Implements a new syntax @{-N} that parses the reflog for the N-th last
interesting 'checkout: moving from $branch to $new' entry and
substitutes $branch. Here, "interesting" is defined as $branch !=
$new. We then substitute the real branch name for the parse.
For example:
git checkout foo
git checkout bar
git checkout master
git checkout master # did not move, so doesn't count
git rev-parse @{-1} # same as bar
git rev-parse @{-2} # same as foo
git rev-parse @{-2}~3 # same as foo~3
Thanks to Junio for much of the code.
Signed-off-by: Thomas Rast <trast@xxxxxxxxxxxxxxx>
---
Documentation/git-rev-parse.txt | 3 +
cache.h | 1 +
sha1_name.c | 79 +++++++++++++++++++++++++++++++++++++-
t/t1505-rev-parse-last.sh | 71 +++++++++++++++++++++++++++++++++++
4 files changed, 151 insertions(+), 3 deletions(-)
create mode 100755 t/t1505-rev-parse-last.sh
diff --git a/Documentation/git-rev-parse.txt b/Documentation/git-rev-parse.txt
index 2921da3..3ccef2f 100644
--- a/Documentation/git-rev-parse.txt
+++ b/Documentation/git-rev-parse.txt
@@ -212,6 +212,9 @@ when you run 'git-merge'.
reflog of the current branch. For example, if you are on the
branch 'blabla', then '@\{1\}' means the same as 'blabla@\{1\}'.
+* The special construct '@\{-<n>\}' means the <n>th branch checked out
+ before the current one.
+
* A suffix '{caret}' to a revision parameter means the first parent of
that commit object. '{caret}<n>' means the <n>th parent (i.e.
'rev{caret}'
diff --git a/cache.h b/cache.h
index 8e1af26..0dd9168 100644
--- a/cache.h
+++ b/cache.h
@@ -663,6 +663,7 @@ static inline unsigned int hexval(unsigned char c)
extern const char *resolve_ref(const char *path, unsigned char *sha1, int, int *);
extern int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref);
extern int dwim_log(const char *str, int len, unsigned char *sha1, char **ref);
+extern int interpret_nth_last_branch(const char *str, struct strbuf *);
extern int refname_match(const char *abbrev_name, const char *full_name, const char **rules);
extern const char *ref_rev_parse_rules[];
diff --git a/sha1_name.c b/sha1_name.c
index 159c2ab..b2dd302 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -297,6 +297,8 @@ int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
return logs_found;
}
+static int get_sha1_1(const char *name, int len, unsigned char *sha1);
+
static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
{
static const char *warning = "warning: refname '%.*s' is ambiguous.\n";
@@ -307,7 +309,7 @@ static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
if (len == 40 && !get_sha1_hex(str, sha1))
return 0;
- /* basic@{time or number} format to query ref-log */
+ /* basic@{time or number or -number} format to query ref-log */
reflog_len = at = 0;
if (str[len-1] == '}') {
for (at = 0; at < len - 1; at++) {
@@ -324,6 +326,14 @@ static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
return -1;
if (!len && reflog_len) {
+ struct strbuf buf = STRBUF_INIT;
+ int ret;
+ /* try the @{-N} syntax for n-th checkout */
+ ret = interpret_nth_last_branch(str+at, &buf);
+ if (ret > 0) {
+ /* substitute this branch name and restart */
+ return get_sha1_1(buf.buf, buf.len, sha1);
+ }
/* allow "@{...}" to mean the current branch reflog */
refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
} else if (reflog_len)
@@ -379,8 +389,6 @@ static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
return 0;
}
-static int get_sha1_1(const char *name, int len, unsigned char *sha1);
-
static int get_parent(const char *name, int len,
unsigned char *result, int idx)
{
@@ -674,6 +682,71 @@ static int get_sha1_oneline(const char *prefix, unsigned char *sha1)
return retval;
}
+struct grab_nth_branch_switch_cbdata {
+ int nth;
+ struct strbuf *buf;
+};
+
+static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
+ const char *email, unsigned long timestamp, int tz,
+ const char *message, void *cb_data)
+{
+ struct grab_nth_branch_switch_cbdata *cb = cb_data;
+ const char *match = NULL, *target = NULL;
+ size_t len;
+
+ if (!prefixcmp(message, "checkout: moving from ")) {
+ match = message + strlen("checkout: moving from ");
+ if ((target = strstr(match, " to ")) != NULL)
+ target += 4;
+ }
+
+ if (!match)
+ return 0;
+
+ len = target - match - 4;
+ if (target[len] == '\n' && !strncmp(match, target, len))
+ return 0;
+
+ if (--cb->nth <= 0) {
+ strbuf_reset(cb->buf);
+ strbuf_add(cb->buf, match, len);
+ return 1;
+ }
+ return 0;
+}
+
+/*
+ * This reads "@{-N}" syntax, finds the name of the Nth previous
+ * branch we were on, and places the name of the branch in the given
+ * buf and returns 0 if successful.
