Re: [PATCH] Introduce <branch>@{tracked} as shortcut to the tracked branch

> 
> Often, it is quite interesting to inspect the branch tracked by a given
> branch.  This patch introduces a nice notation to get at the tracked
> branch: '<branch>@{tracked}' can be used to access that tracked branch.
> 
> A special shortcut '@{tracked}' refers to the branch tracked by the
> current branch.

> 
> Suggested by Pasky.
> 
> The syntax was suggested by Junio.
> 
> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> ---
> 
> 	I decided that I like @{tracked} better than @{upstream} (which
> 	reads to me more like the upstream _repository_), but hey, I made
> 	the code flexible enough to change that at a whim.
> 
>  Documentation/git-rev-parse.txt |    4 ++
>  sha1_name.c                     |   37 ++++++++++++++++++++--
>  t/t1506-rev-parse-tracked.sh    |   64 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 102 insertions(+), 3 deletions(-)
>  create mode 100755 t/t1506-rev-parse-tracked.sh
> 
> diff --git a/Documentation/git-rev-parse.txt b/Documentation/git-rev-parse.txt
> index 82045a2..09a2145 100644
> --- a/Documentation/git-rev-parse.txt
> +++ b/Documentation/git-rev-parse.txt
> @@ -231,6 +231,10 @@ when you run 'git-merge'.
>  * The special construct '@\{-<n>\}' means the <n>th branch checked out
>    before the current one.
>  
> +* The suffix '@{tracked}' to a ref (short form 'blabla@{t}') refers to
> +  the branch tracked by that ref.  If no ref was specified, it means the
> +  branch tracked by the current branch.
> +
>  * 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/sha1_name.c b/sha1_name.c
> index 44bb62d..a886846 100644
> --- a/sha1_name.c
> +++ b/sha1_name.c
> @@ -5,6 +5,7 @@
>  #include "blob.h"
>  #include "tree-walk.h"
>  #include "refs.h"
> +#include "remote.h"
>  
>  static int find_short_object_filename(int len, const char *name, unsigned char *sha1)
>  {
> @@ -238,9 +239,24 @@ static int ambiguous_path(const char *path, int len)
>  	return slash;
>  }
>  
> +static inline int tracked_suffix(const char *string, int len)
> +{
> +	const char *suffix[] = { "@{tracked}", "@{t}" };
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(suffix); i++) {
> +		int suffix_len = strlen(suffix[i]);
> +		if (len >= suffix_len && !memcmp(string + len - suffix_len,
> +					suffix[i], suffix_len))
> +			return suffix_len;
> +	}
> +	return 0;
> +}
> +
>  /*
>   * *string and *len will only be substituted, and *string returned (for
> - * later free()ing) if the string passed in is of the form @{-<n>}.
> + * later free()ing) if the string passed in is of the form @{-<n>} or
> + * of the form <branch>@{tracked}.
>   */
>  static char *substitute_branch_name(const char **string, int *len)
>  {
> @@ -254,6 +270,19 @@ static char *substitute_branch_name(const char **string, int *len)
>  		return (char *)*string;
>  	}
>  
> +	ret = tracked_suffix(*string, *len);
> +	if (ret) {
> +		char *ref = xstrndup(*string, *len - ret);
> +		struct branch *tracking = branch_get(*ref ? ref : NULL);
> +
> +		free(ref);
> +		if (tracking->merge && tracking->merge[0]->dst) {
> +			*string = xstrdup(tracking->merge[0]->dst);
> +			*len = strlen(*string);
> +			return (char *)*string;
> +		}
> +	}
> +
>  	return NULL;
>  }
>  
> @@ -340,8 +369,10 @@ static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
>  	if (len && str[len-1] == '}') {
>  		for (at = len-2; at >= 0; at--) {
>  			if (str[at] == '@' && str[at+1] == '{') {
> -				reflog_len = (len-1) - (at+2);
> -				len = at;
> +				if (!tracked_suffix(str + at, len - at)) {
> +					reflog_len = (len-1) - (at+2);
> +					len = at;
> +				}
>  				break;
>  			}
>  		}
> diff --git a/t/t1506-rev-parse-tracked.sh b/t/t1506-rev-parse-tracked.sh
> new file mode 100755
> index 0000000..89193e1
> --- /dev/null
> +++ b/t/t1506-rev-parse-tracked.sh
> @@ -0,0 +1,64 @@
> +#!/bin/sh
> +
> +test_description='test <branch>@{tracked} syntax'
> +
> +. ./test-lib.sh
> +
> +
> +test_expect_success 'setup' '
> +
> +	test_commit 1 &&
> +	git checkout -b side &&
> +	test_commit 2 &&
> +	git checkout master &&
> +	git clone . clone &&
> +	test_commit 3 &&
> +	(cd clone &&
> +	 test_commit 4 &&
> +	 git branch --track my-side origin/side)
> +
> +'
> +
> +full_name () {
> +	(cd clone &&
> +	 git rev-parse --symbolic-full-name "$@")
> +}
> +
> +commit_subject () {
> +	(cd clone &&
> +	 git show -s --pretty=format:%s "$@")
> +}
> +
> +test_expect_success '@{tracked} resolves to correct full name' '
> +	test refs/remotes/origin/master = "$(full_name @{tracked})"
> +'
> +
> +test_expect_success '@{t} resolves to correct full name' '
> +	test refs/remotes/origin/master = "$(full_name @{t})"
> +'
> +
> +test_expect_success 'my-side@{tracked} resolves to correct full name' '
> +	test refs/remotes/origin/side = "$(full_name my-side@{t})"
> +'
> +
> +test_expect_success 'my-side@{t} resolves to correct commit' '
> +	git checkout side &&
> +	test_commit 5 &&
> +	(cd clone && git fetch) &&
> +	test 2 = "$(commit_subject my-side)" &&
> +	test 5 = "$(commit_subject my-side@{t})"
> +'
> +
> +test_expect_success 'not-tracking@{t} fails' '
> +	test_must_fail full_name non-tracking@{t} &&
> +	(cd clone && git checkout --no-track -b non-tracking) &&
> +	test_must_fail full_name non-tracking@{t}
> +'
> +
> +test_expect_success '<branch>@{t}@{1} resolves correctly' '
> +	test_commit 6 &&
> +	(cd clone && git fetch) &&
> +	test 5 = $(commit_subject my-side@{t}@{1})
> +'
> +
> +test_done