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
33namespace {
34
35const HTMLEntityTableEntry* halfway(const HTMLEntityTableEntry* left, const HTMLEntityTableEntry* right)
36{
37    return &left[(right - left) / 2];
38}
39
40}
41
42HTMLEntitySearch::HTMLEntitySearch()
43    : m_currentLength(0)
44    , m_currentValue(0)
45    , m_mostRecentMatch(0)
46    , m_first(HTMLEntityTable::firstEntry())
47    , m_last(HTMLEntityTable::lastEntry())
48{
49}
50
51HTMLEntitySearch::CompareResult HTMLEntitySearch::compare(const HTMLEntityTableEntry* entry, UChar nextCharacter) const
52{
53    if (entry->length < m_currentLength + 1)
54        return Before;
55    UChar entryNextCharacter = entry->entity[m_currentLength];
56    if (entryNextCharacter == nextCharacter)
57        return Prefix;
58    return entryNextCharacter < nextCharacter ? Before : After;
59}
60
61const HTMLEntityTableEntry* HTMLEntitySearch::findFirst(UChar nextCharacter) const
62{
63    const HTMLEntityTableEntry* left = m_first;
64    const HTMLEntityTableEntry* right = m_last;
65    if (left == right)
66        return left;
67    CompareResult result = compare(left, nextCharacter);
68    if (result == Prefix)
69        return left;
70    if (result == After)
71        return right;
72    while (left + 1 < right) {
73        const HTMLEntityTableEntry* probe = halfway(left, right);
74        result = compare(probe, nextCharacter);
75        if (result == Before)
76            left = probe;
77        else {
78            ASSERT(result == After || result == Prefix);
79            right = probe;
80        }
81    }
82    ASSERT(left + 1 == right);
83    return right;
84}
85
86const HTMLEntityTableEntry* HTMLEntitySearch::findLast(UChar nextCharacter) const
87{
88    const HTMLEntityTableEntry* left = m_first;
89    const HTMLEntityTableEntry* right = m_last;
90    if (left == right)
91        return right;
92    CompareResult result = compare(right, nextCharacter);
93    if (result == Prefix)
94        return right;
95    if (result == Before)
96        return left;
97    while (left + 1 < right) {
98        const HTMLEntityTableEntry* probe = halfway(left, right);
99        result = compare(probe, nextCharacter);
100        if (result == After)
101            right = probe;
102        else {
103            ASSERT(result == Before || result == Prefix);
104            left = probe;
105        }
106    }
107    ASSERT(left + 1 == right);
108    return left;
109}
110
111void HTMLEntitySearch::advance(UChar nextCharacter)
112{
113    ASSERT(isEntityPrefix());
114    if (!m_currentLength) {
115        m_first = HTMLEntityTable::firstEntryStartingWith(nextCharacter);
116        m_last = HTMLEntityTable::lastEntryStartingWith(nextCharacter);
117        if (!m_first || !m_last)
118            return fail();
119    } else {
120        m_first = findFirst(nextCharacter);
121        m_last = findLast(nextCharacter);
122        if (m_first == m_last && compare(m_first, nextCharacter) != Prefix)
123            return fail();
124    }
125    ++m_currentLength;
126    if (m_first->length != m_currentLength) {
127        m_currentValue = 0;
128        return;
129    }
130    m_mostRecentMatch = m_first;
131    m_currentValue = m_mostRecentMatch->value;
132}
133
134}
135