+ *
+ * If the input is not of the accepted format, it returns a negative
+ * number to signal an error.
+ */
+int interpret_nth_last_branch(const char *name, struct strbuf *buf)
+{
+ int nth;
+ struct grab_nth_branch_switch_cbdata cb;
+ const char *brace;
+ char *num_end;
+
+ if (name[0] != '@' || name[1] != '{' || name[2] != '-')
+ return -1;
+ brace = strchr(name, '}');
+ if (!brace)
+ return -1;
+ nth = strtol(name+3, &num_end, 10);
+ if (num_end != brace)
+ return -1;
+
+ cb.nth = nth;
+ cb.buf = buf;
+ for_each_reflog_ent_backward("HEAD", grab_nth_branch_switch, &cb);
+
+ return brace-name+1;
+}
+
/*
* This is like "get_sha1_basic()", except it allows "sha1 expressions",
* notably "xyz^" for "parent of xyz"
diff --git a/t/t1505-rev-parse-last.sh b/t/t1505-rev-parse-last.sh
new file mode 100755
index 0000000..1e49dd2
--- /dev/null
+++ b/t/t1505-rev-parse-last.sh
@@ -0,0 +1,71 @@
+#!/bin/sh
+
+test_description='test @{-N} syntax'
+
+. ./test-lib.sh
+
+
+make_commit () {
+ echo "$1" > "$1" &&
+ git add "$1" &&
+ git commit -m "$1"
+}
+
+
+test_expect_success 'setup' '
+
+ make_commit 1 &&
+ git branch side &&
+ make_commit 2 &&
+ make_commit 3 &&
+ git checkout side &&
+ make_commit 4 &&
+ git merge master &&
+ git checkout master
+
+'
+
+# 1 -- 2 -- 3 master
+# \ \
+# \ \
+# --- 4 --- 5 side
+#
+# and 'side' should be the last branch
+
+git log --graph --all --pretty=oneline --decorate
+
+test_rev_equivalent () {
+
+ git rev-parse "$1" > expect &&
+ git rev-parse "$2" > output &&
+ test_cmp expect output
+
+}
+
+test_expect_success '@{-1} works' '
+ test_rev_equivalent side @{-1}
+'
+
+test_expect_success '@{-1}~2 works' '
+ test_rev_equivalent side~2 @{-1}~2
+'
+
+test_expect_success '@{-1}^2 works' '
+ test_rev_equivalent side^2 @{-1}^2
+'
+
+test_expect_failure '@{-1}@{1} works' '
+ test_rev_equivalent side@{1} @{-1}@{1}
+'
+
+test_expect_success '@{-2} works' '
+ test_rev_equivalent master @{-2}
+'
+
+test_expect_success '@{-3} fails' '
+ test_must_fail git rev-parse @{-3}
+'
+
+test_done
+
+
--
1.6.1.315.g92577
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