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;;; ruby-mode.el --- Major mode for editing Ruby files

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;; Copyright (C) 1994-2013 Free Software Foundation, Inc.
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;; Authors: Yukihiro Matsumoto
;;	Nobuyoshi Nakada
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;; URL: http://www.emacswiki.org/cgi-bin/wiki/RubyMode
;; Created: Fri Feb  4 14:49:13 JST 1994
;; Keywords: languages ruby
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;; Version: 1.2
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;; This file is part of GNU Emacs.

;; GNU Emacs 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.

;; GNU Emacs 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.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; Provides font-locking, indentation support, and navigation for Ruby code.
;;
;; If you're installing manually, you should add this to your .emacs
;; file after putting it on your load path:
;;
;;    (autoload 'ruby-mode "ruby-mode" "Major mode for ruby files" t)
;;    (add-to-list 'auto-mode-alist '("\\.rb$" . ruby-mode))
;;    (add-to-list 'interpreter-mode-alist '("ruby" . ruby-mode))
;;
;; Still needs more docstrings; search below for TODO.

;;; Code:

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

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(defgroup ruby nil
  "Major mode for editing Ruby code."
  :prefix "ruby-"
  :group 'languages)

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(defconst ruby-block-beg-keywords
  '("class" "module" "def" "if" "unless" "case" "while" "until" "for" "begin" "do")
  "Keywords at the beginning of blocks.")

(defconst ruby-block-beg-re
  (regexp-opt ruby-block-beg-keywords)
  "Regexp to match the beginning of blocks.")

(defconst ruby-non-block-do-re
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  (regexp-opt '("while" "until" "for" "rescue") 'symbols)
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  "Regexp to match keywords that nest without blocks.")

(defconst ruby-indent-beg-re
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  (concat "^\\(\\s *" (regexp-opt '("class" "module" "def")) "\\|"
          (regexp-opt '("if" "unless" "case" "while" "until" "for" "begin"))
          "\\)\\_>")
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  "Regexp to match where the indentation gets deeper.")

(defconst ruby-modifier-beg-keywords
  '("if" "unless" "while" "until")
  "Modifiers that are the same as the beginning of blocks.")

(defconst ruby-modifier-beg-re
  (regexp-opt ruby-modifier-beg-keywords)
  "Regexp to match modifiers same as the beginning of blocks.")

(defconst ruby-modifier-re
  (regexp-opt (cons "rescue" ruby-modifier-beg-keywords))
  "Regexp to match modifiers.")

(defconst ruby-block-mid-keywords
  '("then" "else" "elsif" "when" "rescue" "ensure")
  "Keywords where the indentation gets shallower in middle of block statements.")

(defconst ruby-block-mid-re
  (regexp-opt ruby-block-mid-keywords)
  "Regexp to match where the indentation gets shallower in middle of block statements.")

(defconst ruby-block-op-keywords
  '("and" "or" "not")
  "Regexp to match boolean keywords.")

(defconst ruby-block-hanging-re
  (regexp-opt (append ruby-modifier-beg-keywords ruby-block-op-keywords))
  "Regexp to match hanging block modifiers.")

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(defconst ruby-block-end-re "\\_<end\\_>")
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(defconst ruby-defun-beg-re
  '"\\(def\\|class\\|module\\)"
  "Regexp to match the beginning of a defun, in the general sense.")

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(defconst ruby-singleton-class-re
  "class\\s *<<"
  "Regexp to match the beginning of a singleton class context.")

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(eval-and-compile
  (defconst ruby-here-doc-beg-re
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  "\\(<\\)<\\(-\\)?\\(\\([a-zA-Z0-9_]+\\)\\|[\"]\\([^\"]+\\)[\"]\\|[']\\([^']+\\)[']\\)"
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  "Regexp to match the beginning of a heredoc.")

  (defconst ruby-expression-expansion-re
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    "\\(?:[^\\]\\|\\=\\)\\(\\\\\\\\\\)*\\(#\\({[^}\n\\\\]*\\(\\\\.[^}\n\\\\]*\\)*}\\|\\(\\$\\|@\\|@@\\)\\(\\w\\|_\\)+\\)\\)"))
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(defun ruby-here-doc-end-match ()
  "Return a regexp to find the end of a heredoc.

This should only be called after matching against `ruby-here-doc-beg-re'."
  (concat "^"
          (if (match-string 2) "[ \t]*" nil)
          (regexp-quote
           (or (match-string 4)
               (match-string 5)
               (match-string 6)))))

(defconst ruby-delimiter
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  (concat "[?$/%(){}#\"'`.:]\\|<<\\|\\[\\|\\]\\|\\_<\\("
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          ruby-block-beg-re
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          "\\)\\_>\\|" ruby-block-end-re
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          "\\|^=begin\\|" ruby-here-doc-beg-re))

(defconst ruby-negative
  (concat "^[ \t]*\\(\\(" ruby-block-mid-re "\\)\\>\\|"
          ruby-block-end-re "\\|}\\|\\]\\)")
  "Regexp to match where the indentation gets shallower.")

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(defconst ruby-operator-re "[-,.+*/%&|^~=<>:]\\|\\\\$"
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  "Regexp to match operators.")

(defconst ruby-symbol-chars "a-zA-Z0-9_"
  "List of characters that symbol names may contain.")
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(defconst ruby-symbol-re (concat "[" ruby-symbol-chars "]")
  "Regexp to match symbols.")

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(define-abbrev-table 'ruby-mode-abbrev-table ()
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  "Abbrev table in use in Ruby mode buffers.")
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(defvar ruby-use-smie nil)

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(defvar ruby-mode-map
  (let ((map (make-sparse-keymap)))
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    (unless ruby-use-smie
      (define-key map (kbd "M-C-b") 'ruby-backward-sexp)
      (define-key map (kbd "M-C-f") 'ruby-forward-sexp)
      (define-key map (kbd "M-C-q") 'ruby-indent-exp))
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    (define-key map (kbd "M-C-p") 'ruby-beginning-of-block)
    (define-key map (kbd "M-C-n") 'ruby-end-of-block)
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    (define-key map (kbd "C-c {") 'ruby-toggle-block)
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    map)
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  "Keymap used in Ruby mode.")
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(defvar ruby-mode-syntax-table
  (let ((table (make-syntax-table)))
    (modify-syntax-entry ?\' "\"" table)
    (modify-syntax-entry ?\" "\"" table)
    (modify-syntax-entry ?\` "\"" table)
    (modify-syntax-entry ?# "<" table)
    (modify-syntax-entry ?\n ">" table)
    (modify-syntax-entry ?\\ "\\" table)
    (modify-syntax-entry ?$ "." table)
    (modify-syntax-entry ?? "_" table)
    (modify-syntax-entry ?_ "_" table)
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    (modify-syntax-entry ?: "_" table)
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    (modify-syntax-entry ?< "." table)
    (modify-syntax-entry ?> "." table)
    (modify-syntax-entry ?& "." table)
    (modify-syntax-entry ?| "." table)
    (modify-syntax-entry ?% "." table)
    (modify-syntax-entry ?= "." table)
    (modify-syntax-entry ?/ "." table)
    (modify-syntax-entry ?+ "." table)
    (modify-syntax-entry ?* "." table)
    (modify-syntax-entry ?- "." table)
    (modify-syntax-entry ?\; "." table)
    (modify-syntax-entry ?\( "()" table)
    (modify-syntax-entry ?\) ")(" table)
    (modify-syntax-entry ?\{ "(}" table)
    (modify-syntax-entry ?\} "){" table)
    (modify-syntax-entry ?\[ "(]" table)
    (modify-syntax-entry ?\] ")[" table)
    table)
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  "Syntax table to use in Ruby mode.")
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(defcustom ruby-indent-tabs-mode nil
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  "Indentation can insert tabs in Ruby mode if this is non-nil."
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  :type 'boolean :group 'ruby)

(defcustom ruby-indent-level 2
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  "Indentation of Ruby statements."
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  :type 'integer :group 'ruby)

(defcustom ruby-comment-column 32
  "Indentation column of comments."
  :type 'integer :group 'ruby)

