+/* Hash tables for Objective C method dispatch.
+ Copyright (C) 1993, 1995, 1996, 2004, 2009 Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3, or (at your option)
+any later version.
+
+GCC is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+Under Section 7 of GPL version 3, you are granted additional
+permissions described in the GCC Runtime Library Exception, version
+3.1, as published by the Free Software Foundation.
+
+You should have received a copy of the GNU General Public License and
+a copy of the GCC Runtime Library Exception along with this program;
+see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+<http://www.gnu.org/licenses/>. */
+
+/* You need to include this file after including objc.h */
+
+#ifndef __hash_INCLUDE_GNU
+#define __hash_INCLUDE_GNU
+
+#include <stddef.h>
+#include <string.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+/*
+ * This data structure is used to hold items
+ * stored in a hash table. Each node holds
+ * a key/value pair.
+ *
+ * Items in the cache are really of type void *.
+ */
+typedef struct cache_node
+{
+ struct cache_node *next; /* Pointer to next entry on the list.
+ NULL indicates end of list. */
+ const void *key; /* Key used to locate the value. Used
+ to locate value when more than one
+ key computes the same hash
+ value. */
+ void *value; /* Value stored for the key. */
+} *node_ptr;
+
+
+/*
+ * This data type is the function that computes a hash code given a key.
+ * Therefore, the key can be a pointer to anything and the function specific
+ * to the key type.
+ *
+ * Unfortunately there is a mutual data structure reference problem with this
+ * typedef. Therefore, to remove compiler warnings the functions passed to
+ * objc_hash_new will have to be casted to this type.
+ */
+typedef unsigned int (*hash_func_type) (void *, const void *);
+
+/*
+ * This data type is the function that compares two hash keys and returns an
+ * integer greater than, equal to, or less than 0, according as the first
+ * parameter is lexicographically greater than, equal to, or less than the
+ * second.
+ */
+
+typedef int (*compare_func_type) (const void *, const void *);
+
+
+/*
+ * This data structure is the cache.
+ *
+ * It must be passed to all of the hashing routines
+ * (except for new).
+ */
+typedef struct cache
+{
+ /* Variables used to implement the hash itself. */
+ node_ptr *node_table; /* Pointer to an array of hash nodes. */
+ /* Variables used to track the size of the hash table so to determine
+ when to resize it. */
+ unsigned int size; /* Number of buckets allocated for the hash table
+ (number of array entries allocated for
+ "node_table"). Must be a power of two. */
+ unsigned int used; /* Current number of entries in the hash table. */
+ unsigned int mask; /* Precomputed mask. */
+
+ /* Variables used to implement indexing through the hash table. */
+
+ unsigned int last_bucket; /* Tracks which entry in the array where
+ the last value was returned. */
+ /* Function used to compute a hash code given a key.
+ This function is specified when the hash table is created. */
+ hash_func_type hash_func;
+ /* Function used to compare two hash keys to see if they are equal. */
+ compare_func_type compare_func;
+} *cache_ptr;
+
+
+/* Two important hash tables. */
+extern cache_ptr module_hash_table, class_hash_table;
+
+/* Allocate and initialize a hash table. */
+
+cache_ptr objc_hash_new (unsigned int size,
+ hash_func_type hash_func,
+ compare_func_type compare_func);
+
+/* Deallocate all of the hash nodes and the cache itself. */
+
+void objc_hash_delete (cache_ptr cache);
+
+/* Add the key/value pair to the hash table. If the
+ hash table reaches a level of fullness then it will be resized.
+
+ assert if the key is already in the hash. */
+
+void objc_hash_add (cache_ptr *cachep, const void *key, void *value);
+
+/* Remove the key/value pair from the hash table.
+ assert if the key isn't in the table. */
+
+void objc_hash_remove (cache_ptr cache, const void *key);
+
+/* Used to index through the hash table. Start with NULL
+ to get the first entry.
+
+ Successive calls pass the value returned previously.
+ ** Don't modify the hash during this operation ***
+
+ Cache nodes are returned such that key or value can
+ be extracted. */
+
+node_ptr objc_hash_next (cache_ptr cache, node_ptr node);
+
+/* Used to return a value from a hash table using a given key. */
+
+void *objc_hash_value_for_key (cache_ptr cache, const void *key);
+
+/* Used to determine if the given key exists in the hash table */
+
+BOOL objc_hash_is_key_in_hash (cache_ptr cache, const void *key);
+
+/************************************************
+
+ Useful hashing functions.
+
+ Declared inline for your pleasure.
+
+************************************************/
+
+/* Calculate a hash code by performing some
+ manipulation of the key pointer. (Use the lowest bits
+ except for those likely to be 0 due to alignment.) */
+
+static inline unsigned int
+objc_hash_ptr (cache_ptr cache, const void *key)
+{
+ return ((size_t)key / sizeof (void *)) & cache->mask;
+}
+
+
+/* Calculate a hash code by iterating over a NULL
+ terminate string. */
+static inline unsigned int
+objc_hash_string (cache_ptr cache, const void *key)
+{
+ unsigned int ret = 0;
+ unsigned int ctr = 0;
+ const char *ckey = (const char *) key;
+
+ while (*ckey) {
+ ret ^= *ckey++ << ctr;
+ ctr = (ctr + 1) % sizeof (void *);
+ }
+
+ return ret & cache->mask;
+}
+
+
+/* Compare two pointers for equality. */
+static inline int
+objc_compare_ptrs (const void *k1, const void *k2)
+{
+ return (k1 == k2);
+}
+
+
+/* Compare two strings. */
+static inline int
+objc_compare_strings (const void *k1, const void *k2)
+{
+ if (k1 == k2)
+ return 1;
+ else if (k1 == 0 || k2 == 0)
+ return 0;
+ else
+ return ! strcmp ((const char *) k1, (const char *) k2);
+}
+
+
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+
+
+#endif /* not __hash_INCLUDE_GNU */
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