make get_short_ref a public function

Often we want to shorten a full ref name to something "prettier"
to show a user. For example, "refs/heads/master" is often shown
simply as "master", or "refs/remotes/origin/master" is shown as
"origin/master".

Many places in the code use a very simple formula: skip common
prefixes like refs/heads, refs/remotes, etc. This is codified in
the prettify_ref function.

for-each-ref has a more correct (but more expensive) approach:
consider the ref lookup rules, and try shortening as much as
possible while remaining unambiguous.

This patch makes the latter strategy globally available as
shorten_unambiguous_ref.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin-for-each-ref.c b/builtin-for-each-ref.c
index 8796352eb673ff1f52df13329ee99530eaa98c39..c8114c8afdb5e5d8a5f0adac2302aa97c384d232 100644 (file)
--- a/builtin-for-each-ref.c
+++ b/builtin-for-each-ref.c
@@ -545,109 +545,6 @@ static void grab_values(struct atom_value *val, int deref, struct object *obj, v
        }
 }
 
-/*
- * generate a format suitable for scanf from a ref_rev_parse_rules
- * rule, that is replace the "%.*s" spec with a "%s" spec
- */
-static void gen_scanf_fmt(char *scanf_fmt, const char *rule)
-{
-       char *spec;
-
-       spec = strstr(rule, "%.*s");
-       if (!spec || strstr(spec + 4, "%.*s"))
-               die("invalid rule in ref_rev_parse_rules: %s", rule);
-
-       /* copy all until spec */
-       strncpy(scanf_fmt, rule, spec - rule);
-       scanf_fmt[spec - rule] = '\0';
-       /* copy new spec */
-       strcat(scanf_fmt, "%s");
-       /* copy remaining rule */
-       strcat(scanf_fmt, spec + 4);
-
-       return;
-}
-
-/*
- * Shorten the refname to an non-ambiguous form
- */
-static char *get_short_ref(const char *ref)
-{
-       int i;
-       static char **scanf_fmts;
-       static int nr_rules;
-       char *short_name;
-
-       /* pre generate scanf formats from ref_rev_parse_rules[] */
-       if (!nr_rules) {
-               size_t total_len = 0;
-
-               /* the rule list is NULL terminated, count them first */
-               for (; ref_rev_parse_rules[nr_rules]; nr_rules++)
-                       /* no +1 because strlen("%s") < strlen("%.*s") */
-                       total_len += strlen(ref_rev_parse_rules[nr_rules]);
-
-               scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
-
-               total_len = 0;
-               for (i = 0; i < nr_rules; i++) {
-                       scanf_fmts[i] = (char *)&scanf_fmts[nr_rules]
-                                       + total_len;
-                       gen_scanf_fmt(scanf_fmts[i], ref_rev_parse_rules[i]);
-                       total_len += strlen(ref_rev_parse_rules[i]);
-               }
-       }
-
-       /* bail out if there are no rules */
-       if (!nr_rules)
-               return xstrdup(ref);
-
-       /* buffer for scanf result, at most ref must fit */
-       short_name = xstrdup(ref);
-
-       /* skip first rule, it will always match */
-       for (i = nr_rules - 1; i > 0 ; --i) {
-               int j;
-               int short_name_len;
-
-               if (1 != sscanf(ref, scanf_fmts[i], short_name))
-                       continue;
-
-               short_name_len = strlen(short_name);
-
-               /*
-                * check if the short name resolves to a valid ref,
-                * but use only rules prior to the matched one
-                */
-               for (j = 0; j < i; j++) {
-                       const char *rule = ref_rev_parse_rules[j];
-                       unsigned char short_objectname[20];
-                       char refname[PATH_MAX];
-
-                       /*
-                        * the short name is ambiguous, if it resolves
-                        * (with this previous rule) to a valid ref
-                        * read_ref() returns 0 on success
-                        */
-                       mksnpath(refname, sizeof(refname),
-                                rule, short_name_len, short_name);
-                       if (!read_ref(refname, short_objectname))
-                               break;
-               }
-
-               /*
-                * short name is non-ambiguous if all previous rules
-                * haven't resolved to a valid ref
-                */
-               if (j == i)
-                       return short_name;
-       }
-
-       free(short_name);
-       return xstrdup(ref);
-}
-
-
 /*
  * Parse the object referred by ref, and grab needed value.
  */
@@ -704,7 +601,7 @@ static void populate_value(struct refinfo *ref)
                if (formatp) {
                        formatp++;
                        if (!strcmp(formatp, "short"))
-                               refname = get_short_ref(refname);
+                               refname = shorten_unambiguous_ref(refname);
                        else
                                die("unknown %.*s format %s",
                                    (int)(formatp - name), name, formatp);

