gcc/hash.h

   1 /* Header file for generic hash table support.
   2    Copyright (C) 1993, 94 Free Software Foundation, Inc.
   3    Written by Steve Chamberlain <sac@cygnus.com>
   4
   5 This file was lifted from BFD, the Binary File Descriptor library.
   6
   7 This program is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2 of the License, or
  10 (at your option) any later version.
  11
  12 This program is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with this program; if not, write to the Free Software
  19 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  20
  21 #ifdef IN_GCC
  22
  23 /* Add prototype support.  */
  24 #ifndef PROTO
  25 #if defined (USE_PROTOTYPES) ? USE_PROTOTYPES : defined (__STDC__)
  26 #define PROTO(ARGS) ARGS
  27 #else
  28 #define PROTO(ARGS) ()
  29 #endif
  30 #endif
  31
  32 #define PARAMS(ARGS) PROTO(ARGS)
  33
  34 #ifdef __STDC__
  35 #define PTR void *
  36 #else
  37 #ifndef const
  38 #define const
  39 #endif
  40 #define PTR char *
  41 #endif
  42
  43 #else /* ! IN_GCC */
  44 #include <ansidecl.h>
  45 #endif /* IN_GCC */
  46
  47 #include "obstack.h"
  48
  49 typedef enum {false, true} boolean;
  50
  51 /* Hash table routines.  There is no way to free up a hash table.  */
  52
  53 /* An element in the hash table.  Most uses will actually use a larger
  54    structure, and an instance of this will be the first field.  */
  55
  56 struct hash_entry
  57 {
  58   /* Next entry for this hash code.  */
  59   struct hash_entry *next;
  60   /* String being hashed.  */
  61   const char *string;
  62   /* Hash code.  This is the full hash code, not the index into the
  63      table.  */
  64   unsigned long hash;
  65 };
  66
  67 /* A hash table.  */
  68
  69 struct hash_table
  70 {
  71   /* The hash array.  */
  72   struct hash_entry **table;
  73   /* The number of slots in the hash table.  */
  74   unsigned int size;
  75   /* A function used to create new elements in the hash table.  The
  76      first entry is itself a pointer to an element.  When this
  77      function is first invoked, this pointer will be NULL.  However,
  78      having the pointer permits a hierarchy of method functions to be
  79      built each of which calls the function in the superclass.  Thus
  80      each function should be written to allocate a new block of memory
  81      only if the argument is NULL.  */
  82   struct hash_entry *(*newfunc) PARAMS ((struct hash_entry *,
  83                                          struct hash_table *,
  84                                          const char *));
  85   /* An obstack for this hash table.  */
  86   struct obstack memory;
  87 };
  88
  89 /* Initialize a hash table.  */
  90 extern boolean hash_table_init
  91   PARAMS ((struct hash_table *,
  92            struct hash_entry *(*) (struct hash_entry *,
  93                                    struct hash_table *,
  94                                    const char *)));
  95
  96 /* Initialize a hash table specifying a size.  */
  97 extern boolean hash_table_init_n
  98   PARAMS ((struct hash_table *,
  99            struct hash_entry *(*) (struct hash_entry *,
 100                                    struct hash_table *,
 101                                    const char *),
 102            unsigned int size));
 103
 104 /* Free up a hash table.  */
 105 extern void hash_table_free PARAMS ((struct hash_table *));
 106
 107 /* Look up a string in a hash table.  If CREATE is true, a new entry
 108    will be created for this string if one does not already exist.  The
 109    COPY argument must be true if this routine should copy the string
 110    into newly allocated memory when adding an entry.  */
 111 extern struct hash_entry *hash_lookup
 112   PARAMS ((struct hash_table *, const char *, boolean create,
 113            boolean copy));
 114
 115 /* Base method for creating a hash table entry.  */
 116 extern struct hash_entry *hash_newfunc
 117   PARAMS ((struct hash_entry *, struct hash_table *,
 118            const char *));
 119
 120 /* Grab some space for a hash table entry.  */
 121 extern PTR hash_allocate PARAMS ((struct hash_table *,
 122                                   unsigned int));
 123
 124 /* Traverse a hash table in a random order, calling a function on each
 125    element.  If the function returns false, the traversal stops.  The
 126    INFO argument is passed to the function.  */
 127 extern void hash_traverse PARAMS ((struct hash_table *,
 128                                    boolean (*) (struct hash_entry *,
 129                                                 PTR),
 130                                    PTR info));