+
When this parameter names a non-branch (but still a valid commit object),
your HEAD becomes 'detached'.
++
+As a special case, the "`@\{-N\}`" syntax for the N-th last branch
+checks out the branch (instead of detaching). You may also specify
+"`-`" which is synonymous with "`@\{-1\}`".
Detached HEAD
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}'
static void setup_branch_path(struct branch_info *branch)
{
struct strbuf buf = STRBUF_INIT;
- strbuf_addstr(&buf, "refs/heads/");
- strbuf_addstr(&buf, branch->name);
+ int ret;
+
+ if ((ret = interpret_nth_last_branch(branch->name, &buf))
+ && ret == strlen(branch->name)) {
+ branch->name = xstrdup(buf.buf);
+ strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
+ } else {
+ strbuf_addstr(&buf, "refs/heads/");
+ strbuf_addstr(&buf, branch->name);
+ }
branch->path = strbuf_detach(&buf, NULL);
}
arg = argv[0];
has_dash_dash = (argc > 1) && !strcmp(argv[1], "--");
+ if (!strcmp(arg, "-"))
+ arg = "@{-1}";
+
if (get_sha1(arg, rev)) {
if (has_dash_dash) /* case (1) */
die("invalid reference: %s", arg);
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[];
return 1;
}
-int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
+int for_each_recent_reflog_ent(const char *ref, each_reflog_ent_fn fn, long ofs, void *cb_data)
{
const char *logfile;
FILE *logfp;
logfp = fopen(logfile, "r");
if (!logfp)
return -1;
+
+ if (ofs) {
+ struct stat statbuf;
+ if (fstat(fileno(logfp), &statbuf) ||
+ statbuf.st_size < ofs ||
+ fseek(logfp, -ofs, SEEK_END) ||
+ fgets(buf, sizeof(buf), logfp))
+ return -1;
+ }
+
while (fgets(buf, sizeof(buf), logfp)) {
unsigned char osha1[20], nsha1[20];
char *email_end, *message;
return ret;
}
+int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
+{
+ return for_each_recent_reflog_ent(ref, fn, 0, cb_data);
+}
+
static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
{
DIR *dir = opendir(git_path("logs/%s", base));
/* iterate over reflog entries */
typedef int each_reflog_ent_fn(unsigned char *osha1, unsigned char *nsha1, const char *, unsigned long, int, const char *, void *);
int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data);
+int for_each_recent_reflog_ent(const char *ref, each_reflog_ent_fn fn, long, void *cb_data);
/*
* Calls the specified function for each reflog file until it returns nonzero,
return slash;
}
+/*
+ * *string and *len will only be substituted, and *string returned (for
+ * later free()ing) if the string passed in is of the form @{-<n>}.
+ */
+static char *substitute_nth_last_branch(const char **string, int *len)
+{
+ struct strbuf buf = STRBUF_INIT;
+ int ret = interpret_nth_last_branch(*string, &buf);
+
+ if (ret == *len) {
+ size_t size;
+ *string = strbuf_detach(&buf, &size);
+ *len = size;
+ return (char *)*string;
+ }
+
+ return NULL;
+}
+
int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
{
+ char *last_branch = substitute_nth_last_branch(&str, &len);
const char **p, *r;
int refs_found = 0;
break;
}
}
+ free(last_branch);
return refs_found;
}
int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
{
+ char *last_branch = substitute_nth_last_branch(&str, &len);
const char **p;
int logs_found = 0;
if (!warn_ambiguous_refs)
break;
}
+ free(last_branch);
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";
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 (len && str[len-1] == '}') {
- for (at = 0; at < len - 1; at++) {
+ for (at = len-2; at >= 0; at--) {
if (str[at] == '@' && str[at+1] == '{') {
reflog_len = (len-1) - (at+2);
len = at;
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);
+ } else if (ret == 0) {
+ return -1;
+ }
/* allow "@{...}" to mean the current branch reflog */
refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
} else if (reflog_len)
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)
{
return retval;
}
+struct grab_nth_branch_switch_cbdata {
+ long cnt, alloc;
+ 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;
+ int nth;
+
+ if (!prefixcmp(message, "checkout: moving from ")) {
+ match = message + strlen("checkout: moving from ");
+ target = strstr(match, " to ");
+ }
+
+ if (!match || !target)
+ return 0;
+
+ len = target - match;
+ nth = cb->cnt++ % cb->alloc;
+ strbuf_reset(&cb->buf[nth]);
+ strbuf_add(&cb->buf[nth], match, len);
+ 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 the number of characters parsed if successful.
+ *
+ * If the input is not of the accepted format, it returns a negative
+ * number to signal an error.
+ *
+ * If the input was ok but there are not N branch switches in the
+ * reflog, it returns 0.
