper function for building `typescript--font-lock-keywords'.
Create a byte-compiled function for matching a concatenation of
REGEXPS, but only if FRAMEWORK is in `typescript-enabled-frameworks'."
  (setq regexps (apply #'concat regexps))
  (byte-compile
   `(lambda (limit)
      (when (memq (quote ,framework) typescript-enabled-frameworks)
        (re-search-forward ,regexps limit t)))))

(defvar typescript--tmp-location nil)
(make-variable-buffer-local 'typescript--tmp-location)

(defun typescript--forward-destructuring-spec (&optional func)
  "Move forward over a typescript destructuring spec.
If FUNC is supplied, call it with no arguments before every
variable name in the spec.  Return true iff this was actually a
spec.  FUNC must preserve the match data."
  (cl-case (char-after)
    (?\[
     (forward-char)
     (while
         (progn
           (forward-comment most-positive-fixnum)
           (cond ((memq (char-after) '(?\[ ?\{))
                  (typescript--forward-destructuring-spec func))

                 ((eq (char-after) ?,)
                  (forward-char)
                  t)

                 ((looking-at typescript--name-re)
                  (and func (funcall func))
                  (goto-char (match-end 0))
                  t))))
     (when (eq (char-after) ?\])
       (forward-char)
       t))

    (?\{
     (forward-char)
     (forward-comment most-positive-fixnum)
     (while
         (when (looking-at typescript--objfield-re)
           (goto-char (match-end 0))
           (forward-comment most-positive-fixnum)
           (and (cond ((memq (char-after) '(?\[ ?\{))
                       (typescript--forward-destructuring-spec func))
                      ((looking-at typescript--name-re)
                       (and func (funcall func))
                       (goto-char (match-end 0))
                       t))
                (progn (forward-comment most-positive-fixnum)
                       (when (eq (char-after) ?\,)
                         (forward-char)
                         (forward-comment most-positive-fixnum)
                         t)))))
     (when (eq (char-after) ?\})
       (forward-char)
       t))))

(defun typescript--variable-decl-matcher (limit)
  "Font-lock matcher for variable names in a variable declaration.
This is a cc-mode-style matcher that *always* fails, from the
point of view of font-lock.  It applies highlighting directly with
`font-lock-apply-highlight'."
  (condition-case nil
      (save-restriction
        (narrow-to-region (point-min) limit)

        (let ((first t))
          (forward-comment most-positive-fixnum)
          (while
              (and (or first
                       (when (eq (char-after) ?,)
                         (forward-char)
                         (forward-comment most-positive-fixnum)
                         t))
                   (cond ((looking-at typescript--name-re)
                          (font-lock-apply-highlight
                           '(0 font-lock-variable-name-face))
                          (goto-char (match-end 0)))

                         ((save-excursion
                            (typescript--forward-destructuring-spec))

                          (typescript--forward-destructuring-spec
                           (lambda ()
                             (font-lock-apply-highlight
                              '(0 font-lock-variable-name-face)))))))

            (forward-comment most-positive-fixnum)
            (when (eq (char-after) ?=)
              (forward-char)
              (typescript--forward-expression)
              (forward-comment most-positive-fixnum))

            (setq first nil))))

    ;; Conditions to handle
    (scan-error nil)
    (end-of-buffer nil))

  ;; Matcher always "fails"
  nil)

(defun typescript--function-argument-matcher (limit)
  "Font-lock matcher for variables in argument lists.

Because the syntax of the argument list is shared between
functions, arrow functions and methods, this same matcher is used
for all of them.  The context for the search is set up as
anchored matcher.

This is a cc-mode-style matcher that *always* fails, from the
point of view of font-lock.  It applies highlighting directly
with `font-lock-apply-highlight'."
  (condition-case nil
      (save-restriction
        (widen)
        (narrow-to-region (point-min) limit)
        (while (re-search-forward
                (rx (group
                     (regexp "[a-zA-Z_$]\\(?:\\s_\\|\\sw\\)*")
                     ;; name can be optionally followed by ? to mark
                     ;; the argument optional
                     (? "?"))
                    (* whitespace)
                    (group (or "," ":" ")"
                               ;; last variable in the list with a
                               ;; paren on next line and no hanging
                               ;; comma.  extra logic is added to deal
                               ;; with possible comments after the
                               ;; variable.
                               eol
                               (and (* whitespace) (or "//" "/*") (* any) eol))))
                nil t)
          (font-lock-apply-highlight '(1 font-lock-variable-name-face t))

          ;; If ender is a ":" it means that the currently matched
          ;; variable also has a type signature.
          (let ((ender (match-string 2)))
            ;; We need to skip the type specification.  The regexp
            ;; basically either searches for the next thing which we
            ;; believe is a parameter or the end of the argument list.
            (when (equal ender ":")
              (let ((perform-match t))
                (while (and perform-match
                            (re-search-forward
                             (rx (or
                                  ;; variable without type at the end
                                  ;; of line
                                  (and "," eol)
                                  ;; next thing is a functional
                                  ;; argument, such as f:(x) => void
                                  (and "(")
                                  ;; closing of a function type argument.
                                  ;; here, the type of `f'.
                                  ;; (f: (x: number) => foo): void => { }
                                  (and ")" (? (* whitespace) "=>" (* whitespace)))
                                  (and ","
                                       (* whitespace)
                                       (regexp "[a-zA-Z_$]\\(?:\\s_\\|\\sw\\)*")
                                       ;; optional ? to mark the
                                       ;; argument optional
                                       (? "?")
                                       (group (or ":" ")")))))
                             nil t))
                  ;; In case the skipped type was the end of a
                  ;; function type argument, the next token is the
                  ;; return type of the inner function, so we need to
                  ;; match but not fontify the next "name" (which
                  ;; really is the type).
                  (if (string-match-p "=>" (match-string 0))
                      (setq perform-match t)
                    (goto-char (match-beginning 0))
                    (setq perform-match nil))))))))
    ;; conditions to handle
    (scan-error nil)
    (end-of-buffer nil))
  nil)

(defun typescript--in-documentation-comment-p ()
  "Reports whether point is inside a documentation comment."
  (let ((parse (syntax-ppss)))
    (and
     (nth 4 parse) ;; Inside a comment ...
     (save-match-data
       (save-excursion
         (goto-char (nth 8 parse))
         (looking-at "/\\*\\*")))))) ;; ... which starts with /**

(defun typescript--documentation-font-lock-helper (re limit)
  "This is a helper macro that determines whether jsdoc highlighting is to be applied,
and searches for the next token to be highlighted."
  (cl-loop while (re-search-forward re limit t)
        if (typescript--in-documentation-comment-p)
        return (point)))

(defun typescript--jsdoc-param-matcher (limit)
  "Font-lock mode matcher that finds jsdoc parameter tags in documentation."
  (typescript--documentation-font-lock-helper typescript-jsdoc-param-tag-regexp limit))

(defun typescript--jsdoc-typed-tag-matcher (limit)
  "Font-lock mode matcher that finds jsdoc typed tags in documentation."
  (typescript--documentation-font-lock-helper typescript-jsdoc-typed-tag-regexp limit))

(defun typescript--jsdoc-arg-tag-matcher (limit)
  "Font-lock mode matcher that finds jsdoc tags that take one argument in documentation."
  (typescript--documentation-font-lock-helper typescript-jsdoc-arg-tag-regexp limit))

(defun typescript--jsdoc-empty-tag-matcher (limit)
  "Font-lock mode matcher that finds jsdoc tags without argument in documentation."
  (typescript--documentation-font-lock-helper typescript-jsdoc-empty-tag-regexp limit))

