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checkout: split off a function to peel away branchname arg
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The code to parse and consume the tree name and "--" in commands such
as "git checkout @{-1} -- '*.c'" is intimidatingly long.  Split it out
into a separate function and make it easier to skip on first reading
by making the data it uses and produces more explicit.

No functional change intended.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Jonathan Nieder authored and Junio C Hamano committed Feb 8, 2011
1 parent 0cb6ad3 commit 09ebad6
Showing 1 changed file with 131 additions and 98 deletions.
229 changes: 131 additions & 98 deletions builtin/checkout.c
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Original file line number Diff line number Diff line change
Expand Up @@ -675,11 +675,123 @@ static const char *unique_tracking_name(const char *name)
return NULL;
}

static int parse_branchname_arg(int argc, const char **argv,
int dwim_new_local_branch_ok,
struct branch_info *new,
struct tree **source_tree,
unsigned char rev[20],
const char **new_branch)
{
int argcount = 0;
unsigned char branch_rev[20];
const char *arg;
int has_dash_dash;

/*
* case 1: git checkout <ref> -- [<paths>]
*
* <ref> must be a valid tree, everything after the '--' must be
* a path.
*
* case 2: git checkout -- [<paths>]
*
* everything after the '--' must be paths.
*
* case 3: git checkout <something> [<paths>]
*
* With no paths, if <something> is a commit, that is to
* switch to the branch or detach HEAD at it. As a special case,
* if <something> is A...B (missing A or B means HEAD but you can
* omit at most one side), and if there is a unique merge base
* between A and B, A...B names that merge base.
*
* With no paths, if <something> is _not_ a commit, no -t nor -b
* was given, and there is a tracking branch whose name is
* <something> in one and only one remote, then this is a short-hand
* to fork local <something> from that remote tracking branch.
*
* Otherwise <something> shall not be ambiguous.
* - If it's *only* a reference, treat it like case (1).
* - If it's only a path, treat it like case (2).
* - else: fail.
*
*/
if (!argc)
return 0;

if (!strcmp(argv[0], "--")) /* case (2) */
return 1;

arg = argv[0];
has_dash_dash = (argc > 1) && !strcmp(argv[1], "--");

if (!strcmp(arg, "-"))
arg = "@{-1}";

if (get_sha1_mb(arg, rev)) {
if (has_dash_dash) /* case (1) */
die("invalid reference: %s", arg);
if (dwim_new_local_branch_ok &&
!check_filename(NULL, arg) &&
argc == 1) {
const char *remote = unique_tracking_name(arg);
if (!remote || get_sha1(remote, rev))
return argcount;
*new_branch = arg;
arg = remote;
/* DWIMmed to create local branch */
} else {
return argcount;
}
}

/* we can't end up being in (2) anymore, eat the argument */
argcount++;
argv++;
argc--;

new->name = arg;
setup_branch_path(new);

if (check_ref_format(new->path) == CHECK_REF_FORMAT_OK &&
resolve_ref(new->path, branch_rev, 1, NULL))
hashcpy(rev, branch_rev);
else
new->path = NULL; /* not an existing branch */

new->commit = lookup_commit_reference_gently(rev, 1);
if (!new->commit) {
/* not a commit */
*source_tree = parse_tree_indirect(rev);
} else {
parse_commit(new->commit);
*source_tree = new->commit->tree;
}

if (!*source_tree) /* case (1): want a tree */
die("reference is not a tree: %s", arg);
if (!has_dash_dash) {/* case (3 -> 1) */
/*
* Do not complain the most common case
* git checkout branch
* even if there happen to be a file called 'branch';
* it would be extremely annoying.
*/
if (argc)
verify_non_filename(NULL, arg);
} else {
argcount++;
argv++;
argc--;
}

return argcount;
}

int cmd_checkout(int argc, const char **argv, const char *prefix)
{
struct checkout_opts opts;
unsigned char rev[20], branch_rev[20];
const char *arg;
unsigned char rev[20];
struct branch_info new;
struct tree *source_tree = NULL;
char *conflict_style = NULL;
Expand Down Expand Up @@ -709,7 +821,6 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
PARSE_OPT_NOARG | PARSE_OPT_HIDDEN },
OPT_END(),
};
int has_dash_dash;

memset(&opts, 0, sizeof(opts));
memset(&new, 0, sizeof(new));
Expand Down Expand Up @@ -766,108 +877,30 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
die("git checkout: -f and -m are incompatible");

