1 files changed, 93 insertions, 0 deletions
diff --git a/third_party/git/oidmap.h b/third_party/git/oidmap.h
new file mode 100644
index 000000000000..c66a83ab1d68
--- /dev/null
+++ b/third_party/git/oidmap.h
@@ -0,0 +1,93 @@
+#ifndef OIDMAP_H
+#define OIDMAP_H
+
+#include "cache.h"
+#include "hashmap.h"
+
+/*
+ * struct oidmap_entry is a structure representing an entry in the hash table,
+ * which must be used as first member of user data structures.
+ *
+ * Users should set the oid field. oidmap_put() will populate the
+ * internal_entry field.
+ */
+struct oidmap_entry {
+	/* For internal use only */
+	struct hashmap_entry internal_entry;
+
+	struct object_id oid;
+};
+
+struct oidmap {
+	struct hashmap map;
+};
+
+#define OIDMAP_INIT { { NULL } }
+
+/*
+ * Initializes an oidmap structure.
+ *
+ * `map` is the oidmap to initialize.
+ *
+ * If the total number of entries is known in advance, the `initial_size`
+ * parameter may be used to preallocate a sufficiently large table and thus
+ * prevent expensive resizing. If 0, the table is dynamically resized.
+ */
+void oidmap_init(struct oidmap *map, size_t initial_size);
+
+/*
+ * Frees an oidmap structure and allocated memory.
+ *
+ * If `free_entries` is true, each oidmap_entry in the map is freed as well
+ * using stdlibs free().
+ */
+void oidmap_free(struct oidmap *map, int free_entries);
+
+/*
+ * Returns the oidmap entry for the specified oid, or NULL if not found.
+ */
+void *oidmap_get(const struct oidmap *map,
+		 const struct object_id *key);
+
+/*
+ * Adds or replaces an oidmap entry.
+ *
+ * ((struct oidmap_entry *) entry)->internal_entry will be populated by this
+ * function.
+ *
+ * Returns the replaced entry, or NULL if not found (i.e. the entry was added).
+ */
+void *oidmap_put(struct oidmap *map, void *entry);
+
+/*
+ * Removes an oidmap entry matching the specified oid.
+ *
+ * Returns the removed entry, or NULL if not found.
+ */
+void *oidmap_remove(struct oidmap *map, const struct object_id *key);
+
+
+struct oidmap_iter {
+	struct hashmap_iter h_iter;
+};
+
+static inline void oidmap_iter_init(struct oidmap *map, struct oidmap_iter *iter)
+{
+	hashmap_iter_init(&map->map, &iter->h_iter);
+}
+
+static inline void *oidmap_iter_next(struct oidmap_iter *iter)
+{
+	/* TODO: this API could be reworked to do compile-time type checks */
+	return (void *)hashmap_iter_next(&iter->h_iter);
+}
+
+static inline void *oidmap_iter_first(struct oidmap *map,
+				      struct oidmap_iter *iter)
+{
+	oidmap_iter_init(map, iter);
+	/* TODO: this API could be reworked to do compile-time type checks */
+	return (void *)oidmap_iter_next(iter);
+}
+
+#endif