(defcustom ruby-deep-arglist t
  "Deep indent lists in parenthesis when non-nil.
Also ignores spaces after parenthesis when 'space."
  :group 'ruby)

(defcustom ruby-deep-indent-paren '(?\( ?\[ ?\] t)
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  "Deep indent lists in parenthesis when non-nil.
The value t means continuous line.
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Also ignores spaces after parenthesis when 'space."
  :group 'ruby)

(defcustom ruby-deep-indent-paren-style 'space
  "Default deep indent style."
  :options '(t nil space) :group 'ruby)

(defcustom ruby-encoding-map '((shift_jis . cp932) (shift-jis . cp932))
  "Alist to map encoding name from Emacs to Ruby."
  :group 'ruby)

(defcustom ruby-insert-encoding-magic-comment t
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  "Insert a magic Emacs 'coding' comment upon save if this is non-nil."
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  :type 'boolean :group 'ruby)

(defcustom ruby-use-encoding-map t
  "Use `ruby-encoding-map' to set encoding magic comment if this is non-nil."
  :type 'boolean :group 'ruby)

;; Safe file variables
(put 'ruby-indent-tabs-mode 'safe-local-variable 'booleanp)
(put 'ruby-indent-level 'safe-local-variable 'integerp)
(put 'ruby-comment-column 'safe-local-variable 'integerp)
(put 'ruby-deep-arglist 'safe-local-variable 'booleanp)

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;;; SMIE support

(require 'smie)

(defconst ruby-smie-grammar
  ;; FIXME: Add support for Cucumber.
  (smie-prec2->grammar
   (smie-bnf->prec2
    '((id)
      (insts (inst) (insts ";" insts))
      (inst (exp) (inst "iuwu-mod" exp))
      (exp  (exp1) (exp "," exp))
      (exp1 (exp2) (exp2 "?" exp1 ":" exp1))
      (exp2 ("def" insts "end")
            ("begin" insts-rescue-insts "end")
            ("do" insts "end")
            ("class" insts "end") ("module" insts "end")
            ("for" for-body "end")
            ("[" expseq "]")
            ("{" hashvals "}")
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            ("{" insts "}")
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            ("while" insts "end")
            ("until" insts "end")
            ("unless" insts "end")
            ("if" if-body "end")
            ("case"  cases "end"))
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      (formal-params ("opening-|" exp "|"))
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      (for-body (for-head ";" insts))
      (for-head (id "in" exp))
      (cases (exp "then" insts) ;; FIXME: Ruby also allows (exp ":" insts).
	      (cases "when" cases) (insts "else" insts))
      (expseq (exp) );;(expseq "," expseq)
      (hashvals (id "=>" exp1) (hashvals "," hashvals))
      (insts-rescue-insts (insts)
                          (insts-rescue-insts "rescue" insts-rescue-insts)
                          (insts-rescue-insts "ensure" insts-rescue-insts))
      (itheni (insts) (exp "then" insts))
      (ielsei (itheni) (itheni "else" insts))
      (if-body (ielsei) (if-body "elsif" if-body)))
    '((nonassoc "in") (assoc ";") (assoc ","))
    '((assoc "when"))
    '((assoc "elsif"))
    '((assoc "rescue" "ensure"))
    '((assoc ",")))))

(defun ruby-smie--bosp ()
  (save-excursion (skip-chars-backward " \t")
                  (or (bolp) (eq (char-before) ?\;))))

(defun ruby-smie--implicit-semi-p ()
  (save-excursion
    (skip-chars-backward " \t")
    (not (or (bolp)
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             (and (memq (char-before) '(?\; ?- ?+ ?* ?/ ?: ?.))
                  ;; Make sure it's not the end of a regexp.
                  (not (eq (car (syntax-after (1- (point)))) 7)))
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             (and (memq (char-before) '(?\? ?=))
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                  (let ((tok (ruby-smie--backward-token)))
                    (or (equal tok "?")
                        (string-match "\\`\\s." tok))))))))

(defun ruby-smie--opening-pipe-p ()
  (save-excursion
    (if (eq ?| (char-before)) (forward-char -1))
    (skip-chars-backward " \t\n")
    (or (eq ?\{ (char-before))
        (looking-back "\\_<do" (- (point) 2)))))
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(defun ruby-smie--forward-token ()
  (skip-chars-forward " \t")
  (if (and (looking-at "[\n#]")
           ;; Only add implicit ; when needed.
           (ruby-smie--implicit-semi-p))
      (progn
        (if (eolp) (forward-char 1) (forward-comment 1))
        ";")
    (forward-comment (point-max))
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    (if (looking-at ":\\s.+")
        (progn (goto-char (match-end 0)) (match-string 0)) ;; bug#15208.
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    (let ((tok (smie-default-forward-token)))
      (cond
       ((member tok '("unless" "if" "while" "until"))
        (if (save-excursion (forward-word -1) (ruby-smie--bosp))
            tok "iuwu-mod"))
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         ((equal tok "|")
          (if (ruby-smie--opening-pipe-p) "opening-|" tok))
         (t tok))))))
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(defun ruby-smie--backward-token ()
  (let ((pos (point)))
    (forward-comment (- (point)))
    (if (and (> pos (line-end-position))
             (ruby-smie--implicit-semi-p))
        (progn (skip-chars-forward " \t")
               ";")
      (let ((tok (smie-default-backward-token)))
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        (when (and (eq ?: (char-before)) (string-match "\\`\\s." tok))
          (forward-char -1) (setq tok (concat ":" tok))) ;; bug#15208.
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        (cond
         ((member tok '("unless" "if" "while" "until"))
          (if (ruby-smie--bosp)
              tok "iuwu-mod"))
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         ((equal tok "|")
          (if (ruby-smie--opening-pipe-p) "opening-|" tok))
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         (t tok))))))

(defun ruby-smie-rules (kind token)
  (pcase (cons kind token)
    (`(:elem . basic) ruby-indent-level)
    (`(:after . ";")
     (if (smie-rule-parent-p "def" "begin" "do" "class" "module" "for"
                             "[" "{" "while" "until" "unless"
                             "if" "then" "elsif" "else" "when"
                             "rescue" "ensure")
         (smie-rule-parent ruby-indent-level)
       ;; For (invalid) code between switch and case.
       ;; (if (smie-parent-p "switch") 4)
       0))
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    (`(:before . "do")
     (when
         (save-excursion
           (forward-word 1)   ;Skip "do"
           (skip-chars-forward " \t")
           (and (equal (save-excursion (ruby-smie--forward-token)) "opening-|")
                (save-excursion (forward-sexp 1)
                                (skip-chars-forward " \t")
                                (or (eolp)
                                    (looking-at comment-start-skip)))))
       ;; `(column . ,(smie-indent-virtual))
       (smie-rule-parent)))
    (`(:before . ,(or `"else" `"then" `"elsif" `"rescue")) 0)
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    (`(:before . ,(or `"when"))
     (if (not (smie-rule-sibling-p)) 0)) ;; ruby-indent-level
    ;; Hack attack: Since newlines are separators, don't try to align args that
    ;; appear on a separate line.
    (`(:list-intro . ";") t)))

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(defun ruby-imenu-create-index-in-block (prefix beg end)
  "Create an imenu index of methods inside a block."
  (let ((index-alist '()) (case-fold-search nil)
        name next pos decl sing)
    (goto-char beg)
    (while (re-search-forward "^\\s *\\(\\(class\\s +\\|\\(class\\s *<<\\s *\\)\\|module\\s +\\)\\([^\(<\n ]+\\)\\|\\(def\\|alias\\)\\s +\\([^\(\n ]+\\)\\)" end t)
      (setq sing (match-beginning 3))
      (setq decl (match-string 5))
      (setq next (match-end 0))
      (setq name (or (match-string 4) (match-string 6)))
      (setq pos (match-beginning 0))
      (cond
       ((string= "alias" decl)
        (if prefix (setq name (concat prefix name)))
        (push (cons name pos) index-alist))
       ((string= "def" decl)
        (if prefix
            (setq name
                  (cond
                   ((string-match "^self\." name)
                    (concat (substring prefix 0 -1) (substring name 4)))
                  (t (concat prefix name)))))
        (push (cons name pos) index-alist)
        (ruby-accurate-end-of-block end))
       (t
        (if (string= "self" name)
            (if prefix (setq name (substring prefix 0 -1)))
          (if prefix (setq name (concat (substring prefix 0 -1) "::" name)))
          (push (cons name pos) index-alist))
        (ruby-accurate-end-of-block end)
        (setq beg (point))
        (setq index-alist
              (nconc (ruby-imenu-create-index-in-block
                      (concat name (if sing "." "#"))
                      next beg) index-alist))
        (goto-char beg))))
    index-alist))

