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haskell-font-lock.el
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haskell-font-lock.el
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;;; haskell-font-lock.el --- Font locking module for Haskell Mode
;; Copyright 1997-1998 Graeme E Moss, and Tommy Thorn
;; Authors: 1997-1998 Graeme E Moss <gem@cs.york.ac.uk> and
;; Tommy Thorn <thorn@irisa.fr>
;; Keywords: faces files Haskell
;; Version: 1.2
;; URL: http://www.cs.york.ac.uk/~gem/haskell-mode/font-lock.html
;;; 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 2, 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 GNU Emacs; see the file COPYING. If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.
;;; Commentary:
;; Purpose:
;;
;; To support fontification of standard Haskell keywords, symbols,
;; functions, etc. Supports full Latin1 Haskell 1.4 as well as
;; Bird-style literate scripts.
;;
;;
;; Installation:
;;
;; To turn font locking on for all Haskell buffers under the Haskell
;; mode of Moss&Thorn, add this to .emacs:
;;
;; (add-hook haskell-mode-hook 'turn-on-haskell-font-lock)
;;
;; Otherwise, call `turn-on-haskell-font-lock'.
;;
;;
;; Customisation:
;;
;; The colours and level of font locking may be customised. See the
;; documentation on `turn-on-haskell-font-lock' for more details.
;;
;;
;; History:
;;
;; If you have any problems or suggestions, after consulting the list
;; below, email gem@cs.york.ac.uk and thorn@irisa.fr quoting the
;; version of the mode you are using, the version of emacs you are
;; using, and a small example of the problem or suggestion. Note that
;; this module requires a reasonably recent version of Emacs.
;;
;; Version 1.2:
;; Added support for LaTeX-style literate scripts. Allow whitespace
;; after backslash to end a line for string continuations.
;;
;; Version 1.1:
;; Use own syntax table. Use backquote (neater). Stop ''' being
;; highlighted as quoted character. Fixed `\"' fontification bug
;; in comments.
;;
;; Version 1.0:
;; Brought over from Haskell mode v1.1.
;;
;; Present Limitations/Future Work (contributions are most welcome!):
;;
;; . Nested comments are not highlighted properly, eg. {- {- -} -}
;; The first closing dash-brace returns the face to default. It is
;; not known to us if this is actually possible with font lock.
;;
;; . Debatable whether `()' `[]' `(->)' `(,)' `(,,)' etc. should be
;; highlighted as constructors or not. Should the `->' in
;; `id :: a -> a' be considered a constructor or a keyword? If so,
;; how do we distinguish this from `\x -> x'? What about the `\'?
;;
;; . Unicode is still a mystery... has anyone used it yet? We still
;; support Latin-ISO-8859-1 though (the character set of Haskell 1.3).
;;
;; . Font lock fails on:
;; - `\' at the beginning of a line not starting a string continuation
;; that does contain a `"', eg. when defining a lambda expression;
;; - `--' or `{-' used within strings;
;;
;; . XEmacs can support both `--' comments and `{- -}' comments
;; simultaneously. If XEmacs is detected, this should be used.
;;
;; . Support for Green Card?
;;
;; . Support for \begin{code}..\end{code} style of literate scripts?
;;
;;; All functions/variables start with
;;; `(turn-(on/off)-)haskell-font-lock' or `haskell-fl-'.
;; Version.
(defconst haskell-font-lock-version "1.2"
"haskell-font-lock version number.")
(defun haskell-font-lock-version ()
"Echo the current version of haskell-font-lock in the minibuffer."
(interactive)
(message "Using haskell-font-lock version %s" haskell-font-lock-version))
(defvar haskell-font-lock-keywords ()
"The default definitions used by font lock for fontification of
non-literate Haskell scripts. This variable is set by
`turn-on-haskell-font-lock' and then used by `font-lock-defaults'.")
