libcpp/include/symtab.h

   1 /* Hash tables.
   2    Copyright (C) 2000-2023 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   /* This GTY markup arranges that the null-terminated identifier would still
  33      stream to PCH correctly, if a null byte were to make its way into an
  34      identifier somehow.  */
  35   const unsigned char * GTY((string_length ("1 + %h.len"))) str;
  36   unsigned int len;
  37   unsigned int hash_value;
  38 };
  39
  40 #define HT_LEN(NODE) ((NODE)->len)
  41 #define HT_STR(NODE) ((NODE)->str)
  42
  43 typedef struct ht cpp_hash_table;
  44 typedef struct ht_identifier *hashnode;
  45
  46 enum ht_lookup_option {HT_NO_INSERT = 0, HT_ALLOC};
  47
  48 /* An identifier hash table for cpplib and the front ends.  */
  49 struct ht
  50 {
  51   /* Identifiers are allocated from here.  */
  52   struct obstack stack;
  53
  54   hashnode *entries;
  55   /* Call back, allocate a node.  */
  56   hashnode (*alloc_node) (cpp_hash_table *);
  57   /* Call back, allocate something that hangs off a node like a cpp_macro.
  58      NULL means use the usual allocator.  */
  59   void * (*alloc_subobject) (size_t);
  60
  61   unsigned int nslots;          /* Total slots in the entries array.  */
  62   unsigned int nelements;       /* Number of live elements.  */
  63
  64   /* Link to reader, if any.  For the benefit of cpplib.  */
  65   struct cpp_reader *pfile;
  66
  67   /* Table usage statistics.  */
  68   unsigned int searches;
  69   unsigned int collisions;
  70
  71   /* Should 'entries' be freed when it is no longer needed?  */
  72   bool entries_owned;
  73 };
  74
  75 /* Initialize the hashtable with 2 ^ order entries.  */
  76 extern cpp_hash_table *ht_create (unsigned int order);
  77
  78 /* Frees all memory associated with a hash table.  */
  79 extern void ht_destroy (cpp_hash_table *);
  80
  81 extern hashnode ht_lookup (cpp_hash_table *, const unsigned char *,
  82                            size_t, enum ht_lookup_option);
  83 extern hashnode ht_lookup_with_hash (cpp_hash_table *, const unsigned char *,
  84                                      size_t, unsigned int,
  85                                      enum ht_lookup_option);
  86 #define HT_HASHSTEP(r, c) ((r) * 67 + ((c) - 113));
  87 #define HT_HASHFINISH(r, len) ((r) + (len))
  88
  89 /* For all nodes in TABLE, make a callback.  The callback takes
  90    TABLE->PFILE, the node, and a PTR, and the callback sequence stops
  91    if the callback returns zero.  */
  92 typedef int (*ht_cb) (struct cpp_reader *, hashnode, const void *);
  93 extern void ht_forall (cpp_hash_table *, ht_cb, const void *);
  94
  95 /* For all nodes in TABLE, call the callback.  If the callback returns
  96    a nonzero value, the node is removed from the table.  */
  97 extern void ht_purge (cpp_hash_table *, ht_cb, const void *);
  98
  99 /* Restore the hash table.  */
 100 extern void ht_load (cpp_hash_table *ht, hashnode *entries,
 101                      unsigned int nslots, unsigned int nelements, bool own);
 102
 103 /* Dump allocation statistics to stderr.  */
 104 extern void ht_dump_statistics (cpp_hash_table *);
 105
 106 #endif /* LIBCPP_SYMTAB_H */