JavaScriptCore/kjs/identifier.cpp

/*
 *  This file is part of the KDE libraries
 *  Copyright (C) 2003 Apple Computer, Inc
 *
 *  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.
 *
 */

#include "config.h"
// For JavaScriptCore we need to avoid having static constructors.
// Our strategy is to declare the global objects with a different type (initialized to 0)
// and then use placement new to initialize the global objects later. This is not completely
// portable, and it would be good to figure out a 100% clean way that still avoids code that
// runs at init time.

#if !PLATFORM(WIN_OS) // can't get this to compile on Visual C++ yet
#define AVOID_STATIC_CONSTRUCTORS 1
#else
#define AVOID_STATIC_CONSTRUCTORS 0
#endif

#if AVOID_STATIC_CONSTRUCTORS
#define KJS_IDENTIFIER_HIDE_GLOBALS 1
#endif

#include "identifier.h"

#include <wtf/FastMalloc.h>
#include <wtf/HashSet.h>
#include <string.h> // for strlen
#include <new> // for placement new

namespace WTF {

    template<typename T> class DefaultHash;
    template<typename T> class 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::Identifier::equal(a, b); }
    };

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

}

namespace KJS {

typedef HashSet<UString::Rep *> IdentifierTable;
static IdentifierTable *table;

static inline IdentifierTable& identifierTable()
{
    if (!table)
        table = new IdentifierTable;
    return *table;
}


bool Identifier::equal(const UString::Rep *r, const char *s)
{
    int length = r->len;
    const UChar *d = r->data();
    for (int i = 0; i != length; ++i)
        if (d[i].uc != (unsigned char)s[i])
            return false;
    return s[length] == 0;
}

bool Identifier::equal(const UString::Rep *r, const UChar *s, int length)
{
    if (r->len != length)
        return false;
    const UChar *d = r->data();
    for (int i = 0; i != length; ++i)
        if (d[i].uc != s[i].uc)
            return false;
    return true;
}

bool Identifier::equal(const UString::Rep *r, const UString::Rep *b)
{
    int length = r->len;
    if (length != b->len)
        return false;
    const UChar *d = r->data();
    const UChar *s = b->data();
    for (int i = 0; i != length; ++i)
        if (d[i].uc != s[i].uc)
            return false;
    return true;
}

struct CStringTranslator
{
    static unsigned hash(const char *c)
    {
        return UString::Rep::computeHash(c);
    }

    static bool equal(UString::Rep *r, const char *s)
    {
        return Identifier::equal(r, s);
    }

    static void translate(UString::Rep*& location, const char *c, unsigned hash)
    {
        int length = strlen(c);
        UChar *d = static_cast<UChar *>(fastMalloc(sizeof(UChar) * length));
        for (int i = 0; i != length; i++)
            d[i] = c[i];
        
        UString::Rep *r = UString::Rep::create(d, length).release();
        r->isIdentifier = 1;
        r->rc = 0;
        r->_hash = hash;

        location = r;
    }
};

PassRefPtr<UString::Rep> Identifier::add(const char *c)
{
    if (!c)
        return &UString::Rep::null;
    int length = strlen(c);
    if (length == 0)
        return &UString::Rep::empty;
    
    return *identifierTable().add<const char *, CStringTranslator>(c).first;
}

struct UCharBuffer {
    const UChar *s;
    unsigned int length;
};

struct UCharBufferTranslator
{
    static unsigned hash(const UCharBuffer& buf)
    {
        return UString::Rep::computeHash(buf.s, buf.length);
    }

    static bool equal(UString::Rep *str, const UCharBuffer& buf)
    {
        return Identifier::equal(str, buf.s, buf.length);
    }

    static void translate(UString::Rep *& location, const UCharBuffer& buf, unsigned hash)
    {
        UChar *d = static_cast<UChar *>(fastMalloc(sizeof(UChar) * buf.length));
        for (unsigned i = 0; i != buf.length; i++)
            d[i] = buf.s[i];
        
        UString::Rep *r = UString::Rep::create(d, buf.length).release();
        r->isIdentifier = 1;
        r->rc = 0;
        r->_hash = hash;
        
        location = r; 
    }
};

PassRefPtr<UString::Rep> Identifier::add(const UChar *s, int length)
{
    if (length == 0)
        return &UString::Rep::empty;
    
    UCharBuffer buf = {s, length}; 
    return *identifierTable().add<UCharBuffer, UCharBufferTranslator>(buf).first;
}

PassRefPtr<UString::Rep> Identifier::add(UString::Rep *r)
{
    if (r->isIdentifier)
        return r;

    if (r->len == 0)
        return &UString::Rep::empty;

    UString::Rep *result = *identifierTable().add(r).first;
    if (result == r)
        r->isIdentifier = true;
    return result;
}

void Identifier::remove(UString::Rep *r)
{
    identifierTable().remove(r);
}

// Global constants for property name strings.

#if !AVOID_STATIC_CONSTRUCTORS
    // Define an Identifier in the normal way.
    #define DEFINE_GLOBAL(name, string) extern const Identifier name(string);
#else
    // Define an Identifier-sized array of pointers to avoid static initialization.
    // Use an array of pointers instead of an array of char in case there is some alignment issue.
    #define DEFINE_GLOBAL(name, string) \
        void * name[(sizeof(Identifier) + sizeof(void *) - 1) / sizeof(void *)];
#endif

const char * const nullCString = 0;

DEFINE_GLOBAL(nullIdentifier, nullCString)
DEFINE_GLOBAL(specialPrototypePropertyName, "__proto__")

#define DEFINE_PROPERTY_NAME_GLOBAL(name) DEFINE_GLOBAL(name ## PropertyName, #name)
KJS_IDENTIFIER_EACH_PROPERTY_NAME_GLOBAL(DEFINE_PROPERTY_NAME_GLOBAL)

void Identifier::init()
{
#if AVOID_STATIC_CONSTRUCTORS
    static bool initialized;
    if (!initialized) {
        // Use placement new to initialize the globals.

        new (&nullIdentifier) Identifier(nullCString);
        new (&specialPrototypePropertyName) Identifier("__proto__");

        #define PLACEMENT_NEW_PROPERTY_NAME_GLOBAL(name) new(&name ## PropertyName) Identifier(#name);
        KJS_IDENTIFIER_EACH_PROPERTY_NAME_GLOBAL(PLACEMENT_NEW_PROPERTY_NAME_GLOBAL)

        initialized = true;
    }
#endif
}

} // namespace KJS