1 /* Hash tables.
2    Copyright (C) 2000-2021 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   const unsigned char *str;
33   unsigned int len;
34   unsigned int hash_value;
35 };
36 
37 #define HT_LEN(NODE) ((NODE)->len)
38 #define HT_STR(NODE) ((NODE)->str)
39 
40 typedef struct ht cpp_hash_table;
41 typedef struct ht_identifier *hashnode;
42 
43 enum ht_lookup_option {HT_NO_INSERT = 0, HT_ALLOC};
44 
45 /* An identifier hash table for cpplib and the front ends.  */
46 struct ht
47 {
48   /* Identifiers are allocated from here.  */
49   struct obstack stack;
50 
51   hashnode *entries;
52   /* Call back, allocate a node.  */
53   hashnode (*alloc_node) (cpp_hash_table *);
54   /* Call back, allocate something that hangs off a node like a cpp_macro.
55      NULL means use the usual allocator.  */
56   void * (*alloc_subobject) (size_t);
57 
58   unsigned int nslots;		/* Total slots in the entries array.  */
59   unsigned int nelements;	/* Number of live elements.  */
60 
61   /* Link to reader, if any.  For the benefit of cpplib.  */
62   struct cpp_reader *pfile;
63 
64   /* Table usage statistics.  */
65   unsigned int searches;
66   unsigned int collisions;
67 
68   /* Should 'entries' be freed when it is no longer needed?  */
69   bool entries_owned;
70 };
71 
72 /* Initialize the hashtable with 2 ^ order entries.  */
73 extern cpp_hash_table *ht_create (unsigned int order);
74 
75 /* Frees all memory associated with a hash table.  */
76 extern void ht_destroy (cpp_hash_table *);
77 
78 extern hashnode ht_lookup (cpp_hash_table *, const unsigned char *,
79 			   size_t, enum ht_lookup_option);
80 extern hashnode ht_lookup_with_hash (cpp_hash_table *, const unsigned char *,
81                                      size_t, unsigned int,
82                                      enum ht_lookup_option);
83 #define HT_HASHSTEP(r, c) ((r) * 67 + ((c) - 113));
84 #define HT_HASHFINISH(r, len) ((r) + (len))
85 
86 /* For all nodes in TABLE, make a callback.  The callback takes
87    TABLE->PFILE, the node, and a PTR, and the callback sequence stops
88    if the callback returns zero.  */
89 typedef int (*ht_cb) (struct cpp_reader *, hashnode, const void *);
90 extern void ht_forall (cpp_hash_table *, ht_cb, const void *);
91 
92 /* For all nodes in TABLE, call the callback.  If the callback returns
93    a nonzero value, the node is removed from the table.  */
94 extern void ht_purge (cpp_hash_table *, ht_cb, const void *);
95 
96 /* Restore the hash table.  */
97 extern void ht_load (cpp_hash_table *ht, hashnode *entries,
98 		     unsigned int nslots, unsigned int nelements, bool own);
99 
100 /* Dump allocation statistics to stderr.  */
101 extern void ht_dump_statistics (cpp_hash_table *);
102 
103 #endif /* LIBCPP_SYMTAB_H */
104