--- /dev/null
+/*
+ * Copyright (C) 2007 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Hash map.
+ */
+
+#ifndef __HASHMAP_H
+#define __HASHMAP_H
+
+#include <stdbool.h>
+#include <stdlib.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** A hash map. */
+typedef struct Hashmap Hashmap;
+
+/**
+ * Creates a new hash map. Returns NULL if memory allocation fails.
+ *
+ * @param initialCapacity number of expected entries
+ * @param hash function which hashes keys
+ * @param equals function which compares keys for equality
+ */
+Hashmap* hashmapCreate(size_t initialCapacity,
+ int (*hash)(void* key), bool (*equals)(void* keyA, void* keyB));
+
+/**
+ * Frees the hash map. Does not free the keys or values themselves.
+ */
+void hashmapFree(Hashmap* map);
+
+/**
+ * Hashes the memory pointed to by key with the given size. Useful for
+ * implementing hash functions.
+ */
+int hashmapHash(void* key, size_t keySize);
+
+/**
+ * Puts value for the given key in the map. Returns pre-existing value if
+ * any.
+ *
+ * If memory allocation fails, this function returns NULL, the map's size
+ * does not increase, and errno is set to ENOMEM.
+ */
+void* hashmapPut(Hashmap* map, void* key, void* value);
+
+/**
+ * Gets a value from the map. Returns NULL if no entry for the given key is
+ * found or if the value itself is NULL.
+ */
+void* hashmapGet(Hashmap* map, void* key);
+
+/**
+ * Returns true if the map contains an entry for the given key.
+ */
+bool hashmapContainsKey(Hashmap* map, void* key);
+
+/**
+ * Gets the value for a key. If a value is not found, this function gets a
+ * value and creates an entry using the given callback.
+ *
+ * If memory allocation fails, the callback is not called, this function
+ * returns NULL, and errno is set to ENOMEM.
+ */
+void* hashmapMemoize(Hashmap* map, void* key,
+ void* (*initialValue)(void* key, void* context), void* context);
+
+/**
+ * Removes an entry from the map. Returns the removed value or NULL if no
+ * entry was present.
+ */
+void* hashmapRemove(Hashmap* map, void* key);
+
+/**
+ * Gets the number of entries in this map.
+ */
+size_t hashmapSize(Hashmap* map);
+
+/**
+ * Invokes the given callback on each entry in the map. Stops iterating if
+ * the callback returns false.
+ */
+void hashmapForEach(Hashmap* map,
+ bool (*callback)(void* key, void* value, void* context),
+ void* context);
+
+/**
+ * Concurrency support.
+ */
+
+/**
+ * Locks the hash map so only the current thread can access it.
+ */
+void hashmapLock(Hashmap* map);
+
+/**
+ * Unlocks the hash map so other threads can access it.
+ */
+void hashmapUnlock(Hashmap* map);
+
+/**
+ * Key utilities.
+ */
+
+/**
+ * Hashes int keys. 'key' is a pointer to int.
+ */
+int hashmapIntHash(void* key);
+
+/**
+ * Compares two int keys for equality.
+ */
+bool hashmapIntEquals(void* keyA, void* keyB);
+
+/**
+ * For debugging.
+ */
+
+/**
+ * Gets current capacity.
+ */
+size_t hashmapCurrentCapacity(Hashmap* map);
+
+/**
+ * Counts the number of entry collisions.
+ */
+size_t hashmapCountCollisions(Hashmap* map);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __HASHMAP_H */
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