[PATCH v2 2/2] [GSOC] ref-filter: introduce enum atom_type

["ZheNing Hu via GitGitGadget" <gitgitgadget@gmail.com>]

From: ZheNing Hu <adlternative@gmail.com>

In the original ref-filter design, it will copy the parsed
atom's name and attributes to `used_atom[i].name` in the
atom's parsing step, and use it again for string matching
in the later specific ref attributes filling step. It use
a lot of string matching to determine which atom we need.

Introduce the enum "atom_type", each enum value is named
as `ATOM_*`, which is the index of each corresponding
valid_atom entry. In the first step of the atom parsing,
`used_atom.atom_type` will record corresponding enum value
from valid_atom entry index, and then in specific reference
attribute filling step, only need to compare the value of
the `used_atom.atom_type` to judge the atom type.

the enum value of `ATOM_UNKNOWN` is equals to zero, which
could ensure that we can easily distinguish such a struct
where the atom_type is known from such a struct where it
is unknown yet.

the enum value of `ATOM_INVALID` is equals to the size of
valid_atom array, which could help us iterate over
valid_atom array using something like:

for (i = ATOM_UNKNOWN + 1; i < ATOM_INVALID; i++)
        /* do something with valid_atom[i] */;

Signed-off-by: ZheNing Hu <adlternative@gmail.com>
---
 ref-filter.c | 214 ++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 143 insertions(+), 71 deletions(-)

diff --git a/ref-filter.c b/ref-filter.c
index f420bae6e5ba..e3bf2cd1aaec 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -108,6 +108,69 @@ static struct ref_to_worktree_map {
 	struct worktree **worktrees;
 } ref_to_worktree_map;
 
