list-objects-filter: encapsulate filter components

Encapsulate filter_fn, filter_free_fn, and filter_data into their own
opaque struct.

Due to opaqueness, filter_fn and filter_free_fn can no longer be
accessed directly by users. Currently, all usages of filter_fn are
guarded by a necessary check:

	(obj->flags & NOT_USER_GIVEN) && filter_fn

Take the opportunity to include this check into the new function
list_objects_filter__filter_object(), so that we no longer need to write
this check at every caller of the filter function.

Also, the init functions in list-objects-filter.c no longer need to
confusingly return the filter constituents in various places (filter_fn
and filter_free_fn as out parameters, and filter_data as the function's
return value); they can just initialize the "struct filter" passed in.

Helped-by: Jeff Hostetler <git@jeffhostetler.com>
Helped-by: Jonathan Tan <jonathantanmy@google.com>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Matthew DeVore <matvore@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

list-objects-filter.c

@@ -26,6 +26,20 @@
  */
 #define FILTER_SHOWN_BUT_REVISIT (1<<21)
 
+struct filter {
+	enum list_objects_filter_result (*filter_object_fn)(
+		struct repository *r,
+		enum list_objects_filter_situation filter_situation,
+		struct object *obj,
+		const char *pathname,
+		const char *filename,
+		void *filter_data);
+
+	void (*free_fn)(void *filter_data);
+
+	void *filter_data;
+};
+
 /*
  * A filter for list-objects to omit ALL blobs from the traversal.
  * And to OPTIONALLY collect a list of the omitted OIDs.
@@ -67,18 +81,17 @@ static enum list_objects_filter_result filter_blobs_none(
 	}
 }
 
-static void *filter_blobs_none__init(
+static void filter_blobs_none__init(
 	struct oidset *omitted,
 	struct list_objects_filter_options *filter_options,
-	filter_object_fn *filter_fn,
-	filter_free_fn *filter_free_fn)
+	struct filter *filter)
 {
 	struct filter_blobs_none_data *d = xcalloc(1, sizeof(*d));
 	d->omits = omitted;
 
-	*filter_fn = filter_blobs_none;
-	*filter_free_fn = free;
-	return d;
+	filter->filter_data = d;
+	filter->filter_object_fn = filter_blobs_none;
+	filter->free_fn = free;
 }
 
 /*
@@ -201,11 +214,10 @@ static void filter_trees_free(void *filter_data) {
 	free(d);
 }
 
-static void *filter_trees_depth__init(
+static void filter_trees_depth__init(
 	struct oidset *omitted,
 	struct list_objects_filter_options *filter_options,
-	filter_object_fn *filter_fn,
-	filter_free_fn *filter_free_fn)
+	struct filter *filter)
 {
 	struct filter_trees_depth_data *d = xcalloc(1, sizeof(*d));
 	d->omits = omitted;
@@ -213,9 +225,9 @@ static void *filter_trees_depth__init(
 	d->exclude_depth = filter_options->tree_exclude_depth;
 	d->current_depth = 0;
 
-	*filter_fn = filter_trees_depth;
-	*filter_free_fn = filter_trees_free;
-	return d;
+	filter->filter_data = d;
+	filter->filter_object_fn = filter_trees_depth;
+	filter->free_fn = filter_trees_free;
 }
 
 /*
@@ -281,19 +293,18 @@ include_it:
 	return LOFR_MARK_SEEN | LOFR_DO_SHOW;
 }
 
-static void *filter_blobs_limit__init(
+static void filter_blobs_limit__init(
 	struct oidset *omitted,
 	struct list_objects_filter_options *filter_options,
-	filter_object_fn *filter_fn,
-	filter_free_fn *filter_free_fn)
+	struct filter *filter)
 {
 	struct filter_blobs_limit_data *d = xcalloc(1, sizeof(*d));
 	d->omits = omitted;
 	d->max_bytes = filter_options->blob_limit_value;
 
-	*filter_fn = filter_blobs_limit;
-	*filter_free_fn = free;
-	return d;
+	filter->filter_data = d;
+	filter->filter_object_fn = filter_blobs_limit;
+	filter->free_fn = free;
 }
 
 /*
@@ -456,11 +467,10 @@ static void filter_sparse_free(void *filter_data)
 	free(d);
 }
 
-static void *filter_sparse_oid__init(
+static void filter_sparse_oid__init(
 	struct oidset *omitted,
 	struct list_objects_filter_options *filter_options,
-	filter_object_fn *filter_fn,
-	filter_free_fn *filter_free_fn)
+	struct filter *filter)
 {
 	struct filter_sparse_data *d = xcalloc(1, sizeof(*d));
 	d->omits = omitted;
@@ -473,16 +483,15 @@ static void *filter_sparse_oid__init(
 	d->array_frame[d->nr].child_prov_omit = 0;
 	d->nr++;
 
