Move most of the code from 'for-each-ref' to 'ref-filter' to make
it publicly available to other commands, this is to unify the code
of 'tag -l', 'branch -l' and 'for-each-ref' so that they can share
their implementations with each other.

Add 'ref-filter' to the Makefile, this completes the movement of code
from 'for-each-ref' to 'ref-filter'.

Mentored-by: Christian Couder <christian.cou...@gmail.com>
Mentored-by: Matthieu Moy <matthieu....@grenoble-inp.fr>
Signed-off-by: Karthik Nayak <karthik....@gmail.com>
---
 Makefile               |    1 +
 builtin/for-each-ref.c | 1075 +----------------------------------------------
 ref-filter.c           | 1077 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 1079 insertions(+), 1074 deletions(-)
 create mode 100644 ref-filter.c

diff --git a/Makefile b/Makefile
index 54ec511..d715b66 100644
--- a/Makefile
+++ b/Makefile
@@ -762,6 +762,7 @@ LIB_OBJS += reachable.o
 LIB_OBJS += read-cache.o
 LIB_OBJS += reflog-walk.o
 LIB_OBJS += refs.o
+LIB_OBJS += ref-filter.o
 LIB_OBJS += remote.o
 LIB_OBJS += replace_object.o
 LIB_OBJS += rerere.o
diff --git a/builtin/for-each-ref.c b/builtin/for-each-ref.c
index 063de00..4d2d024 100644
--- a/builtin/for-each-ref.c
+++ b/builtin/for-each-ref.c
@@ -2,1082 +2,9 @@
 #include "cache.h"
 #include "refs.h"
 #include "object.h"
-#include "tag.h"
-#include "commit.h"
-#include "tree.h"
-#include "blob.h"
-#include "quote.h"
 #include "parse-options.h"
-#include "remote.h"
-#include "color.h"
 #include "ref-filter.h"
 
-typedef enum { FIELD_STR, FIELD_ULONG, FIELD_TIME } cmp_type;
-
-static struct {
-       const char *name;
-       cmp_type cmp_type;
-} valid_atom[] = {
-       { "refname" },
-       { "objecttype" },
-       { "objectsize", FIELD_ULONG },
-       { "objectname" },
-       { "tree" },
-       { "parent" },
-       { "numparent", FIELD_ULONG },
-       { "object" },
-       { "type" },
-       { "tag" },
-       { "author" },
-       { "authorname" },
-       { "authoremail" },
-       { "authordate", FIELD_TIME },
-       { "committer" },
-       { "committername" },
-       { "committeremail" },
-       { "committerdate", FIELD_TIME },
-       { "tagger" },
-       { "taggername" },
-       { "taggeremail" },
-       { "taggerdate", FIELD_TIME },
-       { "creator" },
-       { "creatordate", FIELD_TIME },
-       { "subject" },
-       { "body" },
-       { "contents" },
-       { "contents:subject" },
-       { "contents:body" },
-       { "contents:signature" },
-       { "upstream" },
-       { "push" },
-       { "symref" },
-       { "flag" },
-       { "HEAD" },
-       { "color" },
-};
-
-/*
- * An atom is a valid field atom listed above, possibly prefixed with
- * a "*" to denote deref_tag().
- *
- * We parse given format string and sort specifiers, and make a list
- * of properties that we need to extract out of objects.  ref_array_item
- * structure will hold an array of values extracted that can be
- * indexed with the "atom number", which is an index into this
- * array.
- */
-static const char **used_atom;
-static cmp_type *used_atom_type;
-static int used_atom_cnt, need_tagged, need_symref;
-static int need_color_reset_at_eol;
-
-/*
- * Used to parse format string and sort specifiers
- */
-int parse_ref_filter_atom(const char *atom, const char *ep)
-{
-       const char *sp;
-       int i, at;
-
-       sp = atom;
-       if (*sp == '*' && sp < ep)
-               sp++; /* deref */
-       if (ep <= sp)
-               die("malformed field name: %.*s", (int)(ep-atom), atom);
-
-       /* Do we have the atom already used elsewhere? */
-       for (i = 0; i < used_atom_cnt; i++) {
-               int len = strlen(used_atom[i]);
-               if (len == ep - atom && !memcmp(used_atom[i], atom, len))
-                       return i;
-       }
-
-       /* Is the atom a valid one? */
-       for (i = 0; i < ARRAY_SIZE(valid_atom); i++) {
-               int len = strlen(valid_atom[i].name);
-               /*
-                * If the atom name has a colon, strip it and everything after
-                * it off - it specifies the format for this entry, and
-                * shouldn't be used for checking against the valid_atom
-                * table.
-                */
-               const char *formatp = strchr(sp, ':');
-               if (!formatp || ep < formatp)
-                       formatp = ep;
-               if (len == formatp - sp && !memcmp(valid_atom[i].name, sp, len))
-                       break;
-       }
-
-       if (ARRAY_SIZE(valid_atom) <= i)
-               die("unknown field name: %.*s", (int)(ep-atom), atom);
-
-       /* Add it in, including the deref prefix */
-       at = used_atom_cnt;
-       used_atom_cnt++;
-       REALLOC_ARRAY(used_atom, used_atom_cnt);
-       REALLOC_ARRAY(used_atom_type, used_atom_cnt);
-       used_atom[at] = xmemdupz(atom, ep - atom);
-       used_atom_type[at] = valid_atom[i].cmp_type;
-       if (*atom == '*')
-               need_tagged = 1;
-       if (!strcmp(used_atom[at], "symref"))
-               need_symref = 1;
-       return at;
-}
-
-/*
- * In a format string, find the next occurrence of %(atom).
- */
-static const char *find_next(const char *cp)
-{
-       while (*cp) {
-               if (*cp == '%') {
-                       /*
-                        * %( is the start of an atom;
-                        * %% is a quoted per-cent.
-                        */
-                       if (cp[1] == '(')
-                               return cp;
-                       else if (cp[1] == '%')
-                               cp++; /* skip over two % */
-                       /* otherwise this is a singleton, literal % */
-               }
-               cp++;
-       }
-       return NULL;
-}
-
-/*
- * Make sure the format string is well formed, and parse out
- * the used atoms.
- */
-int verify_ref_format(const char *format)
-{
-       const char *cp, *sp;
-
-       need_color_reset_at_eol = 0;
-       for (cp = format; *cp && (sp = find_next(cp)); ) {
-               const char *color, *ep = strchr(sp, ')');
-               int at;
-
-               if (!ep)
-                       return error("malformed format string %s", sp);
-               /* sp points at "%(" and ep points at the closing ")" */
-               at = parse_ref_filter_atom(sp + 2, ep);
-               cp = ep + 1;
-
-               if (skip_prefix(used_atom[at], "color:", &color))
-                       need_color_reset_at_eol = !!strcmp(color, "reset");
-       }
-       return 0;
-}
-
-/*
- * Given an object name, read the object data and size, and return a
- * "struct object".  If the object data we are returning is also borrowed
- * by the "struct object" representation, set *eaten as well---it is a
- * signal from parse_object_buffer to us not to free the buffer.
