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TBE/MinGW/lib/gcc-lib/mingw32/3.2.3/include/objc/hash.h

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+/* Hash tables for Objective C method dispatch.
+   Copyright (C) 1993, 1995, 1996 Free Software Foundation, Inc.
+
+This file is part of GNU CC.
+
+GNU CC 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 2, or (at your option)
+any later version.
+
+GNU CC 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.
+
+You should have received a copy of the GNU General Public License
+along with GNU CC; see the file COPYING.  If not, write to
+the Free Software Foundation, 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA.  */
+
+/* As a special exception, if you link this library with files
+   compiled with GCC to produce an executable, this does not cause
+   the resulting executable to be covered by the GNU General Public License.
+   This exception does not however invalidate any other reasons why
+   the executable file might be covered by the GNU General Public License.  */
+
+
+#ifndef __hash_INCLUDE_GNU
+#define __hash_INCLUDE_GNU
+
+#include <stddef.h>
+#include <string.h>
+#include <objc/objc.h>
+
+/*
+ * 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
+ * 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 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 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 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 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 hash_next (cache_ptr cache, node_ptr node);
+
+/* Used to return a value from a hash table using a given key.  */
+
+void *hash_value_for_key (cache_ptr cache, const void *key);
+
+/* Used to determine if the given key exists in the hash table */
+
+BOOL 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
+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 
+hash_string (cache_ptr cache, const void *key)
+{
+  unsigned int ret = 0;
+  unsigned int ctr = 0;
+        
+        
+  while (*(char*)key) {
+    ret ^= *(char*)key++ << ctr;
+    ctr = (ctr + 1) % sizeof (void *);
+  }
+
+  return ret & cache->mask;
+}
+
+
+/* Compare two pointers for equality.  */
+static inline int 
+compare_ptrs (const void *k1, const void *k2)
+{
+  return !(k1 - k2);
+}
+
+
+/* Compare two strings.  */
+static inline int 
+compare_strings (const void *k1, const void *k2)
+{
+  if (k1 == k2)
+    return 1;
+  else if (k1 == 0 || k2 == 0)
+    return 0;
+  else
+    return !strcmp (k1, k2);
+}
+
+
+#endif /* not __hash_INCLUDE_GNU */