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      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 */
    111