diff --git a/refs.c b/refs.c
index 59c373fc6d315aacfc3b1a0cecce0ceb4b65d72f..1e5e7b4ad953ca55ffc4b7da439f90fa4715bbb1 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -1652,3 +1652,102 @@ struct ref *find_ref_by_name(const struct ref *list, const char *name)
                        return (struct ref *)list;
        return NULL;
 }
+
+/*
+ * generate a format suitable for scanf from a ref_rev_parse_rules
+ * rule, that is replace the "%.*s" spec with a "%s" spec
+ */
+static void gen_scanf_fmt(char *scanf_fmt, const char *rule)
+{
+       char *spec;
+
+       spec = strstr(rule, "%.*s");
+       if (!spec || strstr(spec + 4, "%.*s"))
+               die("invalid rule in ref_rev_parse_rules: %s", rule);
+
+       /* copy all until spec */
+       strncpy(scanf_fmt, rule, spec - rule);
+       scanf_fmt[spec - rule] = '\0';
+       /* copy new spec */
+       strcat(scanf_fmt, "%s");
+       /* copy remaining rule */
+       strcat(scanf_fmt, spec + 4);
+
+       return;
+}
+
+char *shorten_unambiguous_ref(const char *ref)
+{
+       int i;
+       static char **scanf_fmts;
+       static int nr_rules;
+       char *short_name;
+
+       /* pre generate scanf formats from ref_rev_parse_rules[] */
+       if (!nr_rules) {
+               size_t total_len = 0;
+
+               /* the rule list is NULL terminated, count them first */
+               for (; ref_rev_parse_rules[nr_rules]; nr_rules++)
+                       /* no +1 because strlen("%s") < strlen("%.*s") */
+                       total_len += strlen(ref_rev_parse_rules[nr_rules]);
+
+               scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
+
+               total_len = 0;
+               for (i = 0; i < nr_rules; i++) {
+                       scanf_fmts[i] = (char *)&scanf_fmts[nr_rules]
+                                       + total_len;
+                       gen_scanf_fmt(scanf_fmts[i], ref_rev_parse_rules[i]);
+                       total_len += strlen(ref_rev_parse_rules[i]);
+               }
+       }
+
+       /* bail out if there are no rules */
+       if (!nr_rules)
+               return xstrdup(ref);
+
+       /* buffer for scanf result, at most ref must fit */
+       short_name = xstrdup(ref);
+
+       /* skip first rule, it will always match */
+       for (i = nr_rules - 1; i > 0 ; --i) {
+               int j;
+               int short_name_len;
+
+               if (1 != sscanf(ref, scanf_fmts[i], short_name))
+                       continue;
+
+               short_name_len = strlen(short_name);
+
+               /*
+                * check if the short name resolves to a valid ref,
+                * but use only rules prior to the matched one
+                */
+               for (j = 0; j < i; j++) {
+                       const char *rule = ref_rev_parse_rules[j];
+                       unsigned char short_objectname[20];
+                       char refname[PATH_MAX];
+
+                       /*
+                        * the short name is ambiguous, if it resolves
+                        * (with this previous rule) to a valid ref
+                        * read_ref() returns 0 on success
+                        */
+                       mksnpath(refname, sizeof(refname),
+                                rule, short_name_len, short_name);
+                       if (!read_ref(refname, short_objectname))
+                               break;
+               }
+
+               /*
+                * short name is non-ambiguous if all previous rules
+                * haven't resolved to a valid ref
+                */
+               if (j == i)
+                       return short_name;
+       }
+
+       free(short_name);
+       return xstrdup(ref);
+}

diff --git a/refs.h b/refs.h
index 68c2d16d5388f5591a610e1d6fcf2f731159ecb2..2d0f961c7c67db113b0eab6c166723c0b4acf8ea 100644 (file)
--- a/refs.h
+++ b/refs.h
@@ -80,6 +80,7 @@ extern int for_each_reflog(each_ref_fn, void *);
 extern int check_ref_format(const char *target);
 
 extern const char *prettify_ref(const struct ref *ref);
+extern char *shorten_unambiguous_ref(const char *ref);
 
 /** rename ref, return 0 on success **/
 extern int rename_ref(const char *oldref, const char *newref, const char *logmsg);