+/*
+ * The enum atom_type is used as the coordinates of valid_atom entry.
+ * In the atom parsing stage, it will be passed to used_atom.atom_type
+ * as the identifier of the atom type. We can judge the type of used_atom
+ * entry by `if (used_atom[i].atom_type == ATOM_*)`.
+ *
+ * ATOM_UNKNOWN equals to 0, used as an enumeration value of uninitialized
+ * atom_type.
+ * ATOM_INVALID equals to the size of valid_atom array, which could help us
+ * iterate over valid_atom array like this:
+ *
+ * 	for (i = ATOM_UNKNOWN + 1; i < ATOM_INVALID; i++) {
+ *		int len = strlen(valid_atom[i].name);
+ *		if (len == atom_len && !memcmp(valid_atom[i].name, sp, len))
+ *			break;
+ *	}
+ */
+enum atom_type {
+ATOM_UNKNOWN,
+ATOM_REFNAME,
+ATOM_OBJECTTYPE,
+ATOM_OBJECTSIZE,
+ATOM_OBJECTNAME,
+ATOM_DELTABASE,
+ATOM_TREE,
+ATOM_PARENT,
+ATOM_NUMPARENT,
+ATOM_OBJECT,
+ATOM_TYPE,
+ATOM_TAG,
+ATOM_AUTHOR,
+ATOM_AUTHORNAME,
+ATOM_AUTHOREMAIL,
+ATOM_AUTHORDATE,
+ATOM_COMMITTER,
+ATOM_COMMITTERNAME,
+ATOM_COMMITTEREMAIL,
+ATOM_COMMITTERDATE,
+ATOM_TAGGER,
+ATOM_TAGGERNAME,
+ATOM_TAGGEREMAIL,
+ATOM_TAGGERDATE,
+ATOM_CREATOR,
+ATOM_CREATORDATE,
+ATOM_SUBJECT,
+ATOM_BODY,
+ATOM_TRAILERS,
+ATOM_CONTENTS,
+ATOM_UPSTREAM,
+ATOM_PUSH,
+ATOM_SYMREF,
+ATOM_FLAG,
+ATOM_HEAD,
+ATOM_COLOR,
+ATOM_WORKTREEPATH,
+ATOM_ALIGN,
+ATOM_END,
+ATOM_IF,
+ATOM_THEN,
+ATOM_ELSE,
+ATOM_INVALID,
+};
+
 /*
  * An atom is a valid field atom listed below, possibly prefixed with
  * a "*" to denote deref_tag().
@@ -119,6 +182,7 @@ static struct ref_to_worktree_map {
  * array.
  */
 static struct used_atom {
+	enum atom_type atom_type;
 	const char *name;
 	cmp_type type;
 	info_source source;
@@ -506,47 +570,47 @@ static struct {
 	int (*parser)(const struct ref_format *format, struct used_atom *atom,
 		      const char *arg, struct strbuf *err);
 } valid_atom[] = {
-	{ "refname", SOURCE_NONE, FIELD_STR, refname_atom_parser },
-	{ "objecttype", SOURCE_OTHER, FIELD_STR, objecttype_atom_parser },
-	{ "objectsize", SOURCE_OTHER, FIELD_ULONG, objectsize_atom_parser },
-	{ "objectname", SOURCE_OTHER, FIELD_STR, oid_atom_parser },
-	{ "deltabase", SOURCE_OTHER, FIELD_STR, deltabase_atom_parser },
-	{ "tree", SOURCE_OBJ, FIELD_STR, oid_atom_parser },
-	{ "parent", SOURCE_OBJ, FIELD_STR, oid_atom_parser },
-	{ "numparent", SOURCE_OBJ, FIELD_ULONG },
-	{ "object", SOURCE_OBJ },
-	{ "type", SOURCE_OBJ },
-	{ "tag", SOURCE_OBJ },
-	{ "author", SOURCE_OBJ },
-	{ "authorname", SOURCE_OBJ },
-	{ "authoremail", SOURCE_OBJ, FIELD_STR, person_email_atom_parser },
-	{ "authordate", SOURCE_OBJ, FIELD_TIME },
-	{ "committer", SOURCE_OBJ },
-	{ "committername", SOURCE_OBJ },
-	{ "committeremail", SOURCE_OBJ, FIELD_STR, person_email_atom_parser },
-	{ "committerdate", SOURCE_OBJ, FIELD_TIME },
-	{ "tagger", SOURCE_OBJ },
-	{ "taggername", SOURCE_OBJ },
-	{ "taggeremail", SOURCE_OBJ, FIELD_STR, person_email_atom_parser },
-	{ "taggerdate", SOURCE_OBJ, FIELD_TIME },
-	{ "creator", SOURCE_OBJ },
-	{ "creatordate", SOURCE_OBJ, FIELD_TIME },
-	{ "subject", SOURCE_OBJ, FIELD_STR, subject_atom_parser },
-	{ "body", SOURCE_OBJ, FIELD_STR, body_atom_parser },
-	{ "trailers", SOURCE_OBJ, FIELD_STR, trailers_atom_parser },
-	{ "contents", SOURCE_OBJ, FIELD_STR, contents_atom_parser },
-	{ "upstream", SOURCE_NONE, FIELD_STR, remote_ref_atom_parser },
-	{ "push", SOURCE_NONE, FIELD_STR, remote_ref_atom_parser },
-	{ "symref", SOURCE_NONE, FIELD_STR, refname_atom_parser },
-	{ "flag", SOURCE_NONE },
-	{ "HEAD", SOURCE_NONE, FIELD_STR, head_atom_parser },
-	{ "color", SOURCE_NONE, FIELD_STR, color_atom_parser },
-	{ "worktreepath", SOURCE_NONE },
-	{ "align", SOURCE_NONE, FIELD_STR, align_atom_parser },
-	{ "end", SOURCE_NONE },
-	{ "if", SOURCE_NONE, FIELD_STR, if_atom_parser },
-	{ "then", SOURCE_NONE },
-	{ "else", SOURCE_NONE },
+	[ATOM_REFNAME] = { "refname", SOURCE_NONE, FIELD_STR, refname_atom_parser },
+	[ATOM_OBJECTTYPE] = { "objecttype", SOURCE_OTHER, FIELD_STR, objecttype_atom_parser },
+	[ATOM_OBJECTSIZE] = { "objectsize", SOURCE_OTHER, FIELD_ULONG, objectsize_atom_parser },
+	[ATOM_OBJECTNAME] = { "objectname", SOURCE_OTHER, FIELD_STR, oid_atom_parser },
+	[ATOM_DELTABASE] = { "deltabase", SOURCE_OTHER, FIELD_STR, deltabase_atom_parser },
+	[ATOM_TREE] = { "tree", SOURCE_OBJ, FIELD_STR, oid_atom_parser },
+	[ATOM_PARENT] = { "parent", SOURCE_OBJ, FIELD_STR, oid_atom_parser },
+	[ATOM_NUMPARENT] = { "numparent", SOURCE_OBJ, FIELD_ULONG },
+	[ATOM_OBJECT] = { "object", SOURCE_OBJ },
+	[ATOM_TYPE] = { "type", SOURCE_OBJ },
+	[ATOM_TAG] = { "tag", SOURCE_OBJ },
+	[ATOM_AUTHOR] = { "author", SOURCE_OBJ },
+	[ATOM_AUTHORNAME] = { "authorname", SOURCE_OBJ },
+	[ATOM_AUTHOREMAIL] = { "authoremail", SOURCE_OBJ, FIELD_STR, person_email_atom_parser },
+	[ATOM_AUTHORDATE] = { "authordate", SOURCE_OBJ, FIELD_TIME },
+	[ATOM_COMMITTER] = { "committer", SOURCE_OBJ },
+	[ATOM_COMMITTERNAME] = { "committername", SOURCE_OBJ },
+	[ATOM_COMMITTEREMAIL] = { "committeremail", SOURCE_OBJ, FIELD_STR, person_email_atom_parser },
+	[ATOM_COMMITTERDATE] = { "committerdate", SOURCE_OBJ, FIELD_TIME },
+	[ATOM_TAGGER] = { "tagger", SOURCE_OBJ },
+	[ATOM_TAGGERNAME] = { "taggername", SOURCE_OBJ },
+	[ATOM_TAGGEREMAIL] = { "taggeremail", SOURCE_OBJ, FIELD_STR, person_email_atom_parser },
+	[ATOM_TAGGERDATE] = { "taggerdate", SOURCE_OBJ, FIELD_TIME },
+	[ATOM_CREATOR] = { "creator", SOURCE_OBJ },
+	[ATOM_CREATORDATE] = { "creatordate", SOURCE_OBJ, FIELD_TIME },
+	[ATOM_SUBJECT] = { "subject", SOURCE_OBJ, FIELD_STR, subject_atom_parser },
+	[ATOM_BODY] = { "body", SOURCE_OBJ, FIELD_STR, body_atom_parser },
+	[ATOM_TRAILERS] = { "trailers", SOURCE_OBJ, FIELD_STR, trailers_atom_parser },
+	[ATOM_CONTENTS] = { "contents", SOURCE_OBJ, FIELD_STR, contents_atom_parser },
+	[ATOM_UPSTREAM] = { "upstream", SOURCE_NONE, FIELD_STR, remote_ref_atom_parser },
+	[ATOM_PUSH] = { "push", SOURCE_NONE, FIELD_STR, remote_ref_atom_parser },
+	[ATOM_SYMREF] = { "symref", SOURCE_NONE, FIELD_STR, refname_atom_parser },
+	[ATOM_FLAG] = { "flag", SOURCE_NONE },
+	[ATOM_HEAD] = { "HEAD", SOURCE_NONE, FIELD_STR, head_atom_parser },
+	[ATOM_COLOR] = { "color", SOURCE_NONE, FIELD_STR, color_atom_parser },
+	[ATOM_WORKTREEPATH] = { "worktreepath", SOURCE_NONE },
+	[ATOM_ALIGN] = { "align", SOURCE_NONE, FIELD_STR, align_atom_parser },
+	[ATOM_END] = { "end", SOURCE_NONE },
+	[ATOM_IF] = { "if", SOURCE_NONE, FIELD_STR, if_atom_parser },
+	[ATOM_THEN] = { "then", SOURCE_NONE },
+	[ATOM_ELSE] = { "else", SOURCE_NONE },
 	/*
 	 * Please update $__git_ref_fieldlist in git-completion.bash
 	 * when you add new atoms
@@ -610,13 +674,13 @@ static int parse_ref_filter_atom(const struct ref_format *format,
 	atom_len = (arg ? arg : ep) - sp;
 
