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adding YAML mode

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jrockway committed Feb 1, 2008
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+;;; yaml-mode.el --- Major mode for editing YAML files
+
+;; Copyright (C) 2006 Yoshiki Kurihara
+
+;; Author: Yoshiki Kurihara <kurihara@cpan.org>
+;; Marshall T. Vandegrift <llasram@gmail.com>
+;; Keywords: data yaml
+;; Version: 0.0.3
+
+;; This file is not part of 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:
+
+;; This is a major mode for editing files in the YAML data
+;; serialization format. It was initially developed by Yoshiki
+;; Kurihara and many features were added by Marshall Vandegrift. As
+;; YAML and Python share the fact that indentation determines
+;; structure, this mode provides indentation and indentation command
+;; behavior very similar to that of python-mode.
+
+;;; Installation:
+
+;; To install, just drop this file into a directory in your
+;; `load-path' and (optionally) byte-compile it. To automatically
+;; handle files ending in '.yml', add something like:
+;;
+;; (require 'yaml-mode)
+;; (add-to-list 'auto-mode-alist '("\\.yml$" . yaml-mode))
+;;
+;; to your .emacs file.
+;;
+;; Unlike python-mode, this mode follows the Emacs convention of not
+;; binding the ENTER key to `newline-and-indent'. To get this
+;; behavior, add the key definition to `yaml-mode-hook':
+;;
+;; (add-hook 'yaml-mode-hook
+;; '(lambda ()
+;; (define-key yaml-mode-map "\C-m" 'newline-and-indent)))
+
+;;; Known Bugs:
+
+;; YAML is easy to write but complex to parse, and this mode doesn't
+;; even really try. Indentation and highlighting will break on
+;; abnormally complicated structures.
+
+;;; Code:
+
+
+;; User definable variables
+
+(defgroup yaml nil
+ "Support for the YAML serialization format"
+ :group 'languages
+ :prefix "yaml-")
+
+(defcustom yaml-mode-hook nil
+ "*Hook run by `yaml-mode'."
+ :type 'hook
+ :group 'yaml)
+
+(defcustom yaml-indent-offset 2
+ "*Amount of offset per level of indentation."
+ :type 'integer
+ :group 'yaml)
+
+(defcustom yaml-backspace-function 'backward-delete-char-untabify
+ "*Function called by `yaml-electric-backspace' when deleting backwards."
+ :type 'function
+ :group 'yaml)
+
+(defcustom yaml-block-literal-search-lines 100
+ "*Maximum number of lines to search for start of block literals."
+ :type 'integer
+ :group 'yaml)
+
+(defcustom yaml-block-literal-electric-alist
+ '((?| . "") (?> . "-"))
+ "*Characters for which to provide electric behavior.
+The association list key should be a key code and the associated value
+should be a string containing additional characters to insert when
+that key is pressed to begin a block literal."
+ :type 'alist
+ :group 'yaml)
+
+(defface yaml-tab-face
+ '((((class color)) (:background "red" :foreground "red" :bold t))
+ (t (:reverse-video t)))
+ "Face to use for highlighting tabs in YAML files."
+ :group 'faces
+ :group 'yaml)
+
+
+;; Constants
+
+(defconst yaml-mode-version "0.0.3" "Version of `yaml-mode.'")
+
+(defconst yaml-blank-line-re "^ *$"
+ "Regexp matching a line containing only (valid) whitespace.")
+
+(defconst yaml-comment-re "\\(#*.*\\)"
+ "Regexp matching a line containing a YAML comment or delimiter.")
+
+(defconst yaml-directive-re "^\\(?:--- \\)? *%\\(\\w+\\)"
+ "Regexp matching a line contatining a YAML directive.")
+
+(defconst yaml-document-delimiter-re "^ *\\(?:---\\|[.][.][.]\\)"
+ "Rexexp matching a YAML document delimiter line.")
+
+(defconst yaml-node-anchor-alias-re "[&*]\\w+"
+ "Regexp matching a YAML node anchor or alias.")
+
+(defconst yaml-tag-re "!!?[^ \n]+"
+ "Rexexp matching a YAML tag.")
