377 lines
13 KiB
C
377 lines
13 KiB
C
/* Abstract map data type.
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Copyright (C) 2006-2007, 2009-2024 Free Software Foundation, Inc.
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Written by Bruno Haible <bruno@clisp.org>, 2018.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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#ifndef _GL_MAP_H
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#define _GL_MAP_H
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/* This file uses _GL_INLINE_HEADER_BEGIN, _GL_INLINE,
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_GL_ATTRIBUTE_NODISCARD. */
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#if !_GL_CONFIG_H_INCLUDED
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#error "Please include config.h first."
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#endif
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#include <stddef.h>
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_GL_INLINE_HEADER_BEGIN
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#ifndef GL_MAP_INLINE
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# define GL_MAP_INLINE _GL_INLINE
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#endif
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* gl_map is an abstract map data type. It can contain any number of
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(key, value) pairs, where
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- keys and values are objects ('void *' or 'const void *' pointers),
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- There are no (key, value1) and (key, value2) pairs with the same key
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(in the sense of a given comparator function).
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There are several implementations of this map datatype, optimized for
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different operations or for memory. You can start using the simplest map
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implementation, GL_ARRAY_MAP, and switch to a different implementation
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later, when you realize which operations are performed the most frequently.
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The API of the different implementations is exactly the same; when switching
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to a different implementation, you only have to change the gl_map_create
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call.
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The implementations are:
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GL_ARRAY_MAP a growable array
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GL_LINKEDHASH_MAP a hash table with a linked list
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GL_HASH_MAP a hash table
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The memory consumption is asymptotically the same: O(1) for every pair
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in the map. When looking more closely at the average memory consumed
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for an object, GL_ARRAY_MAP is the most compact representation, then comes
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GL_HASH_MAP, and GL_LINKEDHASH_MAP needs the most memory.
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The guaranteed average performance of the operations is, for a map of
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n pairs:
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Operation ARRAY LINKEDHASH
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HASH
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gl_map_size O(1) O(1)
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gl_map_get O(n) O(1)
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gl_map_put O(n) O(1)
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gl_map_remove O(n) O(1)
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gl_map_search O(n) O(1)
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gl_map_iterator O(1) O(1)
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gl_map_iterator_next O(1) O(1)
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*/
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/* --------------------------- gl_map_t Data Type --------------------------- */
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/* Type of function used to compare two keys.
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NULL denotes pointer comparison. */
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typedef bool (*gl_mapkey_equals_fn) (const void *key1, const void *key2);
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/* Type of function used to compute a hash code.
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NULL denotes a function that depends only on the pointer itself. */
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typedef size_t (*gl_mapkey_hashcode_fn) (const void *key);
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#ifndef _GL_MAP_DISPOSE_FNS_DEFINED
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/* Type of function used to dispose a key once a (key, value) pair is removed
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from a map. NULL denotes a no-op. */
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typedef void (*gl_mapkey_dispose_fn) (const void *key);
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/* Type of function used to dispose a value once a (key, value) pair is removed
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from a map. NULL denotes a no-op. */
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typedef void (*gl_mapvalue_dispose_fn) (const void *value);
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# define _GL_MAP_DISPOSE_FNS_DEFINED 1
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#endif
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struct gl_map_impl;
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/* Type representing an entire map. */
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typedef struct gl_map_impl * gl_map_t;
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struct gl_map_implementation;
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/* Type representing a map datatype implementation. */
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typedef const struct gl_map_implementation * gl_map_implementation_t;
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#if 0 /* Unless otherwise specified, these are defined inline below. */
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/* Creates an empty map.
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IMPLEMENTATION is one of GL_ARRAY_MAP, GL_LINKEDHASH_MAP, GL_HASH_MAP.
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EQUALS_FN is a key comparison function or NULL.
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HASHCODE_FN is a key hash code function or NULL.
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KDISPOSE_FN is a key disposal function or NULL.
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VDISPOSE_FN is a value disposal function or NULL. */
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/* declared in gl_xmap.h */
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extern gl_map_t gl_map_create_empty (gl_map_implementation_t implementation,
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gl_mapkey_equals_fn equals_fn,
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gl_mapkey_hashcode_fn hashcode_fn,
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gl_mapkey_dispose_fn kdispose_fn,
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gl_mapvalue_dispose_fn vdispose_fn)
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/*_GL_ATTRIBUTE_DEALLOC (gl_map_free, 1)*/
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_GL_ATTRIBUTE_RETURNS_NONNULL;
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/* Likewise. Returns NULL upon out-of-memory. */
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extern gl_map_t gl_map_nx_create_empty (gl_map_implementation_t implementation,
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gl_mapkey_equals_fn equals_fn,
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gl_mapkey_hashcode_fn hashcode_fn,
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gl_mapkey_dispose_fn kdispose_fn,
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gl_mapvalue_dispose_fn vdispose_fn)
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/*_GL_ATTRIBUTE_DEALLOC (gl_map_free, 1)*/;
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/* Returns the current number of pairs in a map. */
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extern size_t gl_map_size (gl_map_t map);
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/* Searches whether a pair with the given key is already in the map.