(defun ruby-imenu-create-index ()
  "Create an imenu index of all methods in the buffer."
  (nreverse (ruby-imenu-create-index-in-block nil (point-min) nil)))

(defun ruby-accurate-end-of-block (&optional end)
  "TODO: document."
  (let (state
        (end (or end (point-max))))
    (while (and (setq state (apply 'ruby-parse-partial end state))
                (>= (nth 2 state) 0) (< (point) end)))))

(defun ruby-mode-variables ()
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  "Set up initial buffer-local variables for Ruby mode."
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  (set-syntax-table ruby-mode-syntax-table)
  (setq local-abbrev-table ruby-mode-abbrev-table)
  (setq indent-tabs-mode ruby-indent-tabs-mode)
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  (if ruby-use-smie
      (smie-setup ruby-smie-grammar #'ruby-smie-rules
                  :forward-token  #'ruby-smie--forward-token
                  :backward-token #'ruby-smie--backward-token)
    (set (make-local-variable 'indent-line-function) 'ruby-indent-line))
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  (set (make-local-variable 'require-final-newline) t)
  (set (make-local-variable 'comment-start) "# ")
  (set (make-local-variable 'comment-end) "")
  (set (make-local-variable 'comment-column) ruby-comment-column)
  (set (make-local-variable 'comment-start-skip) "#+ *")
  (set (make-local-variable 'parse-sexp-ignore-comments) t)
  (set (make-local-variable 'parse-sexp-lookup-properties) t)
  (set (make-local-variable 'paragraph-start) (concat "$\\|" page-delimiter))
  (set (make-local-variable 'paragraph-separate) paragraph-start)
  (set (make-local-variable 'paragraph-ignore-fill-prefix) t))

(defun ruby-mode-set-encoding ()
  "Insert a magic comment header with the proper encoding if necessary."
  (save-excursion
    (widen)
    (goto-char (point-min))
    (when (re-search-forward "[^\0-\177]" nil t)
      (goto-char (point-min))
      (let ((coding-system
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             (or (coding-system-get last-coding-system-used 'mime-charset)
                 (coding-system-change-eol-conversion ast-coding-system-used
                                                      nil))))
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        (setq coding-system
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              (symbol-name (or (and ruby-use-encoding-map
                                    (cdr (assq coding-system ruby-encoding-map)))
                               coding-system)))
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        (if (looking-at "^#!") (beginning-of-line 2))
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        (cond ((looking-at "\\s *#.*-\*-\\s *\\(en\\)?coding\\s *:\\s *\\([-a-z0-9_]*\\)\\s *\\(;\\|-\*-\\)")
               (unless (string= (match-string 2) coding-system)
                 (goto-char (match-beginning 2))
                 (delete-region (point) (match-end 2))
                 (and (looking-at "-\*-")
                      (let ((n (skip-chars-backward " ")))
                        (cond ((= n 0) (insert "  ") (backward-char))
                              ((= n -1) (insert " "))
                              ((forward-char)))))
                 (insert coding-system)))
              ((looking-at "\\s *#.*coding\\s *[:=]"))
              (t (when ruby-insert-encoding-magic-comment
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                   (insert "# -*- coding: " coding-system " -*-\n"))))
        (when (buffer-modified-p)
          (basic-save-buffer-1))))))
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(defun ruby-current-indentation ()
  "Return the indentation level of current line."
  (save-excursion
    (beginning-of-line)
    (back-to-indentation)
    (current-column)))

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(defun ruby-indent-line (&optional ignored)
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  "Correct the indentation of the current Ruby line."
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  (interactive)
  (ruby-indent-to (ruby-calculate-indent)))

(defun ruby-indent-to (column)
  "Indent the current line to COLUMN."
  (when column
    (let (shift top beg)
      (and (< column 0) (error "invalid nest"))
      (setq shift (current-column))
      (beginning-of-line)
      (setq beg (point))
      (back-to-indentation)
      (setq top (current-column))
      (skip-chars-backward " \t")
      (if (>= shift top) (setq shift (- shift top))
        (setq shift 0))
      (if (and (bolp)
               (= column top))
          (move-to-column (+ column shift))
        (move-to-column top)
        (delete-region beg (point))
        (beginning-of-line)
        (indent-to column)
        (move-to-column (+ column shift))))))

(defun ruby-special-char-p (&optional pos)
  "Return t if the character before POS is a special character.
If omitted, POS defaults to the current point.
Special characters are `?', `$', `:' when preceded by whitespace,
and `\\' when preceded by `?'."
  (setq pos (or pos (point)))
  (let ((c (char-before pos)) (b (and (< (point-min) pos)
				      (char-before (1- pos)))))
    (cond ((or (eq c ??) (eq c ?$)))
          ((and (eq c ?:) (or (not b) (eq (char-syntax b) ? ))))
          ((eq c ?\\) (eq b ??)))))

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(defun ruby-singleton-class-p (&optional pos)
  (save-excursion
    (when pos (goto-char pos))
    (forward-word -1)
    (and (or (bolp) (not (eq (char-before (point)) ?_)))
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         (looking-at ruby-singleton-class-re))))
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(defun ruby-expr-beg (&optional option)
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  "Check if point is possibly at the beginning of an expression.
OPTION specifies the type of the expression.
Can be one of `heredoc', `modifier', `expr-qstr', `expr-re'."
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  (save-excursion
    (store-match-data nil)
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    (let ((space (skip-chars-backward " \t"))
          (start (point)))
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      (cond
       ((bolp) t)
       ((progn
          (forward-char -1)
          (and (looking-at "\\?")
               (or (eq (char-syntax (char-before (point))) ?w)
                   (ruby-special-char-p))))
        nil)
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       ((looking-at ruby-operator-re))
       ((eq option 'heredoc)
        (and (< space 0) (not (ruby-singleton-class-p start))))
       ((or (looking-at "[\\[({,;]")
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            (and (looking-at "[!?]")
                 (or (not (eq option 'modifier))
                     (bolp)
                     (save-excursion (forward-char -1) (looking-at "\\Sw$"))))
            (and (looking-at ruby-symbol-re)
                 (skip-chars-backward ruby-symbol-chars)
                 (cond
                  ((looking-at (regexp-opt
                                (append ruby-block-beg-keywords
                                        ruby-block-op-keywords
                                        ruby-block-mid-keywords)
                                'words))
                   (goto-char (match-end 0))
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                   (not (looking-at "\\s_\\|!")))
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                  ((eq option 'expr-qstr)
                   (looking-at "[a-zA-Z][a-zA-z0-9_]* +%[^ \t]"))
                  ((eq option 'expr-re)
                   (looking-at "[a-zA-Z][a-zA-z0-9_]* +/[^ \t]"))
                  (t nil)))))))))

(defun ruby-forward-string (term &optional end no-error expand)
  "TODO: document."
  (let ((n 1) (c (string-to-char term))
        (re (if expand
                (concat "[^\\]\\(\\\\\\\\\\)*\\([" term "]\\|\\(#{\\)\\)")
              (concat "[^\\]\\(\\\\\\\\\\)*[" term "]"))))
    (while (and (re-search-forward re end no-error)
                (if (match-beginning 3)
                    (ruby-forward-string "}{" end no-error nil)
                  (> (setq n (if (eq (char-before (point)) c)
                                     (1- n) (1+ n))) 0)))
      (forward-char -1))
    (cond ((zerop n))
          (no-error nil)
          ((error "unterminated string")))))

