libcpp/identifiers.cc

   1 /* Hash tables for the CPP library.
   2    Copyright (C) 1986-2024 Free Software Foundation, Inc.
   3    Written by Per Bothner, 1994.
   4    Based on CCCP program by Paul Rubin, June 1986
   5    Adapted to ANSI C, Richard Stallman, Jan 1987
   6
   7 This program is free software; you can redistribute it and/or modify it
   8 under the terms of the GNU General Public License as published by the
   9 Free Software Foundation; either version 3, or (at your option) any
  10 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; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.
  20
  21  In other words, you are welcome to use, share and improve this program.
  22  You are forbidden to forbid anyone else to use, share and improve
  23  what you give them.   Help stamp out software-hoarding!  */
  24
  25 #include "config.h"
  26 #include "system.h"
  27 #include "cpplib.h"
  28 #include "internal.h"
  29
  30 /* Return an identifier node for hashtable.c.  Used by cpplib except
  31    when integrated with the C front ends.  */
  32 template<typename Node>
  33 static hashnode
  34 alloc_node (cpp_hash_table *table)
  35 {
  36   const auto node = XOBNEW (&table->pfile->hash_ob, Node);
  37   memset (node, 0, sizeof (Node));
  38   return HT_NODE (node);
  39 }
  40
  41 /* Set up the identifier hash table.  Use TABLE if non-null, otherwise
  42    create our own.  */
  43 void
  44 _cpp_init_hashtable (cpp_reader *pfile, cpp_hash_table *table,
  45                      cpp_hash_table *extra_table)
  46 {
  47   struct spec_nodes *s;
  48
  49   if (table == NULL)
  50     {
  51       pfile->our_hashtable = 1;
  52       table = ht_create (13);   /* 8K (=2^13) entries.  */
  53       table->alloc_node = alloc_node<cpp_hashnode>;
  54     }
  55
  56   if (extra_table == NULL)
  57     {
  58       pfile->our_extra_hashtable = true;
  59       extra_table = ht_create (6); /* 64 entries.  */
  60       extra_table->alloc_node = alloc_node<cpp_hashnode_extra>;
  61     }
  62
  63   if (pfile->our_hashtable || pfile->our_extra_hashtable)
  64     obstack_specify_allocation (&pfile->hash_ob, 0, 0, xmalloc, free);
  65
  66   table->pfile = pfile;
  67   extra_table->pfile = pfile;
  68   pfile->hash_table = table;
  69   pfile->extra_hash_table = extra_table;
  70
  71   /* Now we can initialize things that use the hash table.  */
  72   _cpp_init_directives (pfile);
  73   _cpp_init_internal_pragmas (pfile);
  74
  75   s = &pfile->spec_nodes;
  76   s->n_defined          = cpp_lookup (pfile, DSC("defined"));
  77   s->n_true             = cpp_lookup (pfile, DSC("true"));
  78   s->n_false            = cpp_lookup (pfile, DSC("false"));
  79   s->n__VA_ARGS__       = cpp_lookup (pfile, DSC("__VA_ARGS__"));
  80   s->n__VA_ARGS__->flags |= NODE_DIAGNOSTIC;
  81   s->n__VA_OPT__        = cpp_lookup (pfile, DSC("__VA_OPT__"));
  82   s->n__VA_OPT__->flags |= NODE_DIAGNOSTIC;
  83   /* __has_include{,_next} are inited in cpp_init_builtins.  */
  84 }
  85
  86 /* Tear down the identifier hash table.  */
  87 void
  88 _cpp_destroy_hashtable (cpp_reader *pfile)
  89 {
  90   if (pfile->our_hashtable)
  91     ht_destroy (pfile->hash_table);
  92   if (pfile->our_extra_hashtable)
  93     ht_destroy (pfile->extra_hash_table);
  94   if (pfile->our_hashtable || pfile->our_extra_hashtable)
  95     obstack_free (&pfile->hash_ob, 0);
  96 }
  97
  98 /* Returns the hash entry for the STR of length LEN, creating one
  99    if necessary.  */
 100 cpp_hashnode *
 101 cpp_lookup (cpp_reader *pfile, const unsigned char *str, unsigned int len)
 102 {
 103   /* ht_lookup cannot return NULL.  */
 104   return CPP_HASHNODE (ht_lookup (pfile->hash_table, str, len, HT_ALLOC));
 105 }
 106
 107 /* Determine whether the str STR, of length LEN, is a defined macro.  */
 108 int
 109 cpp_defined (cpp_reader *pfile, const unsigned char *str, int len)
 110 {
 111   cpp_hashnode *node;
 112
 113   node = CPP_HASHNODE (ht_lookup (pfile->hash_table, str, len, HT_NO_INSERT));
 114
 115   /* If it's a macro, it cannot have been poisoned.  */
 116   return node && cpp_macro_p (node);
 117 }
 118
 119 /* We don't need a proxy since the hash table's identifier comes first
 120    in cpp_hashnode.  However, in case this is ever changed, we have a
 121    static assertion for it.  */
 122 static_assert (offsetof (cpp_hashnode, ident) == 0,
 123                "struct cpp_hashnode must have a struct ht_identifier as"
 124                " its first member");
 125 static_assert (offsetof (cpp_hashnode_extra, ident) == 0,
 126                "struct cpp_hashnode_extra must have a struct ht_identifier as"
 127                " its first member");
 128
 129 /* For all nodes in the hashtable, callback CB with parameters PFILE,
 130    the node, and V.  */
 131 void
 132 cpp_forall_identifiers (cpp_reader *pfile, cpp_cb cb, void *v)
 133 {
 134   ht_forall (pfile->hash_table, (ht_cb) cb, v);
 135 }