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Returns the value if found, or NULL if not present in the map. */
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extern const void * gl_map_get (gl_map_t map, const void *key);
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/* Searches whether a pair with the given key is already in the map.
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Returns true and sets *VALUEP to the value if found.
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Returns false if not present in the map. */
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extern bool gl_map_search (gl_map_t map, const void *key, const void **valuep);
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/* Adds a pair to a map.
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Returns true if a pair with the given key was not already in the map and so
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this pair was added.
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Returns false if a pair with the given key was already in the map and only
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its value was replaced. */
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/* declared in gl_xmap.h */
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extern bool gl_map_put (gl_map_t map, const void *key, const void *value);
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/* Likewise. Returns -1 upon out-of-memory. */
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_GL_ATTRIBUTE_NODISCARD
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extern int gl_map_nx_put (gl_map_t map, const void *key, const void *value);
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/* Adds a pair to a map and retrieves the previous value.
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Returns true if a pair with the given key was not already in the map and so
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this pair was added.
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Returns false and sets *OLDVALUEP to the previous value, if a pair with the
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given key was already in the map and only its value was replaced. */
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/* declared in gl_xmap.h */
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extern bool gl_map_getput (gl_map_t map, const void *key, const void *value,
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const void **oldvaluep);
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/* Likewise. Returns -1 upon out-of-memory. */
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_GL_ATTRIBUTE_NODISCARD
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extern int gl_map_nx_getput (gl_map_t map, const void *key, const void *value,
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const void **oldvaluep);
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/* Removes a pair from a map.
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Returns true if the key was found and its pair removed.
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Returns false otherwise. */
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extern bool gl_map_remove (gl_map_t map, const void *key);
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/* Removes a pair from a map and retrieves the previous value.
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Returns true and sets *OLDVALUEP to the previous value, if the key was found
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and its pair removed.
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Returns false otherwise. */
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extern bool gl_map_getremove (gl_map_t map, const void *key,
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const void **oldvaluep);
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/* Frees an entire map.
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(But this call does not free the keys and values of the pairs in the map.
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It only invokes the KDISPOSE_FN on each key and the VDISPOSE_FN on each value
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of the pairs in the map.) */
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extern void gl_map_free (gl_map_t map);
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#endif /* End of inline and gl_xmap.h-defined functions. */
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/* ---------------------- gl_map_iterator_t Data Type ---------------------- */
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/* Functions for iterating through a map.
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Note: Iterating through a map of type GL_HASH_MAP returns the pairs in an
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unpredictable order. If you need a predictable order, use GL_LINKEDHASH_MAP
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instead of GL_HASH_MAP. */
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/* Type of an iterator that traverses a map.
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This is a fixed-size struct, so that creation of an iterator doesn't need
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memory allocation on the heap. */
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typedef struct
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{
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/* For fast dispatch of gl_map_iterator_next. */
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const struct gl_map_implementation *vtable;
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/* For detecting whether the last returned pair was removed. */
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gl_map_t map;
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size_t count;
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/* Other, implementation-private fields. */
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void *p; void *q;
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size_t i; size_t j;
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} gl_map_iterator_t;
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#if 0 /* These are defined inline below. */
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/* Creates an iterator traversing a map.
