libcpp/identifiers.cc

   1 /* Hash tables for the CPP library.
   2    Copyright (C) 1986-2022 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 static hashnode alloc_node (cpp_hash_table *);
  31
  32 /* Return an identifier node for hashtable.c.  Used by cpplib except
  33    when integrated with the C front ends.  */
  34 static hashnode
  35 alloc_node (cpp_hash_table *table)
  36 {
  37   cpp_hashnode *node;
  38
  39   node = XOBNEW (&table->pfile->hash_ob, cpp_hashnode);
  40   memset (node, 0, sizeof (cpp_hashnode));
  41   return HT_NODE (node);
  42 }
  43
  44 /* Set up the identifier hash table.  Use TABLE if non-null, otherwise
  45    create our own.  */
  46 void
  47 _cpp_init_hashtable (cpp_reader *pfile, cpp_hash_table *table)
  48 {
  49   struct spec_nodes *s;
  50
  51   if (table == NULL)
  52     {
  53       pfile->our_hashtable = 1;
  54       table = ht_create (13);   /* 8K (=2^13) entries.  */
  55       table->alloc_node = alloc_node;
  56
  57       obstack_specify_allocation (&pfile->hash_ob, 0, 0, xmalloc, free);
  58     }
  59
  60   table->pfile = pfile;
  61   pfile->hash_table = table;
  62
  63   /* Now we can initialize things that use the hash table.  */
  64   _cpp_init_directives (pfile);
  65   _cpp_init_internal_pragmas (pfile);
  66
  67   s = &pfile->spec_nodes;
  68   s->n_defined          = cpp_lookup (pfile, DSC("defined"));
  69   s->n_true             = cpp_lookup (pfile, DSC("true"));
  70   s->n_false            = cpp_lookup (pfile, DSC("false"));
  71   s->n__VA_ARGS__       = cpp_lookup (pfile, DSC("__VA_ARGS__"));
  72   s->n__VA_ARGS__->flags |= NODE_DIAGNOSTIC;
  73   s->n__VA_OPT__        = cpp_lookup (pfile, DSC("__VA_OPT__"));
  74   s->n__VA_OPT__->flags |= NODE_DIAGNOSTIC;
  75   /* __has_include{,_next} are inited in cpp_init_builtins.  */
  76 }
  77
  78 /* Tear down the identifier hash table.  */
  79 void
  80 _cpp_destroy_hashtable (cpp_reader *pfile)
  81 {
  82   if (pfile->our_hashtable)
  83     {
  84       ht_destroy (pfile->hash_table);
  85       obstack_free (&pfile->hash_ob, 0);
  86     }
  87 }
  88
  89 /* Returns the hash entry for the STR of length LEN, creating one
  90    if necessary.  */
  91 cpp_hashnode *
  92 cpp_lookup (cpp_reader *pfile, const unsigned char *str, unsigned int len)
  93 {
  94   /* ht_lookup cannot return NULL.  */
  95   return CPP_HASHNODE (ht_lookup (pfile->hash_table, str, len, HT_ALLOC));
  96 }
  97
  98 /* Determine whether the str STR, of length LEN, is a defined macro.  */
  99 int
 100 cpp_defined (cpp_reader *pfile, const unsigned char *str, int len)
 101 {
 102   cpp_hashnode *node;
 103
 104   node = CPP_HASHNODE (ht_lookup (pfile->hash_table, str, len, HT_NO_INSERT));
 105
 106   /* If it's a macro, it cannot have been poisoned.  */
 107   return node && cpp_macro_p (node);
 108 }
 109
 110 /* We don't need a proxy since the hash table's identifier comes first
 111    in cpp_hashnode.  However, in case this is ever changed, we have a
 112    static assertion for it.  */
 113 extern char proxy_assertion_broken[offsetof (struct cpp_hashnode, ident) == 0 ? 1 : -1];
 114
 115 /* For all nodes in the hashtable, callback CB with parameters PFILE,
 116    the node, and V.  */
 117 void
 118 cpp_forall_identifiers (cpp_reader *pfile, cpp_cb cb, void *v)
 119 {
 120   ht_forall (pfile->hash_table, (ht_cb) cb, v);
 121 }