- */
-static void *get_obj(const unsigned char *sha1, struct object **obj, unsigned 
long *sz, int *eaten)
-{
-       enum object_type type;
-       void *buf = read_sha1_file(sha1, &type, sz);
-
-       if (buf)
-               *obj = parse_object_buffer(sha1, type, *sz, buf, eaten);
-       else
-               *obj = NULL;
-       return buf;
-}
-
-static int grab_objectname(const char *name, const unsigned char *sha1,
-                           struct atom_value *v)
-{
-       if (!strcmp(name, "objectname")) {
-               char *s = xmalloc(41);
-               strcpy(s, sha1_to_hex(sha1));
-               v->s = s;
-               return 1;
-       }
-       if (!strcmp(name, "objectname:short")) {
-               v->s = xstrdup(find_unique_abbrev(sha1, DEFAULT_ABBREV));
-               return 1;
-       }
-       return 0;
-}
-
-/* See grab_values */
-static void grab_common_values(struct atom_value *val, int deref, struct 
object *obj, void *buf, unsigned long sz)
-{
-       int i;
-
-       for (i = 0; i < used_atom_cnt; i++) {
-               const char *name = used_atom[i];
-               struct atom_value *v = &val[i];
-               if (!!deref != (*name == '*'))
-                       continue;
-               if (deref)
-                       name++;
-               if (!strcmp(name, "objecttype"))
-                       v->s = typename(obj->type);
-               else if (!strcmp(name, "objectsize")) {
-                       char *s = xmalloc(40);
-                       sprintf(s, "%lu", sz);
-                       v->ul = sz;
-                       v->s = s;
-               }
-               else if (deref)
-                       grab_objectname(name, obj->sha1, v);
-       }
-}
-
-/* See grab_values */
-static void grab_tag_values(struct atom_value *val, int deref, struct object 
*obj, void *buf, unsigned long sz)
-{
-       int i;
-       struct tag *tag = (struct tag *) obj;
-
-       for (i = 0; i < used_atom_cnt; i++) {
-               const char *name = used_atom[i];
-               struct atom_value *v = &val[i];
-               if (!!deref != (*name == '*'))
-                       continue;
-               if (deref)
-                       name++;
-               if (!strcmp(name, "tag"))
-                       v->s = tag->tag;
-               else if (!strcmp(name, "type") && tag->tagged)
-                       v->s = typename(tag->tagged->type);
-               else if (!strcmp(name, "object") && tag->tagged) {
-                       char *s = xmalloc(41);
-                       strcpy(s, sha1_to_hex(tag->tagged->sha1));
-                       v->s = s;
-               }
-       }
-}
-
-/* See grab_values */
-static void grab_commit_values(struct atom_value *val, int deref, struct 
object *obj, void *buf, unsigned long sz)
-{
-       int i;
-       struct commit *commit = (struct commit *) obj;
-
-       for (i = 0; i < used_atom_cnt; i++) {
-               const char *name = used_atom[i];
-               struct atom_value *v = &val[i];
-               if (!!deref != (*name == '*'))
-                       continue;
-               if (deref)
-                       name++;
-               if (!strcmp(name, "tree")) {
-                       char *s = xmalloc(41);
-                       strcpy(s, sha1_to_hex(commit->tree->object.sha1));
-                       v->s = s;
-               }
-               if (!strcmp(name, "numparent")) {
-                       char *s = xmalloc(40);
-                       v->ul = commit_list_count(commit->parents);
-                       sprintf(s, "%lu", v->ul);
-                       v->s = s;
-               }
-               else if (!strcmp(name, "parent")) {
-                       int num = commit_list_count(commit->parents);
-                       int i;
-                       struct commit_list *parents;
-                       char *s = xmalloc(41 * num + 1);
-                       v->s = s;
-                       for (i = 0, parents = commit->parents;
-                            parents;
-                            parents = parents->next, i = i + 41) {
-                               struct commit *parent = parents->item;
-                               strcpy(s+i, sha1_to_hex(parent->object.sha1));
-                               if (parents->next)
-                                       s[i+40] = ' ';
-                       }
-                       if (!i)
-                               *s = '\0';
-               }
-       }
-}
-
-static const char *find_wholine(const char *who, int wholen, const char *buf, 
unsigned long sz)
-{
-       const char *eol;
-       while (*buf) {
-               if (!strncmp(buf, who, wholen) &&
-                   buf[wholen] == ' ')
-                       return buf + wholen + 1;
-               eol = strchr(buf, '\n');
-               if (!eol)
-                       return "";
-               eol++;
-               if (*eol == '\n')
-                       return ""; /* end of header */
-               buf = eol;
-       }
-       return "";
-}
-
-static const char *copy_line(const char *buf)
-{
-       const char *eol = strchrnul(buf, '\n');
-       return xmemdupz(buf, eol - buf);
-}
-
-static const char *copy_name(const char *buf)
-{
-       const char *cp;
-       for (cp = buf; *cp && *cp != '\n'; cp++) {
-               if (!strncmp(cp, " <", 2))
-                       return xmemdupz(buf, cp - buf);
-       }
-       return "";
-}
-
-static const char *copy_email(const char *buf)
-{
-       const char *email = strchr(buf, '<');
-       const char *eoemail;
-       if (!email)
-               return "";
-       eoemail = strchr(email, '>');
-       if (!eoemail)
-               return "";
-       return xmemdupz(email, eoemail + 1 - email);
-}
-
-static char *copy_subject(const char *buf, unsigned long len)
-{
-       char *r = xmemdupz(buf, len);
-       int i;
-
-       for (i = 0; i < len; i++)
-               if (r[i] == '\n')
-                       r[i] = ' ';
-
-       return r;
-}
-
-static void grab_date(const char *buf, struct atom_value *v, const char 
*atomname)
-{
-       const char *eoemail = strstr(buf, "> ");
-       char *zone;
-       unsigned long timestamp;
-       long tz;
-       enum date_mode date_mode = DATE_NORMAL;
-       const char *formatp;
-
-       /*
-        * We got here because atomname ends in "date" or "date<something>";
-        * it's not possible that <something> is not ":<format>" because
-        * parse_ref_filter_atom() wouldn't have allowed it, so we can assume 
that no
-        * ":" means no format is specified, and use the default.
-        */
-       formatp = strchr(atomname, ':');
-       if (formatp != NULL) {
-               formatp++;
-               date_mode = parse_date_format(formatp);
-       }
-
-       if (!eoemail)
-               goto bad;
-       timestamp = strtoul(eoemail + 2, &zone, 10);
-       if (timestamp == ULONG_MAX)
-               goto bad;
-       tz = strtol(zone, NULL, 10);
-       if ((tz == LONG_MIN || tz == LONG_MAX) && errno == ERANGE)
-               goto bad;
-       v->s = xstrdup(show_date(timestamp, tz, date_mode));
-       v->ul = timestamp;
-       return;
- bad:
-       v->s = "";
-       v->ul = 0;
-}
-
-/* See grab_values */
-static void grab_person(const char *who, struct atom_value *val, int deref, 
struct object *obj, void *buf, unsigned long sz)
-{
-       int i;
-       int wholen = strlen(who);
-       const char *wholine = NULL;
-
-       for (i = 0; i < used_atom_cnt; i++) {
-               const char *name = used_atom[i];
-               struct atom_value *v = &val[i];
-               if (!!deref != (*name == '*'))
-                       continue;
-               if (deref)
-                       name++;
-               if (strncmp(who, name, wholen))
-                       continue;
-               if (name[wholen] != 0 &&
-                   strcmp(name + wholen, "name") &&
-                   strcmp(name + wholen, "email") &&
-                   !starts_with(name + wholen, "date"))
-                       continue;
-               if (!wholine)
-                       wholine = find_wholine(who, wholen, buf, sz);
-               if (!wholine)
-                       return; /* no point looking for it */
-               if (name[wholen] == 0)
-                       v->s = copy_line(wholine);
-               else if (!strcmp(name + wholen, "name"))
-                       v->s = copy_name(wholine);
-               else if (!strcmp(name + wholen, "email"))
-                       v->s = copy_email(wholine);
-               else if (starts_with(name + wholen, "date"))
-                       grab_date(wholine, v, name);
-       }
-
-       /*
-        * For a tag or a commit object, if "creator" or "creatordate" is
-        * requested, do something special.
-        */
-       if (strcmp(who, "tagger") && strcmp(who, "committer"))
-               return; /* "author" for commit object is not wanted */
-       if (!wholine)
-               wholine = find_wholine(who, wholen, buf, sz);
-       if (!wholine)
-               return;
-       for (i = 0; i < used_atom_cnt; i++) {
-               const char *name = used_atom[i];
-               struct atom_value *v = &val[i];
-               if (!!deref != (*name == '*'))
-                       continue;
-               if (deref)
-                       name++;
-
-               if (starts_with(name, "creatordate"))
-                       grab_date(wholine, v, name);
-               else if (!strcmp(name, "creator"))
-                       v->s = copy_line(wholine);
-       }
-}
-
-static void find_subpos(const char *buf, unsigned long sz,
-                       const char **sub, unsigned long *sublen,
-                       const char **body, unsigned long *bodylen,
-                       unsigned long *nonsiglen,
-                       const char **sig, unsigned long *siglen)
-{
-       const char *eol;
-       /* skip past header until we hit empty line */
-       while (*buf && *buf != '\n') {
-               eol = strchrnul(buf, '\n');
-               if (*eol)
-                       eol++;
-               buf = eol;
-       }
-       /* skip any empty lines */
-       while (*buf == '\n')
-               buf++;
-
-       /* parse signature first; we might not even have a subject line */
-       *sig = buf + parse_signature(buf, strlen(buf));
-       *siglen = strlen(*sig);
-
-       /* subject is first non-empty line */
-       *sub = buf;
-       /* subject goes to first empty line */
-       while (buf < *sig && *buf && *buf != '\n') {
-               eol = strchrnul(buf, '\n');
-               if (*eol)
-                       eol++;
-               buf = eol;
-       }
-       *sublen = buf - *sub;
-       /* drop trailing newline, if present */
-       if (*sublen && (*sub)[*sublen - 1] == '\n')
-               *sublen -= 1;
-
-       /* skip any empty lines */
-       while (*buf == '\n')
-               buf++;
-       *body = buf;
-       *bodylen = strlen(buf);
-       *nonsiglen = *sig - buf;
-}
-
-/* See grab_values */
-static void grab_sub_body_contents(struct atom_value *val, int deref, struct 
object *obj, void *buf, unsigned long sz)
-{
-       int i;
-       const char *subpos = NULL, *bodypos = NULL, *sigpos = NULL;
-       unsigned long sublen = 0, bodylen = 0, nonsiglen = 0, siglen = 0;
-
-       for (i = 0; i < used_atom_cnt; i++) {
-               const char *name = used_atom[i];
-               struct atom_value *v = &val[i];
-               if (!!deref != (*name == '*'))
-                       continue;
-               if (deref)
-                       name++;
-               if (strcmp(name, "subject") &&
-                   strcmp(name, "body") &&
-                   strcmp(name, "contents") &&
-                   strcmp(name, "contents:subject") &&
-                   strcmp(name, "contents:body") &&
-                   strcmp(name, "contents:signature"))
-                       continue;
-               if (!subpos)
-                       find_subpos(buf, sz,
-                                   &subpos, &sublen,
-                                   &bodypos, &bodylen, &nonsiglen,
-                                   &sigpos, &siglen);
-
-               if (!strcmp(name, "subject"))
-                       v->s = copy_subject(subpos, sublen);
-               else if (!strcmp(name, "contents:subject"))
-                       v->s = copy_subject(subpos, sublen);
-               else if (!strcmp(name, "body"))
-                       v->s = xmemdupz(bodypos, bodylen);
-               else if (!strcmp(name, "contents:body"))
-                       v->s = xmemdupz(bodypos, nonsiglen);
-               else if (!strcmp(name, "contents:signature"))
-                       v->s = xmemdupz(sigpos, siglen);
-               else if (!strcmp(name, "contents"))
-                       v->s = xstrdup(subpos);
-       }
-}
-
-/*
- * We want to have empty print-string for field requests
- * that do not apply (e.g. "authordate" for a tag object)
- */
-static void fill_missing_values(struct atom_value *val)
-{
-       int i;
-       for (i = 0; i < used_atom_cnt; i++) {
-               struct atom_value *v = &val[i];
-               if (v->s == NULL)
-                       v->s = "";
-       }
-}
-
-/*
- * val is a list of atom_value to hold returned values.  Extract
- * the values for atoms in used_atom array out of (obj, buf, sz).