(defun typescript--typedoc-link-matcher (limit)
  "Font-lock mode matcher that finds typedoc links in documentation."
  (typescript--documentation-font-lock-helper typescript-typedoc-link-tag-regexp limit))

(defun typescript--typedoc-literal-markup-matcher (limit)
  "Font-lock mode matcher that finds typedoc literal markup in documentation."
  (typescript--documentation-font-lock-helper typescript-typedoc-literal-markup-regexp limit))

(defun typescript--tslint-flag-matcher (limit)
  "Font-lock mode matcher that finds tslint flags in comments."
  (cl-loop while (re-search-forward typescript-tslint-flag-regexp limit t)
        if (nth 4 (syntax-ppss (match-beginning 1)))
        return (point)))

(defconst typescript--font-lock-keywords-3
  `(
    ,@typescript--font-lock-keywords-2

    ;; Remove the fontification of keywords and built-ins when they
    ;; are keys in an interface, object or class.
    (,(rx "{")
     (,(concat "\\(" typescript--keyword-re "\\):")
      (save-excursion (ignore-errors (up-list)) (point))
      nil
      (1 'default t t)))

    (typescript--jsdoc-param-matcher (1 'typescript-jsdoc-tag t t)
                                     (2 'typescript-jsdoc-type t t)
                                     (3 'typescript-jsdoc-value t t))

    (typescript--jsdoc-typed-tag-matcher (1 'typescript-jsdoc-tag t t)
                                         (2 'typescript-jsdoc-type t t))

    (typescript--jsdoc-arg-tag-matcher (1 'typescript-jsdoc-tag t t)
                                       (2 'typescript-jsdoc-value t t))

    (typescript--jsdoc-empty-tag-matcher (1 'typescript-jsdoc-tag t t))

    (typescript--typedoc-link-matcher (0 'typescript-jsdoc-value t))

    (typescript--typedoc-literal-markup-matcher
     (0 'typescript-jsdoc-value t))

    (typescript--tslint-flag-matcher
     (1 'font-lock-preprocessor-face t))

    ("\\.\\(prototype\\)\\_>"
     (1 'font-lock-constant-face))

    (,(rx symbol-start "class" (+ space) (group (+ (or (syntax word) (syntax symbol)))))
     (1 'font-lock-type-face))

    (,(rx symbol-start "extends" (+ space) (group (+ (or (syntax word) (syntax symbol)))))
     (1 'font-lock-type-face))

    (,(rx symbol-start "implements" (+ space))
     (,(rx symbol-start (+ (syntax word))) nil nil (0 'font-lock-type-face)))

    (,(rx symbol-start "interface" (+ space) (group (+ (or (syntax word) (syntax symbol)))))
     (1 'font-lock-type-face))

    (,(rx symbol-start "type" (+ space) (group (+ (or (syntax word) (syntax symbol)))))
     (1 'font-lock-type-face))

    (,(rx symbol-start "enum" (+ space) (group (+ (or (syntax word) (syntax symbol)))))
     (1 'font-lock-type-face))

    ;; Highlights class being declared, in parts
    (typescript--class-decl-matcher
     ,(concat "\\(" typescript--name-re "\\)\\(?:\\.\\|.*$\\)")
     (goto-char (match-beginning 1))
     nil
     (1 'font-lock-type-face))

    ;; Highlights parent class, in parts, if available
    (typescript--class-decl-matcher
     ,(concat "\\(" typescript--name-re "\\)\\(?:\\.\\|.*$\\)")
     (if (match-beginning 2)
         (progn
           (setq typescript--tmp-location (match-end 2))
           (goto-char typescript--tmp-location)
           (insert "=")
           (goto-char (match-beginning 2)))
       (setq typescript--tmp-location nil)
       (goto-char (point-at-eol)))
     (when typescript--tmp-location
       (save-excursion
         (goto-char typescript--tmp-location)
         (delete-char 1)))
     (1 'font-lock-type-face))

    ;; Highlights parent class
    (typescript--class-decl-matcher
     (2 'font-lock-type-face nil t))

    ;; Dojo needs its own matcher to override the string highlighting
    (,(typescript--make-framework-matcher
       'dojo
       "^\\s-*dojo\\.declare\\s-*(\""
       "\\(" typescript--dotted-name-re "\\)"
       "\\(?:\"\\s-*,\\s-*\\(" typescript--dotted-name-re "\\)\\)?")
     (1 'font-lock-type-face t)
     (2 'font-lock-type-face nil t))

    ;; Match Dojo base classes. Of course Mojo has to be different
    ;; from everything else under the sun...
    (,(typescript--make-framework-matcher
       'dojo
       "^\\s-*dojo\\.declare\\s-*(\""
       "\\(" typescript--dotted-name-re "\\)\"\\s-*,\\s-*\\[")
     ,(concat "[[,]\\s-*\\(" typescript--dotted-name-re "\\)\\s-*"
              "\\(?:\\].*$\\)?")
     (backward-char)
     (end-of-line)
     (1 'font-lock-type-face))

    ;; continued Dojo base-class list
    (,(typescript--make-framework-matcher
       'dojo
       "^\\s-*" typescript--dotted-name-re "\\s-*[],]")
     ,(concat "\\(" typescript--dotted-name-re "\\)"
              "\\s-*\\(?:\\].*$\\)?")
     (if (save-excursion (backward-char)
                         (typescript--inside-dojo-class-list-p))
         (forward-symbol -1)
       (end-of-line))
     (end-of-line)
     (1 'font-lock-type-face))

    ;; variable declarations
    ,(list
      (concat "\\_<\\(const\\|var\\|let\\)\\_>\\|" typescript--basic-type-re)
      (list #'typescript--variable-decl-matcher nil nil nil))

    ;; class instantiation
    (,(concat "\\_<new\\_>\\s-+\\(" typescript--dotted-name-re "\\)")
     (1 'font-lock-type-face))

    ;; instanceof
    (,(concat "\\_<instanceof\\_>\\s-+\\(" typescript--dotted-name-re "\\)")
     (1 'font-lock-type-face))

    ;; formal parameters in "function" function call
    ;; function helloWorld(a: number, b: Promise<number>): void { }
    ,(list
      (concat
       "\\_<function\\_>\\(\\s-+" typescript--name-re "\\)?\\s-*\\(<.*>\\)?\\s-*(\\s-*"
       "\\(?:$\\|" typescript--name-start-re "\\)")
      `(typescript--function-argument-matcher
        (prog1 (save-excursion (ignore-errors (up-list)) (point))
          (backward-char))
        nil
        nil))

    ;; formal parameters in arrow function
    ;; const helloWorld = (a: number, b: Promise<number>): void => { }
    ,(list
      (rx (group "=>") (* whitespace) (? eol) (* whitespace) "{")
      '(1 font-lock-keyword-face)
      `(typescript--function-argument-matcher
        (prog1 (progn
                 (backward-char)
                 (typescript--backward-to-parameter-list)
                 (point))
          (backward-sexp))
        (re-search-forward "{" nil t)
        nil))

    ;; formal parameters in method definitions
    ;; class Foo { helloWorld(a: number, b: Promise<number>): void { } }
    ,(list
      typescript--function-call-re
      `(typescript--function-argument-matcher
        (let ((point-orig (point))
              (is-method-def
               (ignore-errors
                 (up-list)
                 (and
                  (or
                   ;; After the "argument list" is a bracket, this is
                   ;; either a special form (if, while...) or a method
                   ;; declaration.
                   (looking-at-p (rx (* (or whitespace ?\n)) "{"))
                   ;; After the "argument list" is a colon, this is
                   ;; either a method declaration with a return type
                   ;; annotation or ternary form.  We need to discard
                   ;; the ternary form case.
                   (and
                    (looking-at-p (rx (* (or whitespace ?\n)) ":"))
                    (save-excursion
                      (backward-sexp 2)
                      (skip-syntax-backward " >")
                      (not (eq (char-before) ??)))))
                  ;; HACK: here we check the fontification of
                  ;; the "function name".  Because the keywords
                  ;; are fontified before this check runs, a
                  ;; keyword would already have been fontified
                  ;; and therefore we can conclude it is not a
                  ;; function/method definition.
                  (save-excursion
                    (backward-sexp)
                    (backward-word)
                    (not (memq
                          'font-lock-keyword-face
                          (face-at-point nil t))))))))
          (if is-method-def
              (prog1 (point) (goto-char point-orig))
            (point)))
        nil
        nil)))
  "Level three font lock for `typescript-mode'.")