 	/* Is the atom a valid one? */
-	for (i = 0; i < ARRAY_SIZE(valid_atom); i++) {
+	for (i = ATOM_UNKNOWN + 1; i < ATOM_INVALID; i++) {
 		int len = strlen(valid_atom[i].name);
 		if (len == atom_len && !memcmp(valid_atom[i].name, sp, len))
 			break;
 	}
 
-	if (ARRAY_SIZE(valid_atom) <= i)
+	if (i == ATOM_INVALID)
 		return strbuf_addf_ret(err, -1, _("unknown field name: %.*s"),
 				       (int)(ep-atom), atom);
 	if (valid_atom[i].source != SOURCE_NONE && !have_git_dir())
@@ -628,6 +692,7 @@ static int parse_ref_filter_atom(const struct ref_format *format,
 	at = used_atom_cnt;
 	used_atom_cnt++;
 	REALLOC_ARRAY(used_atom, used_atom_cnt);
+	used_atom[at].atom_type = i;
 	used_atom[at].name = xmemdupz(atom, ep - atom);
 	used_atom[at].type = valid_atom[i].cmp_type;
 	used_atom[at].source = valid_atom[i].source;
@@ -652,7 +717,7 @@ static int parse_ref_filter_atom(const struct ref_format *format,
 		return -1;
 	if (*atom == '*')
 		need_tagged = 1;
-	if (!strcmp(valid_atom[i].name, "symref"))
+	if (i == ATOM_SYMREF)
 		need_symref = 1;
 	return at;
 }
@@ -965,14 +1030,15 @@ static void grab_common_values(struct atom_value *val, int deref, struct expand_
 
