wtf/text/StringConcatenate.h

/*
 * Copyright (C) 2010 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef StringConcatenate_h
#define StringConcatenate_h

#include <string.h>

#ifndef WTFString_h
#include "wtf/text/AtomicString.h"
#endif

// This macro is helpful for testing how many intermediate Strings are created while evaluating an
// expression containing operator+.
#ifndef WTF_STRINGTYPEADAPTER_COPIED_WTF_STRING
#define WTF_STRINGTYPEADAPTER_COPIED_WTF_STRING() ((void)0)
#endif

namespace WTF {

template<typename StringType>
class StringTypeAdapter {
};

template<>
class StringTypeAdapter<char> {
public:
    StringTypeAdapter<char>(char buffer)
        : m_buffer(buffer)
    {
    }

    unsigned length() { return 1; }

    bool is8Bit() { return true; }

    void writeTo(LChar* destination)
    {
        *destination = m_buffer;
    }

    void writeTo(UChar* destination) { *destination = m_buffer; }

private:
    unsigned char m_buffer;
};

template<>
class StringTypeAdapter<LChar> {
public:
    StringTypeAdapter<LChar>(LChar buffer)
        : m_buffer(buffer)
    {
    }

    unsigned length() { return 1; }

    bool is8Bit() { return true; }

    void writeTo(LChar* destination)
    {
        *destination = m_buffer;
    }

    void writeTo(UChar* destination) { *destination = m_buffer; }

private:
    LChar m_buffer;
};

template<>
class StringTypeAdapter<UChar> {
public:
    StringTypeAdapter<UChar>(UChar buffer)
        : m_buffer(buffer)
    {
    }

    unsigned length() { return 1; }

    bool is8Bit() { return m_buffer <= 0xff; }

    void writeTo(LChar* destination)
    {
        ASSERT(is8Bit());
        *destination = static_cast<LChar>(m_buffer);
    }

    void writeTo(UChar* destination) { *destination = m_buffer; }

private:
    UChar m_buffer;
};

template<>
class StringTypeAdapter<char*> {
public:
    StringTypeAdapter<char*>(char* buffer)
        : m_buffer(buffer)
        , m_length(strlen(buffer))
    {
    }

    unsigned length() { return m_length; }

    bool is8Bit() { return true; }

    void writeTo(LChar* destination)
    {
        for (unsigned i = 0; i < m_length; ++i)
            destination[i] = static_cast<LChar>(m_buffer[i]);
    }

    void writeTo(UChar* destination)
    {
        for (unsigned i = 0; i < m_length; ++i) {
            unsigned char c = m_buffer[i];
            destination[i] = c;
        }
    }

private:
    const char* m_buffer;
    unsigned m_length;
};

template<>
class StringTypeAdapter<LChar*> {
public:
    StringTypeAdapter<LChar*>(LChar* buffer)
    : m_buffer(buffer)
    , m_length(strlen(reinterpret_cast<char*>(buffer)))
    {
    }

    unsigned length() { return m_length; }

    bool is8Bit() { return true; }

    void writeTo(LChar* destination)
    {
        memcpy(destination, m_buffer, m_length * sizeof(LChar));
    }

    void writeTo(UChar* destination)
    {
        StringImpl::copyChars(destination, m_buffer, m_length);
    }

private:
    const LChar* m_buffer;
    unsigned m_length;
};

template<>
class StringTypeAdapter<const UChar*> {
public:
    StringTypeAdapter<const UChar*>(const UChar* buffer)
        : m_buffer(buffer)
    {
        size_t len = 0;
        while (m_buffer[len] != UChar(0))
            ++len;

        RELEASE_ASSERT(len <= std::numeric_limits<unsigned>::max());

        m_length = len;
    }

    unsigned length() { return m_length; }

    bool is8Bit() { return false; }

    NO_RETURN_DUE_TO_CRASH void writeTo(LChar*)
    {
        RELEASE_ASSERT(false);
    }

    void writeTo(UChar* destination)
    {
        memcpy(destination, m_buffer, m_length * sizeof(UChar));
    }

private:
    const UChar* m_buffer;
    unsigned m_length;
};

template<>
class StringTypeAdapter<const char*> {
public:
    StringTypeAdapter<const char*>(const char* buffer)
        : m_buffer(buffer)
        , m_length(strlen(buffer))
    {
    }

    unsigned length() { return m_length; }

    bool is8Bit() { return true; }

    void writeTo(LChar* destination)
    {
        memcpy(destination, m_buffer, static_cast<size_t>(m_length) * sizeof(LChar));
    }

    void writeTo(UChar* destination)
    {
        for (unsigned i = 0; i < m_length; ++i) {
            unsigned char c = m_buffer[i];
            destination[i] = c;
        }
    }

private:
    const char* m_buffer;
    unsigned m_length;
};

template<>
class StringTypeAdapter<const LChar*> {
public:
    StringTypeAdapter<const LChar*>(const LChar* buffer)
        : m_buffer(buffer)
        , m_length(strlen(reinterpret_cast<const char*>(buffer)))
    {
    }

