1/*
2 * Copyright (C) 2010 Google, Inc. All Rights Reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include "config.h"
27#include "HTMLEntitySearch.h"
28
29#include "HTMLEntityTable.h"
30
31namespace WebCore {
32
33static const HTMLEntityTableEntry* halfway(const HTMLEntityTableEntry* left, const HTMLEntityTableEntry* right)
34{
35    return &left[(right - left) / 2];
36}
37
38HTMLEntitySearch::HTMLEntitySearch()
39    : m_currentLength(0)
40    , m_mostRecentMatch(0)
41    , m_first(HTMLEntityTable::firstEntry())
42    , m_last(HTMLEntityTable::lastEntry())
43{
44}
45
46HTMLEntitySearch::CompareResult HTMLEntitySearch::compare(const HTMLEntityTableEntry* entry, UChar nextCharacter) const
47{
48    if (entry->length < m_currentLength + 1)
49        return Before;
50    UChar entryNextCharacter = entry->entity[m_currentLength];
51    if (entryNextCharacter == nextCharacter)
52        return Prefix;
53    return entryNextCharacter < nextCharacter ? Before : After;
54}
55
56const HTMLEntityTableEntry* HTMLEntitySearch::findFirst(UChar nextCharacter) const
57{
58    const HTMLEntityTableEntry* left = m_first;
59    const HTMLEntityTableEntry* right = m_last;
60    if (left == right)
61        return left;
62    CompareResult result = compare(left, nextCharacter);
63    if (result == Prefix)
64        return left;
65    if (result == After)
66        return right;
67    while (left + 1 < right) {
68        const HTMLEntityTableEntry* probe = halfway(left, right);
69        result = compare(probe, nextCharacter);
70        if (result == Before)
71            left = probe;
72        else {
73            ASSERT(result == After || result == Prefix);
74            right = probe;
75        }
76    }
77    ASSERT(left + 1 == right);
78    return right;
79}
80
81const HTMLEntityTableEntry* HTMLEntitySearch::findLast(UChar nextCharacter) const
82{
83    const HTMLEntityTableEntry* left = m_first;
84    const HTMLEntityTableEntry* right = m_last;
85    if (left == right)
86        return right;
87    CompareResult result = compare(right, nextCharacter);
88    if (result == Prefix)
89        return right;
90    if (result == Before)
91        return left;
92    while (left + 1 < right) {
93        const HTMLEntityTableEntry* probe = halfway(left, right);
94        result = compare(probe, nextCharacter);
95        if (result == After)
96            right = probe;
97        else {
98            ASSERT(result == Before || result == Prefix);
99            left = probe;
100        }
101    }
102    ASSERT(left + 1 == right);
103    return left;
104}
105
106void HTMLEntitySearch::advance(UChar nextCharacter)
107{
108    ASSERT(isEntityPrefix());
109    if (!m_currentLength) {
110        m_first = HTMLEntityTable::firstEntryStartingWith(nextCharacter);
111        m_last = HTMLEntityTable::lastEntryStartingWith(nextCharacter);
112        if (!m_first || !m_last)
113            return fail();
114    } else {
115        m_first = findFirst(nextCharacter);
116        m_last = findLast(nextCharacter);
117        if (m_first == m_last && compare(m_first, nextCharacter) != Prefix)
118            return fail();
119    }
120    ++m_currentLength;
121    if (m_first->length != m_currentLength) {
122        return;
123    }
124    m_mostRecentMatch = m_first;
125}
126
127}
128