Support for SRC in VC mode.

doc/emacs/ChangeLog

+2014-11-20  Eric S. Raymond  <esr@snark.thyrsus.com>
+
+	* maintaining.texi: Document SRC support.
+
 2014-11-10  Glenn Morris  <rgm@gnu.org>
 
 	* Makefile.in (top_srcdir, version): New, set by configure.

doc/emacs/maintaining.texi

@@ -193,6 +193,18 @@ both repository-based and decentralized versioning.  VC supports most
 basic editing operations under Bazaar.
 @end itemize
 
+@cindex SRC
+@cindex src
+@item
+SRC (src) is RCS, reloaded - a specialized version-control system
+designed for single-file projects worked on by only one person. It
+allows multiple files with independent version-control histories to
+exisr in one directory, and is thus particularly well suited for
+maintaining small documents, scripts, and dotfiles.  While it uses RCS
+for revision storage, it presents a modern user interface featuring
+lockless operation and integer sequential version numbers.  VC
+supports almost all SRC operations.
+
 @node VCS Concepts
 @subsubsection Concepts of Version Control
 

lisp/ChangeLog

-2014-11-20  Eric S. Raymond  <esr@snark>
+2014-11-20  Eric S. Raymond  <esr@snark.thyrsus.com>
+
+	* vc/vc-src.el, vc/vc.el: Added support for SRC. Needs more
+	testing and a real log-view mode.
 
 	* vc/vc-bzr.el, vc/vc-cvs.el, vc/vc-dav.el, vc/vc-git.el,
 	vc/vc-hg.el, vc/vc-mtn.el, vc/vc-rcs.el, vc/vc-sccs.el,

lisp/vc/vc-hooks.el

@@ -107,8 +107,8 @@ interpreted as hostnames."
   :type 'regexp
   :group 'vc)
 
-(defcustom vc-handled-backends '(RCS CVS SVN SCCS Bzr Git Hg Mtn Arch)
-  ;; RCS, CVS, SVN and SCCS come first because they are per-dir
+(defcustom vc-handled-backends '(RCS CVS SVN SCCS SRC Bzr Git Hg Mtn Arch)
+  ;; RCS, CVS, SVN, SCCS, and SRC come first because they are per-dir
   ;; rather than per-tree.  RCS comes first because of the multibackend
   ;; support intended to use RCS for local commits (with a remote CVS server).
   "List of version control backends for which VC will be used.
@@ -124,7 +124,7 @@ An empty list disables VC altogether."
 ;; Note: we don't actually have a darcs back end yet.
 ;; Also, Meta-CVS (corresponding to MCVS) is unsupported.
 (defcustom vc-directory-exclusion-list (purecopy '("SCCS" "RCS" "CVS" "MCVS"
-					 ".svn" ".git" ".hg" ".bzr"
+					 ".src", ".svn" ".git" ".hg" ".bzr"
 					 "_MTN" "_darcs" "{arch}"))
   "List of directory names to be ignored when walking directory trees."
   :type '(repeat string)