    unsigned length() { return m_length; }

    bool is8Bit() { return true; }

    void writeTo(LChar* destination)
    {
        memcpy(destination, m_buffer, static_cast<size_t>(m_length) * sizeof(LChar));
    }

    void writeTo(UChar* destination)
    {
        StringImpl::copyChars(destination, m_buffer, m_length);
    }

private:
    const LChar* m_buffer;
    unsigned m_length;
};

template<>
class StringTypeAdapter<Vector<char> > {
public:
    StringTypeAdapter<Vector<char> >(const Vector<char>& buffer)
        : m_buffer(buffer)
    {
    }

    size_t length() { return m_buffer.size(); }

    bool is8Bit() { return true; }

    void writeTo(LChar* destination)
    {
        for (size_t i = 0; i < m_buffer.size(); ++i)
            destination[i] = static_cast<unsigned char>(m_buffer[i]);
    }

    void writeTo(UChar* destination)
    {
        for (size_t i = 0; i < m_buffer.size(); ++i)
            destination[i] = static_cast<unsigned char>(m_buffer[i]);
    }

private:
    const Vector<char>& m_buffer;
};

template<>
class StringTypeAdapter<Vector<LChar> > {
public:
    StringTypeAdapter<Vector<LChar> >(const Vector<LChar>& buffer)
        : m_buffer(buffer)
    {
    }

    size_t length() { return m_buffer.size(); }

    bool is8Bit() { return true; }

    void writeTo(LChar* destination)
    {
        for (size_t i = 0; i < m_buffer.size(); ++i)
            destination[i] = m_buffer[i];
    }

    void writeTo(UChar* destination)
    {
        for (size_t i = 0; i < m_buffer.size(); ++i)
            destination[i] = m_buffer[i];
    }

private:
    const Vector<LChar>& m_buffer;
};

template<>
class StringTypeAdapter<String> {
public:
    StringTypeAdapter<String>(const String& string)
        : m_buffer(string)
    {
    }

    unsigned length() { return m_buffer.length(); }

    bool is8Bit() { return m_buffer.isNull() || m_buffer.is8Bit(); }

    void writeTo(LChar* destination)
    {
        unsigned length = m_buffer.length();

        ASSERT(is8Bit());
        const LChar* data = m_buffer.characters8();
        for (unsigned i = 0; i < length; ++i)
            destination[i] = data[i];

        WTF_STRINGTYPEADAPTER_COPIED_WTF_STRING();
    }

    void writeTo(UChar* destination)
    {
        unsigned length = m_buffer.length();

        if (is8Bit()) {
            const LChar* data = m_buffer.characters8();
            for (unsigned i = 0; i < length; ++i)
                destination[i] = data[i];
        } else {
            const UChar* data = m_buffer.characters16();
            for (unsigned i = 0; i < length; ++i)
                destination[i] = data[i];
        }

        WTF_STRINGTYPEADAPTER_COPIED_WTF_STRING();
    }

private:
    const String& m_buffer;
};

template<>
class StringTypeAdapter<AtomicString> {
public:
    StringTypeAdapter<AtomicString>(const AtomicString& string)
        : m_adapter(string.string())
    {
    }

    unsigned length() { return m_adapter.length(); }

    bool is8Bit() { return m_adapter.is8Bit(); }

    void writeTo(LChar* destination) { m_adapter.writeTo(destination); }
    void writeTo(UChar* destination) { m_adapter.writeTo(destination); }

private:
    StringTypeAdapter<String> m_adapter;
};

inline void sumWithOverflow(unsigned& total, unsigned addend, bool& overflow)
{
    unsigned oldTotal = total;
    total = oldTotal + addend;
    if (total < oldTotal)
        overflow = true;
}

template<typename StringType1, typename StringType2>
PassRefPtr<StringImpl> makeString(StringType1 string1, StringType2 string2)
{
    StringTypeAdapter<StringType1> adapter1(string1);
    StringTypeAdapter<StringType2> adapter2(string2);

    bool overflow = false;
    unsigned length = adapter1.length();
    sumWithOverflow(length, adapter2.length(), overflow);
    if (overflow)
        return 0;

    if (adapter1.is8Bit() && adapter2.is8Bit()) {
        LChar* buffer;
        RefPtr<StringImpl> resultImpl = StringImpl::createUninitialized(length, buffer);
        if (!resultImpl)
            return 0;

        LChar* result = buffer;
        adapter1.writeTo(result);
        result += adapter1.length();
        adapter2.writeTo(result);

        return resultImpl.release();
    }

    UChar* buffer;
    RefPtr<StringImpl> resultImpl = StringImpl::createUninitialized(length, buffer);
    if (!resultImpl)
        return 0;

    UChar* result = buffer;
    adapter1.writeTo(result);
    result += adapter1.length();
    adapter2.writeTo(result);

    return resultImpl.release();
}

} // namespace WTF

#include "wtf/text/StringOperators.h"
#endif