runtime/Identifier.cpp

   1 /*
   2  *  Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
   3  *
   4  *  This library is free software; you can redistribute it and/or
   5  *  modify it under the terms of the GNU Library General Public
   6  *  License as published by the Free Software Foundation; either
   7  *  version 2 of the License, or (at your option) any later version.
   8  *
   9  *  This library is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  *  Library General Public License for more details.
  13  *
  14  *  You should have received a copy of the GNU Library General Public License
  15  *  along with this library; see the file COPYING.LIB.  If not, write to
  16  *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  17  *  Boston, MA 02110-1301, USA.
  18  *
  19  */
  20
  21 #include "config.h"
  22 #include "Identifier.h"
  23
  24 #include "CallFrame.h"
  25 #include <new> // for placement new
  26 #include <string.h> // for strlen
  27 #include <wtf/Assertions.h>
  28 #include <wtf/FastMalloc.h>
  29 #include <wtf/HashSet.h>
  30
  31 namespace JSC {
  32
  33 typedef HashMap<const char*, RefPtr<UString::Rep>, PtrHash<const char*> > LiteralIdentifierTable;
  34
  35 class IdentifierTable {
  36 public:
  37     ~IdentifierTable()
  38     {
  39         HashSet<UString::Rep*>::iterator end = m_table.end();
  40         for (HashSet<UString::Rep*>::iterator iter = m_table.begin(); iter != end; ++iter)
  41             (*iter)->setIdentifierTable(0);
  42     }
  43
  44     std::pair<HashSet<UString::Rep*>::iterator, bool> add(UString::Rep* value)
  45     {
  46         std::pair<HashSet<UString::Rep*>::iterator, bool> result = m_table.add(value);
  47         (*result.first)->setIdentifierTable(this);
  48         return result;
  49     }
  50
  51     template<typename U, typename V>
  52     std::pair<HashSet<UString::Rep*>::iterator, bool> add(U value)
  53     {
  54         std::pair<HashSet<UString::Rep*>::iterator, bool> result = m_table.add<U, V>(value);
  55         (*result.first)->setIdentifierTable(this);
  56         return result;
  57     }
  58
  59     void remove(UString::Rep* r) { m_table.remove(r); }
  60
  61     LiteralIdentifierTable& literalTable() { return m_literalTable; }
  62
  63 private:
  64     HashSet<UString::Rep*> m_table;
  65     LiteralIdentifierTable m_literalTable;
  66 };
  67
  68 IdentifierTable* createIdentifierTable()
  69 {
  70     return new IdentifierTable;
  71 }
  72
  73 void deleteIdentifierTable(IdentifierTable* table)
  74 {
  75     delete table;
  76 }
  77
  78 bool Identifier::equal(const UString::Rep* r, const char* s)
  79 {
  80     int length = r->len;
  81     const UChar* d = r->data();
  82     for (int i = 0; i != length; ++i)
  83         if (d[i] != (unsigned char)s[i])
  84             return false;
  85     return s[length] == 0;
  86 }
  87
  88 bool Identifier::equal(const UString::Rep* r, const UChar* s, int length)
  89 {
  90     if (r->len != length)
  91         return false;
  92     const UChar* d = r->data();
  93     for (int i = 0; i != length; ++i)
  94         if (d[i] != s[i])
  95             return false;
  96     return true;
  97 }
  98
  99 struct CStringTranslator {
 100     static unsigned hash(const char* c)
 101     {
 102         return UString::Rep::computeHash(c);
 103     }
 104
 105     static bool equal(UString::Rep* r, const char* s)
 106     {
 107         return Identifier::equal(r, s);
 108     }
 109
 110     static void translate(UString::Rep*& location, const char* c, unsigned hash)
 111     {
 112         size_t length = strlen(c);
 113         UChar* d = static_cast<UChar*>(fastMalloc(sizeof(UChar) * length));
 114         for (size_t i = 0; i != length; i++)
 115             d[i] = static_cast<unsigned char>(c[i]); // use unsigned char to zero-extend instead of sign-extend
 116
 117         UString::Rep* r = UString::Rep::create(d, static_cast<int>(length)).releaseRef();
 118         r->_hash = hash;
 119
 120         location = r;
 121     }
 122 };
 123
 124 PassRefPtr<UString::Rep> Identifier::add(JSGlobalData* globalData, const char* c)
 125 {
 126     if (!c) {
 127         UString::Rep::null().hash();
 128         return &UString::Rep::null();
 129     }
 130     if (!c[0]) {
 131         UString::Rep::empty().hash();
 132         return &UString::Rep::empty();
 133     }
 134     if (!c[1])
 135         return add(globalData, globalData->smallStrings.singleCharacterStringRep(static_cast<unsigned char>(c[0])));
 136
 137     IdentifierTable& identifierTable = *globalData->identifierTable;
 138     LiteralIdentifierTable& literalIdentifierTable = identifierTable.literalTable();
 139
 140     const LiteralIdentifierTable::iterator& iter = literalIdentifierTable.find(c);
 141     if (iter != literalIdentifierTable.end())
 142         return iter->second;
 143
 144     pair<HashSet<UString::Rep*>::iterator, bool> addResult = identifierTable.add<const char*, CStringTranslator>(c);
 145
 146     // If the string is newly-translated, then we need to adopt it.