lisp/vc/vc-src.el

+;;; vc-src.el --- support for SRC version-control  -*- lexical-binding:t -*-
+
+;; Copyright (C) 1992-2014 Free Software Foundation, Inc.
+
+;; Author:     FSF (see vc.el for full credits)
+;; Maintainer: Eric S. Raymond <esr@ythyrsus.com>
+;; Package: vc
+
+;; 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:
+
+;; See vc.el.  SRC requires an underlying RCS version of 4.0 or greater. 
+
+;; FUNCTION NAME                               STATUS
+;; BACKEND PROPERTIES
+;; * revision-granularity                      OK
+;; STATE-QUERYING FUNCTIONS
+;; * registered (file)                         OK
+;; * state (file)                              OK
+;; - state-heuristic (file)                    NOT NEEDED
+;; * dir-status (dir update-function)          OK
+;; - dir-status-files (dir files ds uf)        ??
+;; - dir-extra-headers (dir)                   NOT NEEDED
+;; - dir-printer (fileinfo)                    ??
+;; * working-revision (file)                   OK
+;; - latest-on-branch-p (file)                 ??
+;; * checkout-model (files)                    OK
+;; * workfile-unchanged-p (file)               OK
+;; - mode-line-string (file)                   NOT NEEDED
+;; STATE-CHANGING FUNCTIONS
+;; * register (files &optional rev comment)    OK
+;; * create-repo ()                            OK
+;; - init-revision ()                          NOT NEEDED
+;; * responsible-p (file)                      OK
+;; * could-register (file)                     OK
+;; - receive-file (file rev)                   NOT NEEDED
+;; - unregister (file)                         NOT NEEDED
+;; * checkin (files comment)                   OK
+;; * find-revision (file rev buffer)           OK
+;; * checkout (file &optional rev)             OK
+;; * revert (file &optional contents-done)     OK
+;; - rollback (files)                          NOT NEEDED
+;; - merge (file rev1 rev2)                    NOT NEEDED
+;; - merge-news (file)                         NOT NEEDED
+;; - steal-lock (file &optional revision)      NOT NEEDED
+;; HISTORY FUNCTIONS
+;; * print-log (files buffer &optional shortlog start-revision limit) OK
+;; - log-view-mode ()                          ??
+;; - show-log-entry (revision)                 NOT NEEDED
+;; - comment-history (file)                    NOT NEEDED
+;; - update-changelog (files)                  NOT NEEDED
+;; * diff (files &optional rev1 rev2 buffer)   OK
+;; - revision-completion-table (files)         ??
+;; - annotate-command (file buf &optional rev) ??
+;; - annotate-time ()                          ??
+;; - annotate-current-time ()                  NOT NEEDED
+;; - annotate-extract-revision-at-line ()      ??
+;; TAG SYSTEM
+;; - create-tag (dir name branchp)             ??
+;; - retrieve-tag (dir name update)            ??
+;; MISCELLANEOUS
+;; - make-version-backups-p (file)             ??
+;; - repository-hostname (dirname)             NOT NEEDED
+;; - previous-revision (file rev)              ??
+;; - next-revision (file rev)                  ??
+;; - check-headers ()                          ??
+;; - clear-headers ()                          ??
+;; - delete-file (file)                        ??
+;; * rename-file (old new)                     OK
+;; - find-file-hook ()                         NOT NEEDED
+
+
+;;; Code:
+
+;;;
+;;; Customization options
+;;;
+
+(eval-when-compile
+  (require 'cl-lib)
+  (require 'vc))
+
+(defgroup vc-src nil
+  "VC SRC backend."
+  :version "24.1"
+  :group 'vc)
+
+(defcustom vc-src-release nil
+  "The release number of your SRC installation, as a string.
+If nil, VC itself computes this value when it is first needed."
+  :type '(choice (const :tag "Auto" nil)
+		 (string :tag "Specified")
+		 (const :tag "Unknown" unknown))
+  :group 'vc-src)
+
+(defcustom vc-src-program "src"
+  "Name of the SRC executable (excluding any arguments)."
+  :type 'string
+  :group 'vc-src)
+
+(defcustom vc-src-diff-switches nil
+  "String or list of strings specifying switches for SRC diff under VC.