(defvar haskell-font-lock-keywords-1 ()
"Medium level font lock definitions for non-literate Haskell.")
(defvar haskell-font-lock-keywords-2 ()
"High level font lock definitions for non-literate Haskell.")
(defvar bird-literate-haskell-font-lock-keywords ()
"The default definitions used by font lock for fontification of
Bird-style literate Haskell scripts. This variable is set by
`turn-on-haskell-font-lock' and then used by `font-lock-defaults'.")
(defvar bird-literate-haskell-font-lock-keywords-1 ()
"Medium level font lock definitions for Bird-style literate Haskell.")
(defvar bird-literate-haskell-font-lock-keywords-2 ()
"High level font lock definitions for Bird-style literate Haskell.")
(defvar latex-literate-haskell-font-lock-keywords ()
"The default definitions used by font lock for fontification of
LaTeX-style literate Haskell scripts. This variable is set by
`turn-on-haskell-font-lock' and then used by `font-lock-defaults'.")
(defvar latex-literate-haskell-font-lock-keywords-1 ()
"Medium level font lock definitions for LaTeX-style literate Haskell.")
(defvar latex-literate-haskell-font-lock-keywords-2 ()
"High level font lock definitions for LaTeX-style literate Haskell.")
;; The font lock regular expressions.
(defun haskell-font-lock-keywords-create (bird-literate latex-literate level)
"Creates appropriate LEVEL (1 or 2) of fontification definitions
for (BIRD-LITERATE or LATEX-LITERATE) Haskell scripts. Returns keywords
suitable for `font-lock-keywords'."
(let* (;; Bird-style literate scripts start a line of code with
;; "^>", otherwise a line of code starts with "^".
(line-prefix (if bird-literate "^>" "^"))
;; Most names are borrowed from the lexical syntax of the Haskell
;; report.
;; Some of these definitions have been superseded by using the
;; syntax table instead.
(ASCsymbol "-!#$%&*+./<=>?@\\\\^|~")
;; Put the minus first to make it work in ranges.
(ISOsymbol "\241-\277\327\367")
(ISOlarge "\300-\326\330-\337")
(ISOsmall "\340-\366\370-\377")
(small
(concat "a-z" ISOsmall))
(large
(concat "A-Z" ISOlarge))
(symbol
(concat ASCsymbol ISOsymbol))
;; We allow _ as the first char to fit GHC
(id
(concat "\\b\\([" small large "0-9'_]+\\)\\b"))
(varid
(concat "\\b\\([" small "_][" small large "0-9'_]*\\)\\b"))
(conid
(concat "\\b\\([" large "][" small large "0-9'_]*\\)\\b"))
(modid
(concat "\\b" conid "\\(\\." conid "\\)*\\b"))
(qvarid
(concat modid "\\." varid))
(qconid
(concat modid "\\." conid))
(sym
(concat "[" symbol ":]+"))
;; Reserved operations
(reservedsym
'(".." "::" "=" "\\" "|" "<-" "->" "@" "~" "=>"))
;; Reserved identifiers
;(reservedid
; '("as" "case" "class" "data" "default" "deriving" "do" "else"
; "hiding" "if" "import" "in" "infix" "infixl" "infixr"
; "instance" "let" "module" "newtype" "of" "qualified" "then"
; "type" "where"))
;; make-regexp applied to reservedid creates the following
;; regexp
(reservedid
"\\b\\(c\\(ase\\|lass\\)\\|d\\(ata\\|e\\(fault\\|riving\\)\\|o\\)\\|else\\|hiding\\|i\\([fn]\\|mport\\|n\\(fix\\(\\|[lr]\\)\\|stance\\)\\)\\|let\\|module\\|newtype\\|of\\|qualified\\|t\\(hen\\|ype\\)\\|where\\)\\b")
;; This unreadable regexp matches strings and character
;; constants. We need to do this with one regexp to handle
;; stuff like '"':"'". The regexp is the composition of
;; "([^"\\]|\\.)*" for strings and '([^\\]|\\.[^']*)' for
;; characters, allowing for string continuations.
