[PATCH 11/17] object_array: add function object_array_filter()

[Michael Haggerty <mhagger@alum.mit.edu>]

Add a function that allows unwanted entries in an object_array to be
removed.  This encapsulation is a step towards giving object_array
ownership of its entries' name memory.

Use the new function to replace revision.c:gc_boundary().

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
---
 object.c   | 16 ++++++++++++++++
 object.h   | 11 +++++++++++
 revision.c | 28 ++++++++++------------------
 3 files changed, 37 insertions(+), 18 deletions(-)

diff --git a/object.c b/object.c
index 20703f5..fcd4a82 100644
--- a/object.c
+++ b/object.c
@@ -278,6 +278,22 @@ void add_object_array_with_mode(struct object *obj, const char *name, struct obj
 	array->nr = ++nr;
 }
 
+void object_array_filter(struct object_array *array,
+			 object_array_each_func_t want, void *cb_data)
+{
+	unsigned nr = array->nr, src, dst;
+	struct object_array_entry *objects = array->objects;
+
+	for (src = dst = 0; src < nr; src++) {
+		if (want(&objects[src], cb_data)) {
+			if (src != dst)
+				objects[dst] = objects[src];
+			dst++;
+		}
+	}
+	array->nr = dst;
+}
+
 void object_array_remove_duplicates(struct object_array *array)
 {
 	unsigned int ref, src, dst;
diff --git a/object.h b/object.h
index 97d384b..0d39ff4 100644
--- a/object.h
+++ b/object.h
@@ -85,6 +85,17 @@ int object_list_contains(struct object_list *list, struct object *obj);
 /* Object array handling .. */
 void add_object_array(struct object *obj, const char *name, struct object_array *array);
 void add_object_array_with_mode(struct object *obj, const char *name, struct object_array *array, unsigned mode);
+
+typedef int (*object_array_each_func_t)(struct object_array_entry *, void *);
+
+/*
+ * Apply want to each entry in array, retaining only the entries for
+ * which the function returns true.  Preserve the order of the entries
+ * that are retained.
+ */
+void object_array_filter(struct object_array *array,
+			 object_array_each_func_t want, void *cb_data);
+
 void object_array_remove_duplicates(struct object_array *);
 
 void clear_object_flags(unsigned flags);
diff --git a/revision.c b/revision.c
index 19c59f4..ddc6d7c 100644
--- a/revision.c
+++ b/revision.c
@@ -2435,23 +2435,6 @@ static struct commit *get_revision_1(struct rev_info *revs)
 	return NULL;
 }
 
-static void gc_boundary(struct object_array *array)
-{
-	unsigned nr = array->nr, i, j;
-	struct object_array_entry *objects = array->objects;
-
-	for (i = j = 0; i < nr; i++) {
-		if (objects[i].item->flags & SHOWN)
-			continue;
-		if (i != j)
-			objects[j] = objects[i];
-		j++;
-	}
-	for (i = j; i < nr; i++)
-		objects[i].item = NULL;
-	array->nr = j;
-}
-
 static void create_boundary_commit_list(struct rev_info *revs)
 {
 	unsigned i;
@@ -2493,6 +2476,15 @@ static void create_boundary_commit_list(struct rev_info *revs)
 	sort_in_topological_order(&revs->commits, revs->lifo);
 }
 
+/*
+ * Return true for entries that have not yet been shown.  (This is an
+ * object_array_each_func_t.)
+ */
+static int entry_unshown(struct object_array_entry *entry, void *cb_data_unused)
+{
+	return !(entry->item->flags & SHOWN);
+}
+
 static struct commit *get_revision_internal(struct rev_info *revs)
 {
 	struct commit *c = NULL;
@@ -2575,7 +2567,7 @@ static struct commit *get_revision_internal(struct rev_info *revs)
 		p->flags |= CHILD_SHOWN;
 		if (revs->boundary_commits.nr == revs->boundary_commits.alloc) {
 			/* Try to make space and thereby avoid a realloc(): */
-			gc_boundary(&revs->boundary_commits);
+			object_array_filter(&revs->boundary_commits, entry_unshown, NULL);
 		}
 		add_object_array(p, NULL, &revs->boundary_commits);
 	}
-- 
1.8.2.3