[PATCH 2/2] get_sha1: support ref^{/regex} syntax

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

This works like :/ syntax, but only limited to one ref.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 Documentation/revisions.txt |    7 +++++++
 sha1_name.c                 |   26 ++++++++++++++++++++++----
 2 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/Documentation/revisions.txt b/Documentation/revisions.txt
index 3d4b79c..fbe6245 100644
--- a/Documentation/revisions.txt
+++ b/Documentation/revisions.txt
@@ -106,6 +106,13 @@ the `$GIT_DIR/refs` directory or from the `$GIT_DIR/packed-refs` file.
   and dereference the tag recursively until a non-tag object is
   found.
 
+* A suffix '{caret}' to a revision parameter followed by a brace
+  pair that contains a text led by a slash (e.g. `HEAD^{/fix nasty bug}`):
+  this names a commit whose commit message matches the specified
+  regular expression. This name returns the youngest matching commit
+  which is reachable from the dereferenced commit. The leading '!'
+  in the text is treated especially like in `:/` syntax below.
+
 * A colon, followed by a slash, followed by a text (e.g. `:/fix nasty bug`): this names
   a commit whose commit message matches the specified regular expression.
   This name returns the youngest matching commit which is
diff --git a/sha1_name.c b/sha1_name.c
index f4ccdc5..00e52b0 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -527,6 +527,7 @@ struct object *peel_to_type(const char *name, int namelen,
 	}
 }
 
+static int get_sha1_oneline(const char *, unsigned char *, struct commit_list *);
 static int peel_onion(const char *name, int len, unsigned char *sha1)
 {
 	unsigned char outer[20];
@@ -562,6 +563,11 @@ static int peel_onion(const char *name, int len, unsigned char *sha1)
 		expected_type = OBJ_BLOB;
 	else if (sp[0] == '}')
 		expected_type = OBJ_NONE;
+	else if (sp[0] == '/') {
+		if (sp[1] == '}')
+			return -1;
+		expected_type = OBJ_COMMIT;
+	}
 	else
 		return -1;
 
@@ -584,11 +590,23 @@ static int peel_onion(const char *name, int len, unsigned char *sha1)
 		 * barf.
 		 */
 		o = peel_to_type(name, len, o, expected_type);
-		if (o) {
-			hashcpy(sha1, o->sha1);
-			return 0;
+		if (!o)
+			return -1;
+
+		hashcpy(sha1, o->sha1);
+		if (sp[0] == '/') { /* ^{/foo} */
+			struct commit_list *list = NULL;
+			char *prefix;
+			int ret;
+
+			commit_list_insert((struct commit *)o, &list);
+			prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
+			ret = get_sha1_oneline(prefix, sha1, list);
+			free(prefix);
+			free_commit_list(list);
+			return ret;
 		}
-		return -1;
+		return 0;
 	}
 	return 0;
 }
-- 
1.7.3.2.316.gda8b3