runtime/JSStringJoiner.cpp

   1 /*
   2  * Copyright (C) 2012-2015 Apple 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 "JSStringJoiner.h"
  28
  29 #include "JSCInlines.h"
  30
  31 namespace JSC {
  32
  33 template<typename CharacterType>
  34 static inline void appendStringToData(CharacterType*& data, StringView string)
  35 {
  36     string.getCharactersWithUpconvert(data);
  37     data += string.length();
  38 }
  39
  40 template<typename CharacterType>
  41 static inline String joinStrings(const Vector<StringViewWithUnderlyingString>& strings, StringView separator, unsigned joinedLength)
  42 {
  43     ASSERT(joinedLength);
  44
  45     CharacterType* data;
  46     String result = StringImpl::tryCreateUninitialized(joinedLength, data);
  47     if (result.isNull())
  48         return result;
  49
  50     appendStringToData(data, strings[0].view);
  51
  52     unsigned size = strings.size();
  53
  54     switch (separator.length()) {
  55     case 0:
  56         for (unsigned i = 1; i < size; ++i)
  57             appendStringToData(data, strings[i].view);
  58         break;
  59     case 1: {
  60         CharacterType separatorCharacter = separator[0];
  61         for (unsigned i = 1; i < size; ++i) {
  62             *data++ = separatorCharacter;
  63             appendStringToData(data, strings[i].view);
  64         }
  65         break;
  66     }
  67     default:
  68         for (unsigned i = 1; i < size; ++i) {
  69             appendStringToData(data, separator);
  70             appendStringToData(data, strings[i].view);
  71         }
  72     }
  73     ASSERT(data == result.characters<CharacterType>() + joinedLength);
  74
  75     return result;
  76 }
  77
  78 inline unsigned JSStringJoiner::joinedLength(ExecState& state) const
  79 {
  80     unsigned numberOfStrings = m_strings.size();
  81     if (!numberOfStrings)
  82         return 0;
  83
  84     Checked<unsigned, RecordOverflow> separatorLength = m_separator.length();
  85     Checked<unsigned, RecordOverflow> totalSeparatorsLength = separatorLength * (numberOfStrings - 1);
  86     Checked<unsigned, RecordOverflow> totalLength = totalSeparatorsLength + m_accumulatedStringsLength;
  87
  88     unsigned result;
  89     if (totalLength.safeGet(result) == CheckedState::DidOverflow) {
  90         throwOutOfMemoryError(&state);
  91         return 0;
  92     }
  93     return result;
  94 }
  95
  96 JSValue JSStringJoiner::join(ExecState& state)
  97 {
  98     ASSERT(m_strings.size() <= m_strings.capacity());
  99
 100     unsigned length = joinedLength(state);
 101     if (state.hadException())
 102         return jsUndefined();
 103
 104     if (!length)
 105         return jsEmptyString(&state);
 106
 107     String result;
 108     if (m_isAll8Bit)
 109         result = joinStrings<LChar>(m_strings, m_separator, length);
 110     else
 111         result = joinStrings<UChar>(m_strings, m_separator, length);
 112
 113     if (result.isNull())
 114         return throwOutOfMemoryError(&state);
 115
 116     return jsString(&state, WTF::move(result));
 117 }
 118
 119 }