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The map's contents must not be modified while the iterator is in use,
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except for modifying the value of the last returned key or removing the
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last returned pair. */
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extern gl_map_iterator_t gl_map_iterator (gl_map_t map);
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/* If there is a next pair, stores the next pair in *KEYP and *VALUEP, advances
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the iterator, and returns true. Otherwise, returns false. */
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extern bool gl_map_iterator_next (gl_map_iterator_t *iterator,
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const void **keyp, const void **valuep);
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/* Frees an iterator. */
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extern void gl_map_iterator_free (gl_map_iterator_t *iterator);
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#endif /* End of inline functions. */
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/* ------------------------- Implementation Details ------------------------- */
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struct gl_map_implementation
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{
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/* gl_map_t functions. */
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gl_map_t (*nx_create_empty) (gl_map_implementation_t implementation,
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gl_mapkey_equals_fn equals_fn,
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gl_mapkey_hashcode_fn hashcode_fn,
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gl_mapkey_dispose_fn kdispose_fn,
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gl_mapvalue_dispose_fn vdispose_fn);
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size_t (*size) (gl_map_t map);
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bool (*search) (gl_map_t map, const void *key, const void **valuep);
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int (*nx_getput) (gl_map_t map, const void *key, const void *value,
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const void **oldvaluep);
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bool (*getremove) (gl_map_t map, const void *key, const void **oldvaluep);
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void (*map_free) (gl_map_t map);
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/* gl_map_iterator_t functions. */
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gl_map_iterator_t (*iterator) (gl_map_t map);
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bool (*iterator_next) (gl_map_iterator_t *iterator,
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const void **keyp, const void **valuep);
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void (*iterator_free) (gl_map_iterator_t *iterator);
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};
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struct gl_map_impl_base
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{
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const struct gl_map_implementation *vtable;
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gl_mapkey_equals_fn equals_fn;
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gl_mapkey_dispose_fn kdispose_fn;
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gl_mapvalue_dispose_fn vdispose_fn;
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};
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/* Define most functions of this file as accesses to the
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struct gl_map_implementation. */
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GL_MAP_INLINE
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/*_GL_ATTRIBUTE_DEALLOC (gl_map_free, 1)*/
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gl_map_t
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gl_map_nx_create_empty (gl_map_implementation_t implementation,
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gl_mapkey_equals_fn equals_fn,
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gl_mapkey_hashcode_fn hashcode_fn,
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gl_mapkey_dispose_fn kdispose_fn,
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gl_mapvalue_dispose_fn vdispose_fn)
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{
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return implementation->nx_create_empty (implementation,
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equals_fn, hashcode_fn,
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kdispose_fn, vdispose_fn);
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}
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GL_MAP_INLINE size_t
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gl_map_size (gl_map_t map)
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{
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return ((const struct gl_map_impl_base *) map)->vtable->size (map);
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}
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GL_MAP_INLINE bool
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gl_map_search (gl_map_t map, const void *key, const void **valuep)
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{
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return ((const struct gl_map_impl_base *) map)->vtable
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->search (map, key, valuep);
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}
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_GL_ATTRIBUTE_NODISCARD GL_MAP_INLINE int
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gl_map_nx_getput (gl_map_t map, const void *key, const void *value,
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const void **oldvaluep)
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{
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return ((const struct gl_map_impl_base *) map)->vtable
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->nx_getput (map, key, value, oldvaluep);
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}
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GL_MAP_INLINE bool
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gl_map_getremove (gl_map_t map, const void *key, const void **oldvaluep)
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{
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return ((const struct gl_map_impl_base *) map)->vtable
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->getremove (map, key, oldvaluep);
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}
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GL_MAP_INLINE void
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gl_map_free (gl_map_t map)
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{
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((const struct gl_map_impl_base *) map)->vtable->map_free (map);
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}
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GL_MAP_INLINE gl_map_iterator_t
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gl_map_iterator (gl_map_t map)
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{
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return ((const struct gl_map_impl_base *) map)->vtable->iterator (map);
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}
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GL_MAP_INLINE bool
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gl_map_iterator_next (gl_map_iterator_t *iterator,
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const void **keyp, const void **valuep)
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{
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return iterator->vtable->iterator_next (iterator, keyp, valuep);
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}
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GL_MAP_INLINE void
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gl_map_iterator_free (gl_map_iterator_t *iterator)
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{
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iterator->vtable->iterator_free (iterator);
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}
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/* Define the convenience functions, that is, the functions that are independent
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of the implementation. */
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GL_MAP_INLINE const void *
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gl_map_get (gl_map_t map, const void *key)
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{
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const void *value = NULL;
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gl_map_search (map, key, &value);
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return value;
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}
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_GL_ATTRIBUTE_NODISCARD GL_MAP_INLINE int
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gl_map_nx_put (gl_map_t map, const void *key, const void *value)
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{
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const void *oldvalue;
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int result = gl_map_nx_getput (map, key, value, &oldvalue);
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if (result == 0)
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{
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gl_mapvalue_dispose_fn vdispose_fn =
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((const struct gl_map_impl_base *) map)->vdispose_fn;
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if (vdispose_fn != NULL)
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vdispose_fn (oldvalue);
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}
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return result;
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}
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GL_MAP_INLINE bool
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gl_map_remove (gl_map_t map, const void *key)
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{
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const void *oldvalue;
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bool result = gl_map_getremove (map, key, &oldvalue);
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if (result)
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{
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gl_mapvalue_dispose_fn vdispose_fn =
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((const struct gl_map_impl_base *) map)->vdispose_fn;
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if (vdispose_fn != NULL)
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vdispose_fn (oldvalue);
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}
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return result;
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}
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#ifdef __cplusplus
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}
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#endif
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_GL_INLINE_HEADER_END
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#endif /* _GL_MAP_H */
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