(defun ruby-deep-indent-paren-p (c)
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  "TODO: document."
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  (cond ((listp ruby-deep-indent-paren)
         (let ((deep (assoc c ruby-deep-indent-paren)))
           (cond (deep
                  (or (cdr deep) ruby-deep-indent-paren-style))
                 ((memq c ruby-deep-indent-paren)
                  ruby-deep-indent-paren-style))))
        ((eq c ruby-deep-indent-paren) ruby-deep-indent-paren-style)
        ((eq c ?\( ) ruby-deep-arglist)))

(defun ruby-parse-partial (&optional end in-string nest depth pcol indent)
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  "TODO: document throughout function body."
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  (or depth (setq depth 0))
  (or indent (setq indent 0))
  (when (re-search-forward ruby-delimiter end 'move)
    (let ((pnt (point)) w re expand)
      (goto-char (match-beginning 0))
      (cond
       ((and (memq (char-before) '(?@ ?$)) (looking-at "\\sw"))
        (goto-char pnt))
       ((looking-at "[\"`]")            ;skip string
        (cond
         ((and (not (eobp))
               (ruby-forward-string (buffer-substring (point) (1+ (point))) end t t))
          nil)
         (t
          (setq in-string (point))
          (goto-char end))))
       ((looking-at "'")
        (cond
         ((and (not (eobp))
               (re-search-forward "[^\\]\\(\\\\\\\\\\)*'" end t))
          nil)
         (t
          (setq in-string (point))
          (goto-char end))))
       ((looking-at "/=")
        (goto-char pnt))
       ((looking-at "/")
        (cond
         ((and (not (eobp)) (ruby-expr-beg 'expr-re))
          (if (ruby-forward-string "/" end t t)
              nil
            (setq in-string (point))
            (goto-char end)))
         (t
          (goto-char pnt))))
       ((looking-at "%")
        (cond
         ((and (not (eobp))
               (ruby-expr-beg 'expr-qstr)
               (not (looking-at "%="))
               (looking-at "%[QqrxWw]?\\([^a-zA-Z0-9 \t\n]\\)"))
          (goto-char (match-beginning 1))
          (setq expand (not (memq (char-before) '(?q ?w))))
          (setq w (match-string 1))
          (cond
           ((string= w "[") (setq re "]["))
           ((string= w "{") (setq re "}{"))
           ((string= w "(") (setq re ")("))
           ((string= w "<") (setq re "><"))
           ((and expand (string= w "\\"))
            (setq w (concat "\\" w))))
          (unless (cond (re (ruby-forward-string re end t expand))
                        (expand (ruby-forward-string w end t t))
                        (t (re-search-forward
                            (if (string= w "\\")
                                "\\\\[^\\]*\\\\"
                              (concat "[^\\]\\(\\\\\\\\\\)*" w))
                            end t)))
            (setq in-string (point))
            (goto-char end)))
         (t
          (goto-char pnt))))
       ((looking-at "\\?")              ;skip ?char
        (cond
         ((and (ruby-expr-beg)
               (looking-at "?\\(\\\\C-\\|\\\\M-\\)*\\\\?."))
          (goto-char (match-end 0)))
         (t
          (goto-char pnt))))
       ((looking-at "\\$")              ;skip $char
        (goto-char pnt)
        (forward-char 1))
       ((looking-at "#")                ;skip comment
        (forward-line 1)
        (goto-char (point))
        )
       ((looking-at "[\\[{(]")
        (let ((deep (ruby-deep-indent-paren-p (char-after))))
          (if (and deep (or (not (eq (char-after) ?\{)) (ruby-expr-beg)))
              (progn
                (and (eq deep 'space) (looking-at ".\\s +[^# \t\n]")
                     (setq pnt (1- (match-end 0))))
                (setq nest (cons (cons (char-after (point)) pnt) nest))
                (setq pcol (cons (cons pnt depth) pcol))
                (setq depth 0))
            (setq nest (cons (cons (char-after (point)) pnt) nest))
            (setq depth (1+ depth))))
        (goto-char pnt)
        )
       ((looking-at "[])}]")
        (if (ruby-deep-indent-paren-p (matching-paren (char-after)))
            (setq depth (cdr (car pcol)) pcol (cdr pcol))
          (setq depth (1- depth)))
        (setq nest (cdr nest))
        (goto-char pnt))
       ((looking-at ruby-block-end-re)
        (if (or (and (not (bolp))
                     (progn
                       (forward-char -1)
                       (setq w (char-after (point)))
                       (or (eq ?_ w)
                           (eq ?. w))))
                (progn
                  (goto-char pnt)
                  (setq w (char-after (point)))
                  (or (eq ?_ w)
                      (eq ?! w)
                      (eq ?? w))))
            nil
          (setq nest (cdr nest))
          (setq depth (1- depth)))
        (goto-char pnt))
       ((looking-at "def\\s +[^(\n;]*")
        (if (or (bolp)
                (progn
                  (forward-char -1)
                  (not (eq ?_ (char-after (point))))))
            (progn
              (setq nest (cons (cons nil pnt) nest))
              (setq depth (1+ depth))))
        (goto-char (match-end 0)))
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       ((looking-at (concat "\\_<\\(" ruby-block-beg-re "\\)\\_>"))
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        (and
         (save-match-data
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           (or (not (looking-at "do\\_>"))
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               (save-excursion
                 (back-to-indentation)
                 (not (looking-at ruby-non-block-do-re)))))
         (or (bolp)
             (progn
               (forward-char -1)
               (setq w (char-after (point)))
               (not (or (eq ?_ w)
                        (eq ?. w)))))
         (goto-char pnt)
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         (not (eq ?! (char-after (point))))
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         (skip-chars-forward " \t")
         (goto-char (match-beginning 0))
         (or (not (looking-at ruby-modifier-re))
             (ruby-expr-beg 'modifier))
         (goto-char pnt)
         (setq nest (cons (cons nil pnt) nest))
         (setq depth (1+ depth)))
        (goto-char pnt))
       ((looking-at ":\\(['\"]\\)")
        (goto-char (match-beginning 1))
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        (ruby-forward-string (match-string 1) end t))
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       ((looking-at ":\\([-,.+*/%&|^~<>]=?\\|===?\\|<=>\\|![~=]?\\)")
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        (goto-char (match-end 0)))
       ((looking-at ":\\([a-zA-Z_][a-zA-Z_0-9]*[!?=]?\\)?")
        (goto-char (match-end 0)))
       ((or (looking-at "\\.\\.\\.?")
            (looking-at "\\.[0-9]+")
            (looking-at "\\.[a-zA-Z_0-9]+")
            (looking-at "\\."))
        (goto-char (match-end 0)))
       ((looking-at "^=begin")
        (if (re-search-forward "^=end" end t)
            (forward-line 1)
          (setq in-string (match-end 0))
          (goto-char end)))
       ((looking-at "<<")
        (cond
         ((and (ruby-expr-beg 'heredoc)
               (looking-at "<<\\(-\\)?\\(\\([\"'`]\\)\\([^\n]+?\\)\\3\\|\\(?:\\sw\\|\\s_\\)+\\)"))
          (setq re (regexp-quote (or (match-string 4) (match-string 2))))
          (if (match-beginning 1) (setq re (concat "\\s *" re)))
          (let* ((id-end (goto-char (match-end 0)))
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                 (line-end-position (point-at-eol))
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                 (state (list in-string nest depth pcol indent)))
            ;; parse the rest of the line
            (while (and (> line-end-position (point))
                        (setq state (apply 'ruby-parse-partial
                                           line-end-position state))))
            (setq in-string (car state)
                  nest (nth 1 state)
                  depth (nth 2 state)
                  pcol (nth 3 state)
                  indent (nth 4 state))
            ;; skip heredoc section
            (if (re-search-forward (concat "^" re "$") end 'move)
                (forward-line 1)
              (setq in-string id-end)
              (goto-char end))))
         (t
          (goto-char pnt))))
       ((looking-at "^__END__$")
        (goto-char pnt))
       ((and (looking-at ruby-here-doc-beg-re)
	     (boundp 'ruby-indent-point))
        (if (re-search-forward (ruby-here-doc-end-match)
                               ruby-indent-point t)
            (forward-line 1)
          (setq in-string (match-end 0))
          (goto-char ruby-indent-point)))
       (t
        (error (format "bad string %s"
                       (buffer-substring (point) pnt)
                       ))))))
  (list in-string nest depth pcol))