+ */
+int interpret_nth_last_branch(const char *name, struct strbuf *buf)
+{
+ long nth;
+ int i, retval;
+ 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;
+ if (nth <= 0)
+ return -1;
+ cb.alloc = nth;
+ cb.buf = xmalloc(nth * sizeof(struct strbuf));
+ for (i = 0; i < nth; i++)
+ strbuf_init(&cb.buf[i], 20);
+ cb.cnt = 0;
+ retval = 0;
+ for_each_recent_reflog_ent("HEAD", grab_nth_branch_switch, 40960, &cb);
+ if (cb.cnt < nth) {
+ cb.cnt = 0;
+ for (i = 0; i < nth; i++)
+ strbuf_release(&cb.buf[i]);
+ for_each_reflog_ent("HEAD", grab_nth_branch_switch, &cb);
+ }
+ if (cb.cnt < nth)
+ goto release_return;
+ i = cb.cnt % nth;
+ strbuf_reset(buf);
+ strbuf_add(buf, cb.buf[i].buf, cb.buf[i].len);
+ retval = brace-name+1;
+
+release_return:
+ for (i = 0; i < nth; i++)
+ strbuf_release(&cb.buf[i]);
+ free(cb.buf);
+
+ return retval;
+}
+
/*
* This is like "get_sha1_basic()", except it allows "sha1 expressions",
* notably "xyz^" for "parent of xyz"
--- /dev/null
+#!/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
+
+test_rev_equivalent () {
+
+ git rev-parse "$1" > expect &&
+ git rev-parse "$2" > output &&
+ test_cmp expect output
+
+}
+
+test_expect_success '@{-1} works' '
+ test_rev_equivalent side @{-1}
+'
+
+test_expect_success '@{-1}~2 works' '
+ test_rev_equivalent side~2 @{-1}~2
+'
+
+test_expect_success '@{-1}^2 works' '
+ test_rev_equivalent side^2 @{-1}^2
+'
+
+test_expect_success '@{-1}@{1} works' '
+ test_rev_equivalent side@{1} @{-1}@{1}
+'
+
+test_expect_success '@{-2} works' '
+ test_rev_equivalent master @{-2}
+'
+
+test_expect_success '@{-3} fails' '
+ test_must_fail git rev-parse @{-3}
+'
+
+test_done
+
+
--- /dev/null
+#!/bin/sh
+
+test_description='checkout can switch to last branch'
+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+ echo hello >world &&
+ git add world &&
+ git commit -m initial &&
+ git branch other &&
+ echo "hello again" >>world &&
+ git add world &&
+ git commit -m second
+'
+
+test_expect_success '"checkout -" does not work initially' '
+ test_must_fail git checkout -
+'
+
+test_expect_success 'first branch switch' '
+ git checkout other
+'
+
+test_expect_success '"checkout -" switches back' '
+ git checkout - &&
+ test "z$(git symbolic-ref HEAD)" = "zrefs/heads/master"
+'
+
+test_expect_success '"checkout -" switches forth' '
+ git checkout - &&
+ test "z$(git symbolic-ref HEAD)" = "zrefs/heads/other"
+'
+
+test_expect_success 'detach HEAD' '
+ git checkout $(git rev-parse HEAD)
+'
+
+test_expect_success '"checkout -" attaches again' '
+ git checkout - &&
+ test "z$(git symbolic-ref HEAD)" = "zrefs/heads/other"
+'
+
+test_expect_success '"checkout -" detaches again' '
+ git checkout - &&
+ test "z$(git rev-parse HEAD)" = "z$(git rev-parse other)" &&
+ test_must_fail git symbolic-ref HEAD
+'
+
+test_expect_success 'more switches' '
+ for i in 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
+ do
+ git checkout -b branch$i
+ done
+'
+
+more_switches () {
+ for i in 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
+ do
+ git checkout branch$i
+ done
+}
+
+test_expect_success 'switch to the last' '
+ more_switches &&
+ git checkout @{-1} &&
+ test "z$(git symbolic-ref HEAD)" = "zrefs/heads/branch2"
+'
+
+test_expect_success 'switch to second from the last' '
+ more_switches &&
+ git checkout @{-2} &&
+ test "z$(git symbolic-ref HEAD)" = "zrefs/heads/branch3"
+'
+
+test_expect_success 'switch to third from the last' '
+ more_switches &&
+ git checkout @{-3} &&
+ test "z$(git symbolic-ref HEAD)" = "zrefs/heads/branch4"
+'
+
+test_expect_success 'switch to fourth from the last' '
+ more_switches &&
+ git checkout @{-4} &&
+ test "z$(git symbolic-ref HEAD)" = "zrefs/heads/branch5"
+'
+
+test_expect_success 'switch to twelfth from the last' '
+ more_switches &&
+ git checkout @{-12} &&
+ test "z$(git symbolic-ref HEAD)" = "zrefs/heads/branch13"
+'
+
+test_done