;; Could probably be improved...
(string-and-char
(concat "\\(\\(\"\\|" line-prefix "[ \t]*\\\\\\)\\([^\"\\\\\n]\\|\\\\.\\)*\\(\"\\|\\\\[ \t]*$\\)\\|'\\([^'\\\\\n]\\|\\\\.[^'\n]*\\)'\\)"))
;; Top-level declarations
;; These are not included as they don't work well (yet).
; (topdecl1
; (concat line-prefix "\\(" varid "\\)\\(\\s-\\|::\\|=\\||\\)"))
; (topdecl2
; (concat line-prefix varid "\\s-*\\(" sym "\\)"))
; (topdecl3
; (concat line-prefix "(\\(" sym "\\))"))
font-lock-keywords)
(setq font-lock-keywords
`(
;;
;; NOTICE the ordering below is significant
;;
("--.*$" 0 'haskell-comment-face t)
("^#.*$" 0 'font-lock-warning-face t)
;; Expensive.
,`(,string-and-char 1 'haskell-string-char-face)
;; These four are debatable...
("()" 0 'haskell-constructor-face)
("(,*)" 0 'haskell-constructor-face)
("\\[\\]" 0 'haskell-constructor-face)
("(->)" 0 'haskell-constructor-face)
;; Expensive.
,`(,reservedid 1 'haskell-keyword-face)
,`(,qvarid 0 'haskell-default-face)
,`(,qconid 0 'haskell-constructor-face)
,@(if (eq level 2)
`(,`(,(concat "\`" varid "\`") 0 'haskell-operator-face))
'())
;; Expensive.
,`(,conid 1 'haskell-constructor-face)
;; Very expensive.
,`(,sym 0 ,`(let ((match (match-string 0)))
,`(cond
,`(,`(member match ',reservedsym)
'haskell-operator-face)
((eq (aref match 0) ?:) 'haskell-constructor-face)
,@(if (eq level 2)
'((t 'haskell-operator-face))
'()))))
;; (list topdecl1 1 ''haskell-definition-face t)
;; (list topdecl2 1 ''haskell-definition-face t)
;; (list topdecl3 1 ''haskell-definition-face t)
))
(if bird-literate
(setq font-lock-keywords
`(("^[^>\n].*$" 0 'haskell-comment-face t)
,@font-lock-keywords
("^>" 0 'haskell-default-face t)))
(if latex-literate
(setq font-lock-keywords
`((haskell-fl-latex-comments 0 'font-lock-comment-face t)
,@font-lock-keywords))))
font-lock-keywords))
(defvar haskell-fl-latex-cache-pos nil
"Position of cache point used by `haskell-fl-latex-cache-in-comment'.
Should be at the start of a line.")
(defvar haskell-fl-latex-cache-in-comment nil
"If `haskell-fl-latex-cache-pos' is outside a
\\begin{code}..\\end{code} block (and therefore inside a comment),
this variable is set to t, otherwise nil.")
(defun haskell-fl-latex-comments (end)
"Sets `match-data' according to the region of the buffer before end
that should be commented under LaTeX-style literate scripts."
(let ((start (point)))
(if (= start end)
;; We're at the end. No more to fontify.
nil
(if (not (eq start haskell-fl-latex-cache-pos))
;; If the start position is not cached, calculate the state
;; of the start.
(progn
(setq haskell-fl-latex-cache-pos start)
;; If the previous \begin{code} or \end{code} is a
;; \begin{code}, then start is not in a comment, otherwise
;; it is in a comment.
(setq haskell-fl-latex-cache-in-comment
(if (and
(re-search-backward
"^\\(\\(\\\\begin{code}\\)\\|\\(\\\\end{code}\\)\\)$"
(point-min) t)
(match-end 2))
nil t))
;; Restore position.