(defun typescript--flyspell-mode-predicate ()
  "A custom predicate to help `flyspell-prog-mode' determine whether a word should be checked."
  ;; We depend on fontification for our results. font-lock-ensure is defined on
  ;; Emacs 25 and over. Earlier versions use font-lock-fontify-buffer.
  (if (fboundp 'font-lock-ensure)
      (font-lock-ensure)
    (font-lock-fontify-buffer))
  (and
   ;; Check with the default method that flyspell provides.
   (flyspell-generic-progmode-verify)

   ;;
   ;; And eliminate cases specific to our mode we don't want to have
   ;; spell-checked.
   ;;

   ;; Don't check the module names in import statements.
   (save-excursion
     (not (let* ((parse (syntax-ppss (1- (point))))
                 (string-start-pos (and (nth 3 parse)
                                        (nth 8 parse))))
            (and string-start-pos
                 (save-match-data
                   ;; Move to back to the start of the string, then past any ws
                   ;; and then past any non-ws to see if we have "from" or "import".
                   (goto-char string-start-pos)
                   (typescript--backward-syntactic-ws)
                   (skip-syntax-backward "^-" (point-at-bol))
                   (looking-at "from\\|import\\s-"))))))))

(defun typescript--inside-pitem-p (pitem)
  "Return whether point is inside the given pitem's header or body."
  (typescript--ensure-cache)
  (cl-assert (typescript--pitem-h-begin pitem))
  (cl-assert (typescript--pitem-paren-depth pitem))

  (and (> (point) (typescript--pitem-h-begin pitem))
       (or (null (typescript--pitem-b-end pitem))
           (> (typescript--pitem-b-end pitem) (point)))))

(defun typescript--parse-state-at-point ()
  "Parse the typescript program state at point.
Return a list of `typescript--pitem' instances that apply to point, most
specific first.  In the worst case, the current toplevel instance
will be returned."
  (save-excursion
    (save-restriction
      (widen)
      (typescript--ensure-cache)
      (let* ((bound (if (eobp) (point) (1+ (point))))
             (pstate (or (save-excursion
                           (typescript--backward-pstate))
                         (list typescript--initial-pitem))))

        ;; Loop until we either hit a pitem at BOB or pitem ends after
        ;; point (or at point if we're at eob)
        (cl-loop for pitem = (car pstate)
              until (or (eq (typescript--pitem-type pitem)
                            'toplevel)
                        (typescript--inside-pitem-p pitem))
              do (pop pstate))

        pstate))))

(defun typescript--syntactic-context-from-pstate (pstate)
  "Return the typescript syntactic context corresponding to PSTATE."
  (let ((type (typescript--pitem-type (car pstate))))
    (cond ((memq type '(function macro))
           type)
          ((consp type)
           'class)
          (t 'toplevel))))

(defun typescript-syntactic-context ()
  "Return the typescript syntactic context at point.
When called interactively, also display a message with that
context."
  (interactive)
  (let* ((syntactic-context (typescript--syntactic-context-from-pstate
                             (typescript--parse-state-at-point))))

    (when (called-interactively-p 'interactive)
      (message "Syntactic context: %s" syntactic-context))

   syntactic-context))

(defun typescript--class-decl-matcher (limit)
  "Font lock function used by `typescript-mode'.
This performs fontification according to `typescript--class-styles'."
  (cl-loop initially (typescript--ensure-cache limit)
        while (re-search-forward typescript--quick-match-re limit t)
        for orig-end = (match-end 0)
        do (goto-char (match-beginning 0))
        if (cl-loop for style in typescript--class-styles
                 for decl-re = (plist-get style :class-decl)
                 if (and (memq (plist-get style :framework)
                               typescript-enabled-frameworks)
                         (memq (typescript-syntactic-context)
                               (plist-get style :contexts))
                         decl-re
                         (looking-at decl-re))
                 do (goto-char (match-end 0))
                 and return t)
        return t
        else do (goto-char orig-end)))

(defun typescript--match-subst-in-quotes (limit)
  "Match dollar substitutions inside backticks."
  (catch 'done
    (while (re-search-forward
            ;; `rx' is cool, mkay.
            (rx (or line-start (not (any "\\")))
                (group "${")
                (group (+? nonl))
                (group "}"))
            limit t)
      (let ((string-delim (nth 3 (syntax-ppss))))
        (when (and string-delim (= string-delim 96))
          (throw 'done (point)))))))

(defconst typescript--font-lock-keywords-4
  `(
    ;; highlights that override previous levels
    ;;

    ;; special highlight for `this' keyword
    ("\\(this\\)\\."
     (1 'typescript-this-face))

    (,typescript--access-modifier-re (1 'typescript-access-modifier-face))
    (,typescript--basic-type-re (1 'typescript-primitive-face))

    ;; generics support
    ,(list
      (concat typescript--name-re "\\s-*" "<\\s-*" typescript--name-start-re)
      (list (concat "\\(" typescript--name-re "\\)\\(\\s-*>[^<]*\\)?")
            '(backward-char)
            '(end-of-line)
            '(1 font-lock-type-face)))

    ;; type-highlighting in variable/parameter declarations
    ;; supports a small variety of common declarations:
    ;; - let a: SomeType;
    ;; - private b: SomeType;
    ;; - private someFunc(var: SomeType) {
    ;; - private array: SomeType[]
    ;; - private generic: SomeType<Foo>
    ;; - private genericArray: SomeType<Foo>[]
    ;; - function testFunc(): SomeType<> {
    ;; - function testFunc(a): a is SomeType<> {
    ;; - () => SomeType
    ;; TODO: namespaced classes!
    ,(list
      (concat "\\(?::\\|=>\\)\\s-\\(?:\\s-*\\(" typescript--name-re "\\)\\s-*\\(is\\)\\s-*\\)?" "\\(" typescript--type-name-re "\\)\\(<" typescript--type-name-re ">\\)?\\(\\[\\]\\)?\\([,;]\\)?\\s-*{?")
      '(1 'font-lock-variable-name-face nil t)
      '(2 'font-lock-keyword-face nil t)
      '(3 'font-lock-type-face))

    ;; type-casts
    ,(list
      (concat "<\\(" typescript--type-name-re "\\)>")
      '(1 'font-lock-type-face))

    ;; highlights that append to previous levels
    ;;
    ,@typescript--font-lock-keywords-3

    (,typescript--decorator-re (1 'font-lock-function-call-face))
    (,typescript--function-call-re (1 (typescript--function-face)))
    (,(concat "\\(?:\\.\\s-*\\)" typescript--function-call-re)
     (1 'font-lock-function-call-face t))
    (,typescript--builtin-re (1 'font-lock-type-face))

    ;; arrow function
    ("\\(=>\\)"
     (1 'font-lock-keyword-face))

    (typescript--match-subst-in-quotes
     (1 'font-lock-keyword-face t)
     (2 'default t)
     (3 'font-lock-keyword-face t)))
  "Level four font lock for `typescript-mode'.")

