source: webkit/trunk/JavaScriptCore/kjs/ustring.h@ 35906

/*
 *  Copyright (C) 1999-2000 Harri Porten ([email protected])
 *  Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Library General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Library General Public License for more details.
 *
 *  You should have received a copy of the GNU Library General Public License
 *  along with this library; see the file COPYING.LIB.  If not, write to
 *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 *  Boston, MA 02110-1301, USA.
 *
 */

#ifndef _KJS_USTRING_H_
#define _KJS_USTRING_H_

#include "collector.h"
#include <stdint.h>
#include <string.h>
#include <wtf/Assertions.h>
#include <wtf/FastMalloc.h>
#include <wtf/PassRefPtr.h>
#include <wtf/RefPtr.h>
#include <wtf/Vector.h>
#include <wtf/unicode/Unicode.h>

namespace KJS {

    using WTF::PlacementNewAdoptType;
    using WTF::PlacementNewAdopt;

    class IdentifierTable;
  
    class CString {
    public:
        CString()
            : m_length(0)
            , m_data(0)
        {
        }

        CString(const char*);
        CString(const char*, size_t);
        CString(const CString&);

        ~CString();

        static CString adopt(char*, size_t); // buffer should be allocated with new[].

        CString& append(const CString&);
        CString& operator=(const char* c);
        CString& operator=(const CString&);
        CString& operator+=(const CString& c) { return append(c); }

        size_t size() const { return m_length; }
        const char* c_str() const { return m_data; }

    private:
        size_t m_length;
        char* m_data;
    };

    typedef Vector<char, 32> CStringBuffer;

    class UString {
    friend bool operator==(const UString&, const UString&);

    public:
        struct Rep {
            static PassRefPtr<Rep> create(UChar*, int);
            static PassRefPtr<Rep> createCopying(const UChar*, int);
            static PassRefPtr<Rep> create(PassRefPtr<Rep> base, int offset, int length);

            // Constructs a string from a UTF-8 string, using strict conversion (see comments in UTF8.h).
            // Returns UString::Rep::null for null input or conversion failure.
            static PassRefPtr<Rep> createFromUTF8(const char*);

            void destroy();

            bool baseIsSelf() const { return baseString == this; }
            UChar* data() const { return baseString->buf + baseString->preCapacity + offset; }
            int size() const { return len; }

            unsigned hash() const { if (_hash == 0) _hash = computeHash(data(), len); return _hash; }
            unsigned computedHash() const { ASSERT(_hash); return _hash; } // fast path for Identifiers

            static unsigned computeHash(const UChar*, int length);
            static unsigned computeHash(const char*, int length);
            static unsigned computeHash(const char* s) { return computeHash(s, strlen(s)); }

            IdentifierTable* identifierTable() const { return reinterpret_cast<IdentifierTable*>(m_identifierTable & ~static_cast<uintptr_t>(1)); }
            void setIdentifierTable(IdentifierTable* table) { ASSERT(!isStatic()); m_identifierTable = reinterpret_cast<intptr_t>(table); }

            bool isStatic() const { return m_identifierTable & 1; }
            void setStatic(bool v) { ASSERT(!identifierTable()); m_identifierTable = v; }

            Rep* ref() { ++rc; return this; }
            ALWAYS_INLINE void deref() { if (--rc == 0) destroy(); }

            void checkConsistency() const;

            // unshared data
            int offset;
            int len;
            int rc; // For null and empty static strings, this field does not reflect a correct count, because ref/deref are not thread-safe. A special case in destroy() guarantees that these do not get deleted.
            mutable unsigned _hash;
            intptr_t m_identifierTable; // A pointer to identifier table. The lowest bit is used to indicate whether the string is static (null or empty).
            UString::Rep* baseString;
            size_t reportedCost;

            // potentially shared data. 0 if backed up by a base string.
            UChar* buf;
            int usedCapacity;
            int capacity;
            int usedPreCapacity;
            int preCapacity;

            static Rep null;
            static Rep empty;
        };

    public:
        UString();
        UString(const char*);
        UString(const UChar*, int length);
        UString(UChar*, int length, bool copy);

        UString(const UString& s)
            : m_rep(s.m_rep)
        {
        }

        UString(const Vector<UChar>& buffer);

        // Concatenation constructor. Makes operator+ more efficient.
        UString(const UString&, const UString&);

        ~UString()
        {
        }

        // Special constructor for cases where we overwrite an object in place.
        UString(PlacementNewAdoptType)
            : m_rep(PlacementNewAdopt)
        {
        }

        static UString from(int);
        static UString from(unsigned int);
        static UString from(long);
        static UString from(double);

        struct Range {
        public:
            Range(int pos, int len)
                : position(pos)
                , length(len)
            {
            }

            Range()
            {
            }

            int position;
            int length;
        };

        UString spliceSubstringsWithSeparators(const Range* substringRanges, int rangeCount, const UString* separators, int separatorCount) const;

        UString& append(const UString&);
        UString& append(const char*);
        UString& append(UChar);
        UString& append(char c) { return append(static_cast<UChar>(static_cast<unsigned char>(c))); }
        UString& append(const UChar*, int size);

        bool getCString(CStringBuffer&) const;

        // NOTE: This method should only be used for *debugging* purposes as it
        // is neither Unicode safe nor free from side effects nor thread-safe.
        char* ascii() const;

        /**
         * Convert the string to UTF-8, assuming it is UTF-16 encoded.
         * In non-strict mode, this function is tolerant of badly formed UTF-16, it
         * can create UTF-8 strings that are invalid because they have characters in
         * the range U+D800-U+DDFF, U+FFFE, or U+FFFF, but the UTF-8 string is
         * guaranteed to be otherwise valid.
         * In strict mode, error is returned as null CString.
         */
        CString UTF8String(bool strict = false) const;