+
+(defconst yaml-bare-scalar-re
+ "\\(?:[^-:,#!\n{\\[ ]\\|[^#!\n{\\[ ]\\S-\\)[^#\n]*?"
+ "Rexexp matching a YAML bare scalar.")
+
+(defconst yaml-hash-key-re
+ (concat "\\(?:^\\(?:--- \\)?\\|{\\|\\(?:[-,] +\\)+\\) *"
+ "\\(?:" yaml-tag-re " +\\)?"
+ "\\(" yaml-bare-scalar-re "\\) *:"
+ "\\(?: +\\|$\\)")
+ "Regexp matching a single YAML hash key.")
+
+(defconst yaml-scalar-context-re
+ (concat "\\(?:^\\(?:--- \\)?\\|{\\|\\(?:[-,] +\\)+\\) *"
+ "\\(?:" yaml-bare-scalar-re " *: \\)?")
+ "Regexp indicating the begininng of a scalar context.")
+
+(defconst yaml-nested-map-re
+ (concat ".*: *\\(?:&.*\\|{ *\\|" yaml-tag-re " *\\)?$")
+ "Regexp matching a line beginning a YAML nested structure.")
+
+(defconst yaml-block-literal-base-re " *[>|][-+0-9]* *\\(?:\n\\|\\'\\)"
+ "Regexp matching the substring start of a block literal.")
+
+(defconst yaml-block-literal-re
+ (concat yaml-scalar-context-re
+ "\\(?:" yaml-tag-re "\\)?"
+ yaml-block-literal-base-re)
+ "Regexp matching a line beginning a YAML block literal")
+
+(defconst yaml-nested-sequence-re
+ (concat "^\\(?: *- +\\)+"
+ "\\(?:" yaml-bare-scalar-re " *:\\(?: +.*\\)?\\)?$")
+ "Regexp matching a line containing one or more nested YAML sequences")
+
+(defconst yaml-constant-scalars-re
+ (concat "\\(?:^\\|\\(?::\\|-\\|,\\|{\\|\\[\\) +\\) *"
+ (regexp-opt
+ '("~" "null" "Null" "NULL"
+ ".nan" ".NaN" ".NAN"
+ ".inf" ".Inf" ".INF"
+ "-.inf" "-.Inf" "-.INF"
+ "y" "Y" "yes" "Yes" "YES" "n" "N" "no" "No" "NO"
+ "true" "True" "TRUE" "false" "False" "FALSE"
+ "on" "On" "ON" "off" "Off" "OFF") t)
+ " *$")
+ "Regexp matching certain scalar constants in scalar context")
+
+
+;; Mode setup
+
+(defvar yaml-mode-map ()
+ "Keymap used in `yaml-mode' buffers.")
+(if yaml-mode-map
+ nil
+ (setq yaml-mode-map (make-sparse-keymap))
+ (define-key yaml-mode-map "|" 'yaml-electric-bar-and-angle)
+ (define-key yaml-mode-map ">" 'yaml-electric-bar-and-angle)
+ (define-key yaml-mode-map "-" 'yaml-electric-dash-and-dot)
+ (define-key yaml-mode-map "." 'yaml-electric-dash-and-dot)
+ (define-key yaml-mode-map [backspace] 'yaml-electric-backspace)
+ (define-key yaml-mode-map "\C-j" 'newline-and-indent))
+
+(defvar yaml-mode-syntax-table nil
+ "Syntax table in use in yaml-mode buffers.")
+(if yaml-mode-syntax-table
+ nil
+ (setq yaml-mode-syntax-table (make-syntax-table))
+ (modify-syntax-entry ?\' "\"" yaml-mode-syntax-table)
+ (modify-syntax-entry ?\" "\"" yaml-mode-syntax-table)
+ (modify-syntax-entry ?# "<" yaml-mode-syntax-table)
+ (modify-syntax-entry ?\n ">" yaml-mode-syntax-table)
+ (modify-syntax-entry ?\\ "\\" yaml-mode-syntax-table)
+ (modify-syntax-entry ?- "." yaml-mode-syntax-table)
+ (modify-syntax-entry ?_ "_" yaml-mode-syntax-table)
+ (modify-syntax-entry ?\( "." yaml-mode-syntax-table)
+ (modify-syntax-entry ?\) "." yaml-mode-syntax-table)
+ (modify-syntax-entry ?\{ "(}" yaml-mode-syntax-table)
+ (modify-syntax-entry ?\} "){" yaml-mode-syntax-table)
+ (modify-syntax-entry ?\[ "(]" yaml-mode-syntax-table)
+ (modify-syntax-entry ?\] ")[" yaml-mode-syntax-table))
+
+(define-derived-mode yaml-mode fundamental-mode "YAML"
+ "Simple mode to edit YAML.