(defun typescript--function-face ()
  "Return the face to use depending if it's a definition or a call.
Point is assumed to be right after the open paren."
  (save-excursion
    (forward-char -1)
    (if (condition-case nil
            (progn
              (forward-sexp 1)
              (forward-comment (point-max))
              (memq (char-after) '(?: ?\{)))
          (scan-error nil))
        ;; Looks like a declaration/definition.
        'font-lock-function-name-face
      ;; Probably just a call.
      'font-lock-function-call-face)))

(defconst typescript--font-lock-keywords
  '(typescript--font-lock-keywords-4 typescript--font-lock-keywords-1
                                   typescript--font-lock-keywords-2
                                   typescript--font-lock-keywords-3
                                   typescript--font-lock-keywords-4)
  "Font lock keywords for `typescript-mode'.  See `font-lock-keywords'.")

;;; Propertize

;;
;; The propertize code was adapted from:
;; https://github.com/emacs-mirror/emacs/blob/489d6466372f488adc53897435fff290394b62f7/lisp/progmodes/js.el
;;

(defconst typescript--syntax-propertize-regexp-regexp
  (rx
   ;; Start of regexp.
   "/"
   (0+ (or
        ;; Match characters outside of a character class.
        (not (any ?\[ ?/ ?\\))
        ;; Match backslash quoted characters.
        (and "\\" not-newline)
        ;; Match character class.
        (and
         "["
         (0+ (or
              (not (any ?\] ?\\))
              (and "\\" not-newline)))
         "]")))
   (group (zero-or-one "/")))
  "Regular expression matching a JavaScript regexp literal.")

(defun typescript-syntax-propertize-regexp (end)
  (let ((ppss (syntax-ppss)))
    (when (eq (nth 3 ppss) ?/)
      ;; A /.../ regexp.
      (goto-char (nth 8 ppss))
      (when (looking-at typescript--syntax-propertize-regexp-regexp)
        ;; Don't touch text after END.
        (when (> end (match-end 1))
          (setq end (match-end 1)))
        (put-text-property (match-beginning 1) end
                           'syntax-table (string-to-syntax "\"/"))
        (goto-char end)))))

(defun typescript-syntax-propertize (start end)
  ;; JavaScript allows immediate regular expression objects, written /.../.
  (funcall
   (syntax-propertize-rules
    ;; Distinguish /-division from /-regexp chars (and from /-comment-starter).
    ;; FIXME: Allow regexps after infix ops like + ...
    ;; https://developer.mozilla.org/en/JavaScript/Reference/Operators
    ;; We can probably just add +, -, <, >, %, ^, ~, ?, : at which
    ;; point I think only * and / would be missing which could also be added,
    ;; but need care to avoid affecting the // and */ comment markers.
    ("\\(?:^\\|[=([{,:;|&!]\\|\\_<return\\_>\\)\\(?:[ \t]\\)*\\(/\\)[^/*]"
     (1 (ignore
     (forward-char -1)
         (when (or (not (memq (char-after (match-beginning 0)) '(?\s ?\t)))
                   ;; If the / is at the beginning of line, we have to check
                   ;; the end of the previous text.
                   (save-excursion
                     (goto-char (match-beginning 0))
                     (forward-comment (- (point)))
                     (memq (char-before)
                           (eval-when-compile (append "=({[,:;" '(nil))))))
           (put-text-property (match-beginning 1) (match-end 1)
                              'syntax-table (string-to-syntax "\"/"))
           (typescript-syntax-propertize-regexp end)))))
    ;; Hash-bang at beginning of buffer.
    ("\\`\\(#\\)!" (1 "< b")))
   start end))

;;; Indentation

(defconst typescript--possibly-braceless-keyword-re
  (typescript--regexp-opt-symbol
   '("catch" "do" "else" "finally" "for" "if" "try" "while" "with"))
  "Regexp matching keywords optionally followed by an opening brace.")

(defconst typescript--indent-keyword-re
  (typescript--regexp-opt-symbol '("in" "instanceof"))
  "Regexp matching keywords that affect indentation of continued expressions.")

(defconst typescript--indent-operator-re
  (concat "[-+*/%<>=&^|?:.]\\([^-+*/]\\|$\\)\\|" typescript--indent-keyword-re)
  "Regexp matching operators that affect indentation of continued expressions.")

;;
;; We purposely do not allow the plus symbol as a prefix here, as this
;; regex is used to check number literal in type annotations, and TS
;; does not allow to use a plus symbol to prefix numbers there: you
;; can use 1, but not +1 in a type annotation.
;;
;; This is meant to match NaN, floats, decimals, the two infinities
;; and numbers recorded in binary, octal and hex.
;;
;; This regular expression was derived from:
;; https://stackoverflow.com/a/30987109/
;;
(defconst typescript--number-literal-re
  "\\(?:NaN\\|-?\\(?:0[Bb][01]+\\|0[Oo][0-7]+\\|0[Xx][0-9a-fA-F]+\\|Infinity\\|\\(?:[[:digit:]]*\\.[[:digit:]]+\\|[[:digit:]]+\\)\\(?:[Ee][+-]?[[:digit:]]+\\)?\\)\\)"
  "Regexp that matches number literals.")

(defconst typescript--reserved-start-keywords
  '("const" "export" "function" "let" "var")
  "These keywords cannot be variable or type names and start a new sentence.
Note that the \"import\" keyword can be a type import since TS2.9, so it might
not start a sentence!")

(defconst typescript--reserved-start-keywords-re
  (typescript--regexp-opt-symbol '("const" "export" "function" "let" "var"))
  "A regular expression matching `typescript--reserved-start-keywords'.")

(defconst typescript--type-vs-ternary-re
  (concat "[?]\\|" (typescript--regexp-opt-symbol
                    (append typescript--reserved-start-keywords
                            '("as" "class" "interface" "private" "public" "readonly"))))
  "Keywords/Symbols that help tell apart colon for types vs ternary operators.")

(defun typescript--search-backward-matching-angle-bracket-inner (depth)
  "Auxiliary function for `typescript--search-backward-matching-angle-bracket'.
DEPTH indicates how nested we think we are: it increases when we cross closing
brackets, and decreases when we cross opening brackets."
  ;; We look backwards for a "<" that would correspond to the ">" we started
  ;; from.  However, there is no guarantee that it exists, since our ">" could
  ;; be a greater-than operation.  Some symbols will make it clear that we are
  ;; *not* in a type annotation, so we can return nil.  Otherwise, we keep
  ;; looking for the matching one.
  (or (<= depth 0)
      (and
       ;; If we cross over a reserved start keyword, we abandon hope of finding
       ;; a matching angle bracket.  This prevents extreme recursion depths.
       (typescript--re-search-backward (concat "[<>]\\|" typescript--reserved-start-keywords-re) nil t)
       (cl-case (char-after)
         (?< (typescript--search-backward-matching-angle-bracket-inner (- depth 1)))
         (?> (typescript--search-backward-matching-angle-bracket-inner (+ depth 1)))))))

(defun typescript--search-backward-matching-angle-bracket ()
  "Search for matching \"<\" preceding a starting \">\".
DEPTH indicates how nested we think we are.  Assumes the starting position is
right before the closing \">\".  Returns nil when a match was not found,
otherwise returns t and the current position is right before the matching
\"<\"."
  (typescript--search-backward-matching-angle-bracket-inner 1))

(defun typescript--re-search-backward-ignoring-angle-brackets ()
  "Search backwards, jumping over text within angle brackets.
Searches specifically for any of \"=\", \"}\", and \"type\"."
  (and
   (typescript--re-search-backward "[>=}]\\|\\_<type\\_>" nil t)
   (or (not (looking-at ">"))
       (and
        (typescript--search-backward-matching-angle-bracket)
        (typescript--re-search-backward-ignoring-angle-brackets)))))

