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 "core/html/parser/HTMLEntitySearch.h"
28
29#include "core/html/parser/HTMLEntityTable.h"
30
31namespace blink {
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    const LChar* entityString = HTMLEntityTable::entityString(*entry);
51    UChar entryNextCharacter = entityString[m_currentLength];
52    if (entryNextCharacter == nextCharacter)
53        return Prefix;
54    return entryNextCharacter < nextCharacter ? Before : After;
55}
56
57const HTMLEntityTableEntry* HTMLEntitySearch::findFirst(UChar nextCharacter) const
58{
59    const HTMLEntityTableEntry* left = m_first;
60    const HTMLEntityTableEntry* right = m_last;
61    if (left == right)
62        return left;
63    CompareResult result = compare(left, nextCharacter);
64    if (result == Prefix)
65        return left;
66    if (result == After)
67        return right;
68    while (left + 1 < right) {
69        const HTMLEntityTableEntry* probe = halfway(left, right);
70        result = compare(probe, nextCharacter);
71        if (result == Before)
72            left = probe;
73        else {
74            ASSERT(result == After || result == Prefix);
75            right = probe;
76        }
77    }
78    ASSERT(left + 1 == right);
79    return right;
80}
81
82const HTMLEntityTableEntry* HTMLEntitySearch::findLast(UChar nextCharacter) const
83{
84    const HTMLEntityTableEntry* left = m_first;
85    const HTMLEntityTableEntry* right = m_last;
86    if (left == right)
87        return right;
88    CompareResult result = compare(right, nextCharacter);
89    if (result == Prefix)
90        return right;
91    if (result == Before)
92        return left;
93    while (left + 1 < right) {
94        const HTMLEntityTableEntry* probe = halfway(left, right);
95        result = compare(probe, nextCharacter);
96        if (result == After)
97            right = probe;
98        else {
99            ASSERT(result == Before || result == Prefix);
100            left = probe;
101        }
102    }
103    ASSERT(left + 1 == right);
104    return left;
105}
106
107void HTMLEntitySearch::advance(UChar nextCharacter)
108{
109    ASSERT(isEntityPrefix());
110    if (!m_currentLength) {
111        m_first = HTMLEntityTable::firstEntryStartingWith(nextCharacter);
112        m_last = HTMLEntityTable::lastEntryStartingWith(nextCharacter);
113        if (!m_first || !m_last)
114            return fail();
115    } else {
116        m_first = findFirst(nextCharacter);
117        m_last = findLast(nextCharacter);
118        if (m_first == m_last && compare(m_first, nextCharacter) != Prefix)
119            return fail();
120    }
121    ++m_currentLength;
122    if (m_first->length != m_currentLength) {
123        return;
124    }
125    m_mostRecentMatch = m_first;
126}
127
128}
129