 	for (i = 0; i < used_atom_cnt; i++) {
 		const char *name = used_atom[i].name;
+		enum atom_type atom_type = used_atom[i].atom_type;
 		struct atom_value *v = &val[i];
 		if (!!deref != (*name == '*'))
 			continue;
 		if (deref)
 			name++;
-		if (!strcmp(name, "objecttype"))
+		if (atom_type == ATOM_OBJECTTYPE)
 			v->s = xstrdup(type_name(oi->type));
-		else if (starts_with(name, "objectsize")) {
+		else if (atom_type == ATOM_OBJECTSIZE) {
 			if (used_atom[i].u.objectsize.option == O_SIZE_DISK) {
 				v->value = oi->disk_size;
 				v->s = xstrfmt("%"PRIuMAX, (uintmax_t)oi->disk_size);
@@ -980,9 +1046,9 @@ static void grab_common_values(struct atom_value *val, int deref, struct expand_
 				v->value = oi->size;
 				v->s = xstrfmt("%"PRIuMAX , (uintmax_t)oi->size);
 			}
-		} else if (!strcmp(name, "deltabase"))
+		} else if (atom_type == ATOM_DELTABASE)
 			v->s = xstrdup(oid_to_hex(&oi->delta_base_oid));
-		else if (deref)
+		else if (atom_type == ATOM_OBJECTNAME && deref)
 			grab_oid(name, "objectname", &oi->oid, v, &used_atom[i]);
 	}
 }
@@ -995,16 +1061,17 @@ static void grab_tag_values(struct atom_value *val, int deref, struct object *ob
 
 	for (i = 0; i < used_atom_cnt; i++) {
 		const char *name = used_atom[i].name;
+		enum atom_type atom_type = used_atom[i].atom_type;
 		struct atom_value *v = &val[i];
 		if (!!deref != (*name == '*'))
 			continue;
 		if (deref)
 			name++;
-		if (!strcmp(name, "tag"))
+		if (atom_type == ATOM_TAG)
 			v->s = xstrdup(tag->tag);
-		else if (!strcmp(name, "type") && tag->tagged)
+		else if (atom_type == ATOM_TYPE && tag->tagged)
 			v->s = xstrdup(type_name(tag->tagged->type));
-		else if (!strcmp(name, "object") && tag->tagged)
+		else if (atom_type == ATOM_OBJECT && tag->tagged)
 			v->s = xstrdup(oid_to_hex(&tag->tagged->oid));
 	}
 }
@@ -1017,18 +1084,20 @@ static void grab_commit_values(struct atom_value *val, int deref, struct object
 
 	for (i = 0; i < used_atom_cnt; i++) {
 		const char *name = used_atom[i].name;
+		enum atom_type atom_type = used_atom[i].atom_type;
 		struct atom_value *v = &val[i];
 		if (!!deref != (*name == '*'))
 			continue;
 		if (deref)
 			name++;
-		if (grab_oid(name, "tree", get_commit_tree_oid(commit), v, &used_atom[i]))
+		if (atom_type == ATOM_TREE &&
+		    grab_oid(name, "tree", get_commit_tree_oid(commit), v, &used_atom[i]))
 			continue;
-		if (!strcmp(name, "numparent")) {
+		if (atom_type == ATOM_NUMPARENT) {
 			v->value = commit_list_count(commit->parents);
 			v->s = xstrfmt("%lu", (unsigned long)v->value);
 		}
-		else if (starts_with(name, "parent")) {
+		else if (atom_type == ATOM_PARENT) {
 			struct commit_list *parents;
 			struct strbuf s = STRBUF_INIT;
 			for (parents = commit->parents; parents; parents = parents->next) {
@@ -1208,15 +1277,16 @@ static void grab_person(const char *who, struct atom_value *val, int deref, void
 		return;
 	for (i = 0; i < used_atom_cnt; i++) {
 		const char *name = used_atom[i].name;
+		enum atom_type atom_type = used_atom[i].atom_type;
 		struct atom_value *v = &val[i];
 		if (!!deref != (*name == '*'))
 			continue;
 		if (deref)
 			name++;
 
