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      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 
     31 namespace WebCore {
     32 
     33 namespace {
     34 
     35 const HTMLEntityTableEntry* halfway(const HTMLEntityTableEntry* left, const HTMLEntityTableEntry* right)
     36 {
     37     return &left[(right - left) / 2];
     38 }
     39 
     40 }
     41 
     42 HTMLEntitySearch::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 
     51 HTMLEntitySearch::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 
     61 const 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 
     86 const 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 
    111 void 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