-	*filter_fn = filter_sparse;
-	*filter_free_fn = filter_sparse_free;
-	return d;
+	filter->filter_data = d;
+	filter->filter_object_fn = filter_sparse;
+	filter->free_fn = filter_sparse_free;
 }
 
-typedef void *(*filter_init_fn)(
+typedef void (*filter_init_fn)(
 	struct oidset *omitted,
 	struct list_objects_filter_options *filter_options,
-	filter_object_fn *filter_fn,
-	filter_free_fn *filter_free_fn);
+	struct filter *filter);
 
 /*
  * Must match "enum list_objects_filter_choice".
@@ -495,12 +504,11 @@ static filter_init_fn s_filters[] = {
 	filter_sparse_oid__init,
 };
 
-void *list_objects_filter__init(
+struct filter *list_objects_filter__init(
 	struct oidset *omitted,
-	struct list_objects_filter_options *filter_options,
-	filter_object_fn *filter_fn,
-	filter_free_fn *filter_free_fn)
+	struct list_objects_filter_options *filter_options)
 {
+	struct filter *filter;
 	filter_init_fn init_fn;
 
 	assert((sizeof(s_filters) / sizeof(s_filters[0])) == LOFC__COUNT);
@@ -510,10 +518,40 @@ void *list_objects_filter__init(
 		    filter_options->choice);
 
 	init_fn = s_filters[filter_options->choice];
-	if (init_fn)
-		return init_fn(omitted, filter_options,
-			       filter_fn, filter_free_fn);
-	*filter_fn = NULL;
-	*filter_free_fn = NULL;
+	if (!init_fn)
 		return NULL;
+
+	filter = xcalloc(1, sizeof(*filter));
+	init_fn(omitted, filter_options, filter);
+	return filter;
+}
+
+enum list_objects_filter_result list_objects_filter__filter_object(
+	struct repository *r,
+	enum list_objects_filter_situation filter_situation,
+	struct object *obj,
+	const char *pathname,
+	const char *filename,
+	struct filter *filter)
+{
+	if (filter && (obj->flags & NOT_USER_GIVEN))
+		return filter->filter_object_fn(r, filter_situation, obj,
+						pathname, filename,
+						filter->filter_data);
+	/*
+	 * No filter is active or user gave object explicitly. In this case,
+	 * always show the object (except when LOFS_END_TREE, since this tree
+	 * had already been shown when LOFS_BEGIN_TREE).
+	 */
+	if (filter_situation == LOFS_END_TREE)
+		return 0;
+	return LOFR_MARK_SEEN | LOFR_DO_SHOW;
+}
+
+void list_objects_filter__free(struct filter *filter)
+{
+	if (!filter)
+		return;
+	filter->free_fn(filter->filter_data);
+	free(filter);
 }

list-objects-filter.h

@@ -60,30 +60,27 @@ enum list_objects_filter_situation {
 	LOFS_BLOB
 };
 
-typedef enum list_objects_filter_result (*filter_object_fn)(
+struct filter;
+
+/* Constructor for the set of defined list-objects filters. */
+struct filter *list_objects_filter__init(
+	struct oidset *omitted,
+	struct list_objects_filter_options *filter_options);
+
+/*
+ * Lets `filter` decide how to handle the `obj`. If `filter` is NULL, this
+ * function behaves as expected if no filter is configured: all objects are
+ * included.
+ */
+enum list_objects_filter_result list_objects_filter__filter_object(
 	struct repository *r,
 	enum list_objects_filter_situation filter_situation,
 	struct object *obj,
 	const char *pathname,
 	const char *filename,
-	void *filter_data);
-
-typedef void (*filter_free_fn)(void *filter_data);
+	struct filter *filter);
 
-/*
- * Constructor for the set of defined list-objects filters.
- * Returns a generic "void *filter_data".
- *
- * The returned "filter_fn" will be used by traverse_commit_list()
- * to filter the results.
- *
- * The returned "filter_free_fn" is a destructor for the
- * filter_data.
- */
-void *list_objects_filter__init(
-	struct oidset *omitted,
-	struct list_objects_filter_options *filter_options,
-	filter_object_fn *filter_fn,
-	filter_free_fn *filter_free_fn);
+/* Destroys `filter`. Does nothing if `filter` is null. */
+void list_objects_filter__free(struct filter *filter);
 