- * when deref is false, (obj, buf, sz) is the object that is
- * pointed at by the ref itself; otherwise it is the object the
- * ref (which is a tag) refers to.
- */
-static void grab_values(struct atom_value *val, int deref, struct object *obj, 
void *buf, unsigned long sz)
-{
-       grab_common_values(val, deref, obj, buf, sz);
-       switch (obj->type) {
-       case OBJ_TAG:
-               grab_tag_values(val, deref, obj, buf, sz);
-               grab_sub_body_contents(val, deref, obj, buf, sz);
-               grab_person("tagger", val, deref, obj, buf, sz);
-               break;
-       case OBJ_COMMIT:
-               grab_commit_values(val, deref, obj, buf, sz);
-               grab_sub_body_contents(val, deref, obj, buf, sz);
-               grab_person("author", val, deref, obj, buf, sz);
-               grab_person("committer", val, deref, obj, buf, sz);
-               break;
-       case OBJ_TREE:
-               /* grab_tree_values(val, deref, obj, buf, sz); */
-               break;
-       case OBJ_BLOB:
-               /* grab_blob_values(val, deref, obj, buf, sz); */
-               break;
-       default:
-               die("Eh?  Object of type %d?", obj->type);
-       }
-}
-
-static inline char *copy_advance(char *dst, const char *src)
-{
-       while (*src)
-               *dst++ = *src++;
-       return dst;
-}
-
-/*
- * Parse the object referred by ref, and grab needed value.
- */
-static void populate_value(struct ref_array_item *ref)
-{
-       void *buf;
-       struct object *obj;
-       int eaten, i;
-       unsigned long size;
-       const unsigned char *tagged;
-
-       ref->value = xcalloc(used_atom_cnt, sizeof(struct atom_value));
-
-       if (need_symref && (ref->flag & REF_ISSYMREF) && !ref->symref) {
-               unsigned char unused1[20];
-               ref->symref = resolve_refdup(ref->refname, RESOLVE_REF_READING,
-                                            unused1, NULL);
-               if (!ref->symref)
-                       ref->symref = "";
-       }
-
-       /* Fill in specials first */
-       for (i = 0; i < used_atom_cnt; i++) {
-               const char *name = used_atom[i];
-               struct atom_value *v = &ref->value[i];
-               int deref = 0;
-               const char *refname;
-               const char *formatp;
-               struct branch *branch = NULL;
-
-               if (*name == '*') {
-                       deref = 1;
-                       name++;
-               }
-
-               if (starts_with(name, "refname"))
-                       refname = ref->refname;
-               else if (starts_with(name, "symref"))
-                       refname = ref->symref ? ref->symref : "";
-               else if (starts_with(name, "upstream")) {
-                       const char *branch_name;
-                       /* only local branches may have an upstream */
-                       if (!skip_prefix(ref->refname, "refs/heads/",
-                                        &branch_name))
-                               continue;
-                       branch = branch_get(branch_name);
-
-                       refname = branch_get_upstream(branch, NULL);
-                       if (!refname)
-                               continue;
-               } else if (starts_with(name, "push")) {
-                       const char *branch_name;
-                       if (!skip_prefix(ref->refname, "refs/heads/",
-                                        &branch_name))
-                               continue;
-                       branch = branch_get(branch_name);
-
-                       refname = branch_get_push(branch, NULL);
-                       if (!refname)
-                               continue;
-               } else if (starts_with(name, "color:")) {
-                       char color[COLOR_MAXLEN] = "";
-
-                       if (color_parse(name + 6, color) < 0)
-                               die(_("unable to parse format"));
-                       v->s = xstrdup(color);
-                       continue;
-               } else if (!strcmp(name, "flag")) {
-                       char buf[256], *cp = buf;
-                       if (ref->flag & REF_ISSYMREF)
-                               cp = copy_advance(cp, ",symref");
-                       if (ref->flag & REF_ISPACKED)
-                               cp = copy_advance(cp, ",packed");
-                       if (cp == buf)
-                               v->s = "";
-                       else {
-                               *cp = '\0';
-                               v->s = xstrdup(buf + 1);
-                       }
-                       continue;
-               } else if (!deref && grab_objectname(name, ref->objectname, v)) 
{
-                       continue;
-               } else if (!strcmp(name, "HEAD")) {
-                       const char *head;
-                       unsigned char sha1[20];
-
-                       head = resolve_ref_unsafe("HEAD", RESOLVE_REF_READING,
-                                                 sha1, NULL);
-                       if (!strcmp(ref->refname, head))
-                               v->s = "*";
-                       else
-                               v->s = " ";
-                       continue;
-               } else
-                       continue;
-
-               formatp = strchr(name, ':');
-               if (formatp) {
-                       int num_ours, num_theirs;
-
-                       formatp++;
-                       if (!strcmp(formatp, "short"))
-                               refname = shorten_unambiguous_ref(refname,
-                                                     warn_ambiguous_refs);
-                       else if (!strcmp(formatp, "track") &&
-                                (starts_with(name, "upstream") ||
-                                 starts_with(name, "push"))) {
-                               char buf[40];
-
-                               if (stat_tracking_info(branch, &num_ours,
-                                                      &num_theirs, NULL))
-                                       continue;
-
-                               if (!num_ours && !num_theirs)
-                                       v->s = "";
-                               else if (!num_ours) {
-                                       sprintf(buf, "[behind %d]", num_theirs);
-                                       v->s = xstrdup(buf);
-                               } else if (!num_theirs) {
-                                       sprintf(buf, "[ahead %d]", num_ours);
-                                       v->s = xstrdup(buf);
-                               } else {
-                                       sprintf(buf, "[ahead %d, behind %d]",
-                                               num_ours, num_theirs);
-                                       v->s = xstrdup(buf);
-                               }
-                               continue;
-                       } else if (!strcmp(formatp, "trackshort") &&
-                                  (starts_with(name, "upstream") ||
-                                   starts_with(name, "push"))) {
-                               assert(branch);
-
-                               if (stat_tracking_info(branch, &num_ours,
-                                                       &num_theirs, NULL))
-                                       continue;
-
-                               if (!num_ours && !num_theirs)
-                                       v->s = "=";
-                               else if (!num_ours)
-                                       v->s = "<";
-                               else if (!num_theirs)
-                                       v->s = ">";
-                               else
-                                       v->s = "<>";
-                               continue;
-                       } else
-                               die("unknown %.*s format %s",
-                                   (int)(formatp - name), name, formatp);
-               }
-
-               if (!deref)
-                       v->s = refname;
-               else {
-                       int len = strlen(refname);
-                       char *s = xmalloc(len + 4);
-                       sprintf(s, "%s^{}", refname);
-                       v->s = s;
-               }
-       }
-
-       for (i = 0; i < used_atom_cnt; i++) {
-               struct atom_value *v = &ref->value[i];
-               if (v->s == NULL)
-                       goto need_obj;
-       }
-       return;
-
- need_obj:
-       buf = get_obj(ref->objectname, &obj, &size, &eaten);
-       if (!buf)
-               die("missing object %s for %s",
-                   sha1_to_hex(ref->objectname), ref->refname);
-       if (!obj)
-               die("parse_object_buffer failed on %s for %s",
-                   sha1_to_hex(ref->objectname), ref->refname);
-
-       grab_values(ref->value, 0, obj, buf, size);
-       if (!eaten)
-               free(buf);
-
-       /*
-        * If there is no atom that wants to know about tagged
-        * object, we are done.
-        */
-       if (!need_tagged || (obj->type != OBJ_TAG))
-               return;
-
-       /*
-        * If it is a tag object, see if we use a value that derefs
-        * the object, and if we do grab the object it refers to.