 147     // The boolean in the pair tells us if that is so.
 148     RefPtr<UString::Rep> addedString = addResult.second ? adoptRef(*addResult.first) : *addResult.first;
 149
 150     literalIdentifierTable.add(c, addedString.get());
 151
 152     return addedString.release();
 153 }
 154
 155 PassRefPtr<UString::Rep> Identifier::add(ExecState* exec, const char* c)
 156 {
 157     return add(&exec->globalData(), c);
 158 }
 159
 160 struct UCharBuffer {
 161     const UChar* s;
 162     unsigned int length;
 163 };
 164
 165 struct UCharBufferTranslator {
 166     static unsigned hash(const UCharBuffer& buf)
 167     {
 168         return UString::Rep::computeHash(buf.s, buf.length);
 169     }
 170
 171     static bool equal(UString::Rep* str, const UCharBuffer& buf)
 172     {
 173         return Identifier::equal(str, buf.s, buf.length);
 174     }
 175
 176     static void translate(UString::Rep*& location, const UCharBuffer& buf, unsigned hash)
 177     {
 178         UChar* d = static_cast<UChar*>(fastMalloc(sizeof(UChar) * buf.length));
 179         for (unsigned i = 0; i != buf.length; i++)
 180             d[i] = buf.s[i];
 181
 182         UString::Rep* r = UString::Rep::create(d, buf.length).releaseRef();
 183         r->_hash = hash;
 184
 185         location = r;
 186     }
 187 };
 188
 189 PassRefPtr<UString::Rep> Identifier::add(JSGlobalData* globalData, const UChar* s, int length)
 190 {
 191     if (length == 1) {
 192         UChar c = s[0];
 193         if (c <= 0xFF)
 194             return add(globalData, globalData->smallStrings.singleCharacterStringRep(c));
 195     }
 196     if (!length) {
 197         UString::Rep::empty().hash();
 198         return &UString::Rep::empty();
 199     }
 200     UCharBuffer buf = {s, length};
 201     pair<HashSet<UString::Rep*>::iterator, bool> addResult = globalData->identifierTable->add<UCharBuffer, UCharBufferTranslator>(buf);
 202
 203     // If the string is newly-translated, then we need to adopt it.
 204     // The boolean in the pair tells us if that is so.
 205     return addResult.second ? adoptRef(*addResult.first) : *addResult.first;
 206 }
 207
 208 PassRefPtr<UString::Rep> Identifier::add(ExecState* exec, const UChar* s, int length)
 209 {
 210     return add(&exec->globalData(), s, length);
 211 }
 212
 213 PassRefPtr<UString::Rep> Identifier::addSlowCase(JSGlobalData* globalData, UString::Rep* r)
 214 {
 215     ASSERT(!r->identifierTable());
 216     if (r->len == 1) {
 217         UChar c = r->data()[0];
 218         if (c <= 0xFF)
 219             r = globalData->smallStrings.singleCharacterStringRep(c);
 220             if (r->identifierTable()) {
 221 #ifndef NDEBUG
 222                 checkSameIdentifierTable(globalData, r);
 223 #endif
 224                 return r;
 225             }
 226     }
 227     if (!r->len) {
 228         UString::Rep::empty().hash();
 229         return &UString::Rep::empty();
 230     }
 231     return *globalData->identifierTable->add(r).first;
 232 }
 233
 234 PassRefPtr<UString::Rep> Identifier::addSlowCase(ExecState* exec, UString::Rep* r)
 235 {
 236     return addSlowCase(&exec->globalData(), r);
 237 }
 238
 239 void Identifier::remove(UString::Rep* r)
 240 {
 241     r->identifierTable()->remove(r);
 242 }
 243
 244 #ifndef NDEBUG
 245
 246 void Identifier::checkSameIdentifierTable(ExecState* exec, UString::Rep* rep)
 247 {
 248     ASSERT(rep->identifierTable() == exec->globalData().identifierTable);
 249 }
 250
 251 void Identifier::checkSameIdentifierTable(JSGlobalData* globalData, UString::Rep* rep)
 252 {
 253     ASSERT(rep->identifierTable() == globalData->identifierTable);
 254 }
 255
 256 #else
 257
 258 void Identifier::checkSameIdentifierTable(ExecState*, UString::Rep*)
 259 {
 260 }
 261
 262 void Identifier::checkSameIdentifierTable(JSGlobalData*, UString::Rep*)
 263 {
 264 }
 265
 266 #endif
 267
 268 } // namespace JSC