(defun ruby-parse-region (start end)
  "TODO: document."
  (let (state)
    (save-excursion
      (if start
          (goto-char start)
        (ruby-beginning-of-indent))
      (save-restriction
        (narrow-to-region (point) end)
        (while (and (> end (point))
                    (setq state (apply 'ruby-parse-partial end state))))))
    (list (nth 0 state)                 ; in-string
          (car (nth 1 state))           ; nest
          (nth 2 state)                 ; depth
          (car (car (nth 3 state)))     ; pcol
          ;(car (nth 5 state))          ; indent
          )))

(defun ruby-indent-size (pos nest)
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  "Return the indentation level in spaces NEST levels deeper than POS."
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  (+ pos (* (or nest 1) ruby-indent-level)))

(defun ruby-calculate-indent (&optional parse-start)
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  "Return the proper indentation level of the current line."
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  ;; TODO: Document body
  (save-excursion
    (beginning-of-line)
    (let ((ruby-indent-point (point))
          (case-fold-search nil)
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          state eol begin op-end
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          (paren (progn (skip-syntax-forward " ")
                        (and (char-after) (matching-paren (char-after)))))
          (indent 0))
      (if parse-start
          (goto-char parse-start)
        (ruby-beginning-of-indent)
        (setq parse-start (point)))
      (back-to-indentation)
      (setq indent (current-column))
      (setq state (ruby-parse-region parse-start ruby-indent-point))
      (cond
       ((nth 0 state)                   ; within string
        (setq indent nil))              ;  do nothing
       ((car (nth 1 state))             ; in paren
        (goto-char (setq begin (cdr (nth 1 state))))
        (let ((deep (ruby-deep-indent-paren-p (car (nth 1 state)))))
          (if deep
              (cond ((and (eq deep t) (eq (car (nth 1 state)) paren))
                     (skip-syntax-backward " ")
                     (setq indent (1- (current-column))))
                    ((let ((s (ruby-parse-region (point) ruby-indent-point)))
                       (and (nth 2 s) (> (nth 2 s) 0)
                            (or (goto-char (cdr (nth 1 s))) t)))
                     (forward-word -1)
                     (setq indent (ruby-indent-size (current-column)
						    (nth 2 state))))
                    (t
                     (setq indent (current-column))
                     (cond ((eq deep 'space))
                           (paren (setq indent (1- indent)))
                           (t (setq indent (ruby-indent-size (1- indent) 1))))))
            (if (nth 3 state) (goto-char (nth 3 state))
              (goto-char parse-start) (back-to-indentation))
            (setq indent (ruby-indent-size (current-column) (nth 2 state))))
          (and (eq (car (nth 1 state)) paren)
               (ruby-deep-indent-paren-p (matching-paren paren))
               (search-backward (char-to-string paren))
               (setq indent (current-column)))))
       ((and (nth 2 state) (> (nth 2 state) 0)) ; in nest
        (if (null (cdr (nth 1 state)))
            (error "invalid nest"))
        (goto-char (cdr (nth 1 state)))
        (forward-word -1)               ; skip back a keyword
        (setq begin (point))
        (cond
         ((looking-at "do\\>[^_]")      ; iter block is a special case
          (if (nth 3 state) (goto-char (nth 3 state))
            (goto-char parse-start) (back-to-indentation))
          (setq indent (ruby-indent-size (current-column) (nth 2 state))))
         (t
          (setq indent (+ (current-column) ruby-indent-level)))))
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       ((and (nth 2 state) (< (nth 2 state) 0)) ; in negative nest
        (setq indent (ruby-indent-size (current-column) (nth 2 state)))))
      (when indent
        (goto-char ruby-indent-point)
        (end-of-line)
        (setq eol (point))
        (beginning-of-line)
        (cond
         ((and (not (ruby-deep-indent-paren-p paren))
               (re-search-forward ruby-negative eol t))
          (and (not (eq ?_ (char-after (match-end 0))))
               (setq indent (- indent ruby-indent-level))))
         ((and
           (save-excursion
             (beginning-of-line)
             (not (bobp)))
           (or (ruby-deep-indent-paren-p t)
               (null (car (nth 1 state)))))
          ;; goto beginning of non-empty no-comment line
          (let (end done)
            (while (not done)
              (skip-chars-backward " \t\n")
              (setq end (point))
              (beginning-of-line)
              (if (re-search-forward "^\\s *#" end t)
                  (beginning-of-line)
                (setq done t))))
          (end-of-line)
          ;; skip the comment at the end
          (skip-chars-backward " \t")
          (let (end (pos (point)))
            (beginning-of-line)
            (while (and (re-search-forward "#" pos t)
                        (setq end (1- (point)))
                        (or (ruby-special-char-p end)
                            (and (setq state (ruby-parse-region parse-start end))
                                 (nth 0 state))))
              (setq end nil))
            (goto-char (or end pos))
            (skip-chars-backward " \t")
            (setq begin (if (and end (nth 0 state)) pos (cdr (nth 1 state))))
            (setq state (ruby-parse-region parse-start (point))))
          (or (bobp) (forward-char -1))
          (and
           (or (and (looking-at ruby-symbol-re)
                    (skip-chars-backward ruby-symbol-chars)
                    (looking-at (concat "\\<\\(" ruby-block-hanging-re "\\)\\>"))
                    (not (eq (point) (nth 3 state)))
                    (save-excursion
                      (goto-char (match-end 0))
                      (not (looking-at "[a-z_]"))))
               (and (looking-at ruby-operator-re)
                    (not (ruby-special-char-p))
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                    (save-excursion
                      (forward-char -1)
                      (or (not (looking-at ruby-operator-re))
                          (not (eq (char-before) ?:))))
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                    ;; Operator at the end of line.
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                    (let ((c (char-after (point))))
                      (and
;;                     (or (null begin)
;;                         (save-excursion
;;                           (goto-char begin)
;;                           (skip-chars-forward " \t")
;;                           (not (or (eolp) (looking-at "#")
;;                                    (and (eq (car (nth 1 state)) ?{)
;;                                         (looking-at "|"))))))
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                       ;; Not a regexp or percent literal.
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                       (null (nth 0 (ruby-parse-region (or begin parse-start)
                                                       (point))))
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                       (or (not (eq ?| (char-after (point))))
                           (save-excursion
                             (or (eolp) (forward-char -1))
                             (cond
                              ((search-backward "|" nil t)
                               (skip-chars-backward " \t\n")
                               (and (not (eolp))
                                    (progn
                                      (forward-char -1)
                                      (not (looking-at "{")))
                                    (progn
                                      (forward-word -1)
                                      (not (looking-at "do\\>[^_]")))))
                              (t t))))
                       (not (eq ?, c))
                       (setq op-end t)))))
           (setq indent
                 (cond
                  ((and
                    (null op-end)
                    (not (looking-at (concat "\\<\\(" ruby-block-hanging-re "\\)\\>")))
                    (eq (ruby-deep-indent-paren-p t) 'space)
                    (not (bobp)))
                   (widen)
                   (goto-char (or begin parse-start))
                   (skip-syntax-forward " ")
                   (current-column))
                  ((car (nth 1 state)) indent)
                  (t
                   (+ indent ruby-indent-level))))))))
      (goto-char ruby-indent-point)
      (beginning-of-line)
      (skip-syntax-forward " ")
      (if (looking-at "\\.[^.]")
          (+ indent ruby-indent-level)
        indent))))

(defun ruby-beginning-of-defun (&optional arg)
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  "Move backward to the beginning of the current defun.
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With ARG, move backward multiple defuns.  Negative ARG means
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move forward."
  (interactive "p")
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  (let (case-fold-search)
    (and (re-search-backward (concat "^\\s *" ruby-defun-beg-re "\\_>")
                             nil t (or arg 1))
         (beginning-of-line))))