-        */
-       tagged = ((struct tag *)obj)->tagged->sha1;
-
-       /*
-        * NEEDSWORK: This derefs tag only once, which
-        * is good to deal with chains of trust, but
-        * is not consistent with what deref_tag() does
-        * which peels the onion to the core.
-        */
-       buf = get_obj(tagged, &obj, &size, &eaten);
-       if (!buf)
-               die("missing object %s for %s",
-                   sha1_to_hex(tagged), ref->refname);
-       if (!obj)
-               die("parse_object_buffer failed on %s for %s",
-                   sha1_to_hex(tagged), ref->refname);
-       grab_values(ref->value, 1, obj, buf, size);
-       if (!eaten)
-               free(buf);
-}
-
-/*
- * Given a ref, return the value for the atom.  This lazily gets value
- * out of the object by calling populate value.
- */
-static void get_ref_atom_value(struct ref_array_item *ref, int atom, struct 
atom_value **v)
-{
-       if (!ref->value) {
-               populate_value(ref);
-               fill_missing_values(ref->value);
-       }
-       *v = &ref->value[atom];
-}
-
-/*
- * Given a refname, return 1 if the refname matches with one of the patterns
- * while the pattern is a pathname like 'refs/tags' or 'refs/heads/master'
- * and so on, else return 0. Supports use of wild characters.
- */
-static int match_name_as_path(const char **pattern, const char *refname)
-{
-       int namelen = strlen(refname);
-       for (; *pattern; pattern++) {
-               const char *p = *pattern;
-               int plen = strlen(p);
-
-               if ((plen <= namelen) &&
-                   !strncmp(refname, p, plen) &&
-                   (refname[plen] == '\0' ||
-                    refname[plen] == '/' ||
-                    p[plen-1] == '/'))
-                       return 1;
-               if (!wildmatch(p, refname, WM_PATHNAME, NULL))
-                       return 1;
-       }
-       return 0;
-}
-
-/* Allocate space for a new ref_array_item and copy the objectname and flag to 
it */
-static struct ref_array_item *new_ref_array_item(const char *refname,
-                                                const unsigned char 
*objectname,
-                                                int flag)
-{
-       struct ref_array_item *ref = xcalloc(1, sizeof(struct ref_array_item));
-       ref->refname = xstrdup(refname);
-       hashcpy(ref->objectname, objectname);
-       ref->flag = flag;
-
-       return ref;
-}
-
-/*
- * A call-back given to for_each_ref().  Filter refs and keep them for
- * later object processing.
- */
-int ref_filter_handler(const char *refname, const struct object_id *oid, int 
flag, void *cb_data)
-{
-       struct ref_filter_cbdata *ref_cbdata = cb_data;
-       struct ref_filter *filter = &ref_cbdata->filter;
-       struct ref_array_item *ref;
-
-       if (flag & REF_BAD_NAME) {
-                 warning("ignoring ref with broken name %s", refname);
-                 return 0;
-       }
-
-       if (*filter->name_patterns && 
!match_name_as_path(filter->name_patterns, refname))
-               return 0;
-
-       /*
-        * We do not open the object yet; sort may only need refname
-        * to do its job and the resulting list may yet to be pruned
-        * by maxcount logic.
-        */
-       ref = new_ref_array_item(refname, oid->hash, flag);
-
-       REALLOC_ARRAY(ref_cbdata->array.items, ref_cbdata->array.nr + 1);
-       ref_cbdata->array.items[ref_cbdata->array.nr++] = ref;
-       return 0;
-}
-
-/*  Free memory allocated for a ref_array_item */
-static void free_array_item(struct ref_array_item *item)
-{
-       free(item->symref);
-       free(item->refname);
-       free(item);
-}
-
-/* Free all memory allocated for ref_array */
-void ref_array_clear(struct ref_array *array)
-{
-       int i;
-
-       for (i = 0; i < array->nr; i++)
-               free_array_item(array->items[i]);
-       free(array->items);
-       array->items = NULL;
-       array->nr = array->alloc = 0;
-}
-
-static int cmp_ref_sorting(struct ref_sorting *s, struct ref_array_item *a, 
struct ref_array_item *b)
-{
-       struct atom_value *va, *vb;
-       int cmp;
-       cmp_type cmp_type = used_atom_type[s->atom];
-
-       get_ref_atom_value(a, s->atom, &va);
-       get_ref_atom_value(b, s->atom, &vb);
-       switch (cmp_type) {
-       case FIELD_STR:
-               cmp = strcmp(va->s, vb->s);
-               break;
-       default:
-               if (va->ul < vb->ul)
-                       cmp = -1;
-               else if (va->ul == vb->ul)
-                       cmp = 0;
-               else
-                       cmp = 1;
-               break;
-       }
-       return (s->reverse) ? -cmp : cmp;
-}
-
-static struct ref_sorting *ref_sorting;
-static int compare_refs(const void *a_, const void *b_)
-{
-       struct ref_array_item *a = *((struct ref_array_item **)a_);
-       struct ref_array_item *b = *((struct ref_array_item **)b_);
-       struct ref_sorting *s;
-
-       for (s = ref_sorting; s; s = s->next) {
-               int cmp = cmp_ref_sorting(s, a, b);
-               if (cmp)
-                       return cmp;
-       }
-       return 0;
-}
-
-void ref_array_sort(struct ref_sorting *sorting, struct ref_array *array)
-{
-       ref_sorting = sorting;
-       qsort(array->items, array->nr, sizeof(struct ref_array_item *), 
compare_refs);
-}
-
-static void print_value(struct atom_value *v, int quote_style)
-{
-       struct strbuf sb = STRBUF_INIT;
-       switch (quote_style) {
-       case QUOTE_NONE:
-               fputs(v->s, stdout);
-               break;
-       case QUOTE_SHELL:
-               sq_quote_buf(&sb, v->s);
-               break;
-       case QUOTE_PERL:
-               perl_quote_buf(&sb, v->s);
-               break;
-       case QUOTE_PYTHON:
-               python_quote_buf(&sb, v->s);
-               break;
-       case QUOTE_TCL:
-               tcl_quote_buf(&sb, v->s);
-               break;
-       }
-       if (quote_style != QUOTE_NONE) {
-               fputs(sb.buf, stdout);
-               strbuf_release(&sb);
-       }
-}
-
-static int hex1(char ch)
-{
-       if ('0' <= ch && ch <= '9')
-               return ch - '0';
-       else if ('a' <= ch && ch <= 'f')
-               return ch - 'a' + 10;
-       else if ('A' <= ch && ch <= 'F')
-               return ch - 'A' + 10;
-       return -1;
-}
-static int hex2(const char *cp)
-{
-       if (cp[0] && cp[1])
-               return (hex1(cp[0]) << 4) | hex1(cp[1]);
-       else
-               return -1;
-}
-
-static void emit(const char *cp, const char *ep)
-{
-       while (*cp && (!ep || cp < ep)) {
-               if (*cp == '%') {
-                       if (cp[1] == '%')
-                               cp++;
-                       else {
-                               int ch = hex2(cp + 1);
-                               if (0 <= ch) {
-                                       putchar(ch);
-                                       cp += 3;
-                                       continue;
-                               }
-                       }
-               }
-               putchar(*cp);
-               cp++;
-       }
-}
-
-void show_ref_array_item(struct ref_array_item *info, const char *format, int 
quote_style)
-{
-       const char *cp, *sp, *ep;
-
-       for (cp = format; *cp && (sp = find_next(cp)); cp = ep + 1) {
-               struct atom_value *atomv;
-
-               ep = strchr(sp, ')');
-               if (cp < sp)
-                       emit(cp, sp);
-               get_ref_atom_value(info, parse_ref_filter_atom(sp + 2, ep), 
&atomv);