-		if (starts_with(name, "creatordate"))
+		if (atom_type == ATOM_CREATORDATE)
 			grab_date(wholine, v, name);
-		else if (!strcmp(name, "creator"))
+		else if (atom_type == ATOM_CREATOR)
 			v->s = copy_line(wholine);
 	}
 }
@@ -1696,6 +1766,7 @@ static int populate_value(struct ref_array_item *ref, struct strbuf *err)
 	/* Fill in specials first */
 	for (i = 0; i < used_atom_cnt; i++) {
 		struct used_atom *atom = &used_atom[i];
+		enum atom_type atom_type = atom->atom_type;
 		const char *name = used_atom[i].name;
 		struct atom_value *v = &ref->value[i];
 		int deref = 0;
@@ -1710,18 +1781,18 @@ static int populate_value(struct ref_array_item *ref, struct strbuf *err)
 			name++;
 		}
 
-		if (starts_with(name, "refname"))
+		if (atom_type == ATOM_REFNAME)
 			refname = get_refname(atom, ref);
-		else if (!strcmp(name, "worktreepath")) {
+		else if (atom_type == ATOM_WORKTREEPATH) {
 			if (ref->kind == FILTER_REFS_BRANCHES)
 				v->s = get_worktree_path(atom, ref);
 			else
 				v->s = xstrdup("");
 			continue;
 		}
-		else if (starts_with(name, "symref"))
+		else if (atom_type == ATOM_SYMREF)
 			refname = get_symref(atom, ref);
-		else if (starts_with(name, "upstream")) {
+		else if (atom_type == ATOM_UPSTREAM) {
 			const char *branch_name;
 			/* only local branches may have an upstream */
 			if (!skip_prefix(ref->refname, "refs/heads/",
@@ -1737,7 +1808,7 @@ static int populate_value(struct ref_array_item *ref, struct strbuf *err)
 			else
 				v->s = xstrdup("");
 			continue;
-		} else if (atom->u.remote_ref.push) {
+		} else if (atom_type == ATOM_PUSH && atom->u.remote_ref.push) {
 			const char *branch_name;
 			v->s = xstrdup("");
 			if (!skip_prefix(ref->refname, "refs/heads/",
@@ -1756,10 +1827,10 @@ static int populate_value(struct ref_array_item *ref, struct strbuf *err)
 			free((char *)v->s);
 			fill_remote_ref_details(atom, refname, branch, &v->s);
 			continue;
-		} else if (starts_with(name, "color:")) {
+		} else if (atom_type == ATOM_COLOR) {
 			v->s = xstrdup(atom->u.color);
 			continue;
-		} else if (!strcmp(name, "flag")) {
+		} else if (atom_type == ATOM_FLAG) {
 			char buf[256], *cp = buf;
 			if (ref->flag & REF_ISSYMREF)
 				cp = copy_advance(cp, ",symref");
@@ -1772,23 +1843,24 @@ static int populate_value(struct ref_array_item *ref, struct strbuf *err)
 				v->s = xstrdup(buf + 1);
 			}
 			continue;
-		} else if (!deref && grab_oid(name, "objectname", &ref->objectname, v, atom)) {
-			continue;
-		} else if (!strcmp(name, "HEAD")) {
+		} else if (!deref && atom_type == ATOM_OBJECTNAME &&
+			   grab_oid(name, "objectname", &ref->objectname, v, atom)) {
+				continue;
+		} else if (atom_type == ATOM_HEAD) {
 			if (atom->u.head && !strcmp(ref->refname, atom->u.head))
 				v->s = xstrdup("*");
 			else
 				v->s = xstrdup(" ");
 			continue;
-		} else if (starts_with(name, "align")) {
+		} else if (atom_type == ATOM_ALIGN) {
 			v->handler = align_atom_handler;
 			v->s = xstrdup("");
 			continue;
-		} else if (!strcmp(name, "end")) {
+		} else if (atom_type == ATOM_END) {
 			v->handler = end_atom_handler;
 			v->s = xstrdup("");
 			continue;
-		} else if (starts_with(name, "if")) {
+		} else if (atom_type == ATOM_IF) {
 			const char *s;
 			if (skip_prefix(name, "if:", &s))
 				v->s = xstrdup(s);
@@ -1796,11 +1868,11 @@ static int populate_value(struct ref_array_item *ref, struct strbuf *err)
 				v->s = xstrdup("");
 			v->handler = if_atom_handler;
 			continue;
-		} else if (!strcmp(name, "then")) {
+		} else if (atom_type == ATOM_THEN) {
 			v->handler = then_atom_handler;
 			v->s = xstrdup("");
 			continue;
-		} else if (!strcmp(name, "else")) {
+		} else if (atom_type == ATOM_ELSE) {
 			v->handler = else_atom_handler;
 			v->s = xstrdup("");
 			continue;
-- 
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