Support showing a single log entry from vc-annotate.

* vc.el (print-log): Add a new argument: START-REVISION.
(vc-print-log-internal): Add a new optional argument and
pass it to the backend.
(vc-print-log, vc-print-root-log): Adjust callers.
* vc-annotate.el (vc-annotate-show-log-revision-at-line): If a
buffer already displays the requested log entry, use it.
Otherwise display only the log entry in question.
* vc-svn.el (vc-svn-print-log):
* vc-mtn.el (log-view-file-re):
* vc-hg.el (vc-hg-state):
* vc-git.el (vc-git-print-log): Add support for new argument START-REVISION.
(vc-git-show-log-entry): Return t on success.
* vc-bzr.el (vc-bzr-print-log): Add support new argument START-REVISION.
(vc-bzr-show-log-entry): Return t on success.
* vc-rcs.el (vc-rcs-print-log):
* vc-sccs.el (vc-sccs-print-log):
* vc-cvs.el (vc-cvs-print-log): Add new argument, ignore it.

1 files changed, 14 insertions, 9 deletions

diff --git a/lisp/vc.el b/lisp/vc.el
index cd9f11bcf3a..9a71286d685 100644
--- a/lisp/vc.el
+++ b/lisp/vc.el
@@ -333,13 +333,16 @@
 ;;
 ;; HISTORY FUNCTIONS
 ;;
-;; * print-log (files buffer &optional shortlog limit)
+;; * print-log (files buffer &optional shortlog start-revision limit)
 ;;
 ;;   Insert the revision log for FILES into BUFFER.
 ;;   If SHORTLOG is true insert a short version of the log.
 ;;   If LIMIT is true insert only insert LIMIT log entries.  If the
 ;;   backend does not support limiting the number of entries to show
 ;;   it should return `limit-unsupported'.
+;;   If START-REVISION is given, then show the log starting from the
+;;   revision.  At this point START-REVISION is only required to work
+;;   in conjunction with LIMIT = 1.
 ;;
 ;; - log-view-mode ()
 ;;
@@ -1863,7 +1866,7 @@ Not all VC backends support short logs!")
 (defvar log-view-vc-fileset)
 
 (defun vc-print-log-internal (backend files working-revision
-                                      &optional limit)
+                                      &optional is-start-revision limit)
   ;; Don't switch to the output buffer before running the command,
   ;; so that any buffer-local settings in the vc-controlled
   ;; buffer can be accessed by the command.
@@ -1878,8 +1881,9 @@ Not all VC backends support short logs!")
 			 (memq 'directory vc-log-short-style)
 		       (memq 'file vc-log-short-style)))))
 
-    (setq pl-return (vc-call-backend backend 'print-log files "*vc-change-log*"
-				     vc-short-log limit))
+    (setq pl-return (vc-call-backend
+		     backend 'print-log files "*vc-change-log*"
+		     vc-short-log (when is-start-revision working-revision) limit))
     (pop-to-buffer "*vc-change-log*")
     (let ((inhibit-read-only t))
       ;; log-view-mode used to be called with inhibit-read-only bound
@@ -1890,19 +1894,20 @@ Not all VC backends support short logs!")
 
     (vc-exec-after
      `(let ((inhibit-read-only t))
-	(when (and ,limit (not ,(eq 'limit-unsupported pl-return)))
+	(when (and ,limit (not ,(eq 'limit-unsupported pl-return))
+		   (not ,is-start-revision))
 	  (goto-char (point-max))
 	  (widget-create 'push-button
 			 :notify (lambda (&rest ignore)
 				   (vc-print-log-internal
-				    ',backend ',files ',working-revision (* 2 ,limit)))
+				    ',backend ',files ',working-revision nil (* 2 ,limit)))
 			 :help-echo "Show the log again, and double the number of log entries shown"
 			 "Show 2X entries")
 	  (widget-insert "    ")
 	  (widget-create 'push-button
 			 :notify (lambda (&rest ignore)
 				   (vc-print-log-internal
-				    ',backend ',files ',working-revision nil))
+				    ',backend ',files ',working-revision nil nil))
 			 :help-echo "Show the log again, showing all entries"
 			 "Show unlimited entries")
 	  (widget-setup))
@@ -1936,7 +1941,7 @@ If WORKING-REVISION is non-nil, leave the point at that revision."
 	 (backend (car vc-fileset))
 	 (files (cadr vc-fileset))
 	 (working-revision (or working-revision (vc-working-revision (car files)))))
-    (vc-print-log-internal backend files working-revision limit)))
+    (vc-print-log-internal backend files working-revision nil limit)))
 
 ;;;###autoload
 (defun vc-print-root-log (&optional limit)
@@ -1962,7 +1967,7 @@ If WORKING-REVISION is non-nil, leave the point at that revision."
       (error "Buffer is not version controlled"))
     (setq rootdir (vc-call-backend backend 'root default-directory))
     (setq working-revision (vc-working-revision rootdir))
-    (vc-print-log-internal backend (list rootdir) working-revision limit)))
+    (vc-print-log-internal backend (list rootdir) working-revision nil limit)))
 
 ;;;###autoload
 (defun vc-revert ()