;;; semantic/symref/grep.el --- Symref implementation using find/grep

;; Copyright (C) 2008-2013 Free Software Foundation, Inc.

;; Author: Eric M. Ludlam <eric@siege-engine.com>

;; 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:
;;
;; Implement the symref tool API using the external tools find/grep.
;;
;; The symref GREP tool uses grep in a project to find symbol references.
;; This is a lowest-common-denominator tool with sucky performance that
;; can be used in small projects to find symbol references.

(require 'semantic/symref)
(require 'grep)

;;; Code:

;;; GREP
;;;###autoload
(defclass semantic-symref-tool-grep (semantic-symref-tool-baseclass)
  (
   )
  "A symref tool implementation using grep.
This tool uses EDE to find he root of the project, then executes
find-grep in the project.  The output is parsed for hits
and those hits returned.")

(defvar semantic-symref-filepattern-alist
  '((c-mode "*.[ch]")
    (c++-mode "*.[chCH]" "*.[ch]pp" "*.cc" "*.hh")
    (html-mode "*.s?html" "*.php")
    )
  "List of major modes and file extension pattern regexp.
See find -regex man page for format.")

(defun semantic-symref-derive-find-filepatterns (&optional mode)
  "Derive a list of file patterns for the current buffer.
Looks first in `semantic-symref-filepattern-alist'.  If it is not
there, it then looks in `auto-mode-alist', and attempts to derive something
from that.
Optional argument MODE specifies the `major-mode' to test."
  ;; First, try the filepattern alist.
  (let* ((mode (or mode major-mode))
	 (pat (cdr (assoc mode semantic-symref-filepattern-alist))))
    (when (not pat)
      ;; No hit, try auto-mode-alist.
      (dolist (X auto-mode-alist)
	(when (eq (cdr X) mode)
	  ;; Only take in simple patterns, so try to convert this one.
	  (let ((Xp
		 (cond ((string-match "\\\\\\.\\([^\\'>]+\\)\\\\'" (car X))
			(concat "*." (match-string 1 (car X))))
		       (t nil))))
	    (when Xp
	      (setq pat (cons Xp pat))))
	  )))
    ;; Convert the list into some find-flags.
    (cond ((= (length pat) 1)
	   (concat "-name \"" (car pat) "\""))
	  ((consp pat)
	   (concat "\\( "
		   (mapconcat (lambda (s)
				(concat "-name \"" s "\""))
			      pat
			      " -o ")
		   " \\)"))
	  (t
	   (error "Customize `semantic-symref-filepattern-alist' for %s" major-mode))
	  )))

(defvar semantic-symref-grep-expand-keywords
  (condition-case nil
      (let* ((kw (copy-alist grep-expand-keywords))
	     (C (assoc "<C>" kw))
	     (R (assoc "<R>" kw)))
	(setcdr C 'grepflags)
	(setcdr R 'greppattern)
	kw)
    (error nil))
  "Grep expand keywords used when expanding templates for symref.")

(defun semantic-symref-grep-use-template (rootdir filepattern grepflags greppattern)
  "Use the grep template expand feature to create a grep command.
ROOTDIR is the root location to run the `find' from.
FILEPATTERN is a string representing find flags for searching file patterns.
GREPFLAGS are flags passed to grep, such as -n or -l.
GREPPATTERN is the pattern used by grep."
  ;; We have grep-compute-defaults.  Let's use it.
  (grep-compute-defaults)
  (let* ((grep-expand-keywords semantic-symref-grep-expand-keywords)
	 (cmd (grep-expand-template grep-find-template
				    greppattern
				    filepattern
				    rootdir)))
    ;; For some reason, my default has no <D> in it.
    (when (string-match "find \\(\\.\\)" cmd)
      (setq cmd (replace-match rootdir t t cmd 1)))
    ;;(message "New command: %s" cmd)
    cmd))

(defcustom semantic-symref-grep-shell "sh"
  "The shell command to use for executing find/grep.
This shell should support pipe redirect syntax."
  :group 'semantic
  :type 'string)

(defmethod semantic-symref-perform-search ((tool semantic-symref-tool-grep))
  "Perform a search with Grep."
  ;; Grep doesn't support some types of searches.
  (let ((st (oref tool :searchtype)))
    (when (not (eq st 'symbol))
      (error "Symref impl GREP does not support searchtype of %s" st))
    )
  ;; Find the root of the project, and do a find-grep...
  (let* (;; Find the file patterns to use.
	 (pat (cdr (assoc major-mode semantic-symref-filepattern-alist)))
	 (rootdir (semantic-symref-calculate-rootdir))
	 (filepattern (semantic-symref-derive-find-filepatterns))
	 ;; Grep based flags.
	 (grepflags (cond ((eq (oref tool :resulttype) 'file)
			  "-l ")
			 (t "-n ")))
	 (greppat (cond ((eq (oref tool :searchtype) 'regexp)
			 (oref tool searchfor))
			(t
			 (concat "'\\<" (oref tool searchfor) "\\>'"))))
	 ;; Misc
	 (b (get-buffer-create "*Semantic SymRef*"))
	 (ans nil)
	 )

    (with-current-buffer b
      (erase-buffer)
      (setq default-directory rootdir)

      (if (not (fboundp 'grep-compute-defaults))

	  ;; find . -type f -print0 | xargs -0 -e grep -nH -e
	  ;; Note : I removed -e as it is not posix, nor necessary it seems.

	  (let ((cmd (concat "find " default-directory " -type f " filepattern " -print0 "
			     "| xargs -0 grep -H " grepflags "-e " greppat)))
	    ;;(message "Old command: %s" cmd)
	    (call-process semantic-symref-grep-shell nil b nil "-c" cmd)
	    )
	(let ((cmd (semantic-symref-grep-use-template rootdir filepattern grepflags greppat)))
	  (call-process semantic-symref-grep-shell nil b nil "-c" cmd))
	))
    (setq ans (semantic-symref-parse-tool-output tool b))
    ;; Return the answer
    ans))

(defmethod semantic-symref-parse-tool-output-one-line ((tool semantic-symref-tool-grep))
  "Parse one line of grep output, and return it as a match list.
Moves cursor to end of the match."
  (cond ((eq (oref tool :resulttype) 'file)
	 ;; Search for files
	 (when (re-search-forward "^\\([^\n]+\\)$" nil t)
	   (match-string 1)))
	(t
	 (when (re-search-forward  "^\\(\\(?:[a-zA-Z]:\\)?[^:\n]+\\):\\([0-9]+\\):" nil t)
	   (cons (string-to-number (match-string 2))
		 (match-string 1))
	   ))))

(provide 'semantic/symref/grep)

;; Local variables:
;; generated-autoload-file: "../loaddefs.el"
;; generated-autoload-load-name: "semantic/symref/grep"
;; End:

;;; semantic/symref/grep.el ends here