(goto-char start)))
(if haskell-fl-latex-cache-in-comment
(progn
;; If start is inside a comment, search for next \begin{code}.
(re-search-forward "^\\\\begin{code}$" end 'move)
;; Mark start to end of \begin{code} (if present, till end
;; otherwise), as a comment.
(set-match-data (list start (point)))
;; Return point, as a normal regexp would.
(point))
;; If start is inside a code block, search for next \end{code}.
(if (re-search-forward "^\\\\end{code}$" end t)
;; If one found, mark it as a comment, otherwise finish.
(point))))))
(defvar haskell-fl-syntax
;; It's easier for us to manually set the ISO Latin1 syntax as I'm
;; not sure what libraries are available and how they differ from
;; Haskell, eg. the iso-syntax library of Emacs 19.34 defines \241
;; as punctuation for good reasons but this conflicts with Haskell
;; so we would have to redefine it. It's simpler for us to set the
;; syntax table according to the Haskell report for all of the 8-bit
;; characters.
`((?\ . " ")
(?\t . " ")
(?\" . " ")
(?\' . "w")
(?_ . "w")
(?\( . "()")
(?\) . ")(")
(?[ . "(]")
(?] . ")[")
(?{ . "(}1")
(?} . "){4")
(?- . "_ 23")
(?\` . "$`")
,@(mapcar (lambda (x) (cons x "_"))
(concat "!#$%&*+./:<=>?@\\^|~" (haskell-enum-from-to ?\241 ?\277)
"\327\367"))
,@(mapcar (lambda (x) (cons x "w"))
(concat (haskell-enum-from-to ?\300 ?\326) (haskell-enum-from-to ?\330 ?\337)
(haskell-enum-from-to ?\340 ?\366) (haskell-enum-from-to ?\370 ?\377))))
"Syntax required for font locking. Given as a list of pairs for use
in `font-lock-defaults'.")
(defun haskell-font-lock-defaults-create (bird-literate latex-literate)
"Makes local variable `font-lock-defaults' suitable for Haskell font
locking. If BIRD-LITERATE is non-nil then the font locking is made
suitable for Bird-style literate Haskell scripts, and similarly for
LATEX-LITERATE and LaTeX-style literate Haskell scripts."
(setq haskell-font-lock-keywords-1
(haskell-font-lock-keywords-create nil nil 1))
(setq haskell-font-lock-keywords-2
(haskell-font-lock-keywords-create nil nil 2))
(setq haskell-font-lock-keywords
haskell-font-lock-keywords-1)
(setq bird-literate-haskell-font-lock-keywords-1
(haskell-font-lock-keywords-create t nil 1))
(setq bird-literate-haskell-font-lock-keywords-2
(haskell-font-lock-keywords-create t nil 2))
(setq bird-literate-haskell-font-lock-keywords
bird-literate-haskell-font-lock-keywords-1)
(setq latex-literate-haskell-font-lock-keywords-1
(haskell-font-lock-keywords-create nil t 1))
(setq latex-literate-haskell-font-lock-keywords-2
(haskell-font-lock-keywords-create nil t 2))
(setq latex-literate-haskell-font-lock-keywords
latex-literate-haskell-font-lock-keywords-1)
(make-local-variable 'font-lock-defaults)
(setq font-lock-defaults
(if bird-literate
(list '(bird-literate-haskell-font-lock-keywords
bird-literate-haskell-font-lock-keywords-1
bird-literate-haskell-font-lock-keywords-2)
nil nil haskell-fl-syntax)
(if latex-literate
(list '(latex-literate-haskell-font-lock-keywords
latex-literate-haskell-font-lock-keywords-1
latex-literate-haskell-font-lock-keywords-2)
nil nil haskell-fl-syntax)
(list '(haskell-font-lock-keywords
haskell-font-lock-keywords-1
haskell-font-lock-keywords-2)
nil nil haskell-fl-syntax)))))
;; Faces required for font locking.
