filter-branch: introduce convenience function "skip_commit"

With this function, a commit filter can leave out unwanted commits
(such as temporary commits).  It does _not_ undo the changeset
corresponding to that commit, but it _skips_ the revision.  IOW
no tree object is changed by this.

If you like to commit early and often, but want to filter out all
intermediate commits, marked by "@@@" in the commit message, you can
now do this with

	git filter-branch --commit-filter '
		if git cat-file commit $GIT_COMMIT | grep '@@@' > /dev/null;
		then
			skip_commit "$@";
		else
			git commit-tree "$@";
		fi' newbranch

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/git-filter-branch.txt b/Documentation/git-filter-branch.txt
index 456d52bb2490ded4552bb3ea2a00e30d27b73770..29bb8cec0c34709ef0fab7523be3b0b43c4c43c7 100644 (file)
--- a/Documentation/git-filter-branch.txt
+++ b/Documentation/git-filter-branch.txt
@@ -112,6 +112,11 @@ OPTIONS
 As a special extension, the commit filter may emit multiple
 commit ids; in that case, ancestors of the original commit will
 have all of them as parents.
++
+You can use the 'map' convenience function in this filter, and other
+convenience functions, too.  For example, calling 'skip_commit "$@"'
+will leave out the current commit (but not its changes! If you want
+that, use gitlink:git-rebase[1] instead).
 
 --tag-name-filter <command>::
        This is the filter for rewriting tag names. When passed,
@@ -209,24 +214,39 @@ To remove commits authored by "Darl McBribe" from the history:
 git filter-branch --commit-filter '
        if [ "$GIT_AUTHOR_NAME" = "Darl McBribe" ];
        then
-               shift;
-               while [ -n "$1" ];
-               do
-                       shift;
-                       echo "$1";
-                       shift;
-               done;
+               skip_commit "$@";
        else
                git commit-tree "$@";
        fi' HEAD
 ------------------------------------------------------------------------------
 
+Note that the changes introduced by the commits, and not reverted by
+subsequent commits, will still be in the rewritten branch. If you want
+to throw out _changes_ together with the commits, you should use the
+interactive mode of gitlink:git-rebase[1].
+
+The function 'skip_commits' is defined as follows:
+
+--------------------------
+skip_commit()
+{
+       shift;
+       while [ -n "$1" ];
+       do
+               shift;
+               map "$1";
+               shift;
+       done;
+}
+--------------------------
+
 The shift magic first throws away the tree id and then the -p
 parameters.  Note that this handles merges properly! In case Darl
 committed a merge between P1 and P2, it will be propagated properly
 and all children of the merge will become merge commits with P1,P2
 as their parents instead of the merge commit.
 
+
 To restrict rewriting to only part of the history, specify a revision
 range in addition to the new branch name.  The new branch name will
 point to the top-most revision that a 'git rev-list' of this range

diff --git a/git-filter-branch.sh b/git-filter-branch.sh
index 3b041d81efd7e96a49c40eba0e23fc0b18508c82..a4b6577bd496819232754c1275b7c1e798b0470c 100755 (executable)
--- a/git-filter-branch.sh
+++ b/git-filter-branch.sh
@@ -23,6 +23,20 @@ map()
        fi
 }
 
+# if you run 'skip_commit "$@"' in a commit filter, it will print
+# the (mapped) parents, effectively skipping the commit.
+
+skip_commit()
+{
+       shift;
+       while [ -n "$1" ];
+       do
+               shift;
+               map "$1";
+               shift;
+       done;
+}
+
 # override die(): this version puts in an extra line break, so that
 # the progress is still visible
 

diff --git a/t/t7003-filter-branch.sh b/t/t7003-filter-branch.sh
index c79853d986ab31da6813576fe003f8a5885e0b64..e935b2000ac6589a4940f585616f8bf3be95223b 100755 (executable)
--- a/t/t7003-filter-branch.sh
+++ b/t/t7003-filter-branch.sh
@@ -138,13 +138,7 @@ test_expect_success "remove a certain author's commits" '
        git-filter-branch -f --commit-filter "\
                if [ \"\$GIT_AUTHOR_NAME\" = \"B V Uips\" ];\
                then\
-                       shift;\
-                       while [ -n \"\$1\" ];\
-                       do\
-                               shift;\
-                               echo \"\$1\";\
-                               shift;\
-                       done;\
+                       skip_commit \"\$@\";
                else\
                        git commit-tree \"\$@\";\
                fi" removed-author &&