Add new @ shortcut for HEAD

Typing 'HEAD' is tedious, especially when we can use '@' instead.

The reason for choosing '@' is that it follows naturally from the
ref@op syntax (e.g. HEAD@{u}), except we have no ref, and no
operation, and when we don't have those, it makes sens to assume
'HEAD'.

So now we can use 'git show @~1', and all that goody goodness.

Until now '@' was a valid name, but it conflicts with this idea, so
let's make it invalid. Probably very few people, if any, used this name.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/git-check-ref-format.txt b/Documentation/git-check-ref-format.txt
index a49be1bab49ddcdb65e4b45b578bd183a94657a5..fc02959ba4ab1ae6acc3dc5f707e870e42144f1c 100644 (file)
--- a/Documentation/git-check-ref-format.txt
+++ b/Documentation/git-check-ref-format.txt
@@ -54,6 +54,8 @@ Git imposes the following rules on how references are named:
 
 . They cannot contain a sequence `@{`.
 
+. They cannot be the single character `@`.
+
 . They cannot contain a `\`.
 
 These rules make it easy for shell script based tools to parse

diff --git a/Documentation/revisions.txt b/Documentation/revisions.txt
index d477b3f6bcb2c410952b573421d28189d1d1a790..09896a37b1a7b735b0defc9d2c7eb2a14cc713ab 100644 (file)
--- a/Documentation/revisions.txt
+++ b/Documentation/revisions.txt
@@ -58,6 +58,9 @@ the '$GIT_DIR/refs' directory or from the '$GIT_DIR/packed-refs' file.
 While the ref name encoding is unspecified, UTF-8 is preferred as
 some output processing may assume ref names in UTF-8.
 
+'@'::
+  '@' alone is a shortcut for 'HEAD'.
+
 '<refname>@\{<date>\}', e.g. 'master@\{yesterday\}', 'HEAD@\{5 minutes ago\}'::
   A ref followed by the suffix '@' with a date specification
   enclosed in a brace

diff --git a/refs.c b/refs.c
index 8fd5faf8de0976f50becabaf50d73e01bd2d57b6..bfe10e2d17ab915bdd336e07b84dd6344ba22535 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -72,6 +72,10 @@ int check_refname_format(const char *refname, int flags)
 {
        int component_len, component_count = 0;
 
+       if (!strcmp(refname, "@"))
+               /* Refname is a single character '@'. */
+               return -1;
+
        while (1) {
                /* We are at the start of a path component. */
                component_len = check_refname_component(refname, flags);

diff --git a/sha1_name.c b/sha1_name.c
index 93197b91e34df885fa2f5c5100f1be60c8a6acd9..a0b59235a96e05778c3334eeae0d4d1cdb24e11b 100644 (file)
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -1004,6 +1004,28 @@ int get_sha1_mb(const char *name, unsigned char *sha1)
        return st;
 }
 
+/* parse @something syntax, when 'something' is not {.*} */
+static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
+{
+       const char *next;
+
+       if (len || name[1] == '{')
+               return -1;
+
+       /* make sure it's a single @, or @@{.*}, not @foo */
+       next = strchr(name + len + 1, '@');
+       if (next && next[1] != '{')
+               return -1;
+       if (!next)
+               next = name + namelen;
+       if (next != name + 1)
+               return -1;
+
+       strbuf_reset(buf);
+       strbuf_add(buf, "HEAD", 4);
+       return 1;
+}
+
 static int reinterpret(const char *name, int namelen, int len, struct strbuf *buf)
 {
        /* we have extra data, which might need further processing */
@@ -1068,9 +1090,15 @@ int interpret_branch_name(const char *name, int namelen, struct strbuf *buf)
        cp = strchr(name, '@');
        if (!cp)
                return -1;
+
+       len = interpret_empty_at(name, namelen, cp - name, buf);
+       if (len > 0)
+               return reinterpret(name, namelen, len, buf);
+
        tmp_len = upstream_mark(cp, namelen - (cp - name));
        if (!tmp_len)
                return -1;
+
        len = cp + tmp_len - name;
        cp = xstrndup(name, cp - name);
        upstream = branch_get(*cp ? cp : NULL);

diff --git a/t/t1508-at-combinations.sh b/t/t1508-at-combinations.sh
index e5aea3b89602fdaf5ed3a9a230a604dd3f48cda0..ceb844985f97e9472ffcc3fe2f375912d126a4e8 100755 (executable)
--- a/t/t1508-at-combinations.sh
+++ b/t/t1508-at-combinations.sh
@@ -32,6 +32,9 @@ test_expect_success 'setup' '
        git checkout -b upstream-branch &&
        test_commit upstream-one &&
        test_commit upstream-two &&
+       git checkout -b @/at-test &&
+       git checkout -b @@/at-test &&
+       git checkout -b @at-test &&
        git checkout -b old-branch &&
        test_commit old-one &&
        test_commit old-two &&
@@ -55,6 +58,11 @@ check "HEAD@{u}" ref refs/heads/upstream-branch
 check "@{u}@{1}" commit upstream-one
 check "@{-1}@{u}" ref refs/heads/master
 check "@{-1}@{u}@{1}" commit master-one
+check "@" commit new-two
+check "@@{u}" ref refs/heads/upstream-branch
+check "@@/at-test" ref refs/heads/@@/at-test
+check "@/at-test" ref refs/heads/@/at-test
+check "@at-test" ref refs/heads/@at-test
 nonsense "@{u}@{-1}"
 nonsense "@{0}@{0}"
 nonsense "@{1}@{u}"