-               print_value(atomv, quote_style);
-       }
-       if (*cp) {
-               sp = cp + strlen(cp);
-               emit(cp, sp);
-       }
-       if (need_color_reset_at_eol) {
-               struct atom_value resetv;
-               char color[COLOR_MAXLEN] = "";
-
-               if (color_parse("reset", color) < 0)
-                       die("BUG: couldn't parse 'reset' as a color");
-               resetv.s = color;
-               print_value(&resetv, quote_style);
-       }
-       putchar('\n');
-}
-
-/*  If no sorting option is given, use refname to sort as default */
-struct ref_sorting *ref_default_sorting(void)
-{
-       static const char cstr_name[] = "refname";
-
-       struct ref_sorting *sorting = xcalloc(1, sizeof(*sorting));
-
-       sorting->next = NULL;
-       sorting->atom = parse_ref_filter_atom(cstr_name, cstr_name + 
strlen(cstr_name));
-       return sorting;
-}
-
-int parse_opt_ref_sorting(const struct option *opt, const char *arg, int unset)
-{
-       struct ref_sorting **sorting_tail = opt->value;
-       struct ref_sorting *s;
-       int len;
-
-       if (!arg) /* should --no-sort void the list ? */
-               return -1;
-
-       s = xcalloc(1, sizeof(*s));
-       s->next = *sorting_tail;
-       *sorting_tail = s;
-
-       if (*arg == '-') {
-               s->reverse = 1;
-               arg++;
-       }
-       len = strlen(arg);
-       s->atom = parse_ref_filter_atom(arg, arg+len);
-       return 0;
-}
-
 static char const * const for_each_ref_usage[] = {
        N_("git for-each-ref [<options>] [<pattern>]"),
        NULL
@@ -1129,7 +56,7 @@ int cmd_for_each_ref(int argc, const char **argv, const 
char *prefix)
 
        memset(&ref_cbdata, 0, sizeof(ref_cbdata));
        ref_cbdata.filter.name_patterns = argv;
-       for_each_rawref(ref_filter_handler, &ref_cbdata);
+       filter_refs(for_each_rawref, &ref_cbdata);
 
        ref_array_sort(sorting, &ref_cbdata.array);
 
diff --git a/ref-filter.c b/ref-filter.c
new file mode 100644
index 0000000..ece16a1
--- /dev/null
+++ b/ref-filter.c
@@ -0,0 +1,1077 @@
+#include "builtin.h"
+#include "cache.h"
+#include "parse-options.h"
+#include "refs.h"
+#include "wildmatch.h"
+#include "commit.h"
+#include "remote.h"
+#include "color.h"
+#include "tag.h"
+#include "quote.h"
+#include "ref-filter.h"
+
+typedef enum { FIELD_STR, FIELD_ULONG, FIELD_TIME } cmp_type;
+
+static struct {
+       const char *name;
+       cmp_type cmp_type;
+} valid_atom[] = {
+       { "refname" },
+       { "objecttype" },
+       { "objectsize", FIELD_ULONG },
+       { "objectname" },
+       { "tree" },
+       { "parent" },
+       { "numparent", FIELD_ULONG },
+       { "object" },
+       { "type" },
+       { "tag" },
+       { "author" },
+       { "authorname" },
+       { "authoremail" },
+       { "authordate", FIELD_TIME },
+       { "committer" },
+       { "committername" },
+       { "committeremail" },
+       { "committerdate", FIELD_TIME },
+       { "tagger" },
+       { "taggername" },
+       { "taggeremail" },
+       { "taggerdate", FIELD_TIME },
+       { "creator" },
+       { "creatordate", FIELD_TIME },
+       { "subject" },
+       { "body" },
+       { "contents" },
+       { "contents:subject" },
+       { "contents:body" },
+       { "contents:signature" },
+       { "upstream" },
+       { "push" },
+       { "symref" },
+       { "flag" },
+       { "HEAD" },
+       { "color" },
+};
+
+/*
+ * An atom is a valid field atom listed above, possibly prefixed with
+ * a "*" to denote deref_tag().
+ *
+ * We parse given format string and sort specifiers, and make a list
+ * of properties that we need to extract out of objects.  ref_array_item
+ * structure will hold an array of values extracted that can be
+ * indexed with the "atom number", which is an index into this
+ * array.
+ */
+static const char **used_atom;
+static cmp_type *used_atom_type;
+static int used_atom_cnt, need_tagged, need_symref;
+static int need_color_reset_at_eol;
+
+/*
+ * Used to parse format string and sort specifiers
+ */
+int parse_ref_filter_atom(const char *atom, const char *ep)
+{
+       const char *sp;
+       int i, at;
+
+       sp = atom;
+       if (*sp == '*' && sp < ep)
+               sp++; /* deref */
+       if (ep <= sp)
+               die("malformed field name: %.*s", (int)(ep-atom), atom);
+
+       /* Do we have the atom already used elsewhere? */
+       for (i = 0; i < used_atom_cnt; i++) {
+               int len = strlen(used_atom[i]);
+               if (len == ep - atom && !memcmp(used_atom[i], atom, len))
+                       return i;
+       }
+
+       /* Is the atom a valid one? */
+       for (i = 0; i < ARRAY_SIZE(valid_atom); i++) {
+               int len = strlen(valid_atom[i].name);
+               /*
+                * If the atom name has a colon, strip it and everything after
+                * it off - it specifies the format for this entry, and
+                * shouldn't be used for checking against the valid_atom
+                * table.
+                */
+               const char *formatp = strchr(sp, ':');
+               if (!formatp || ep < formatp)
+                       formatp = ep;
+               if (len == formatp - sp && !memcmp(valid_atom[i].name, sp, len))
+                       break;
+       }
+
+       if (ARRAY_SIZE(valid_atom) <= i)
+               die("unknown field name: %.*s", (int)(ep-atom), atom);
+
+       /* Add it in, including the deref prefix */
+       at = used_atom_cnt;
+       used_atom_cnt++;
+       REALLOC_ARRAY(used_atom, used_atom_cnt);
+       REALLOC_ARRAY(used_atom_type, used_atom_cnt);
+       used_atom[at] = xmemdupz(atom, ep - atom);
+       used_atom_type[at] = valid_atom[i].cmp_type;
+       if (*atom == '*')
+               need_tagged = 1;
+       if (!strcmp(used_atom[at], "symref"))
+               need_symref = 1;
+       return at;
+}
+
+/*
+ * In a format string, find the next occurrence of %(atom).
+ */
+static const char *find_next(const char *cp)
+{
+       while (*cp) {
+               if (*cp == '%') {
+                       /*
+                        * %( is the start of an atom;
+                        * %% is a quoted per-cent.
+                        */
+                       if (cp[1] == '(')
+                               return cp;
+                       else if (cp[1] == '%')
+                               cp++; /* skip over two % */
+                       /* otherwise this is a singleton, literal % */
+               }
+               cp++;
+       }
+       return NULL;
+}
+
+/*
+ * Make sure the format string is well formed, and parse out
+ * the used atoms.
+ */
+int verify_ref_format(const char *format)
+{
+       const char *cp, *sp;
+
+       need_color_reset_at_eol = 0;
+       for (cp = format; *cp && (sp = find_next(cp)); ) {
+               const char *color, *ep = strchr(sp, ')');
+               int at;
+
+               if (!ep)
+                       return error("malformed format string %s", sp);
+               /* sp points at "%(" and ep points at the closing ")" */
+               at = parse_ref_filter_atom(sp + 2, ep);
+               cp = ep + 1;
+
+               if (skip_prefix(used_atom[at], "color:", &color))
+                       need_color_reset_at_eol = !!strcmp(color, "reset");
+       }
+       return 0;
+}
+
+/*
+ * Given an object name, read the object data and size, and return a
+ * "struct object".  If the object data we are returning is also borrowed
+ * by the "struct object" representation, set *eaten as well---it is a
+ * signal from parse_object_buffer to us not to free the buffer.