(defun ruby-end-of-defun ()
  "Move point to the end of the current defun.
The defun begins at or after the point.  This function is called
by `end-of-defun'."
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  (interactive "p")
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  (ruby-forward-sexp)
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  (let (case-fold-search)
    (when (looking-back (concat "^\\s *" ruby-block-end-re))
      (forward-line 1))))
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(defun ruby-beginning-of-indent ()
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  "Backtrack to a line which can be used as a reference for
calculating indentation on the lines after it."
  (while (and (re-search-backward ruby-indent-beg-re nil 'move)
              (if (ruby-in-ppss-context-p 'anything)
                  t
                ;; We can stop, then.
                (beginning-of-line)))))
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(defun ruby-move-to-block (n)
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  "Move to the beginning (N < 0) or the end (N > 0) of the
current block, a sibling block, or an outer block.  Do that (abs N) times."
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  (back-to-indentation)
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  (let ((signum (if (> n 0) 1 -1))
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        (backward (< n 0))
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        (depth (or (nth 2 (ruby-parse-region (point) (line-end-position))) 0))
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        case-fold-search
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        down done)
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    (when (looking-at ruby-block-mid-re)
      (setq depth (+ depth signum)))
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    (when (< (* depth signum) 0)
      ;; Moving end -> end or beginning -> beginning.
      (setq depth 0))
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    (dotimes (_ (abs n))
      (setq done nil)
      (setq down (save-excursion
                   (back-to-indentation)
                   ;; There is a block start or block end keyword on this
                   ;; line, don't need to look for another block.
                   (and (re-search-forward
                         (if backward ruby-block-end-re
                           (concat "\\_<\\(" ruby-block-beg-re "\\)\\_>"))
                         (line-end-position) t)
                        (not (nth 8 (syntax-ppss))))))
      (while (and (not done) (not (if backward (bobp) (eobp))))
        (forward-line signum)
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        (cond
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         ;; Skip empty and commented out lines.
         ((looking-at "^\\s *$"))
         ((looking-at "^\\s *#"))
         ;; Skip block comments;
         ((and (not backward) (looking-at "^=begin\\>"))
          (re-search-forward "^=end\\>"))
         ((and backward (looking-at "^=end\\>"))
          (re-search-backward "^=begin\\>"))
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         ;; Jump over a multiline literal.
         ((ruby-in-ppss-context-p 'string)
          (goto-char (nth 8 (syntax-ppss)))
          (unless backward
            (forward-sexp)
            (when (bolp) (forward-char -1)))) ; After a heredoc.
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         (t
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          (let ((state (ruby-parse-region (point) (line-end-position))))
            (unless (car state) ; Line ends with unfinished string.
              (setq depth (+ (nth 2 state) depth))))
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          (cond
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           ;; Increased depth, we found a block.
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           ((> (* signum depth) 0)
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            (setq down t))
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           ;; We're at the same depth as when we started, and we've
           ;; encountered a block before.  Stop.
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           ((and down (zerop depth))
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            (setq done t))
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           ;; Lower depth, means outer block, can stop now.
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           ((< (* signum depth) 0)
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            (setq done t)))))))
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    (back-to-indentation)))
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(defun ruby-beginning-of-block (&optional arg)
  "Move backward to the beginning of the current block.
With ARG, move up multiple blocks."
  (interactive "p")
  (ruby-move-to-block (- (or arg 1))))

(defun ruby-end-of-block (&optional arg)
  "Move forward to the end of the current block.
With ARG, move out of multiple blocks."
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  (interactive "p")
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  (ruby-move-to-block (or arg 1)))

(defun ruby-forward-sexp (&optional arg)
  "Move forward across one balanced expression (sexp).
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With ARG, do it many times.  Negative ARG means move backward."
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  ;; TODO: Document body
  (interactive "p")
  (if (and (numberp arg) (< arg 0))
      (ruby-backward-sexp (- arg))
    (let ((i (or arg 1)))
      (condition-case nil
          (while (> i 0)
            (skip-syntax-forward " ")
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	    (if (looking-at ",\\s *") (goto-char (match-end 0)))
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            (cond ((looking-at "\\?\\(\\\\[CM]-\\)*\\\\?\\S ")
                   (goto-char (match-end 0)))
                  ((progn
                     (skip-chars-forward ",.:;|&^~=!?\\+\\-\\*")
                     (looking-at "\\s("))
                   (goto-char (scan-sexps (point) 1)))
                  ((and (looking-at (concat "\\<\\(" ruby-block-beg-re "\\)\\>"))
                        (not (eq (char-before (point)) ?.))
                        (not (eq (char-before (point)) ?:)))
                   (ruby-end-of-block)
                   (forward-word 1))
                  ((looking-at "\\(\\$\\|@@?\\)?\\sw")
                   (while (progn
                            (while (progn (forward-word 1) (looking-at "_")))
                            (cond ((looking-at "::") (forward-char 2) t)
                                  ((> (skip-chars-forward ".") 0))
                                  ((looking-at "\\?\\|!\\(=[~=>]\\|[^~=]\\)")
                                   (forward-char 1) nil)))))
                  ((let (state expr)
                     (while
                         (progn
                           (setq expr (or expr (ruby-expr-beg)
                                          (looking-at "%\\sw?\\Sw\\|[\"'`/]")))
                           (nth 1 (setq state (apply 'ruby-parse-partial nil state))))
                       (setq expr t)
                       (skip-chars-forward "<"))
                     (not expr))))
            (setq i (1- i)))
        ((error) (forward-word 1)))
      i)))

(defun ruby-backward-sexp (&optional arg)
  "Move backward across one balanced expression (sexp).
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With ARG, do it many times.  Negative ARG means move forward."
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  ;; TODO: Document body
  (interactive "p")
  (if (and (numberp arg) (< arg 0))
      (ruby-forward-sexp (- arg))
    (let ((i (or arg 1)))
      (condition-case nil
          (while (> i 0)
            (skip-chars-backward " \t\n,.:;|&^~=!?\\+\\-\\*")
            (forward-char -1)
            (cond ((looking-at "\\s)")
                   (goto-char (scan-sexps (1+ (point)) -1))
                   (case (char-before)
                     (?% (forward-char -1))
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                     ((?q ?Q ?w ?W ?r ?x)
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                      (if (eq (char-before (1- (point))) ?%) (forward-char -2))))
                   nil)
                  ((looking-at "\\s\"\\|\\\\\\S_")
                   (let ((c (char-to-string (char-before (match-end 0)))))
                     (while (and (search-backward c)
				 (eq (logand (skip-chars-backward "\\") 1)
				     1))))
                   nil)
                  ((looking-at "\\s.\\|\\s\\")
                   (if (ruby-special-char-p) (forward-char -1)))
                  ((looking-at "\\s(") nil)
                  (t
                   (forward-char 1)
                   (while (progn (forward-word -1)
                                 (case (char-before)
                                   (?_ t)
                                   (?. (forward-char -1) t)
                                   ((?$ ?@)
                                    (forward-char -1)
                                    (and (eq (char-before) (char-after)) (forward-char -1)))
                                   (?:
                                    (forward-char -1)
                                    (eq (char-before) :)))))
                   (if (looking-at ruby-block-end-re)
                       (ruby-beginning-of-block))
                   nil))
            (setq i (1- i)))
        ((error)))
      i)))

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(defun ruby-indent-exp (&optional ignored)
  "Indent each line in the balanced expression following the point."
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  (interactive "*P")
  (let ((here (point-marker)) start top column (nest t))
    (set-marker-insertion-type here t)
    (unwind-protect
        (progn
          (beginning-of-line)
          (setq start (point) top (current-indentation))
          (while (and (not (eobp))
                      (progn
                        (setq column (ruby-calculate-indent start))
                        (cond ((> column top)
                               (setq nest t))
                              ((and (= column top) nest)
                               (setq nest nil) t))))
            (ruby-indent-to column)
            (beginning-of-line 2)))
      (goto-char here)
      (set-marker here nil))))

(defun ruby-add-log-current-method ()
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  "Return the current method name as a string.
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This string includes all namespaces.