+
+\\{yaml-mode-map}"
+ (set (make-local-variable 'comment-start) "# ")
+ (set (make-local-variable 'comment-start-skip) "#+ *")
+ (set (make-local-variable 'indent-line-function) 'yaml-indent-line)
+ (set (make-local-variable 'font-lock-defaults)
+ '(yaml-font-lock-keywords
+ nil nil nil nil
+ (font-lock-syntactic-keywords . yaml-font-lock-syntactic-keywords))))
+
+
+;; Font-lock support
+
+(defvar yaml-font-lock-keywords
+ (list
+ (cons yaml-comment-re '(1 font-lock-comment-face))
+ (cons yaml-constant-scalars-re '(1 font-lock-constant-face))
+ (cons yaml-tag-re '(0 font-lock-type-face))
+ (cons yaml-node-anchor-alias-re '(0 font-lock-function-name-face t))
+ (cons yaml-hash-key-re '(1 font-lock-variable-name-face t))
+ (cons yaml-document-delimiter-re '(0 font-lock-comment-face))
+ (cons yaml-directive-re '(1 font-lock-builtin-face))
+ '(yaml-font-lock-block-literals 0 font-lock-string-face t)
+ '("^[\t]+" 0 'yaml-tab-face t))
+ "Additional expressions to highlight in YAML mode.")
+
+(defvar yaml-font-lock-syntactic-keywords
+ (list '(yaml-syntactic-block-literals 0 "." t))
+ "Additional syntax features to highlight in YAML mode.")
+
+
+(defun yaml-font-lock-block-literals (bound)
+ "Find lines within block literals.
+Find the next line of the first (if any) block literal after point and
+prior to BOUND. Returns the beginning and end of the block literal
+line in the match data, as consumed by `font-lock-keywords' matcher
+functions. The function begins by searching backwards to determine
+whether or not the current line is within a block literal. This could
+be time-consuming in large buffers, so the number of lines searched is
+artificially limitted to the value of
+`yaml-block-literal-search-lines'."
+ (if (eolp) (goto-char (1+ (point))))
+ (unless (or (eobp) (>= (point) bound))
+ (let ((begin (point))
+ (end (min (1+ (point-at-eol)) bound)))
+ (goto-char (point-at-bol))
+ (while (and (looking-at yaml-blank-line-re) (not (bobp)))
+ (forward-line -1))
+ (let ((nlines yaml-block-literal-search-lines)
+ (min-level (current-indentation)))
+ (forward-line -1)
+ (while (and (/= nlines 0)
+ (/= min-level 0)
+ (not (looking-at yaml-block-literal-re))
+ (not (bobp)))
+ (set 'nlines (1- nlines))
+ (unless (looking-at yaml-blank-line-re)
+ (set 'min-level (min min-level (current-indentation))))
+ (forward-line -1))
+ (cond
+ ((and (< (current-indentation) min-level)
+ (looking-at yaml-block-literal-re))
+ (goto-char end) (set-match-data (list begin end)) t)
+ ((progn
+ (goto-char begin)
+ (re-search-forward (concat yaml-block-literal-re
+ " *\\(.*\\)\n")
+ bound t))
+ (set-match-data (nthcdr 2 (match-data))) t))))))
+
+(defun yaml-syntactic-block-literals (bound)
+ "Find quote characters within block literals.
+Finds the first quote character within a block literal (if any) after
+point and prior to BOUND. Returns the position of the quote character
+in the match data, as consumed by matcher functions in
+`font-lock-syntactic-keywords'. This allows the mode to treat ['\"]
+characters in block literals as punctuation syntax instead of string
+syntax, preventing unmatched quotes in block literals from painting
+the entire buffer in `font-lock-string-face'."
