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      1 /* Hash tables.
      2    Copyright (C) 2000, 2001, 2003, 2004, 2007, 2008, 2009
      3    Free Software Foundation, Inc.
      4 
      5 This program is free software; you can redistribute it and/or modify it
      6 under the terms of the GNU General Public License as published by the
      7 Free Software Foundation; either version 3, or (at your option) any
      8 later version.
      9 
     10 This program is distributed in the hope that it will be useful,
     11 but WITHOUT ANY WARRANTY; without even the implied warranty of
     12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     13 GNU General Public License for more details.
     14 
     15 You should have received a copy of the GNU General Public License
     16 along with this program; see the file COPYING3.  If not see
     17 <http://www.gnu.org/licenses/>.  */
     18 
     19 #ifndef LIBCPP_SYMTAB_H
     20 #define LIBCPP_SYMTAB_H
     21 
     22 #include "obstack.h"
     23 #ifndef GTY
     24 #define GTY(x) /* nothing */
     25 #endif
     26 
     27 /* This is what each hash table entry points to.  It may be embedded
     28    deeply within another object.  */
     29 typedef struct ht_identifier ht_identifier;
     30 struct ht_identifier GTY(())
     31 {
     32   const unsigned char *str;
     33   unsigned int len;
     34   unsigned int hash_value;
     35 };
     36 
     37 #define HT_LEN(NODE) ((NODE)->len)
     38 #define HT_STR(NODE) ((NODE)->str)
     39 
     40 typedef struct ht hash_table;
     41 typedef struct ht_identifier *hashnode;
     42 
     43 enum ht_lookup_option {HT_NO_INSERT = 0, HT_ALLOC};
     44 
     45 /* An identifier hash table for cpplib and the front ends.  */
     46 struct ht
     47 {
     48   /* Identifiers are allocated from here.  */
     49   struct obstack stack;
     50 
     51   hashnode *entries;
     52   /* Call back, allocate a node.  */
     53   hashnode (*alloc_node) (hash_table *);
     54   /* Call back, allocate something that hangs off a node like a cpp_macro.
     55      NULL means use the usual allocator.  */
     56   void * (*alloc_subobject) (size_t);
     57 
     58   unsigned int nslots;		/* Total slots in the entries array.  */
     59   unsigned int nelements;	/* Number of live elements.  */
     60 
     61   /* Link to reader, if any.  For the benefit of cpplib.  */
     62   struct cpp_reader *pfile;
     63 
     64   /* Table usage statistics.  */
     65   unsigned int searches;
     66   unsigned int collisions;
     67 
     68   /* Should 'entries' be freed when it is no longer needed?  */
     69   bool entries_owned;
     70 };
     71 
     72 /* Initialize the hashtable with 2 ^ order entries.  */
     73 extern hash_table *ht_create (unsigned int order);
     74 
     75 /* Frees all memory associated with a hash table.  */
     76 extern void ht_destroy (hash_table *);
     77 
     78 extern hashnode ht_lookup (hash_table *, const unsigned char *,
     79 			   size_t, enum ht_lookup_option);
     80 extern hashnode ht_lookup_with_hash (hash_table *, const unsigned char *,
     81                                      size_t, unsigned int,
     82                                      enum ht_lookup_option);
     83 #define HT_HASHSTEP(r, c) ((r) * 67 + ((c) - 113));
     84 #define HT_HASHFINISH(r, len) ((r) + (len))
     85 
     86 /* For all nodes in TABLE, make a callback.  The callback takes
     87    TABLE->PFILE, the node, and a PTR, and the callback sequence stops
     88    if the callback returns zero.  */
     89 typedef int (*ht_cb) (struct cpp_reader *, hashnode, const void *);
     90 extern void ht_forall (hash_table *, ht_cb, const void *);
     91 
     92 /* For all nodes in TABLE, call the callback.  If the callback returns
     93    a nonzero value, the node is removed from the table.  */
     94 extern void ht_purge (hash_table *, ht_cb, const void *);
     95 
     96 /* Restore the hash table.  */
     97 extern void ht_load (hash_table *ht, hashnode *entries,
     98 		     unsigned int nslots, unsigned int nelements, bool own);
     99 
    100 /* Dump allocation statistics to stderr.  */
    101 extern void ht_dump_statistics (hash_table *);
    102 
    103 #endif /* LIBCPP_SYMTAB_H */
    104