+If nil, use the value of `vc-diff-switches'.  If t, use no switches."
+  :type '(choice (const :tag "Unspecified" nil)
+                 (const :tag "None" t)
+		 (string :tag "Argument String")
+		 (repeat :tag "Argument List" :value ("") string))
+  :version "21.1"
+  :group 'vc-src)
+
+;; This needs to be autoloaded because vc-src-registered uses it (via
+;; vc-default-registered), and vc-hooks needs to be able to check
+;; for a registered backend without loading every backend.
+;;;###autoload
+(defcustom vc-src-master-templates
+  (purecopy '("%s.src/%s,v"))
+  "Where to look for SRC master files.
+For a description of possible values, see `vc-check-master-templates'."
+  :type '(choice (const :tag "Use standard SRC file names"
+			'("%s.src/%s,v"))
+		 (repeat :tag "User-specified"
+			 (choice string
+				 function)))
+  :version "21.1"
+  :group 'vc-src)
+
+
+;;; Properties of the backend
+
+(defun vc-src-revision-granularity () 'file)
+(defun vc-hg-checkout-model (_files) 'implicit)
+
+;;;
+;;; State-querying functions
+;;;
+
+;; The autoload cookie below places vc-src-registered directly into
+;; loaddefs.el, so that vc-src.el does not need to be loaded for
+;; every file that is visited.
+;;;###autoload
+(progn
+(defun vc-src-registered (f) (vc-default-registered 'src f)))
+
+(defun vc-src-state (file)
+  "SRC-specific version of `vc-state'."
+  (let*
+      ((status nil)
+       (out
+	(with-output-to-string
+	  (with-current-buffer
+	      standard-output
+	    (setq status
+		  ;; Ignore all errors.
+		  (condition-case nil
+		      (process-file
+		       vc-src-program nil t nil
+		       "status" "-a" file)
+		    (error nil)))))))
+    (when (eq 0 status)
+      (when (null (string-match "does not exist or is unreadable" out))
+	(let ((state (aref out 0)))
+	  (cond
+	   ;; FIXME: What to do about A and L codes?
+	   ((eq state ?.) 'up-to-date)
+	   ((eq state ?A) 'added)
+	   ((eq state ?M) 'edited)
+	   ((eq state ?I) 'ignored)
+	   ((eq state ?R) 'removed)
+	   ((eq state ?!) 'missing)
+	   ((eq state ??) 'unregistered)
+	   (t 'up-to-date)))))))
+
+(autoload 'vc-expand-dirs "vc")
+
+(defun vc-src-dir-status (dir update-function)
+  ;; FIXME: this function should be rewritten or `vc-expand-dirs'
+  ;; should be changed to take a backend parameter.  Using
+  ;; `vc-expand-dirs' is not TRTD because it returns files from
+  ;; multiple backends.  It should also return 'unregistered files.
+
+  ;; FIXME: Use one src status -a call for this
+  (let ((flist (vc-expand-dirs (list dir)))
+	(result nil))
+    (dolist (file flist)
+      (let ((state (vc-state file))
+	    (frel (file-relative-name file)))
+	(when (and (eq (vc-backend file) 'SRC)
+		   (not (eq state 'up-to-date)))
+	  (push (list frel state) result))))
+    (funcall update-function result)))
+
+(defun vc-src-command (buffer file-or-list &rest flags)
+  "A wrapper around `vc-do-command' for use in vc-src.el.
+This function differs from vc-do-command in that it invokes `vc-src-program'."
+  (apply 'vc-do-command (or buffer "*vc*") 0 vc-src-program file-or-list flags))
+
+(defun vc-src-working-revision (file)
+  "SRC-specific version of `vc-working-revision'."
+  (or (ignore-errors
+        (with-output-to-string
+          (vc-src-command standard-output file "list" "-f{1}" "@")))
+      "0"))
+
+(defun vc-src-workfile-unchanged-p (file)
+  (eq 'up-to-date (vc-src-state file)))
+
+;;;
+;;; State-changing functions
+;;;
+
+(defun vc-src-create-repo ()
+  "Create a new SRC repository."
+  ;; SRC is totally file-oriented, so all we have to do is make the directory.
+  (make-directory ".src"))
+
+(autoload 'vc-switches "vc")
+
+(defun vc-src-register (files &optional _rev _comment)
+  "Register FILES under src.
+REV is ignored.
+COMMENT is ignored."
+  (vc-src-command nil files "add"))
+
+(defun vc-rcs-responsible-p (file)
+  "Return non-nil if SRC thinks it would be responsible for registering FILE."
+  (file-directory-p (expand-file-name ".src"
+                                      (if (file-directory-p file)