 #endif /* LIST_OBJECTS_FILTER_H */

list-objects.c

@@ -18,8 +18,7 @@ struct traversal_context {
 	show_object_fn show_object;
 	show_commit_fn show_commit;
 	void *show_data;
-	filter_object_fn filter_fn;
-	void *filter_data;
+	struct filter *filter;
 };
 
 static void process_blob(struct traversal_context *ctx,
@@ -29,7 +28,7 @@ static void process_blob(struct traversal_context *ctx,
 {
 	struct object *obj = &blob->object;
 	size_t pathlen;
-	enum list_objects_filter_result r = LOFR_MARK_SEEN | LOFR_DO_SHOW;
+	enum list_objects_filter_result r;
 
 	if (!ctx->revs->blob_objects)
 		return;
@@ -54,11 +53,10 @@ static void process_blob(struct traversal_context *ctx,
 
 	pathlen = path->len;
 	strbuf_addstr(path, name);
-	if ((obj->flags & NOT_USER_GIVEN) && ctx->filter_fn)
-		r = ctx->filter_fn(ctx->revs->repo,
+	r = list_objects_filter__filter_object(ctx->revs->repo,
 					       LOFS_BLOB, obj,
 					       path->buf, &path->buf[pathlen],
-				   ctx->filter_data);
+					       ctx->filter);
 	if (r & LOFR_MARK_SEEN)
 		obj->flags |= SEEN;
 	if (r & LOFR_DO_SHOW)
@@ -157,7 +155,7 @@ static void process_tree(struct traversal_context *ctx,
 	struct object *obj = &tree->object;
 	struct rev_info *revs = ctx->revs;
 	int baselen = base->len;
-	enum list_objects_filter_result r = LOFR_MARK_SEEN | LOFR_DO_SHOW;
+	enum list_objects_filter_result r;
 	int failed_parse;
 
 	if (!revs->tree_objects)
@@ -186,11 +184,10 @@ static void process_tree(struct traversal_context *ctx,
 	}
 
 	strbuf_addstr(base, name);
-	if ((obj->flags & NOT_USER_GIVEN) && ctx->filter_fn)
-		r = ctx->filter_fn(ctx->revs->repo,
+	r = list_objects_filter__filter_object(ctx->revs->repo,
 					       LOFS_BEGIN_TREE, obj,
 					       base->buf, &base->buf[baselen],
-				   ctx->filter_data);
+					       ctx->filter);
 	if (r & LOFR_MARK_SEEN)
 		obj->flags |= SEEN;
 	if (r & LOFR_DO_SHOW)
@@ -203,16 +200,14 @@ static void process_tree(struct traversal_context *ctx,
 	else if (!failed_parse)
 		process_tree_contents(ctx, tree, base);
 
-	if ((obj->flags & NOT_USER_GIVEN) && ctx->filter_fn) {
-		r = ctx->filter_fn(ctx->revs->repo,
+	r = list_objects_filter__filter_object(ctx->revs->repo,
 					       LOFS_END_TREE, obj,
 					       base->buf, &base->buf[baselen],
-				   ctx->filter_data);
+					       ctx->filter);
 	if (r & LOFR_MARK_SEEN)
 		obj->flags |= SEEN;
 	if (r & LOFR_DO_SHOW)
 		ctx->show_object(obj, base->buf, ctx->show_data);
-	}
 
 	strbuf_setlen(base, baselen);
 	free_tree_buffer(tree);
@@ -402,8 +397,7 @@ void traverse_commit_list(struct rev_info *revs,
 	ctx.show_commit = show_commit;
 	ctx.show_object = show_object;
 	ctx.show_data = show_data;
-	ctx.filter_fn = NULL;
-	ctx.filter_data = NULL;
+	ctx.filter = NULL;
 	do_traverse(&ctx);
 }
 
@@ -416,17 +410,12 @@ void traverse_commit_list_filtered(
 	struct oidset *omitted)
 {
 	struct traversal_context ctx;
-	filter_free_fn filter_free_fn = NULL;
 
 	ctx.revs = revs;
 	ctx.show_object = show_object;
 	ctx.show_commit = show_commit;
 	ctx.show_data = show_data;
-	ctx.filter_fn = NULL;
-
-	ctx.filter_data = list_objects_filter__init(omitted, filter_options,
-						    &ctx.filter_fn, &filter_free_fn);
+	ctx.filter = list_objects_filter__init(omitted, filter_options);
 	do_traverse(&ctx);
-	if (ctx.filter_data && filter_free_fn)
-		filter_free_fn(ctx.filter_data);
+	list_objects_filter__free(ctx.filter);
 }