Extract helper bits from c-merge-recursive work

This backports the pieces that are not uncooked from the merge-recursive
WIP we have seen earlier, to be used in git-mv rewritten in C.

Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 105 insertions, 0 deletions

diff --git a/path-list.c b/path-list.c
new file mode 100644
index 000000000..f15a10de3
--- /dev/null
+++ b/path-list.c
@@ -0,0 +1,105 @@
+#include <stdio.h>
+#include "cache.h"
+#include "path-list.h"
+
+/* if there is no exact match, point to the index where the entry could be
+ * inserted */
+static int get_entry_index(const struct path_list *list, const char *path,
+		int *exact_match)
+{
+	int left = -1, right = list->nr;
+
+	while (left + 1 < right) {
+		int middle = (left + right) / 2;
+		int compare = strcmp(path, list->items[middle].path);
+		if (compare < 0)
+			right = middle;
+		else if (compare > 0)
+			left = middle;
+		else {
+			*exact_match = 1;
+			return middle;
+		}
+	}
+
+	*exact_match = 0;
+	return right;
+}
+
+/* returns -1-index if already exists */
+static int add_entry(struct path_list *list, const char *path)
+{
+	int exact_match;
+	int index = get_entry_index(list, path, &exact_match);
+
+	if (exact_match)
+		return -1 - index;
+
+	if (list->nr + 1 >= list->alloc) {
+		list->alloc += 32;
+		list->items = xrealloc(list->items, list->alloc
+				* sizeof(struct path_list_item));
+	}
+	if (index < list->nr)
+		memmove(list->items + index + 1, list->items + index,
+				(list->nr - index)
+				* sizeof(struct path_list_item));
+	list->items[index].path = list->strdup_paths ?
+		strdup(path) : (char *)path;
+	list->items[index].util = NULL;
+	list->nr++;
+
+	return index;
+}
+
+struct path_list_item *path_list_insert(const char *path, struct path_list *list)
+{
+	int index = add_entry(list, path);
+
+	if (index < 0)
+		index = 1 - index;
+
+	return list->items + index;
+}
+
+int path_list_has_path(const struct path_list *list, const char *path)
+{
+	int exact_match;
+	get_entry_index(list, path, &exact_match);
+	return exact_match;
+}
+
+struct path_list_item *path_list_lookup(const char *path, struct path_list *list)
+{
+	int exact_match, i = get_entry_index(list, path, &exact_match);
+	if (!exact_match)
+		return NULL;
+	return list->items + i;
+}
+
+void path_list_clear(struct path_list *list, int free_items)
+{
+	if (list->items) {
+		int i;
+		if (free_items)
+			for (i = 0; i < list->nr; i++) {
+				if (list->strdup_paths)
+					free(list->items[i].path);
+				if (list->items[i].util)
+					free(list->items[i].util);
+			}
+		free(list->items);
+	}
+	list->items = NULL;
+	list->nr = list->alloc = 0;
+}
+
+void print_path_list(const char *text, const struct path_list *p)
+{
+	int i;
+	if ( text )
+		printf("%s\n", text);
+	for (i = 0; i < p->nr; i++)
+		printf("%s:%p\n", p->items[i].path, p->items[i].util);
+}
+