Replace.cpp

   1 /* Cycript - Inlining/Optimizing JavaScript Compiler
   2  * Copyright (C) 2009  Jay Freeman (saurik)
   3 */
   4
   5 /* Modified BSD License {{{ */
   6 /*
   7  *        Redistribution and use in source and binary
   8  * forms, with or without modification, are permitted
   9  * provided that the following conditions are met:
  10  *
  11  * 1. Redistributions of source code must retain the
  12  *    above copyright notice, this list of conditions
  13  *    and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the
  15  *    above copyright notice, this list of conditions
  16  *    and the following disclaimer in the documentation
  17  *    and/or other materials provided with the
  18  *    distribution.
  19  * 3. The name of the author may not be used to endorse
  20  *    or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS''
  24  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
  25  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  26  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
  28  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  29  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  30  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  31  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  32  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  33  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
  34  * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  35  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  36  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  37 */
  38 /* }}} */
  39
  40 #include "Parser.hpp"
  41 #include "Replace.hpp"
  42
  43 #include <iomanip>
  44
  45 CYExpression *CYAdd::Replace(CYContext &context) {
  46     CYInfix::Replace(context);
  47
  48     CYExpression *lhp(lhs_->Primitive(context));
  49     CYExpression *rhp(rhs_->Primitive(context));
  50
  51     CYString *lhs(dynamic_cast<CYString *>(lhp));
  52     CYString *rhs(dynamic_cast<CYString *>(rhp));
  53
  54     if (lhs != NULL || rhs != NULL) {
  55         if (lhs == NULL) {
  56             lhs = lhp->String(context);
  57             if (lhs == NULL)
  58                 return this;
  59         } else if (rhs == NULL) {
  60             rhs = rhp->String(context);
  61             if (rhs == NULL)
  62                 return this;
  63         }
  64
  65         return lhs->Concat(context, rhs);
  66     }
  67
  68     if (CYNumber *lhn = lhp->Number(context))
  69         if (CYNumber *rhn = rhp->Number(context))
  70             return $D(lhn->Value() + rhn->Value());
  71
  72     return this;
  73 }
  74
  75 CYExpression *CYAddressOf::Replace(CYContext &context) {
  76     CYPrefix::Replace(context);
  77     return $C0($M(rhs_, $S("$cya")));
  78 }
  79
  80 void CYArgument::Replace(CYContext &context) { $T()
  81     context.Replace(value_);
  82     next_->Replace(context);
  83 }
  84
  85 CYExpression *CYArray::Replace(CYContext &context) {
  86     elements_->Replace(context);
  87     return this;
  88 }
  89
  90 CYExpression *CYArrayComprehension::Replace(CYContext &context) {
  91     CYVariable *cyv($V("$cyv"));
  92
  93     return $C0($F(NULL, $P1("$cyv", comprehensions_->Parameters(context)), $$->*
  94         $E($ CYAssign(cyv, $ CYArray()))->*
  95         comprehensions_->Replace(context, $E($C1($M(cyv, $S("push")), expression_)))->*
  96         $ CYReturn(cyv)
  97     ));
  98 }
  99
 100 CYExpression *CYAssignment::Replace(CYContext &context) {
 101     context.Replace(lhs_);
 102     context.Replace(rhs_);
 103     return this;
 104 }
 105
 106 CYStatement *CYBlock::Replace(CYContext &context) {
 107     statements_ = statements_->ReplaceAll(context);
 108     if (statements_ == NULL)
 109         return $ CYEmpty();
 110     return this;
 111 }
 112
 113 CYStatement *CYBreak::Replace(CYContext &context) {
 114     return this;
 115 }
 116
 117 CYExpression *CYCall::Replace(CYContext &context) {
 118     context.Replace(function_);
 119     arguments_->Replace(context);
 120     return this;
 121 }
 122
 123 namespace cy {
 124 namespace Syntax {
