libcpp/include/symtab.h

   1 /* Hash tables.
   2    Copyright (C) 2000-2024 Free Software Foundation, Inc.
   3
   4 This program is free software; you can redistribute it and/or modify it
   5 under the terms of the GNU General Public License as published by the
   6 Free Software Foundation; either version 3, or (at your option) any
   7 later version.
   8
   9 This program is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 GNU General Public License for more details.
  13
  14 You should have received a copy of the GNU General Public License
  15 along with this program; see the file COPYING3.  If not see
  16 <http://www.gnu.org/licenses/>.  */
  17
  18 #ifndef LIBCPP_SYMTAB_H
  19 #define LIBCPP_SYMTAB_H
  20
  21 #include "obstack.h"
  22
  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 typedef struct ht_identifier *ht_identifier_ptr;
  31 struct GTY(()) ht_identifier {
  32   /* We know the 'len'gth of the 'str'ing; use it in the GTY markup.  */
  33   const unsigned char * GTY((string_length ("1 + %h.len"))) str;
  34   unsigned int len;
  35   unsigned int hash_value;
  36 };
  37
  38 #define HT_LEN(NODE) ((NODE)->len)
  39 #define HT_STR(NODE) ((NODE)->str)
  40
  41 typedef struct ht cpp_hash_table;
  42 typedef struct ht_identifier *hashnode;
  43
  44 enum ht_lookup_option {HT_NO_INSERT = 0, HT_ALLOC};
  45
  46 /* An identifier hash table for cpplib and the front ends.  */
  47 struct ht
  48 {
  49   /* Identifiers are allocated from here.  */
  50   struct obstack stack;
  51
  52   hashnode *entries;
  53   /* Call back, allocate a node.  */
  54   hashnode (*alloc_node) (cpp_hash_table *);
  55   /* Call back, allocate something that hangs off a node like a cpp_macro.
  56      NULL means use the usual allocator.  */
  57   void * (*alloc_subobject) (size_t);
  58
  59   unsigned int nslots;          /* Total slots in the entries array.  */
  60   unsigned int nelements;       /* Number of live elements.  */
  61
  62   /* Link to reader, if any.  For the benefit of cpplib.  */
  63   struct cpp_reader *pfile;
  64
  65   /* Table usage statistics.  */
  66   unsigned int searches;
  67   unsigned int collisions;
  68
  69   /* Should 'entries' be freed when it is no longer needed?  */
  70   bool entries_owned;
  71 };
  72
  73 /* Initialize the hashtable with 2 ^ order entries.  */
  74 extern cpp_hash_table *ht_create (unsigned int order);
  75
  76 /* Frees all memory associated with a hash table.  */
  77 extern void ht_destroy (cpp_hash_table *);
  78
  79 extern hashnode ht_lookup (cpp_hash_table *, const unsigned char *,
  80                            size_t, enum ht_lookup_option);
  81 extern hashnode ht_lookup_with_hash (cpp_hash_table *, const unsigned char *,
  82                                      size_t, unsigned int,
  83                                      enum ht_lookup_option);
  84 inline hashnode ht_lookup (cpp_hash_table *ht, const ht_identifier &id,
  85                            ht_lookup_option opt)
  86 {
  87   return ht_lookup_with_hash (ht, id.str, id.len, id.hash_value, opt);
  88 }
  89
  90 #define HT_HASHSTEP(r, c) ((r) * 67 + ((c) - 113));
  91 #define HT_HASHFINISH(r, len) ((r) + (len))
  92
  93 /* For all nodes in TABLE, make a callback.  The callback takes
  94    TABLE->PFILE, the node, and a PTR, and the callback sequence stops
  95    if the callback returns zero.  */
  96 typedef int (*ht_cb) (struct cpp_reader *, hashnode, const void *);
  97 extern void ht_forall (cpp_hash_table *, ht_cb, const void *);
  98
  99 /* For all nodes in TABLE, call the callback.  If the callback returns
 100    a nonzero value, the node is removed from the table.  */
 101 extern void ht_purge (cpp_hash_table *, ht_cb, const void *);
 102
 103 /* Restore the hash table.  */
 104 extern void ht_load (cpp_hash_table *ht, hashnode *entries,
 105                      unsigned int nslots, unsigned int nelements, bool own);
 106
 107 /* Dump allocation statistics to stderr.  */
 108 extern void ht_dump_statistics (cpp_hash_table *);
 109
 110 #endif /* LIBCPP_SYMTAB_H */