For example:

  #exit
  String#gsub
  Net::HTTP#active?
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  File.open
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See `add-log-current-defun-function'."
  (condition-case nil
      (save-excursion
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        (let* ((indent 0) mname mlist
               (start (point))
               (make-definition-re
                (lambda (re)
                  (concat "^[ \t]*" re "[ \t]+"
                          "\\("
                          ;; \\. and :: for class methods
                          "\\([A-Za-z_]" ruby-symbol-re "*\\|\\.\\|::" "\\)"
                          "+\\)")))
               (definition-re (funcall make-definition-re ruby-defun-beg-re))
               (module-re (funcall make-definition-re "\\(class\\|module\\)")))
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          ;; Get the current method definition (or class/module).
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          (when (re-search-backward definition-re nil t)
            (goto-char (match-beginning 1))
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            (if (not (string-equal "def" (match-string 1)))
                (setq mlist (list (match-string 2)))
              ;; We're inside the method. For classes and modules,
              ;; this check is skipped for performance.
              (when (ruby-block-contains-point start)
                (setq mname (match-string 2))))
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            (setq indent (current-column))
            (beginning-of-line))
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          ;; Walk up the class/module nesting.
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          (while (and (> indent 0)
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                      (re-search-backward module-re nil t))
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            (goto-char (match-beginning 1))
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            (when (< (current-column) indent)
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              (setq mlist (cons (match-string 2) mlist))
              (setq indent (current-column))
              (beginning-of-line)))
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          ;; Process the method name.
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          (when mname
            (let ((mn (split-string mname "\\.\\|::")))
              (if (cdr mn)
                  (progn
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                    (unless (string-equal "self" (car mn)) ; def self.foo
                      ;; def C.foo
                      (let ((ml (nreverse mlist)))
                        ;; If the method name references one of the
                        ;; containing modules, drop the more nested ones.
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                        (while ml
                          (if (string-equal (car ml) (car mn))
                              (setq mlist (nreverse (cdr ml)) ml nil))
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                          (or (setq ml (cdr ml)) (nreverse mlist))))
                      (if mlist
                          (setcdr (last mlist) (butlast mn))
                        (setq mlist (butlast mn))))
                    (setq mname (concat "." (car (last mn)))))
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                ;; See if the method is in singleton class context.
                (let ((in-singleton-class
                       (when (re-search-forward ruby-singleton-class-re start t)
                         (goto-char (match-beginning 0))
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                         ;; FIXME: Optimize it out, too?
                         ;; This can be slow in a large file, but
                         ;; unlike class/module declaration
                         ;; indentations, method definitions can be
                         ;; intermixed with these, and may or may not
                         ;; be additionally indented after visibility
                         ;; keywords.
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                         (ruby-block-contains-point start))))
                  (setq mname (concat
                               (if in-singleton-class "." "#")
                               mname))))))
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          ;; Generate the string.
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          (if (consp mlist)
              (setq mlist (mapconcat (function identity) mlist "::")))
          (if mname
              (if mlist (concat mlist mname) mname)
            mlist)))))

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(defun ruby-block-contains-point (pt)
  (save-excursion
    (save-match-data
      (ruby-forward-sexp)
      (> (point) pt))))

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(defun ruby-brace-to-do-end (orig end)
  (let (beg-marker end-marker)
    (goto-char end)
    (when (eq (char-before) ?\})
      (delete-char -1)
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      (when (save-excursion
              (skip-chars-backward " \t")
              (not (bolp)))
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        (insert "\n"))
      (insert "end")
      (setq end-marker (point-marker))
      (when (and (not (eobp)) (eq (char-syntax (char-after)) ?w))
        (insert " "))
      (goto-char orig)
      (delete-char 1)
      (when (eq (char-syntax (char-before)) ?w)
        (insert " "))
      (insert "do")
      (setq beg-marker (point-marker))
      (when (looking-at "\\(\\s \\)*|")
        (unless (match-beginning 1)
          (insert " "))
        (goto-char (1+ (match-end 0)))
        (search-forward "|"))
      (unless (looking-at "\\s *$")
        (insert "\n"))
      (indent-region beg-marker end-marker)
      (goto-char beg-marker)
      t)))

(defun ruby-do-end-to-brace (orig end)
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  (let (beg-marker end-marker beg-pos end-pos)
    (goto-char (- end 3))
    (when (looking-at ruby-block-end-re)
      (delete-char 3)
      (setq end-marker (point-marker))
      (insert "}")
      (goto-char orig)
      (delete-char 2)
      (insert "{")
      (setq beg-marker (point-marker))
      (when (looking-at "\\s +|")
        (delete-char (- (match-end 0) (match-beginning 0) 1))
        (forward-char)
        (re-search-forward "|" (line-end-position) t))
      (save-excursion
        (skip-chars-forward " \t\n\r")
        (setq beg-pos (point))
        (goto-char end-marker)
        (skip-chars-backward " \t\n\r")
        (setq end-pos (point)))
      (when (or
             (< end-pos beg-pos)
             (and (= (line-number-at-pos beg-pos) (line-number-at-pos end-pos))
                  (< (+ (current-column) (- end-pos beg-pos) 2) fill-column)))
        (just-one-space -1)
        (goto-char end-marker)
        (just-one-space -1))
      (goto-char beg-marker)
      t)))
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(defun ruby-toggle-block ()
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  "Toggle block type from do-end to braces or back.
The block must begin on the current line or above it and end after the point.
If the result is do-end block, it will always be multiline."
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  (interactive)
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  (let ((start (point)) beg end)
    (end-of-line)
    (unless
        (if (and (re-search-backward "\\({\\)\\|\\_<do\\(\\s \\|$\\||\\)")
                 (progn
                   (setq beg (point))
                   (save-match-data (ruby-forward-sexp))
                   (setq end (point))
                   (> end start)))
            (if (match-beginning 1)
                (ruby-brace-to-do-end beg end)
              (ruby-do-end-to-brace beg end)))
      (goto-char start))))
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(declare-function ruby-syntax-propertize-heredoc "ruby-mode" (limit))
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(declare-function ruby-syntax-enclosing-percent-literal "ruby-mode" (limit))
(declare-function ruby-syntax-propertize-percent-literal "ruby-mode" (limit))
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;; Unusual code layout confuses the byte-compiler.
(declare-function ruby-syntax-propertize-expansion "ruby-mode" ())
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(declare-function ruby-syntax-expansion-allowed-p "ruby-mode" (parse-state))
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(declare-function ruby-syntax-propertize-function "ruby-mode" (start end))
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(if (eval-when-compile (fboundp #'syntax-propertize-rules))
    ;; New code that works independently from font-lock.
    (progn
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      (eval-and-compile
        (defconst ruby-percent-literal-beg-re
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          "\\(%\\)[qQrswWxIi]?\\([[:punct:]]\\)"
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          "Regexp to match the beginning of percent literal.")

        (defconst ruby-syntax-methods-before-regexp
          '("gsub" "gsub!" "sub" "sub!" "scan" "split" "split!" "index" "match"
            "assert_match" "Given" "Then" "When")
          "Methods that can take regexp as the first argument.
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It will be properly highlighted even when the call omits parens.")

