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lookup.cpp
1/*
2 * This file is part of the KDE libraries
3 * Copyright (C) 1999-2000 Harri Porten (porten@kde.org)
4 * Copyright (C) 2003 Apple Computer, Inc.
5 *
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2 of the License, or (at your option) any later version.
10 *
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 *
20 */
21
22#include <stdio.h>
23#include <string.h>
24
25#include "lookup.h"
26
27#ifdef HAVE_CONFIG_H
28#include <config.h>
29#endif
30
31using namespace KJS;
32
33static bool keysMatch(const UChar *c, unsigned len, const char *s)
34{
35 for (unsigned i = 0; i != len; i++, c++, s++)
36 if (c->uc != (unsigned char)*s)
37 return false;
38 return *s == 0;
39}
40
41const HashEntry* Lookup::findEntry( const struct HashTable *table,
42 const UChar *c, unsigned int len )
43{
44#ifndef NDEBUG
45 if (table->type != 2) {
46 fprintf(stderr, "KJS: Unknown hash table version.\n");
47 return 0;
48 }
49#endif
50
51 int h = hash(c, len) % table->hashSize;
52 const HashEntry *e = &table->entries[h];
53
54 // empty bucket ?
55 if (!e->soffset)
56 return 0;
57
58 while(1) {
59 // compare strings
60 if (keysMatch(c, len, &table->sbase[e->soffset]))
61 return e;
62 // try next bucket
63 if(e->next < 0) break;
64
65 e = &table->entries[e->next];
66 }
67
68 return 0;
69}
70
71const HashEntry* Lookup::findEntry( const struct HashTable *table,
72 const Identifier &s )
73{
74 return findEntry( table, s.data(), s.size() );
75}
76
77int Lookup::find(const struct HashTable *table,
78 const UChar *c, unsigned int len)
79{
80 const HashEntry *entry = findEntry( table, c, len );
81 if (entry)
82 return entry->value;
83 return -1;
84}
85
86int Lookup::find(const struct HashTable *table, const Identifier &s)
87{
88 return find(table, s.data(), s.size());
89}
90
91unsigned int Lookup::hash(const UChar *c, unsigned int len)
92{
93 unsigned int val = 0;
94 // ignoring higher byte
95 for (unsigned int i = 0; i < len; i++, c++)
96 val += c->low();
97
98 return val;
99}
100
101unsigned int Lookup::hash(const Identifier &key)
102{
103 return hash(key.data(), key.size());
104}
105
106unsigned int Lookup::hash(const char *s)
107{
108 unsigned int val = 0;
109 while (*s)
110 val += *s++;
111
112 return val;
113}
KJS::Identifier
Represents an Identifier for a Javascript object.
Definition: identifier.h:32
KJS::Identifier::size
int size() const
The size of the UChar string returned.
Definition: identifier.h:66
KJS::Identifier::data
const UChar * data() const
returns a UChar pointer to the string of the identifier with a size defined by size().
Definition: identifier.h:62
KJS::Lookup::find
static int find(const struct HashTable *table, const Identifier &s)
Find an entry in the table, and return its value (i.e.
Definition: lookup.cpp:86
KJS::Lookup::findEntry
static const HashEntry * findEntry(const struct HashTable *table, const Identifier &s)
Find an entry in the table, and return the entry This variant gives access to the other attributes of...
Definition: lookup.cpp:71
KJS::Lookup::hash
static unsigned int hash(const Identifier &key)
Calculate the hash value for a given key.
Definition: lookup.cpp:101
KJS::HashEntry
An entry in a hash table.
Definition: lookup.h:36
KJS::HashEntry::next
short next
next is the index to the next entry for the same hash value
Definition: lookup.h:57
KJS::HashEntry::value
short int value
value is the result value (usually an enum value)
Definition: lookup.h:44
KJS::HashEntry::soffset
unsigned short soffset
s is the offset to the string key (e.g.
Definition: lookup.h:40
KJS::HashTable
A hash table Usually the hashtable is generated by the create_hash_table script, from a ....
Definition: lookup.h:71
KJS::HashTable::sbase
const char *const sbase
pointer to the string table.
Definition: lookup.h:95
KJS::HashTable::entries
const HashEntry *const entries
pointer to the array of entries Mind that some entries in the array are null (0,0,...
Definition: lookup.h:86
KJS::HashTable::hashSize
int hashSize
the maximum value for the hash.
Definition: lookup.h:90
KJS::HashTable::type
int type
type is a version number.
Definition: lookup.h:75
KJS::UChar
Unicode character.
Definition: ustring.h:51
KJS::UChar::low
unsigned char low() const
Definition: ustring.h:77

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