(defun haskell-fl-faces ()
"Defines faces required for Haskell font locking."
;; XEmacs does not have a simple function for making the faces but
;; makes them when `require'd which was done by
;; turn-on-haskell-font-lock, so we don't need to explicitly make
;; them for XEmacs, and in fact we shouldn't as an error will be
;; produced.
(if (fboundp 'font-lock-make-faces) (font-lock-make-faces))
(copy-face 'font-lock-keyword-face 'haskell-keyword-face)
(copy-face 'font-lock-type-face 'haskell-constructor-face)
(copy-face 'font-lock-string-face 'haskell-string-char-face)
(copy-face 'font-lock-function-name-face 'haskell-operator-face)
(copy-face 'font-lock-comment-face 'haskell-comment-face)
(copy-face 'default 'haskell-default-face)
; (copy-face 'font-lock-reference-face 'haskell-definition-face)
)
;; The main functions.
(defun turn-on-haskell-font-lock ()
"Turns on font locking in current buffer for Haskell 1.4 scripts.
Changes the current buffer's `font-lock-defaults', and adds the
following faces:
`haskell-keyword-face' for reserved keywords and syntax,
`haskell-constructor-face' for data- and type-constructors, class names,
and module names,
`haskell-string-char-face' for strings and characters,
`haskell-operator-face' for symbolic and alphanumeric operators,
`haskell-comment-face' for comments, and
`haskell-default-face' for ordinary code.
The faces are initialised to the following font lock defaults:
`haskell-keyword-face' `font-lock-keyword-face'
`haskell-constructor-face' `font-lock-type-face'
`haskell-string-char-face' `font-lock-string-face'
`haskell-operator-face' `font-lock-function-name-face'
`haskell-comment-face' `font-lock-comment-face'
`haskell-default-face' <default face>
Two levels of fontification are defined: level one (the default)
and level two (more colour). The former does not colour operators.
Use the variable `font-lock-maximum-decoration' to choose
non-default levels of fontification. For example, adding this to
.emacs:
(setq font-lock-maximum-decoration '((haskell-mode . 2) (t . 0)))
uses level two fontification for `haskell-mode' and default level for
all other modes. See documentation on this variable for further
details.
To alter an attribute of a face, add a hook. For example, to change
the foreground colour of comments to brown, add the following line to
.emacs:
(add-hook 'haskell-font-lock-hook
(lambda ()
(set-face-foreground 'haskell-comment-face \"brown\")))
Note that the colours available vary from system to system. To see
what colours are available on your system, call
`list-colors-display' from emacs.
To turn font locking on for all Haskell buffers, add this to .emacs:
(add-hook 'haskell-mode-hook 'turn-on-haskell-font-lock)
To turn font locking on for the current buffer, call
`turn-on-haskell-font-lock'. To turn font locking off in the current
buffer, call `turn-off-haskell-font-lock'.
Bird-style literate Haskell scripts are supported: If the value of
`haskell-literate-bird-style' (automatically set by the Haskell mode
of Moss&Thorn) is non-nil, a Bird-style literate script is assumed.
Invokes `haskell-font-lock-hook' if not nil.
Use `haskell-font-lock-version' to find out what version this is."
(interactive)
(require 'font-lock)
(haskell-fl-faces)
(let ((literate (if (boundp 'haskell-literate) haskell-literate)))
(haskell-font-lock-defaults-create (eq literate 'bird)
(eq literate 'latex)))
(run-hooks 'haskell-font-lock-hook)
(turn-on-font-lock))
(defun turn-off-haskell-font-lock ()
"Turns off font locking in current buffer."
(interactive)
(if (and (boundp 'font-lock-mode) font-lock-mode)
(font-lock-mode)))
;;; Provide ourselves:
(provide 'haskell-font-lock)
;;; haskell-font-lock ends here.