(defun typescript--looking-at-operator-p ()
  "Return non-nil if point is on a typescript operator, other than a comma."
  (save-match-data
    (and (looking-at typescript--indent-operator-re)
         (or (not (looking-at ":"))
             (save-excursion
               (backward-sexp)
               (and
                (typescript--re-search-backward "[?:{]\\|\\_<case\\_>" nil t)
                (looking-at "?"))))
         ;; Do not identify forward slashes appearing in a "list" as
         ;; an operator. The lists are: arrays, or lists of
         ;; arguments. In this context, they must be part of regular
         ;; expressions, and not math operators.
         (not (and (looking-at "/")
                   (save-excursion
                     (typescript--backward-syntactic-ws)
                     (memq (char-before) '(?, ?\[ ?\()))))
         ;; Do not identify methods, or fields, that are named "in" or
         ;; "instanceof" as being operator keywords.
         (not (and
               (looking-at typescript--indent-keyword-re)
               (save-excursion
                 (typescript--backward-syntactic-ws)
                 (memq (char-before) '(?, ?{ ?} ?\;)))))
         ;; Do not identify the symbol > if it is likely part of a type argument
         ;; T<A>, but identify it if it is likely a greater-than symbol. This is
         ;; a hard problem in the absence of semicolons, see:
         ;; https://github.com/ananthakumaran/typescript.el/issues/81
         (not (and
               (looking-at ">")
               (save-excursion
                 (and
                  (typescript--search-backward-matching-angle-bracket)
                  ;; If we made it here, we found a candidate matching opening
                  ;; angle bracket. We still need to guess whether it actually
                  ;; is one, and not a spurious less-than operator!

                  ;; Look backwards for the first of:
                  ;; - one of the symbols: = :
                  ;; - or a TypeScript keyword
                  ;; Depending on what comes first, we can make an educated
                  ;; guess on the nature of our ">" of interest.
                  (typescript--re-search-backward (concat "[=:]\\|" typescript--keyword-re) nil t)
                  (or
                   ;; If the previous keyword is "as", definitely a type.
                   (looking-at "\\_<as\\_>")
                   ;; Same goes for type imports.
                   (looking-at "\\_<import\\_>")
                   ;; A colon could be either a type symbol, or a ternary
                   ;; operator, try to guess which.
                   (and (looking-at ":")
                        (typescript--re-search-backward typescript--type-vs-ternary-re nil t)
                        (not (looking-at "?")))
                   ;; This final check lets us distinguish between a
                   ;; 2-argument type "t < a , b > ..." and a use of the ","
                   ;; operator between two comparisons "t < a , b > ...".
                   ;; Looking back a little more lets us guess.
                   (and (looking-at "=")
                        (typescript--re-search-backward-ignoring-angle-brackets)
                        (looking-at "\\_<type\\_>")))))))
         (not (and
               (looking-at "*")
               ;; Generator method (possibly using computed property).
               (looking-at (concat "\\* *\\(?:\\[\\|" typescript--name-re
                                   " *(\\)"))
               (save-excursion
                 (typescript--backward-syntactic-ws)
                 ;; We might misindent some expressions that would
                 ;; return NaN anyway.  Shouldn't be a problem.
                 (memq (char-before) '(?, ?} ?{ ?\;))))))))


(defun typescript--continued-expression-p ()
  "Return non-nil if the current line continues an expression."
  (save-excursion
    (back-to-indentation)
    (let ((list-start (nth 1 (syntax-ppss))))
      (and
       ;; This not clause is there to eliminate degenerate cases where we have
       ;; something that looks like a continued expression but we are in fact at
       ;; the beginning of the expression. Example: in `if (a) { .q(1)` when the
       ;; point is on the dot, the expression that follows looks like a member
       ;; expression but the object on which it is a member is missing. If we
       ;; naively treat this as a continued expression, we run into trouble
       ;; later. (An infinite loop.)
       (not (and list-start
                 (save-excursion
                   (typescript--backward-syntactic-ws)
                   (backward-char)
                   (eq (point) list-start))))
       ;; Don't identify the spread syntax or rest operator as a "continuation".
       (not (looking-at "\\.\\.\\."))
       (or (typescript--looking-at-operator-p)
           (and (progn
                  (typescript--backward-syntactic-ws)
                  (or (bobp) (backward-char))
                  (and (> (point) (point-min))
                       (save-excursion (backward-char) (not (looking-at "[/*]/")))
                       (typescript--looking-at-operator-p)
                       (and (progn (backward-char)
                                   (not (looking-at "++\\|--\\|/[/*]"))))))))))))

(cl-defun typescript--compute-member-expression-indent ()
  "Determine the indent of a member expression.

This function must be called with point located at the dot that
starts the member expression.
"
  ;; Find the line that has the object from which we are getting thismember.
  ;; And set an indent relative to that.
  (while (looking-at "\\.")
    (typescript--backward-syntactic-ws)
    (while (eq (char-before) ?\;)
      (backward-char))
    (when (memq (char-before) '(?\? ?\!))
      (backward-char))
    (while (memq (char-before) '(?\] ?} ?\) ?>))
      (if (not (eq (char-before) ?>))
          (backward-list)
        (backward-char)
        (typescript--backward-over-generic-parameter-list))
      (typescript--backward-syntactic-ws))
    (if (looking-back typescript--dotted-name-re nil)
        (back-to-indentation)
      (typescript--forward-syntactic-ws)))
  (+ (current-column) typescript-indent-level))

(defun typescript--end-of-do-while-loop-p ()
  "Return non-nil if point is on the \"while\" of a do-while statement.
Otherwise, return nil.  A braceless do-while statement spanning
several lines requires that the start of the loop is indented to
the same column as the current line."
  (interactive)
  (save-excursion
    (save-match-data
      (when (looking-at "\\s-*\\_<while\\_>")
    (if (save-excursion
          (skip-chars-backward "[ \t\n]*}")
          (looking-at "[ \t\n]*}"))
        (save-excursion
          (backward-list) (forward-symbol -1) (looking-at "\\_<do\\_>"))
      (typescript--re-search-backward "\\_<do\\_>" (point-at-bol) t)
      (or (looking-at "\\_<do\\_>")
          (let ((saved-indent (current-indentation)))
        (while (and (typescript--re-search-backward "^\\s-*\\_<" nil t)
                (/= (current-indentation) saved-indent)))
        (and (looking-at "\\s-*\\_<do\\_>")
             (not (typescript--re-search-forward
               "\\_<while\\_>" (point-at-eol) t))
             (= (current-indentation) saved-indent)))))))))


(defun typescript--ctrl-statement-indentation ()
  "Helper function for `typescript--proper-indentation'.
Return the proper indentation of the current line if it starts
the body of a control statement without braces; otherwise, return
nil."
  (save-excursion
    (back-to-indentation)
    (when (save-excursion
            (and (not (eq (point-at-bol) (point-min)))
                 (not (looking-at "[{]"))
                 (progn
                   (typescript--re-search-backward "[[:graph:]]" nil t)
                   (or (eobp) (forward-char))
                   (when (= (char-before) ?\)) (backward-list))
                   (skip-syntax-backward " ")
                   (skip-syntax-backward "w_")
                   (and
                    (looking-at typescript--possibly-braceless-keyword-re)
                    ;; If preceded by period, it's a method call.
                    (not (= (char-before) ?.))))
                 (not (typescript--end-of-do-while-loop-p))))
      (save-excursion
        (goto-char (match-beginning 0))
        (+ (current-indentation) typescript-indent-level)))))

(defun typescript--get-c-offset (symbol anchor)
  (let ((c-offsets-alist
         (list (cons 'c typescript-comment-lineup-func))))
    (c-get-syntactic-indentation (list (cons symbol anchor)))))

(defun typescript--backward-over-generic-parameter-list ()
  "Search backward for the start of a generic's parameter list and move to it.