+ */
+static void *get_obj(const unsigned char *sha1, struct object **obj, unsigned 
long *sz, int *eaten)
+{
+       enum object_type type;
+       void *buf = read_sha1_file(sha1, &type, sz);
+
+       if (buf)
+               *obj = parse_object_buffer(sha1, type, *sz, buf, eaten);
+       else
+               *obj = NULL;
+       return buf;
+}
+
+static int grab_objectname(const char *name, const unsigned char *sha1,
+                           struct atom_value *v)
+{
+       if (!strcmp(name, "objectname")) {
+               char *s = xmalloc(41);
+               strcpy(s, sha1_to_hex(sha1));
+               v->s = s;
+               return 1;
+       }
+       if (!strcmp(name, "objectname:short")) {
+               v->s = xstrdup(find_unique_abbrev(sha1, DEFAULT_ABBREV));
+               return 1;
+       }
+       return 0;
+}
+
+/* See grab_values */
+static void grab_common_values(struct atom_value *val, int deref, struct 
object *obj, void *buf, unsigned long sz)
+{
+       int i;
+
+       for (i = 0; i < used_atom_cnt; i++) {
+               const char *name = used_atom[i];
+               struct atom_value *v = &val[i];
+               if (!!deref != (*name == '*'))
+                       continue;
+               if (deref)
+                       name++;
+               if (!strcmp(name, "objecttype"))
+                       v->s = typename(obj->type);
+               else if (!strcmp(name, "objectsize")) {
+                       char *s = xmalloc(40);
+                       sprintf(s, "%lu", sz);
+                       v->ul = sz;
+                       v->s = s;
+               }
+               else if (deref)
+                       grab_objectname(name, obj->sha1, v);
+       }
+}
+
+/* See grab_values */
+static void grab_tag_values(struct atom_value *val, int deref, struct object 
*obj, void *buf, unsigned long sz)
+{
+       int i;
+       struct tag *tag = (struct tag *) obj;
+
+       for (i = 0; i < used_atom_cnt; i++) {
+               const char *name = used_atom[i];
+               struct atom_value *v = &val[i];
+               if (!!deref != (*name == '*'))
+                       continue;
+               if (deref)
+                       name++;
+               if (!strcmp(name, "tag"))
+                       v->s = tag->tag;
+               else if (!strcmp(name, "type") && tag->tagged)
+                       v->s = typename(tag->tagged->type);
+               else if (!strcmp(name, "object") && tag->tagged) {
+                       char *s = xmalloc(41);
+                       strcpy(s, sha1_to_hex(tag->tagged->sha1));
+                       v->s = s;
+               }
+       }
+}
+
+/* See grab_values */
+static void grab_commit_values(struct atom_value *val, int deref, struct 
object *obj, void *buf, unsigned long sz)
+{
+       int i;
+       struct commit *commit = (struct commit *) obj;
+
+       for (i = 0; i < used_atom_cnt; i++) {
+               const char *name = used_atom[i];
+               struct atom_value *v = &val[i];
+               if (!!deref != (*name == '*'))
+                       continue;
+               if (deref)
+                       name++;
+               if (!strcmp(name, "tree")) {
+                       char *s = xmalloc(41);
+                       strcpy(s, sha1_to_hex(commit->tree->object.sha1));
+                       v->s = s;
+               }
+               if (!strcmp(name, "numparent")) {
+                       char *s = xmalloc(40);
+                       v->ul = commit_list_count(commit->parents);
+                       sprintf(s, "%lu", v->ul);
+                       v->s = s;
+               }
+               else if (!strcmp(name, "parent")) {
+                       int num = commit_list_count(commit->parents);
+                       int i;
+                       struct commit_list *parents;
+                       char *s = xmalloc(41 * num + 1);
+                       v->s = s;
+                       for (i = 0, parents = commit->parents;
+                            parents;
+                            parents = parents->next, i = i + 41) {
+                               struct commit *parent = parents->item;
+                               strcpy(s+i, sha1_to_hex(parent->object.sha1));
+                               if (parents->next)
+                                       s[i+40] = ' ';
+                       }
+                       if (!i)
+                               *s = '\0';
+               }
+       }
+}
+
+static const char *find_wholine(const char *who, int wholen, const char *buf, 
unsigned long sz)
+{
+       const char *eol;
+       while (*buf) {
+               if (!strncmp(buf, who, wholen) &&
+                   buf[wholen] == ' ')
+                       return buf + wholen + 1;
+               eol = strchr(buf, '\n');
+               if (!eol)
+                       return "";
+               eol++;
+               if (*eol == '\n')
+                       return ""; /* end of header */
+               buf = eol;
+       }
+       return "";
+}
+
+static const char *copy_line(const char *buf)
+{
+       const char *eol = strchrnul(buf, '\n');
+       return xmemdupz(buf, eol - buf);
+}
+
+static const char *copy_name(const char *buf)
+{
+       const char *cp;
+       for (cp = buf; *cp && *cp != '\n'; cp++) {
+               if (!strncmp(cp, " <", 2))
+                       return xmemdupz(buf, cp - buf);
+       }
+       return "";
+}
+
+static const char *copy_email(const char *buf)
+{
+       const char *email = strchr(buf, '<');
+       const char *eoemail;
+       if (!email)
+               return "";
+       eoemail = strchr(email, '>');
+       if (!eoemail)
+               return "";
+       return xmemdupz(email, eoemail + 1 - email);
+}
+
+static char *copy_subject(const char *buf, unsigned long len)
+{
+       char *r = xmemdupz(buf, len);
+       int i;
+
+       for (i = 0; i < len; i++)
+               if (r[i] == '\n')
+                       r[i] = ' ';
+
+       return r;
+}
+
+static void grab_date(const char *buf, struct atom_value *v, const char 
*atomname)
+{
+       const char *eoemail = strstr(buf, "> ");
+       char *zone;
+       unsigned long timestamp;
+       long tz;
+       enum date_mode date_mode = DATE_NORMAL;
+       const char *formatp;
+
+       /*
+        * We got here because atomname ends in "date" or "date<something>";
+        * it's not possible that <something> is not ":<format>" because
+        * parse_ref_filter_atom() wouldn't have allowed it, so we can assume 
that no
+        * ":" means no format is specified, and use the default.
+        */
+       formatp = strchr(atomname, ':');
+       if (formatp != NULL) {
+               formatp++;
+               date_mode = parse_date_format(formatp);
+       }
+
+       if (!eoemail)
+               goto bad;
+       timestamp = strtoul(eoemail + 2, &zone, 10);
+       if (timestamp == ULONG_MAX)
+               goto bad;
+       tz = strtol(zone, NULL, 10);
+       if ((tz == LONG_MIN || tz == LONG_MAX) && errno == ERANGE)
+               goto bad;
+       v->s = xstrdup(show_date(timestamp, tz, date_mode));
+       v->ul = timestamp;
+       return;
+ bad:
+       v->s = "";
+       v->ul = 0;
+}
+
+/* See grab_values */
+static void grab_person(const char *who, struct atom_value *val, int deref, 
struct object *obj, void *buf, unsigned long sz)
+{
+       int i;
+       int wholen = strlen(who);
+       const char *wholine = NULL;
+
+       for (i = 0; i < used_atom_cnt; i++) {
+               const char *name = used_atom[i];
+               struct atom_value *v = &val[i];
+               if (!!deref != (*name == '*'))
+                       continue;
+               if (deref)
+                       name++;
+               if (strncmp(who, name, wholen))
+                       continue;
+               if (name[wholen] != 0 &&
+                   strcmp(name + wholen, "name") &&
+                   strcmp(name + wholen, "email") &&
+                   !starts_with(name + wholen, "date"))
+                       continue;
+               if (!wholine)
+                       wholine = find_wholine(who, wholen, buf, sz);
+               if (!wholine)
+                       return; /* no point looking for it */
+               if (name[wholen] == 0)
+                       v->s = copy_line(wholine);
+               else if (!strcmp(name + wholen, "name"))
+                       v->s = copy_name(wholine);
+               else if (!strcmp(name + wholen, "email"))
+                       v->s = copy_email(wholine);
+               else if (starts_with(name + wholen, "date"))
+                       grab_date(wholine, v, name);
+       }
+
+       /*
+        * For a tag or a commit object, if "creator" or "creatordate" is
+        * requested, do something special.
+        */
+       if (strcmp(who, "tagger") && strcmp(who, "committer"))
+               return; /* "author" for commit object is not wanted */
+       if (!wholine)
+               wholine = find_wholine(who, wholen, buf, sz);
+       if (!wholine)
+               return;
+       for (i = 0; i < used_atom_cnt; i++) {
+               const char *name = used_atom[i];
+               struct atom_value *v = &val[i];
+               if (!!deref != (*name == '*'))
+                       continue;
+               if (deref)
+                       name++;
+
+               if (starts_with(name, "creatordate"))
+                       grab_date(wholine, v, name);
+               else if (!strcmp(name, "creator"))
+                       v->s = copy_line(wholine);
+       }
+}
+
+static void find_subpos(const char *buf, unsigned long sz,
+                       const char **sub, unsigned long *sublen,
+                       const char **body, unsigned long *bodylen,
+                       unsigned long *nonsiglen,
+                       const char **sig, unsigned long *siglen)
+{
+       const char *eol;
+       /* skip past header until we hit empty line */
+       while (*buf && *buf != '\n') {
+               eol = strchrnul(buf, '\n');
+               if (*eol)
+                       eol++;
+               buf = eol;
+       }
+       /* skip any empty lines */
+       while (*buf == '\n')
+               buf++;
+
+       /* parse signature first; we might not even have a subject line */
+       *sig = buf + parse_signature(buf, strlen(buf));
+       *siglen = strlen(*sig);
+
+       /* subject is first non-empty line */
+       *sub = buf;
+       /* subject goes to first empty line */
+       while (buf < *sig && *buf && *buf != '\n') {
+               eol = strchrnul(buf, '\n');
+               if (*eol)
+                       eol++;
+               buf = eol;
+       }
+       *sublen = buf - *sub;
+       /* drop trailing newline, if present */
+       if (*sublen && (*sub)[*sublen - 1] == '\n')
+               *sublen -= 1;
+
+       /* skip any empty lines */
+       while (*buf == '\n')
+               buf++;
+       *body = buf;
+       *bodylen = strlen(buf);
+       *nonsiglen = *sig - buf;
+}
+
+/* See grab_values */
+static void grab_sub_body_contents(struct atom_value *val, int deref, struct 
object *obj, void *buf, unsigned long sz)
+{
+       int i;
+       const char *subpos = NULL, *bodypos = NULL, *sigpos = NULL;
+       unsigned long sublen = 0, bodylen = 0, nonsiglen = 0, siglen = 0;
+
+       for (i = 0; i < used_atom_cnt; i++) {
+               const char *name = used_atom[i];
+               struct atom_value *v = &val[i];
+               if (!!deref != (*name == '*'))
+                       continue;
+               if (deref)
+                       name++;
+               if (strcmp(name, "subject") &&
+                   strcmp(name, "body") &&
+                   strcmp(name, "contents") &&
+                   strcmp(name, "contents:subject") &&
+                   strcmp(name, "contents:body") &&
+                   strcmp(name, "contents:signature"))
+                       continue;
+               if (!subpos)
+                       find_subpos(buf, sz,
+                                   &subpos, &sublen,
+                                   &bodypos, &bodylen, &nonsiglen,
+                                   &sigpos, &siglen);
+
+               if (!strcmp(name, "subject"))
+                       v->s = copy_subject(subpos, sublen);
+               else if (!strcmp(name, "contents:subject"))
+                       v->s = copy_subject(subpos, sublen);
+               else if (!strcmp(name, "body"))
+                       v->s = xmemdupz(bodypos, bodylen);
+               else if (!strcmp(name, "contents:body"))
+                       v->s = xmemdupz(bodypos, nonsiglen);
+               else if (!strcmp(name, "contents:signature"))
+                       v->s = xmemdupz(sigpos, siglen);
+               else if (!strcmp(name, "contents"))
+                       v->s = xstrdup(subpos);
+       }
+}
+
+/*
+ * We want to have empty print-string for field requests
+ * that do not apply (e.g. "authordate" for a tag object)
+ */
+static void fill_missing_values(struct atom_value *val)
+{
+       int i;
+       for (i = 0; i < used_atom_cnt; i++) {
+               struct atom_value *v = &val[i];
+               if (v->s == NULL)
+                       v->s = "";
+       }
+}
+
+/*
+ * val is a list of atom_value to hold returned values.  Extract
+ * the values for atoms in used_atom array out of (obj, buf, sz).