        UString& operator=(const char*c);

        UString& operator+=(const UString& s) { return append(s); }
        UString& operator+=(const char* s) { return append(s); }

        const UChar* data() const { return m_rep->data(); }

        bool isNull() const { return (m_rep == &Rep::null); }
        bool isEmpty() const { return (!m_rep->len); }

        bool is8Bit() const;

        int size() const { return m_rep->size(); }

        UChar operator[](int pos) const;

        double toDouble(bool tolerateTrailingJunk, bool tolerateEmptyString) const;
        double toDouble(bool tolerateTrailingJunk) const;
        double toDouble() const;

        uint32_t toUInt32(bool* ok = 0) const;
        uint32_t toUInt32(bool* ok, bool tolerateEmptyString) const;
        uint32_t toStrictUInt32(bool* ok = 0) const;

        unsigned toArrayIndex(bool* ok = 0) const;

        int find(const UString& f, int pos = 0) const;
        int find(UChar, int pos = 0) const;
        int rfind(const UString& f, int pos) const;
        int rfind(UChar, int pos) const;

        UString substr(int pos = 0, int len = -1) const;

        static const UString& null();

        Rep* rep() const { return m_rep.get(); }

        UString(PassRefPtr<Rep> r)
            : m_rep(r)
        {
            ASSERT(m_rep);
        }

        size_t cost() const;

    private:
        size_t expandedSize(size_t size, size_t otherSize) const;
        int usedCapacity() const;
        int usedPreCapacity() const;
        void expandCapacity(int requiredLength);
        void expandPreCapacity(int requiredPreCap);

        RefPtr<Rep> m_rep;
    };

    bool operator==(const UString& s1, const UString& s2);

    inline bool operator!=(const UString& s1, const UString& s2)
    {
        return !KJS::operator==(s1, s2);
    }

    bool operator<(const UString& s1, const UString& s2);
    bool operator>(const UString& s1, const UString& s2);

    bool operator==(const UString& s1, const char* s2);

    inline bool operator!=(const UString& s1, const char* s2)
    {
        return !KJS::operator==(s1, s2);
    }

    inline bool operator==(const char *s1, const UString& s2)
    {
        return operator==(s2, s1);
    }

    inline bool operator!=(const char *s1, const UString& s2)
    {
        return !KJS::operator==(s1, s2);
    }

    bool operator==(const CString& s1, const CString& s2);

    inline UString operator+(const UString& s1, const UString& s2)
    {
        return UString(s1, s2);
    }

    int compare(const UString&, const UString&);

    bool equal(const UString::Rep*, const UString::Rep*);

#ifdef NDEBUG
    inline void UString::Rep::checkConsistency() const
    {
    }
#endif

    inline UString::UString()
        : m_rep(&Rep::null)
    {
    }

    // Rule from ECMA 15.2 about what an array index is.
    // Must exactly match string form of an unsigned integer, and be less than 2^32 - 1.
    inline unsigned UString::toArrayIndex(bool* ok) const
    {
        unsigned i = toStrictUInt32(ok);
        if (ok && i >= 0xFFFFFFFFU)
            *ok = false;
        return i;
    }

    // We'd rather not do shared substring append for small strings, since
    // this runs too much risk of a tiny initial string holding down a
    // huge buffer.
    // FIXME: this should be size_t but that would cause warnings until we
    // fix UString sizes to be size_t instead of int
    static const int minShareSize = Heap::minExtraCostSize / sizeof(UChar);

    inline size_t UString::cost() const
    {
        size_t capacity = (m_rep->baseString->capacity + m_rep->baseString->preCapacity) * sizeof(UChar);
        size_t reportedCost = m_rep->baseString->reportedCost;
        ASSERT(capacity >= reportedCost);

        size_t capacityDelta = capacity - reportedCost;

        if (capacityDelta < static_cast<size_t>(minShareSize))
            return 0;

        m_rep->baseString->reportedCost = capacity;

        return capacityDelta;
    }

} // namespace KJS

namespace WTF {

    template<typename T> struct DefaultHash;
    template<typename T> struct StrHash;

    template<> struct StrHash<KJS::UString::Rep*> {
        static unsigned hash(const KJS::UString::Rep* key) { return key->hash(); }
        static bool equal(const KJS::UString::Rep* a, const KJS::UString::Rep* b) { return KJS::equal(a, b); }
        static const bool safeToCompareToEmptyOrDeleted = false;
    };

    template<> struct StrHash<RefPtr<KJS::UString::Rep> > : public StrHash<KJS::UString::Rep*> {
        using StrHash<KJS::UString::Rep*>::hash;
        static unsigned hash(const RefPtr<KJS::UString::Rep>& key) { return key->hash(); }
        using StrHash<KJS::UString::Rep*>::equal;
        static bool equal(const RefPtr<KJS::UString::Rep>& a, const RefPtr<KJS::UString::Rep>& b) { return KJS::equal(a.get(), b.get()); }
        static bool equal(const KJS::UString::Rep* a, const RefPtr<KJS::UString::Rep>& b) { return KJS::equal(a, b.get()); }
        static bool equal(const RefPtr<KJS::UString::Rep>& a, const KJS::UString::Rep* b) { return KJS::equal(a.get(), b); }

        static const bool safeToCompareToEmptyOrDeleted = false;
    };

    template<> struct DefaultHash<KJS::UString::Rep*> {
        typedef StrHash<KJS::UString::Rep*> Hash;
    };

    template<> struct DefaultHash<RefPtr<KJS::UString::Rep> > {
        typedef StrHash<RefPtr<KJS::UString::Rep> > Hash;
    };
} // namespace WTF

#endif