This is a utility function for
`typescript--backward-to-parameter-list'.

This function must be called with the point placed on the final >
of the generic's parameter list.  It will scan backwards to find
the start.  If successful, it will move the point to the start of
the list.  If not, it does not move the point.

Returns nil on failure, or the position to which the point was
moved on success."
  (when (eq (char-after) ?>)
    (let ((depth 1))
      (cl-loop named search-loop
            while (> depth 0)
            do (progn
                 (unless (re-search-backward "[<>]" nil t)
                   (cl-return-from search-loop nil))
                 (cond
                  ((looking-at ">")
                   (unless (eq (char-before) ?=)
                     (setq depth (1+ depth))))
                  ((looking-at "<") (setq depth (1- depth)))))
            finally return (point)))))

(defun typescript--backward-to-parameter-list ()
  "Search backward for the end of a parameter list and move to it.

This is a utility function for `typescript--proper-indentation'.

This function must be called with the point placed before an
opening curly brace.  It will try to skip over the type
annotation that would mark the return value of a function and
move to the end of the parameter list.  If it is unsuccessful, it
does not move the point. \"Unsuccessful\" here also means that
the position at which we started did not in fact mark the
beginning of a function. The curly brace belonged to some other
syntactic construct than a function.

Returns nil on failure, or the position to which the point was
moved on success."
  (let ((location
         (or
          ;; This handles the case of a function with return type annotation.
          (save-excursion
            (cl-loop named search-loop
                  do
                  (typescript--backward-syntactic-ws)
                  ;; Check whether we are at "):".
                  (when (and (eq (char-before) ?\:)
                             (progn
                               (backward-char)
                               (skip-syntax-backward " ")
                               (eq (char-before) ?\))))
                    ;; Success! This the end of the parameter list.
                    (cl-return-from search-loop (point)))
                  ;; If we recognize a structure that belongs in a return type annotation,
                  ;; skip back over it, or fail.
                  (cond
                   ;; Arrow of a function definition, or typeguard (eg. foo is SomeClass)
                   ((looking-back "=>\\|is" (- (point) 2))
                    (backward-char 2))
                   ;; End of the parameters list of a generic.
                   ((eq (char-before) ?>)
                    (backward-char)
                    (typescript--backward-over-generic-parameter-list))
                   ;; Union of types, or a dot in a dotted name.
                   ((memq (char-before) '(?| ?.))
                    (backward-char))
                   ((or
                     ;; End-delimiter of a delimited construct, for constructs
                     ;; not handled above.
                     (memq (char-before) '(?\) ?} ?\" ?\]))
                     ;; This is also dealing with dotted names. This may come
                     ;; into play if a jump back moves over an entire dotted
                     ;; name at once.
                     ;;
                     ;; The earlier test for dotted names comes into play if the
                     ;; logic moves over one part of a dotted name at a time (which
                     ;; is what `backward-sexp` normally does).
                     (and (looking-back typescript--dotted-name-re nil)
                          ;; We don't want the loop to walk over constructs like switch (...) or for (...), etc.
                          (not (save-excursion
                                 (backward-word)
                                 (looking-at "\\_<\\(switch\\|if\\|while\\|until\\|for\\)\\_>\\(?:\\s-\\|\n\\)*(")))))
                    (condition-case nil
                        (backward-sexp)
                      (scan-error (cl-return-from search-loop nil))))
                   ((looking-back typescript--number-literal-re
                                  ;; We limit the search back to the previous space or end of line (if possible)
                                  ;; to prevent the search from going over the whole buffer.
                                  (save-excursion (re-search-backward "\\(?:\\s-\\|\n\\)" nil t)) t)
                    (goto-char (match-beginning 0)))
                   ;; Otherwise, we failed to find a location.
                   (t
                    (cl-return-from search-loop nil)))))
          ;; This handles the case of a function without return type annotation.
          (progn
            (typescript--backward-syntactic-ws)
            (when (eq (char-before) ?\))
              (point))))))
    (when location
      (goto-char location))))

(defun typescript--proper-indentation (parse-status)
  "Return the proper indentation for the current line."
  (save-excursion
    (back-to-indentation)
    (let ((member-expr-p (looking-at "\\.")))
      (cond ((nth 4 parse-status) ;; Inside a comment.
             (typescript--get-c-offset 'c (nth 8 parse-status)))
            ((nth 8 parse-status) 0) ;; Inside a string.
            ((typescript--ctrl-statement-indentation)) ;; Control statements.
            ((eq (char-after) ?#) 0) ;; Looking at a pragma.
            ;; Inside a list of things. Note that in the TS contents, the curly braces
            ;; marking code blocks are "list of things".
            ((nth 1 parse-status)
             (let ((indent-start (point))
                   (same-indent-p (looking-at "[]})]"))
                   (switch-keyword-p (looking-at "\\_<default\\_>\\|\\_<case\\_>[^:]"))
                   (continued-expr-p (typescript--continued-expression-p))
                   (list-start (nth 1 parse-status)))
               (goto-char list-start)
               (if (looking-at "[({[]\\s-*\\(/[/*]\\|$\\)")
                   (progn
                     (skip-syntax-backward " ")
                     (cond
                      ((or (typescript--backward-to-parameter-list)
                           (eq (char-before) ?\)))
                       ;; Take the curly brace as marking off the body of a function.
                       ;; In that case, we want the code that follows to see the indentation
                       ;; that was in effect at the beginning of the function declaration, and thus
                       ;; we want to move back over the list of function parameters.
                       (condition-case nil
                           (backward-list)
                         (error nil)))
                      ((looking-back "," nil)
                       ;; If we get here, we have a comma, spaces and an opening curly brace. (And
                       ;; (point) is just after the comma.) We don't want to move from the current position
                       ;; so that object literals in parameter lists are properly indented.
                       nil)
                      (t
                       ;; In all other cases, we don't want to move from the curly brace.
                       (goto-char list-start)))
                     (back-to-indentation)
                     (let* ((in-switch-p (unless same-indent-p
                                           (looking-at "\\_<switch\\_>")))
                            (same-indent-p (or same-indent-p
                                               (and switch-keyword-p
                                                    in-switch-p)))
                            (indent
                             (cond (same-indent-p
                                    (current-column))
                                   (continued-expr-p
                                    (if (not member-expr-p)
                                        (+ (current-column) (* 2 typescript-indent-level)
                                           typescript-expr-indent-offset)
                                      (goto-char indent-start)
                                      (typescript--compute-member-expression-indent)))
                                   (t
                                    (+ (current-column) typescript-indent-level)))))
                       (if (and in-switch-p typescript-indent-switch-clauses)
                           (+ indent typescript-indent-level)
                         indent)))
                 (when (and (not same-indent-p)
                            typescript-indent-list-items)
                   (forward-char)
                   (skip-chars-forward " \t"))
                 (if continued-expr-p
                     (if (not member-expr-p)
                         (progn (back-to-indentation)
                                (+ (current-column) typescript-indent-level
                                   typescript-expr-indent-offset))
                       (goto-char indent-start)
                       (typescript--compute-member-expression-indent))
                   (current-column)))))

            ((typescript--continued-expression-p) ;; Inside a continued expression.
             (if member-expr-p
                 (typescript--compute-member-expression-indent)
               (+ typescript-indent-level typescript-expr-indent-offset)))
            (t 0)))))