+ * when deref is false, (obj, buf, sz) is the object that is
+ * pointed at by the ref itself; otherwise it is the object the
+ * ref (which is a tag) refers to.
+ */
+static void grab_values(struct atom_value *val, int deref, struct object *obj, 
void *buf, unsigned long sz)
+{
+       grab_common_values(val, deref, obj, buf, sz);
+       switch (obj->type) {
+       case OBJ_TAG:
+               grab_tag_values(val, deref, obj, buf, sz);
+               grab_sub_body_contents(val, deref, obj, buf, sz);
+               grab_person("tagger", val, deref, obj, buf, sz);
+               break;
+       case OBJ_COMMIT:
+               grab_commit_values(val, deref, obj, buf, sz);
+               grab_sub_body_contents(val, deref, obj, buf, sz);
+               grab_person("author", val, deref, obj, buf, sz);
+               grab_person("committer", val, deref, obj, buf, sz);
+               break;
+       case OBJ_TREE:
+               /* grab_tree_values(val, deref, obj, buf, sz); */
+               break;
+       case OBJ_BLOB:
+               /* grab_blob_values(val, deref, obj, buf, sz); */
+               break;
+       default:
+               die("Eh?  Object of type %d?", obj->type);
+       }
+}
+
+static inline char *copy_advance(char *dst, const char *src)
+{
+       while (*src)
+               *dst++ = *src++;
+       return dst;
+}
+
+/*
+ * Parse the object referred by ref, and grab needed value.
+ */
+static void populate_value(struct ref_array_item *ref)
+{
+       void *buf;
+       struct object *obj;
+       int eaten, i;
+       unsigned long size;
+       const unsigned char *tagged;
+
+       ref->value = xcalloc(used_atom_cnt, sizeof(struct atom_value));
+
+       if (need_symref && (ref->flag & REF_ISSYMREF) && !ref->symref) {
+               unsigned char unused1[20];
+               ref->symref = resolve_refdup(ref->refname, RESOLVE_REF_READING,
+                                            unused1, NULL);
+               if (!ref->symref)
+                       ref->symref = "";
+       }
+
+       /* Fill in specials first */
+       for (i = 0; i < used_atom_cnt; i++) {
+               const char *name = used_atom[i];
+               struct atom_value *v = &ref->value[i];
+               int deref = 0;
+               const char *refname;
+               const char *formatp;
+               struct branch *branch = NULL;
+
+               if (*name == '*') {
+                       deref = 1;
+                       name++;
+               }
+
+               if (starts_with(name, "refname"))
+                       refname = ref->refname;
+               else if (starts_with(name, "symref"))
+                       refname = ref->symref ? ref->symref : "";
+               else if (starts_with(name, "upstream")) {
+                       const char *branch_name;
+                       /* only local branches may have an upstream */
+                       if (!skip_prefix(ref->refname, "refs/heads/",
+                                        &branch_name))
+                               continue;
+                       branch = branch_get(branch_name);
+
+                       refname = branch_get_upstream(branch, NULL);
+                       if (!refname)
+                               continue;
+               } else if (starts_with(name, "push")) {
+                       const char *branch_name;
+                       if (!skip_prefix(ref->refname, "refs/heads/",
+                                        &branch_name))
+                               continue;
+                       branch = branch_get(branch_name);
+
+                       refname = branch_get_push(branch, NULL);
+                       if (!refname)
+                               continue;
+               } else if (starts_with(name, "color:")) {
+                       char color[COLOR_MAXLEN] = "";
+
+                       if (color_parse(name + 6, color) < 0)
+                               die(_("unable to parse format"));
+                       v->s = xstrdup(color);
+                       continue;
+               } else if (!strcmp(name, "flag")) {
+                       char buf[256], *cp = buf;
+                       if (ref->flag & REF_ISSYMREF)
+                               cp = copy_advance(cp, ",symref");
+                       if (ref->flag & REF_ISPACKED)
+                               cp = copy_advance(cp, ",packed");
+                       if (cp == buf)
+                               v->s = "";
+                       else {
+                               *cp = '\0';
+                               v->s = xstrdup(buf + 1);
+                       }
+                       continue;
+               } else if (!deref && grab_objectname(name, ref->objectname, v)) 
{
+                       continue;
+               } else if (!strcmp(name, "HEAD")) {
+                       const char *head;
+                       unsigned char sha1[20];
+
+                       head = resolve_ref_unsafe("HEAD", RESOLVE_REF_READING,
+                                                 sha1, NULL);
+                       if (!strcmp(ref->refname, head))
+                               v->s = "*";
+                       else
+                               v->s = " ";
+                       continue;
+               } else
+                       continue;
+
+               formatp = strchr(name, ':');
+               if (formatp) {
+                       int num_ours, num_theirs;
+
+                       formatp++;
+                       if (!strcmp(formatp, "short"))
+                               refname = shorten_unambiguous_ref(refname,
+                                                     warn_ambiguous_refs);
+                       else if (!strcmp(formatp, "track") &&
+                                (starts_with(name, "upstream") ||
+                                 starts_with(name, "push"))) {
+                               char buf[40];
+
+                               if (stat_tracking_info(branch, &num_ours,
+                                                      &num_theirs, NULL))
+                                       continue;
+
+                               if (!num_ours && !num_theirs)
+                                       v->s = "";
+                               else if (!num_ours) {
+                                       sprintf(buf, "[behind %d]", num_theirs);
+                                       v->s = xstrdup(buf);
+                               } else if (!num_theirs) {
+                                       sprintf(buf, "[ahead %d]", num_ours);
+                                       v->s = xstrdup(buf);
+                               } else {
+                                       sprintf(buf, "[ahead %d, behind %d]",
+                                               num_ours, num_theirs);
+                                       v->s = xstrdup(buf);
+                               }
+                               continue;
+                       } else if (!strcmp(formatp, "trackshort") &&
+                                  (starts_with(name, "upstream") ||
+                                   starts_with(name, "push"))) {
+                               assert(branch);
+
+                               if (stat_tracking_info(branch, &num_ours,
+                                                       &num_theirs, NULL))
+                                       continue;
+
+                               if (!num_ours && !num_theirs)
+                                       v->s = "=";
+                               else if (!num_ours)
+                                       v->s = "<";
+                               else if (!num_theirs)
+                                       v->s = ">";
+                               else
+                                       v->s = "<>";
+                               continue;
+                       } else
+                               die("unknown %.*s format %s",
+                                   (int)(formatp - name), name, formatp);
+               }
+
+               if (!deref)
+                       v->s = refname;
+               else {
+                       int len = strlen(refname);
+                       char *s = xmalloc(len + 4);
+                       sprintf(s, "%s^{}", refname);
+                       v->s = s;
+               }
+       }
+
+       for (i = 0; i < used_atom_cnt; i++) {
+               struct atom_value *v = &ref->value[i];
+               if (v->s == NULL)
+                       goto need_obj;
+       }
+       return;
+
+ need_obj:
+       buf = get_obj(ref->objectname, &obj, &size, &eaten);
+       if (!buf)
+               die("missing object %s for %s",
+                   sha1_to_hex(ref->objectname), ref->refname);
+       if (!obj)
+               die("parse_object_buffer failed on %s for %s",
+                   sha1_to_hex(ref->objectname), ref->refname);
+
+       grab_values(ref->value, 0, obj, buf, size);
+       if (!eaten)
+               free(buf);
+
+       /*
+        * If there is no atom that wants to know about tagged
+        * object, we are done.
+        */
+       if (!need_tagged || (obj->type != OBJ_TAG))
+               return;
+
+       /*
+        * If it is a tag object, see if we use a value that derefs
+        * the object, and if we do grab the object it refers to.
+        */
+       tagged = ((struct tag *)obj)->tagged->sha1;
+
+       /*
+        * NEEDSWORK: This derefs tag only once, which
+        * is good to deal with chains of trust, but
+        * is not consistent with what deref_tag() does
+        * which peels the onion to the core.