+ (let ((found nil))
+ (while (and (not found)
+ (/= (point) bound)
+ (yaml-font-lock-block-literals bound))
+ (let ((begin (match-beginning 0)) (end (match-end 0)))
+ (goto-char begin)
+ (cond
+ ((re-search-forward "['\"]" end t) (setq found t))
+ ((goto-char end)))))
+ found))
+
+
+;; Indentation and electric keys
+
+(defun yaml-compute-indentation ()
+ "Calculate the maximum sensible indentation for the current line."
+ (save-excursion
+ (beginning-of-line)
+ (if (looking-at yaml-document-delimiter-re) 0
+ (forward-line -1)
+ (while (and (looking-at yaml-blank-line-re)
+ (> (point) (point-min)))
+ (forward-line -1))
+ (+ (current-indentation)
+ (if (looking-at yaml-nested-map-re) yaml-indent-offset 0)
+ (if (looking-at yaml-nested-sequence-re) yaml-indent-offset 0)
+ (if (looking-at yaml-block-literal-re) yaml-indent-offset 0)))))
+
+(defun yaml-indent-line ()
+ "Indent the current line.
+The first time this command is used, the line will be indented to the
+maximum sensible indentation. Each immediately subsequent usage will
+back-dent the line by `yaml-indent-offset' spaces. On reaching column
+0, it will cycle back to the maximum sensible indentation."
+ (interactive "*")
+ (let ((ci (current-indentation))
+ (cc (current-column))
+ (need (yaml-compute-indentation)))
+ (save-excursion
+ (beginning-of-line)
+ (delete-horizontal-space)
+ (if (and (equal last-command this-command) (/= ci 0))
+ (indent-to (* (/ (- ci 1) yaml-indent-offset) yaml-indent-offset))
+ (indent-to need)))
+ (if (< (current-column) (current-indentation))
+ (forward-to-indentation 0))))
+
+(defun yaml-electric-backspace (arg)
+ "Delete characters or back-dent the current line.
+If invoked following only whitespace on a line, will back-dent to the
+immediately previous multiple of `yaml-indent-offset' spaces."
+ (interactive "*p")
+ (if (or (/= (current-indentation) (current-column)) (bolp))
+ (funcall yaml-backspace-function arg)
+ (let ((ci (current-column)))
+ (beginning-of-line)
+ (delete-horizontal-space)
+ (indent-to (* (/ (- ci (* arg yaml-indent-offset))
+ yaml-indent-offset)
+ yaml-indent-offset)))))
+
+(defun yaml-electric-bar-and-angle (arg)
+ "Insert the bound key and possibly begin a block literal.
+Inserts the bound key. If inserting the bound key causes the current
+line to match the initial line of a block literal, then inserts the
+matching string from `yaml-block-literal-electric-alist', a newline,
+and indents appropriately."
+ (interactive "*P")
+ (self-insert-command (prefix-numeric-value arg))
+ (let ((extra-chars
+ (assoc last-command-char
+ yaml-block-literal-electric-alist)))
+ (cond
+ ((and extra-chars (not arg) (eolp)
+ (save-excursion
+ (beginning-of-line)
+ (looking-at yaml-block-literal-re)))
+ (insert (cdr extra-chars))
+ (newline-and-indent)))))
+
+(defun yaml-electric-dash-and-dot (arg)
+ "Insert the bound key and possibly de-dent line.
+Inserts the bound key. If inserting the bound key causes the current
+line to match a document delimiter, de-dent the line to the left
+margin."
+ (interactive "*P")
+ (self-insert-command (prefix-numeric-value arg))
+ (save-excursion
+ (beginning-of-line)
+ (if (and (not arg) (looking-at yaml-document-delimiter-re))
+ (delete-horizontal-space))))
+
+(defun yaml-mode-version ()
+ "Diplay version of `yaml-mode'."
+ (interactive)
+ (message "yaml-mode %s" yaml-mode-version)
+ yaml-mode-version)
+
+(provide 'yaml-mode)
+
+;;; yaml-mode.el ends here

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