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|
;;; elm-font-lock.el --- Font locking module for Elm mode.
;; Copyright (C) 2013, 2014 Joseph Collard
;; Copyright (C) 2015 Bogdan Popa
;; Authors: Joseph Collard
;; URL: https://github.com/jcollard/elm-mode
;; This file is not part of GNU Emacs.
;; This file 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, or (at your option)
;; any later version.
;; This file 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/>.
;;; Commentary:
;;; Code:
(require 'font-lock)
(require 'rx)
(defgroup elm-font-lock nil
"Font locking for Elm code."
:group 'faces)
(defface elm-font-lock-operators
'((t :inherit font-lock-builtin-face))
"The default face used to highlight operators inside expressions."
:group 'elm-font-lock)
(defcustom elm-font-lock-operators-face 'elm-font-lock-operators
"The face used to highlight operators inside expressions.
To disable this highlighting, set this to nil."
:type '(choice (const nil)
face)
:group 'elm-font-lock)
(defface elm-font-lock-multiline-list-delimiters
'((t :inherit font-lock-keyword-face))
"The default face used to highlight brackets and commas in multiline lists."
:group 'elm-font-lock)
(defcustom elm-font-lock-multiline-list-delimiters-face 'elm-font-lock-multiline-list-delimiters
"The face used to highlight brackets and commas in multilist lists.
To disable this highlighting, set this to nil."
:type '(choice (const nil)
face)
:group 'elm-font-lock)
(defconst elm--keywords
'("let" "case" "in" "if" "of" "then" "else" "effect"
"module" "import" "as" "exposing" "type" "where"
"alias" "port" "infix" "infixr" "infixl")
"Reserved keywords.")
(defconst elm--regexp-keywords
(concat (regexp-opt elm--keywords 'words) "[^']")
"A regular expression representing the reserved keywords.")
(defconst elm--font-lock-keywords
(cons elm--regexp-keywords font-lock-keyword-face)
"Highlighting for keywords.")
(defun elm--syntax-stringify ()
"Syntax propertize triple quoted strings."
(let* ((ppss (save-excursion
(backward-char 3)
(syntax-ppss)))
(string-started (and (not (nth 4 ppss)) (nth 8 ppss)))
(quote-starting-pos (- (point) 3))
(quote-ending-pos (point)))
(if (not string-started)
(put-text-property quote-starting-pos (1+ quote-starting-pos)
'syntax-table (string-to-syntax "|"))
(put-text-property (1- quote-ending-pos) quote-ending-pos
'syntax-table (string-to-syntax "|")))))
(defconst elm--syntax-propertize
(syntax-propertize-rules
;;; Syntax rule for -- comments
((rx (and (0+ " ") (group "--")
(0+ any) (group "\n")))
(1 "< b")
(2 "> b"))
;;; Syntax rule for char literals
((rx (and (1+ " ")
(group "'")
(optional "\\") any
(group "'")))
(1 "\"")
(2 "\""))
((rx (and (or point
(not (any ?\\ ?\"))
(and (or (not (any ?\\)) point) ?\\ (* ?\\ ?\\) (any ?\")))
(* ?\\ ?\\)
"\"\"\""))
(0 (ignore (elm--syntax-stringify))))))
(defun elm--syntax-propertize-function (begin end)
"Mark special lexemes between BEGIN and END."
(funcall elm--syntax-propertize begin end)
(save-excursion
(goto-char begin)
(while (re-search-forward "\\\\[({]" end t)
(let ((open (match-beginning 0)))
(add-text-properties open (1+ open) '(syntax-table (1 . nil)))))))
(defvar elm--syntax-table
(let ((st (make-syntax-table)))
;;; Syntax entry for {- -} type comments.
(modify-syntax-entry ?{ "(} 1n" st)
(modify-syntax-entry ?- ". 23n" st)
(modify-syntax-entry ?} "){ 4n" st)
(modify-syntax-entry ?\" "\"\"" st)
(modify-syntax-entry ?\\ "\\" st)
st))
;;; Name regexp is according to https://github.com/elm-lang/elm-compiler/blob/353930a474fee4d833f962100edde70417691bca/src/Parse/Helpers.hs#L65
(defconst elm--regexp-function
"^\\([a-z_][0-9A-Za-z_']*\\|([^)]+)\\)"
"A regular expression representing function names.")
(defconst elm--font-lock-functions
(cons elm--regexp-function font-lock-function-name-face)
"Highlighting for function names.")
(defconst elm--regexp-type
"\\<[A-Z][0-9A-Za-z_']*"
"A regular expression representing modules and types.")
(defconst elm--font-lock-types
(cons elm--regexp-type font-lock-type-face)
"Highlighting for module names and types.")
(defconst elm--regexp-operators
(concat "\\(" "`[^`]+`"
"\\|" "\\B\\\\"
"\\|" "[-+*/\\\\|<>=:!@#$%^&,.]+"
"\\)")
"A regular expression representing operators inside expressions.")
(defconst elm--font-lock-operators
(cons elm--regexp-operators '(1 elm-font-lock-operators-face))
"Highlighting for operators inside expressions.")
(defconst elm--regexp-multiline-list-comma-closing-brackets
(concat "^[[:space:]]*" (regexp-opt '("," "]" "}") t))
"A regular expression representing commas and closing brackets in multiline lists and records.")
(defconst elm--font-lock-multiline-list-comma-closing-brackets
(cons elm--regexp-multiline-list-comma-closing-brackets
'(1 elm-font-lock-multiline-list-delimiters-face))
"Highlighting for commas and closing brackets in multiline lists and records.")
(defun elm--match-multiline-list-opening-bracket (limit)
"Highlighting search function for opening brackets in multiline lists and records.
Also highlights opening brackets without a matching bracket."
(when (elm--search-forward-opening-bracket limit)
(let ((opening (point))
(eol (line-end-position))
(closing (elm--search-forward-closing-bracket)))
(if (or (= closing opening) (> closing eol))
(progn
(set-match-data (match-data))
(goto-char (+ 1 opening))
t)
(elm--match-multiline-list-opening-bracket limit)))))
(defun elm--search-forward-opening-bracket (limit)
"Go to the next opening bracket up to LIMIT."
(if (search-forward-regexp (regexp-opt '("[" "{")) limit t)
(progn
(backward-char)
t)))
(defun elm--search-forward-closing-bracket ()
"Go to the next matching bracket, assuming that the cursor is on an opening bracket."
(ignore-errors
(save-match-data
(forward-sexp)))
(point))
(defconst elm--font-lock-multiline-list-opening-brackets
'(elm--match-multiline-list-opening-bracket (0 elm-font-lock-multiline-list-delimiters-face))
"Highlighting for opening brackets in multiline lists and records.")
(defconst elm--font-lock-highlighting
(list (list elm--font-lock-keywords
elm--font-lock-functions
elm--font-lock-types
elm--font-lock-multiline-list-comma-closing-brackets
elm--font-lock-multiline-list-opening-brackets
elm--font-lock-operators)
nil nil))
(defun turn-on-elm-font-lock ()
"Turn on Elm font lock."
(setq font-lock-multiline t)
(set-syntax-table elm--syntax-table)
(set (make-local-variable 'syntax-propertize-function) #'elm--syntax-propertize-function)
(set (make-local-variable 'font-lock-defaults) elm--font-lock-highlighting))
(provide 'elm-font-lock)
;;; elm-font-lock.el ends here
|