 125
 126 void Catch::Replace(CYContext &context) { $T()
 127     code_.Replace(context);
 128 }
 129
 130 } }
 131
 132 void CYClause::Replace(CYContext &context) { $T()
 133     context.Replace(case_);
 134     statements_ = statements_->ReplaceAll(context);
 135     next_->Replace(context);
 136 }
 137
 138 CYStatement *CYComment::Replace(CYContext &context) {
 139     return this;
 140 }
 141
 142 CYExpression *CYCompound::Replace(CYContext &context) {
 143     expressions_ = expressions_->ReplaceAll(context);
 144     return expressions_ == NULL ? NULL : this;
 145 }
 146
 147 CYFunctionParameter *CYComprehension::Parameters(CYContext &context) const { $T(NULL)
 148     CYFunctionParameter *next(next_->Parameters(context));
 149     if (CYFunctionParameter *parameter = Parameter(context)) {
 150         parameter->SetNext(next);
 151         return parameter;
 152     } else
 153         return next;
 154 }
 155
 156 CYStatement *CYComprehension::Replace(CYContext &context, CYStatement *statement) const {
 157     return next_ == NULL ? statement : next_->Replace(context, statement);
 158 }
 159
 160 CYExpression *CYCondition::Replace(CYContext &context) {
 161     context.Replace(test_);
 162     context.Replace(true_);
 163     context.Replace(false_);
 164     return this;
 165 }
 166
 167 CYStatement *CYContinue::Replace(CYContext &context) {
 168     return this;
 169 }
 170
 171 CYAssignment *CYDeclaration::Assignment(CYContext &context) {
 172     CYExpression *variable(Replace(context));
 173     return initialiser_ == NULL ? NULL : $ CYAssign(variable, initialiser_);
 174 }
 175
 176 CYExpression *CYDeclaration::ForEachIn(CYContext &context) {
 177     return $ CYVariable(identifier_);
 178 }
 179
 180 CYExpression *CYDeclaration::Replace(CYContext &context) {
 181     context.Replace(identifier_);
 182     context.scope_->Declare(context, identifier_, CYIdentifierVariable);
 183     return $ CYVariable(identifier_);
 184 }
 185
 186 CYProperty *CYDeclarations::Property(CYContext &context) { $T(NULL)
 187     return $ CYProperty(declaration_->identifier_, declaration_->initialiser_ ?: $U, next_->Property(context));
 188 }
 189
 190 CYCompound *CYDeclarations::Replace(CYContext &context) {
 191     CYCompound *compound;
 192     if (next_ == NULL) compound:
 193         compound = $ CYCompound();
 194     else {
 195         compound = next_->Replace(context);
 196         if (compound == NULL)
 197             goto compound;
 198     }
 199
 200     if (CYAssignment *assignment = declaration_->Assignment(context))
 201         compound->AddPrev(assignment);
 202     return compound;
 203 }
 204
 205 CYExpression *CYDirectMember::Replace(CYContext &context) {
 206     Replace_(context);
 207     return this;
 208 }
 209
 210 CYStatement *CYDoWhile::Replace(CYContext &context) {
 211     context.Replace(test_);
 212     context.Replace(code_);
 213     return this;
 214 }
 215
 216 void CYElement::Replace(CYContext &context) { $T()
 217     context.Replace(value_);
 218     next_->Replace(context);
 219 }
 220
 221 CYStatement *CYEmpty::Collapse(CYContext &context) {
 222     return next_;
 223 }
 224
 225 CYStatement *CYEmpty::Replace(CYContext &context) {
 226     return this;
 227 }
 228
 229 CYStatement *CYExpress::Collapse(CYContext &context) {
 230     if (CYExpress *express = dynamic_cast<CYExpress *>(next_)) {
 231         CYCompound *next(dynamic_cast<CYCompound *>(express->expression_));
 232         if (next == NULL)
 233             next = $ CYCompound(express->expression_);
 234         next->AddPrev(expression_);
 235         expression_ = next;
 236         SetNext(express->next_);
 237     }
 238
 239     return this;
 240 }
 241
 242 CYStatement *CYExpress::Replace(CYContext &context) {
 243     context.Replace(expression_);
 244     if (expression_ == NULL)
 245         return $ CYEmpty();
 246     return this;
 247 }
 248
 249 CYExpression *CYExpression::ClassName(CYContext &context, bool object) {
 250     return this;
 251 }
 252
 253 CYExpression *CYExpression::ForEachIn(CYContext &context) {
 254     return this;
 255 }