(defun typescript-indent-line ()
  "Indent the current line as typescript."
  (interactive)
  (save-restriction
    (widen)
    (let* ((parse-status
            (save-excursion (syntax-ppss (point-at-bol))))
           (offset (- (current-column) (current-indentation))))
      (indent-line-to (typescript--proper-indentation parse-status))
      (when (> offset 0) (move-to-column (+ offset (current-indentation)))))))

;;; Filling

(defun typescript-c-fill-paragraph (&optional justify)
  "Fill the paragraph with `c-fill-paragraph'."
  (interactive "*P")
  ;; Dynamically replace functions using the lexically scoped cl-letf.
  ;; See below for more details:
  ;; http://endlessparentheses.com/understanding-letf-and-how-it-replaces-flet.html
  (cl-letf (((symbol-function 'c-forward-sws)
             (lambda  (&optional limit)
               (typescript--forward-syntactic-ws limit)))
            ((symbol-function 'c-backward-sws)
             (lambda  (&optional limit)
               (typescript--backward-syntactic-ws limit))))
    (let ((fill-paragraph-function 'c-fill-paragraph))
      (c-fill-paragraph justify))))

;; We maintain a cache of semantic information, i.e., the classes and
;; functions we've encountered so far. In order to avoid having to
;; re-parse the buffer on every change, we cache the parse state at
;; each interesting point in the buffer. Each parse state is a
;; modified copy of the previous one, or in the case of the first
;; parse state, the empty state.
;;
;; The parse state itself is just a stack of typescript--pitem
;; instances. It starts off containing one element that is never
;; closed, that is initially typescript--initial-pitem.
;;


(defun typescript--pitem-format (pitem)
  (let ((name (typescript--pitem-name pitem))
        (type (typescript--pitem-type pitem)))

    (format "name:%S type:%S"
            name
            (if (atom type)
                type
              (plist-get type :name)))))

(defun typescript--make-merged-item (item child name-parts)
  "Helper function for `typescript--splice-into-items'.
Return a new item that is the result of merging CHILD into
ITEM.  NAME-PARTS is a list of parts of the name of CHILD
that we haven't consumed yet."
  (typescript--debug "typescript--make-merged-item: {%s} into {%s}"
                   (typescript--pitem-format child)
                   (typescript--pitem-format item))

  ;; If the item we're merging into isn't a class, make it into one
  (unless (consp (typescript--pitem-type item))
    (typescript--debug "typescript--make-merged-item: changing dest into class")
    (setq item (make-typescript--pitem
                :children (list item)

                ;; Use the child's class-style if it's available
                :type (if (atom (typescript--pitem-type child))
                          typescript--dummy-class-style
                  (typescript--pitem-type child))

                :name (typescript--pitem-strname item))))

  ;; Now we can merge either a function or a class into a class
  (cons (cond
         ((cdr name-parts)
          (typescript--debug "typescript--make-merged-item: recursing")
          ;; if we have more name-parts to go before we get to the
          ;; bottom of the class hierarchy, call the merger
          ;; recursively
          (typescript--splice-into-items (car item) child
                                       (cdr name-parts)))

         ((atom (typescript--pitem-type child))
          (typescript--debug "typescript--make-merged-item: straight merge")
          ;; Not merging a class, but something else, so just prepend
          ;; it
          (cons child (car item)))

         (t
          ;; Otherwise, merge the new child's items into those
          ;; of the new class
          (typescript--debug "typescript--make-merged-item: merging class contents")
          (append (car child) (car item))))
        (cdr item)))

(defun typescript--pitem-strname (pitem)
  "Last part of the name of PITEM, as a string or symbol."
  (let ((name (typescript--pitem-name pitem)))
    (if (consp name)
        (car (last name))
      name)))

(defun typescript--splice-into-items (items child name-parts)
  "Splice CHILD into the `typescript--pitem' ITEMS at NAME-PARTS.
If a class doesn't exist in the tree, create it.  Return
the new items list.  NAME-PARTS is a list of strings given
the broken-down class name of the item to insert."

  (let ((top-name (car name-parts))
        (item-ptr items)
        new-items last-new-item new-cons item)

    (typescript--debug "typescript--splice-into-items: name-parts: %S items:%S"
             name-parts
             (mapcar #'typescript--pitem-name items))

    (cl-assert (stringp top-name))
    (cl-assert (> (length top-name) 0))

    ;; If top-name isn't found in items, then we build a copy of items
    ;; and throw it away. But that's okay, since most of the time, we
    ;; *will* find an instance.

    (while (and item-ptr
                (cond ((equal (typescript--pitem-strname (car item-ptr)) top-name)
                       ;; Okay, we found an entry with the right name. Splice
                       ;; the merged item into the list...
                       (setq new-cons (cons (typescript--make-merged-item
                                             (car item-ptr) child
                                             name-parts)
                                            (cdr item-ptr)))

                       (if last-new-item
                           (setcdr last-new-item new-cons)
                         (setq new-items new-cons))

                       ;; ...and terminate the loop
                       nil)

                      (t
                       ;; Otherwise, copy the current cons and move onto the
                       ;; text. This is tricky; we keep track of the tail of
                       ;; the list that begins with new-items in
                       ;; last-new-item.
                       (setq new-cons (cons (car item-ptr) nil))
                       (if last-new-item
                           (setcdr last-new-item new-cons)
                         (setq new-items new-cons))
                       (setq last-new-item new-cons)

                       ;; Go to the next cell in items
                       (setq item-ptr (cdr item-ptr))))))

    (if item-ptr
        ;; Yay! We stopped because we found something, not because
        ;; we ran out of items to search. Just return the new
        ;; list.
        (progn
          (typescript--debug "search succeeded: %S" name-parts)
          new-items)

      ;; We didn't find anything. If the child is a class and we don't
      ;; have any classes to drill down into, just push that class;
      ;; otherwise, make a fake class and carry on.
      (typescript--debug "search failed: %S" name-parts)
      (cons (if (cdr name-parts)
                ;; We have name-parts left to process. Make a fake
                ;; class for this particular part...
                (make-typescript--pitem
                 ;; ...and recursively digest the rest of the name
                 :children (typescript--splice-into-items
                            nil child (cdr name-parts))
                 :type typescript--dummy-class-style
                 :name top-name)

              ;; Otherwise, this is the only name we have, so stick
              ;; the item on the front of the list
              child)
            items))))

(defun typescript--pitem-add-child (pitem child)
  "Copy `typescript--pitem' PITEM, and push CHILD onto its list of children."
  (cl-assert (integerp (typescript--pitem-h-begin child)))
  (cl-assert (if (consp (typescript--pitem-name child))
              (cl-loop for part in (typescript--pitem-name child)
                    always (stringp part))
            t))

  ;; This trick works because we know (based on our cl-defstructs) that
  ;; the child list is always the first element, and so the second
  ;; element and beyond can be shared when we make our "copy".
  (cons

   (let ((name (typescript--pitem-name child))
         (type (typescript--pitem-type child)))

     (cond ((cdr-safe name) ; true if a list of at least two elements
            ;; Use slow path because we need class lookup
            (typescript--splice-into-items (car pitem) child name))

           ((and (consp type)
                 (plist-get type :prototype))

            ;; Use slow path because we need class merging. We know
            ;; name is a list here because down in
            ;; `typescript--ensure-cache', we made sure to only add
            ;; class entries with lists for :name
            (cl-assert (consp name))
            (typescript--splice-into-items (car pitem) child name))

           (t
            ;; Fast path
            (cons child (car pitem)))))

   (cdr pitem)))

;;; compilation-mode support

;; tsc supports formatting errors in two general ways: plain and
;; pretty. ("Plain" is our term for "not pretty".) In tsc versions
;; prior to 2.7, the plain and pretty formats both used the same
;; format for references into files. `typescript-tsc-error-regexp`
;; covers both plain and pretty for those versions.
;;
;; Version 2.7 changed the pretty format so as to format source code
;; references differently. This required the introduction of
;; `typescript-tsc-pretty-error-regexp`. The format of plain error
;; messages did not change. So from that version onwards,
;; `typescript-tsc-error-regexp` covers plain error messages and
;; `typescript-tsc-pretty-error-regexp` covers pretty error messages.