        (defvar ruby-syntax-before-regexp-re
          (concat
           ;; Special tokens that can't be followed by a division operator.
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           "\\(^\\|[[=(,~;<>]"
           ;; Distinguish ternary operator tokens.
           ;; FIXME: They don't really have to be separated with spaces.
           "\\|[?:] "
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           ;; Control flow keywords and operators following bol or whitespace.
           "\\|\\(?:^\\|\\s \\)"
           (regexp-opt '("if" "elsif" "unless" "while" "until" "when" "and"
                         "or" "not" "&&" "||"))
           ;; Method name from the list.
           "\\|\\_<"
           (regexp-opt ruby-syntax-methods-before-regexp)
           "\\)\\s *")
          "Regexp to match text that can be followed by a regular expression."))
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      (defun ruby-syntax-propertize-function (start end)
        "Syntactic keywords for Ruby mode.  See `syntax-propertize-function'."
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        (let (case-fold-search)
          (goto-char start)
          (remove-text-properties start end '(ruby-expansion-match-data))
          (ruby-syntax-propertize-heredoc end)
          (ruby-syntax-enclosing-percent-literal end)
          (funcall
           (syntax-propertize-rules
            ;; $' $" $` .... are variables.
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            ;; ?' ?" ?` are character literals (one-char strings in 1.9+).
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            ("\\([?$]\\)[#\"'`]"
             (1 (unless (save-excursion
                          ;; Not within a string.
                          (nth 3 (syntax-ppss (match-beginning 0))))
                  (string-to-syntax "\\"))))
            ;; Regular expressions.  Start with matching unescaped slash.
            ("\\(?:\\=\\|[^\\]\\)\\(?:\\\\\\\\\\)*\\(/\\)"
             (1 (let ((state (save-excursion (syntax-ppss (match-beginning 1)))))
                  (when (or
                         ;; Beginning of a regexp.
                         (and (null (nth 8 state))
                              (save-excursion
                                (forward-char -1)
                                (looking-back ruby-syntax-before-regexp-re
                                              (point-at-bol))))
                         ;; End of regexp.  We don't match the whole
                         ;; regexp at once because it can have
                         ;; string interpolation inside, or span
                         ;; several lines.
                         (eq ?/ (nth 3 state)))
                    (string-to-syntax "\"/")))))
            ;; Expression expansions in strings.  We're handling them
            ;; here, so that the regexp rule never matches inside them.
            (ruby-expression-expansion-re
             (0 (ignore (ruby-syntax-propertize-expansion))))
            ("^=en\\(d\\)\\_>" (1 "!"))
            ("^\\(=\\)begin\\_>" (1 "!"))
            ;; Handle here documents.
            ((concat ruby-here-doc-beg-re ".*\\(\n\\)")
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             (7 (unless (or (nth 8 (save-excursion
                                     (syntax-ppss (match-beginning 0))))
                            (ruby-singleton-class-p (match-beginning 0)))
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                  (put-text-property (match-beginning 7) (match-end 7)
                                     'syntax-table (string-to-syntax "\""))
                  (ruby-syntax-propertize-heredoc end))))
            ;; Handle percent literals: %w(), %q{}, etc.
            ((concat "\\(?:^\\|[[ \t\n<+(,=]\\)" ruby-percent-literal-beg-re)
             (1 (prog1 "|" (ruby-syntax-propertize-percent-literal end)))))
           (point) end)))
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      (defun ruby-syntax-propertize-heredoc (limit)
        (let ((ppss (syntax-ppss))
              (res '()))
          (when (eq ?\n (nth 3 ppss))
            (save-excursion
              (goto-char (nth 8 ppss))
              (beginning-of-line)
              (while (re-search-forward ruby-here-doc-beg-re
                                        (line-end-position) t)
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                (unless (ruby-singleton-class-p (match-beginning 0))
                  (push (concat (ruby-here-doc-end-match) "\n") res))))
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            (save-excursion
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              ;; With multiple openers on the same line, we don't know in which
              ;; part `start' is, so we have to go back to the beginning.
              (when (cdr res)
                (goto-char (nth 8 ppss))
                (setq res (nreverse res)))
              (while (and res (re-search-forward (pop res) limit 'move))
                (if (null res)
                    (put-text-property (1- (point)) (point)
                                       'syntax-table (string-to-syntax "\""))))
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              ;; End up at bol following the heredoc openers.
              ;; Propertize expression expansions from this point forward.
              ))))
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      (defun ruby-syntax-enclosing-percent-literal (limit)
        (let ((state (syntax-ppss))
              (start (point)))
          ;; When already inside percent literal, re-propertize it.
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          (when (eq t (nth 3 state))
            (goto-char (nth 8 state))
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            (when (looking-at ruby-percent-literal-beg-re)
              (ruby-syntax-propertize-percent-literal limit))
            (when (< (point) start) (goto-char start)))))
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      (defun ruby-syntax-propertize-percent-literal (limit)
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        (goto-char (match-beginning 2))
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        ;; Not inside a simple string or comment.
        (when (eq t (nth 3 (syntax-ppss)))
          (let* ((op (char-after))
                 (ops (char-to-string op))
                 (cl (or (cdr (aref (syntax-table) op))
                         (cdr (assoc op '((?< . ?>))))))
                 parse-sexp-lookup-properties)
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            (save-excursion
              (condition-case nil
                  (progn
                    (if cl              ; Paired delimiters.
                        ;; Delimiter pairs of the same kind can be nested
                        ;; inside the literal, as long as they are balanced.
                        ;; Create syntax table that ignores other characters.
                        (with-syntax-table (make-char-table 'syntax-table nil)
                          (modify-syntax-entry op (concat "(" (char-to-string cl)))
                          (modify-syntax-entry cl (concat ")" ops))
                          (modify-syntax-entry ?\\ "\\")
                          (save-restriction
                            (narrow-to-region (point) limit)
                            (forward-list))) ; skip to the paired character
                      ;; Single character delimiter.
                      (re-search-forward (concat "[^\\]\\(?:\\\\\\\\\\)*"
                                                 (regexp-quote ops)) limit nil))
                    ;; Found the closing delimiter.
                    (put-text-property (1- (point)) (point) 'syntax-table
                                       (string-to-syntax "|")))
                ;; Unclosed literal, do nothing.
                ((scan-error search-failed)))))))

      (defun ruby-syntax-propertize-expansion ()
        ;; Save the match data to a text property, for font-locking later.
        ;; Set the syntax of all double quotes and backticks to punctuation.
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        (let* ((beg (match-beginning 2))
               (end (match-end 2))
               (state (and beg (save-excursion (syntax-ppss beg)))))
          (when (ruby-syntax-expansion-allowed-p state)
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            (put-text-property beg (1+ beg) 'ruby-expansion-match-data
                               (match-data))
            (goto-char beg)
            (while (re-search-forward "[\"`]" end 'move)
              (put-text-property (match-beginning 0) (match-end 0)
                                 'syntax-table (string-to-syntax "."))))))
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      (defun ruby-syntax-expansion-allowed-p (parse-state)
        "Return non-nil if expression expansion is allowed."
        (let ((term (nth 3 parse-state)))
          (cond
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           ((memq term '(?\" ?` ?\n ?/)))
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           ((eq term t)
            (save-match-data
              (save-excursion
                (goto-char (nth 8 parse-state))
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                (looking-at "%\\(?:[QWrxI]\\|\\W\\)")))))))
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      (defun ruby-syntax-propertize-expansions (start end)
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        (save-excursion
          (goto-char start)
          (while (re-search-forward ruby-expression-expansion-re end 'move)
            (ruby-syntax-propertize-expansion))))
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      )
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  ;; For Emacsen where syntax-propertize-rules is not (yet) available,
  ;; fallback on the old font-lock-syntactic-keywords stuff.

  (defconst ruby-here-doc-end-re
    "^\\([ \t]+\\)?\\(.*\\)\\(\n\\)"
    "Regexp to match the end of heredocs.

This will actually match any line with one or more characters.
It's useful in that it divides up the match string so that
`ruby-here-doc-beg-match' can search for the beginning of the heredoc.")

  (defun ruby-here-doc-beg-match ()
    "Return a regexp to find the beginning of a heredoc.

This should only be called after matching against `ruby-here-doc-end-re'."
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    (let ((contents (concat
                     (regexp-quote (concat (match-string 2) (match-string 3)))
                     (if (string= (match-string 3) "_") "\\B" "\\b"))))
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      (concat "<<"
              (let ((match (match-string 1)))
                (if (and match (> (length match) 0))
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                    (concat "\\(?:-\\([\"']?\\)\\|\\([\"']\\)"
                            (match-string 1) "\\)"
                            contents "\\(\\1\\|\\2\\)")
                  (concat "-?\\([\"']\\|\\)" contents "\\1"))))))