/*
* case 1: git checkout <ref> -- [<paths>]
*
* <ref> must be a valid tree, everything after the '--' must be
* a path.
*
* case 2: git checkout -- [<paths>]
*
* everything after the '--' must be paths.
* Extract branch name from command line arguments, so
* all that is left is pathspecs.
*
* case 3: git checkout <something> [<paths>]
*
* With no paths, if <something> is a commit, that is to
* switch to the branch or detach HEAD at it. As a special case,
* if <something> is A...B (missing A or B means HEAD but you can
* omit at most one side), and if there is a unique merge base
* between A and B, A...B names that merge base.
*
* With no paths, if <something> is _not_ a commit, no -t nor -b
* was given, and there is a tracking branch whose name is
* <something> in one and only one remote, then this is a short-hand
* to fork local <something> from that remote tracking branch.
* Handle
*
* Otherwise <something> shall not be ambiguous.
* - If it's *only* a reference, treat it like case (1).
* - If it's only a path, treat it like case (2).
* - else: fail.
* 1) git checkout <tree> -- [<paths>]
* 2) git checkout -- [<paths>]
* 3) git checkout <something> [<paths>]
*
* including "last branch" syntax and DWIM-ery for names of
* remote branches, erroring out for invalid or ambiguous cases.
*/
if (argc) {
if (!strcmp(argv[0], "--")) { /* case (2) */
argv++;
argc--;
goto no_reference;
}

arg = argv[0];
has_dash_dash = (argc > 1) && !strcmp(argv[1], "--");

if (!strcmp(arg, "-"))
arg = "@{-1}";

if (get_sha1_mb(arg, rev)) {
if (has_dash_dash) /* case (1) */
die("invalid reference: %s", arg);
if (!patch_mode &&
dwim_new_local_branch &&
opts.track == BRANCH_TRACK_UNSPECIFIED &&
!opts.new_branch &&
!check_filename(NULL, arg) &&
argc == 1) {
const char *remote = unique_tracking_name(arg);
if (!remote || get_sha1(remote, rev))
goto no_reference;
opts.new_branch = arg;
arg = remote;
/* DWIMmed to create local branch */
}
else
goto no_reference;
}

/* we can't end up being in (2) anymore, eat the argument */
argv++;
argc--;

new.name = arg;
setup_branch_path(&new);

if (check_ref_format(new.path) == CHECK_REF_FORMAT_OK &&
resolve_ref(new.path, branch_rev, 1, NULL))
hashcpy(rev, branch_rev);
else
new.path = NULL; /* not an existing branch */

if (!(new.commit = lookup_commit_reference_gently(rev, 1))) {
/* not a commit */
source_tree = parse_tree_indirect(rev);
} else {
parse_commit(new.commit);
source_tree = new.commit->tree;
}

if (!source_tree) /* case (1): want a tree */
die("reference is not a tree: %s", arg);
if (!has_dash_dash) {/* case (3 -> 1) */
/*
* Do not complain the most common case
* git checkout branch
* even if there happen to be a file called 'branch';
* it would be extremely annoying.
*/
if (argc)
verify_non_filename(NULL, arg);
}
else {
argv++;
argc--;
}
int dwim_ok =
!patch_mode &&
dwim_new_local_branch &&
opts.track == BRANCH_TRACK_UNSPECIFIED &&
!opts.new_branch;
int n = parse_branchname_arg(argc, argv, dwim_ok,
&new, &source_tree, rev, &opts.new_branch);
argv += n;
argc -= n;
}

no_reference:

if (opts.track == BRANCH_TRACK_UNSPECIFIED)
opts.track = git_branch_track;

Expand Down

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