;; handle plain compiler-errors like the following when doing M-x compile<ret>tsc<ret>
;;
;; greeter.ts(24,9): error TS2362: The left-hand side of an arithmetic operation must be of type 'any', 'number' or an enum type.
;; greeter.ts(30,12): error TS2339: Property 'indexOf' does not exist on type 'number'.
(defconst typescript-tsc-error-regexp
  (concat
   "^[[:blank:]]*"
   "\\([^(\r\n)]+\\)(\\([0-9]+\\),\\([0-9]+\\)):[[:blank:]]+"
   "error [[:alnum:]]+: [^\r\n]+$")
  "Regexp to match errors generated by tsc.")

;; handle pretty compiler-errors like the following when doing M-x compile<ret>tsc<ret>
;; test.ts:2:7 - error TS2322: Type '2' is not assignable to type 'string'.
(defconst typescript-tsc-pretty-error-regexp
  (concat
   "^[[:blank:]]*"
   "\\([^(\r\n)]+\\):\\([0-9]+\\):\\([0-9]+\\) - [[:blank:]]*"
   "error [[:alnum:]]+: [^\r\n]+$")
  "Regexp to match errors generated by tsc.")

;;
;; Should handle output like:
;; src/modules/authenticator.ts[1, 83]: ' should be "
;; (quotemarks) src/modules/authenticator.ts[2, 26]: ' should be "
;; ERROR: (quotemarks) src/modules/authenticator.ts[2, 26]: ' should be "
;; WARNING: src/modules/authenticator.ts[2, 26]: ' should be "
;;
;; "(quotemarks)" it the rule name. It is produced when using the
;; "verbose" formatter. The "verbose" formatter is identical to the
;; default ("prose") formatter, except for the additional rule name.
;;
;; "ERROR:" and "WARNING:" are the severity. This was added in tslint
;; 5.0. Prior versions have no notion of severity and simply omit this
;; part.
;;
(defconst typescript-tslint-report-regexp
  (concat
   "^[[:blank:]]*"
   ;; severity ("type" in Emacs' parlance)
   "\\(?:\\(?:ERROR\\|\\(WARNING\\)\\):[[:blank:]]+\\)?"
   ;; rule name
   "\\((.*)[[:blank:]]+\\)?"
   ;; filename
   "\\([^(\r\n)]+\\)"
   "\\["
   ;; line
   "\\([[:digit:]]+\\)"
   ", "
   ;; column
   "\\([[:digit:]]+\\)"
   "\\]: "
   ;; message
   ".*$")
  "Regexp to match reports generated by tslint.")

(defconst typescript-nglint-error-regexp
  (concat
   ;; severity ("type" in Emacs' parlance)
   "ERROR:[[:blank:]]+"

   ;; filename
   "\\([^(\r\n)]+\\)"
   ":"
   ;; line
   "\\([[:digit:]]+\\)"
   ":"
   ;; column
   "\\([[:digit:]]+\\)"

   " - "
   ;; message
   ".*$"))

(defconst typescript-nglint-warning-regexp
  (concat
   ;; severity ("type" in Emacs' parlance)
   "WARNING:[[:blank:]]+"

   ;; filename
   "\\([^(\r\n)]+\\)"
   ":"
   ;; line
   "\\([[:digit:]]+\\)"
   ":"
   ;; column
   "\\([[:digit:]]+\\)"

   " - "
   ;; message
   ".*$"))

(dolist
    (regexp
     `((typescript-tsc
        ,typescript-tsc-error-regexp
        1 2 3 2)

       (typescript-tsc-pretty
        ,typescript-tsc-pretty-error-regexp
        1 2 3 2)

       (typescript-tslint
        ,typescript-tslint-report-regexp
        3 4 5 (1))

       (typescript-nglint-error
        ,typescript-nglint-error-regexp
        1 2 3 2)

       (typescript-nglint-warning
        ,typescript-nglint-warning-regexp
        1 2 3 1)))
  (add-to-list 'compilation-error-regexp-alist-alist regexp)
  (add-to-list 'compilation-error-regexp-alist (car regexp)))

;;; Main Function

;;;###autoload
(define-derived-mode typescript-mode prog-mode "TypeScript"
  "Major mode for editing typescript.

Key bindings:

\\{typescript-mode-map}"

  :group 'typescript
  :syntax-table typescript-mode-syntax-table

  (setq-local indent-line-function 'typescript-indent-line)
  (setq-local beginning-of-defun-function 'typescript-beginning-of-defun)
  (setq-local end-of-defun-function 'typescript-end-of-defun)
  (setq-local open-paren-in-column-0-is-defun-start nil)
  (setq-local font-lock-defaults (list typescript--font-lock-keywords))
  (setq-local font-lock-multiline t)
  (setq-local syntax-propertize-function #'typescript-syntax-propertize)
  (setq-local parse-sexp-ignore-comments t)
  (setq-local parse-sexp-lookup-properties t)

  ;; Comments
  (setq-local comment-start "// ")
  (setq-local comment-end "")
  (setq-local fill-paragraph-function 'typescript-c-fill-paragraph)

  ;; Parse cache
  (add-hook 'before-change-functions #'typescript--flush-caches t t)

  ;; Frameworks
  (typescript--update-quick-match-re)

  ;; for filling, pretend we're cc-mode
  (setq c-comment-prefix-regexp "//+\\|\\**"
        c-paragraph-start "$"
        c-paragraph-separate "$"
        c-block-comment-prefix "* "
        c-block-comment-ender-regexp "\\*/"
        c-line-comment-starter "//"
        c-comment-start-regexp "/[*/]\\|\\s!"
        comment-start-skip "\\(//+\\|/\\*+\\)\\s *")

  (setq-local electric-indent-chars
          (append "{}():;," electric-indent-chars))
  (setq-local electric-layout-rules
          '((?\; . after) (?\{ . after) (?\} . before)))

  (let ((c-buffer-is-cc-mode t))
    ;; FIXME: These are normally set by `c-basic-common-init'.  Should
    ;; we call it instead?  (Bug#6071)
    (make-local-variable 'paragraph-start)
    (make-local-variable 'paragraph-separate)
    (make-local-variable 'paragraph-ignore-fill-prefix)
    (make-local-variable 'adaptive-fill-mode)
    (make-local-variable 'adaptive-fill-regexp)
    (c-setup-paragraph-variables))

  (add-hook 'post-self-insert-hook
            #'typescript--post-self-insert-function)

  (setq-local syntax-begin-function #'typescript--syntax-begin-function))

;; Set our custom predicate for flyspell prog mode
(put 'typescript-mode 'flyspell-mode-predicate
     'typescript--flyspell-mode-predicate)

;;;###autoload
(eval-after-load 'folding
  '(when (fboundp 'folding-add-to-marks-list)
     (folding-add-to-marks-list 'typescript-mode "// {{{" "// }}}" )))

;;;###autoload
(add-to-list 'auto-mode-alist '("\\.tsx?\\'" . typescript-mode))

(provide 'typescript-mode)

;;; typescript-mode.el ends here