+                                          file
+                                        (file-name-directory file)))))
+
+(defalias 'vc-could-register 'vc-src-responsible-p)
+
+(defun vc-src-checkin (files comment)
+  "SRC-specific version of `vc-backend-checkin'.
+REV is ignored."
+  (vc-src-command nil files "commit" "-m" comment))
+
+(defun vc-src-find-revision (file rev buffer)
+  (let ((coding-system-for-read 'binary)
+        (coding-system-for-write 'binary))
+    (if rev
+        (vc-src-command buffer file "cat" rev)
+      (vc-src-command buffer file "cat"))))
+
+(defun vc-src-checkout (file &optional rev)
+  "Retrieve a revision of FILE.
+REV is the revision to check out into WORKFILE."
+  (if rev
+      (vc-src-command nil file "co" rev)
+    (vc-src-command nil file "co")))
+
+(defun vc-src-revert (file &optional _contents-done)
+  "Revert FILE to the version it was based on.  If FILE is a directory,
+revert all registered files beneath it."
+  (if (file-directory-p file)
+      (mapc 'vc-src-revert (vc-expand-dirs (list file)))
+    (vc-src-command nil file "co")))
+
+(defun vc-src-modify-change-comment (files rev comment)
+  "Modify the change comments change on FILES on a specified REV.  If FILE is a
+directory the operation is applied to all registered files beneath it."
+  (dolist (file (vc-expand-dirs files))
+    (vc-src-command nil file "amend" "-m" comment rev)))
+
+;; History functions
+
+(defcustom vc-src-log-switches nil
+  "String or list of strings specifying switches for src log under VC."
+  :type '(choice (const :tag "None" nil)
+                 (string :tag "Argument String")
+                 (repeat :tag "Argument List" :value ("") string))
+  :group 'vc-src)
+
+(defun vc-src-print-log (files buffer &optional shortlog start-revision limit)
+  "Print commit log associated with FILES into specified BUFFER.
+If SHORTLOG is non-nil, use the list method.
+If START-REVISION is non-nil, it is the newest revision to show.
+If LIMIT is non-nil, show no more than this many entries."
+  ;; FIXME: Implement the range restrictions.
+  ;; `vc-do-command' creates the buffer, but we need it before running
+  ;; the command.
+  (vc-setup-buffer buffer)
+  ;; If the buffer exists from a previous invocation it might be
+  ;; read-only.
+  (let ((inhibit-read-only t))
+    (with-current-buffer
+	buffer
+      (apply 'vc-src-command buffer files (if shortlog "list" "log")
+	     (nconc
+	      ;;(when start-revision (list (format "%s-1" start-revision)))
+	      ;;(when limit (list "-l" (format "%s" limit)))
+	      vc-src-log-switches)))))
+
+(defun vc-src-diff (files &optional oldvers newvers buffer)
+  "Get a difference report using src between two revisions of FILES."
+  (let* ((firstfile (car files))
+         (working (and firstfile (vc-working-revision firstfile))))
+    (when (and (equal oldvers working) (not newvers))
+      (setq oldvers nil))
+    (when (and (not oldvers) newvers)
+      (setq oldvers working))
+    (apply #'vc-src-command (or buffer "*vc-diff*") files "diff"
+	   (when oldvers
+	     (if newvers
+		 (list (concat oldvers "-" newvers))
+	       (list oldvers))))))
+
+;; Miscellaneous
+
+(defun vc-src-rename-file (old new)
+  "Rename file from OLD to NEW using `src mv'."
+  (vc-src-command nil 0 new "mv" old))
+
+(provide 'vc-src)
+
+;;; vc-src.el ends here

lisp/vc/vc.el

@@ -52,7 +52,7 @@
 
 ;; This mode is fully documented in the Emacs user's manual.
 ;;
-;; Supported version-control systems presently include CVS, RCS, GNU
+;; Supported version-control systems presently include CVS, RCS, SCR, GNU
 ;; Arch, Subversion, Bzr, Git, Mercurial, Monotone and SCCS
 ;; (or its free replacement, CSSC).
 ;;
@@ -74,6 +74,9 @@
 ;; operations. Under these VC does little state caching, because local
 ;; operations are assumed to be fast.
 ;;
+;; The 'assumed to be fast' category includes SRC, even though it's
+;; a wrapper around RCS.
+;;
 ;; ADDING SUPPORT FOR OTHER BACKENDS
 ;;
 ;; VC can use arbitrary version control systems as a backend.  To add