+        */
+       buf = get_obj(tagged, &obj, &size, &eaten);
+       if (!buf)
+               die("missing object %s for %s",
+                   sha1_to_hex(tagged), ref->refname);
+       if (!obj)
+               die("parse_object_buffer failed on %s for %s",
+                   sha1_to_hex(tagged), ref->refname);
+       grab_values(ref->value, 1, obj, buf, size);
+       if (!eaten)
+               free(buf);
+}
+
+/*
+ * Given a ref, return the value for the atom.  This lazily gets value
+ * out of the object by calling populate value.
+ */
+static void get_ref_atom_value(struct ref_array_item *ref, int atom, struct 
atom_value **v)
+{
+       if (!ref->value) {
+               populate_value(ref);
+               fill_missing_values(ref->value);
+       }
+       *v = &ref->value[atom];
+}
+
+/*
+ * Given a refname, return 1 if the refname matches with one of the patterns
+ * while the pattern is a pathname like 'refs/tags' or 'refs/heads/master'
+ * and so on, else return 0. Supports use of wild characters.
+ */
+static int match_name_as_path(const char **pattern, const char *refname)
+{
+       int namelen = strlen(refname);
+       for (; *pattern; pattern++) {
+               const char *p = *pattern;
+               int plen = strlen(p);
+
+               if ((plen <= namelen) &&
+                   !strncmp(refname, p, plen) &&
+                   (refname[plen] == '\0' ||
+                    refname[plen] == '/' ||
+                    p[plen-1] == '/'))
+                       return 1;
+               if (!wildmatch(p, refname, WM_PATHNAME, NULL))
+                       return 1;
+       }
+       return 0;
+}
+
+/* Allocate space for a new ref_array_item and copy the objectname and flag to 
it */
+static struct ref_array_item *new_ref_array_item(const char *refname,
+                                                const unsigned char 
*objectname,
+                                                int flag)
+{
+       struct ref_array_item *ref = xcalloc(1, sizeof(struct ref_array_item));
+       ref->refname = xstrdup(refname);
+       hashcpy(ref->objectname, objectname);
+       ref->flag = flag;
+
+       return ref;
+}
+
+/*
+ * A call-back given to for_each_ref().  Filter refs and keep them for
+ * later object processing.
+ */
+int ref_filter_handler(const char *refname, const struct object_id *oid, int 
flag, void *cb_data)
+{
+       struct ref_filter_cbdata *ref_cbdata = cb_data;
+       struct ref_filter *filter = &ref_cbdata->filter;
+       struct ref_array_item *ref;
+
+       if (flag & REF_BAD_NAME) {
+                 warning("ignoring ref with broken name %s", refname);
+                 return 0;
+       }
+
+       if (*filter->name_patterns && 
!match_name_as_path(filter->name_patterns, refname))
+               return 0;
+
+       /*
+        * We do not open the object yet; sort may only need refname
+        * to do its job and the resulting list may yet to be pruned
+        * by maxcount logic.
+        */
+       ref = new_ref_array_item(refname, oid->hash, flag);
+
+       REALLOC_ARRAY(ref_cbdata->array.items, ref_cbdata->array.nr + 1);
+       ref_cbdata->array.items[ref_cbdata->array.nr++] = ref;
+       return 0;
+}
+
+/*  Free memory allocated for a ref_array_item */
+static void free_array_item(struct ref_array_item *item)
+{
+       free(item->symref);
+       free(item->refname);
+       free(item);
+}
+
+/* Free all memory allocated for ref_array */
+void ref_array_clear(struct ref_array *array)
+{
+       int i;
+
+       for (i = 0; i < array->nr; i++)
+               free_array_item(array->items[i]);
+       free(array->items);
+       array->items = NULL;
+       array->nr = array->alloc = 0;
+}
+
+static int cmp_ref_sorting(struct ref_sorting *s, struct ref_array_item *a, 
struct ref_array_item *b)
+{
+       struct atom_value *va, *vb;
+       int cmp;
+       cmp_type cmp_type = used_atom_type[s->atom];
+
+       get_ref_atom_value(a, s->atom, &va);
+       get_ref_atom_value(b, s->atom, &vb);
+       switch (cmp_type) {
+       case FIELD_STR:
+               cmp = strcmp(va->s, vb->s);
+               break;
+       default:
+               if (va->ul < vb->ul)
+                       cmp = -1;
+               else if (va->ul == vb->ul)
+                       cmp = 0;
+               else
+                       cmp = 1;
+               break;
+       }
+       return (s->reverse) ? -cmp : cmp;
+}
+
+static struct ref_sorting *ref_sorting;
+static int compare_refs(const void *a_, const void *b_)
+{
+       struct ref_array_item *a = *((struct ref_array_item **)a_);
+       struct ref_array_item *b = *((struct ref_array_item **)b_);
+       struct ref_sorting *s;
+
+       for (s = ref_sorting; s; s = s->next) {
+               int cmp = cmp_ref_sorting(s, a, b);
+               if (cmp)
+                       return cmp;
+       }
+       return 0;
+}
+
+void ref_array_sort(struct ref_sorting *sorting, struct ref_array *array)
+{
+       ref_sorting = sorting;
+       qsort(array->items, array->nr, sizeof(struct ref_array_item *), 
compare_refs);
+}
+
+static void print_value(struct atom_value *v, int quote_style)
+{
+       struct strbuf sb = STRBUF_INIT;
+       switch (quote_style) {
+       case QUOTE_NONE:
+               fputs(v->s, stdout);
+               break;
+       case QUOTE_SHELL:
+               sq_quote_buf(&sb, v->s);
+               break;
+       case QUOTE_PERL:
+               perl_quote_buf(&sb, v->s);
+               break;
+       case QUOTE_PYTHON:
+               python_quote_buf(&sb, v->s);
+               break;
+       case QUOTE_TCL:
+               tcl_quote_buf(&sb, v->s);
+               break;
+       }
+       if (quote_style != QUOTE_NONE) {
+               fputs(sb.buf, stdout);
+               strbuf_release(&sb);
+       }
+}
+
+static int hex1(char ch)
+{
+       if ('0' <= ch && ch <= '9')
+               return ch - '0';
+       else if ('a' <= ch && ch <= 'f')
+               return ch - 'a' + 10;
+       else if ('A' <= ch && ch <= 'F')
+               return ch - 'A' + 10;
+       return -1;
+}
+static int hex2(const char *cp)
+{
+       if (cp[0] && cp[1])
+               return (hex1(cp[0]) << 4) | hex1(cp[1]);
+       else
+               return -1;
+}
+
+static void emit(const char *cp, const char *ep)
+{
+       while (*cp && (!ep || cp < ep)) {
+               if (*cp == '%') {
+                       if (cp[1] == '%')
+                               cp++;
+                       else {
+                               int ch = hex2(cp + 1);
+                               if (0 <= ch) {
+                                       putchar(ch);
+                                       cp += 3;
+                                       continue;
+                               }
+                       }
+               }
+               putchar(*cp);
+               cp++;
+       }
+}
+
+void show_ref_array_item(struct ref_array_item *info, const char *format, int 
quote_style)
+{
+       const char *cp, *sp, *ep;
+
+       for (cp = format; *cp && (sp = find_next(cp)); cp = ep + 1) {
+               struct atom_value *atomv;
+
+               ep = strchr(sp, ')');
+               if (cp < sp)
+                       emit(cp, sp);
+               get_ref_atom_value(info, parse_ref_filter_atom(sp + 2, ep), 
&atomv);
+               print_value(atomv, quote_style);
+       }
+       if (*cp) {
+               sp = cp + strlen(cp);
+               emit(cp, sp);
+       }
+       if (need_color_reset_at_eol) {
+               struct atom_value resetv;
+               char color[COLOR_MAXLEN] = "";
+
+               if (color_parse("reset", color) < 0)
+                       die("BUG: couldn't parse 'reset' as a color");
+               resetv.s = color;
+               print_value(&resetv, quote_style);
+       }
+       putchar('\n');
+}
+
+/*  If no sorting option is given, use refname to sort as default */
+struct ref_sorting *ref_default_sorting(void)
+{
+       static const char cstr_name[] = "refname";
+
+       struct ref_sorting *sorting = xcalloc(1, sizeof(*sorting));
+
+       sorting->next = NULL;
+       sorting->atom = parse_ref_filter_atom(cstr_name, cstr_name + 
strlen(cstr_name));
+       return sorting;
+}
+
+int parse_opt_ref_sorting(const struct option *opt, const char *arg, int unset)
+{
+       struct ref_sorting **sorting_tail = opt->value;
+       struct ref_sorting *s;
+       int len;
+
+       if (!arg) /* should --no-sort void the list ? */
+               return -1;
+
+       s = xcalloc(1, sizeof(*s));
+       s->next = *sorting_tail;
+       *sorting_tail = s;
+
+       if (*arg == '-') {
+               s->reverse = 1;
+               arg++;
+       }
+       len = strlen(arg);
+       s->atom = parse_ref_filter_atom(arg, arg+len);
+       return 0;
+}
-- 
2.4.2

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