 256
 257 CYExpression *CYExpression::ReplaceAll(CYContext &context) { $T(NULL)
 258     CYExpression *replace(this);
 259     context.Replace(replace);
 260
 261     if (CYExpression *next = next_->ReplaceAll(context))
 262         replace->SetNext(next);
 263     else
 264         replace->SetNext(next_);
 265
 266     return replace;
 267 }
 268
 269 CYNumber *CYFalse::Number(CYContext &context) {
 270     return $D(0);
 271 }
 272
 273 CYString *CYFalse::String(CYContext &context) {
 274     return $S("false");
 275 }
 276
 277 void CYFinally::Replace(CYContext &context) { $T()
 278     code_.Replace(context);
 279 }
 280
 281 CYStatement *CYFor::Replace(CYContext &context) {
 282     context.Replace(initialiser_);
 283     context.Replace(test_);
 284     context.Replace(increment_);
 285     context.Replace(code_);
 286     return this;
 287 }
 288
 289 CYStatement *CYForIn::Replace(CYContext &context) {
 290     // XXX: this actually might need a prefix statement
 291     context.Replace(initialiser_);
 292     context.Replace(set_);
 293     context.Replace(code_);
 294     return this;
 295 }
 296
 297 CYFunctionParameter *CYForInComprehension::Parameter(CYContext &context) const {
 298     return $ CYFunctionParameter(name_);
 299 }
 300
 301 CYStatement *CYForInComprehension::Replace(CYContext &context, CYStatement *statement) const {
 302     return $ CYForIn($ CYVariable(name_), set_, CYComprehension::Replace(context, statement));
 303 }
 304
 305 CYStatement *CYForEachIn::Replace(CYContext &context) {
 306     CYVariable *cys($V("$cys")), *cyt($V("$cyt"));
 307
 308     return $ CYLet($L2($L($I("$cys"), set_), $L($I("$cyt"))), $$->*
 309         $ CYForIn(cyt, cys, $ CYBlock($$->*
 310             $E($ CYAssign(initialiser_->ForEachIn(context), $M(cys, cyt)))->*
 311             code_
 312         ))
 313     );
 314 }
 315
 316 CYFunctionParameter *CYForEachInComprehension::Parameter(CYContext &context) const {
 317     return $ CYFunctionParameter(name_);
 318 }
 319
 320 CYStatement *CYForEachInComprehension::Replace(CYContext &context, CYStatement *statement) const {
 321     CYVariable *cys($V("$cys")), *name($ CYVariable(name_));
 322
 323     return $E($C0($F(NULL, $P1("$cys"), $$->*
 324         $E($ CYAssign(cys, set_))->*
 325         $ CYForIn(name, cys, $ CYBlock($$->*
 326             $E($ CYAssign(name, $M(cys, name)))->*
 327             CYComprehension::Replace(context, statement)
 328         ))
 329     )));
 330 }
 331
 332 void CYFunction::Inject(CYContext &context) {
 333     context.Replace(name_);
 334     context.scope_->Declare(context, name_, CYIdentifierOther);
 335 }
 336
 337 void CYFunction::Replace_(CYContext &context, bool outer) {
 338     if (outer)
 339         Inject(context);
 340
 341     parent_ = context.scope_;
 342     context.scope_ = this;
 343
 344     if (!outer && name_ != NULL)
 345         Inject(context);
 346
 347     parameters_->Replace(context);
 348     code_.Replace(context);
 349
 350     context.scope_ = parent_;
 351     Scope(context, code_.statements_);
 352 }
 353
 354 CYExpression *CYFunctionExpression::Replace(CYContext &context) {
 355     Replace_(context, false);
 356     return this;
 357 }
 358
 359 void CYFunctionParameter::Replace(CYContext &context) { $T()
 360     name_ = name_->Replace(context);
 361     context.scope_->Declare(context, name_, CYIdentifierArgument);
 362     next_->Replace(context);
 363 }
 364
 365 CYStatement *CYFunctionStatement::Replace(CYContext &context) {
 366     Replace_(context, true);
 367     return this;
 368 }
 369
 370 CYIdentifier *CYIdentifier::Replace(CYContext &context) {
 371     if (replace_ == NULL) {
 372         replace_ = context.scope_->Lookup(context, this);
 373         ++replace_->usage_;
 374     } else if (replace_ != this)
 375         return replace_->Replace(context);
 376     return replace_;
 377 }
 378
 379 CYStatement *CYIf::Replace(CYContext &context) {
 380     context.Replace(test_);
 381     context.Replace(true_);
 382     context.Replace(false_);
 383     return this;
 384 }
 385
 386 CYFunctionParameter *CYIfComprehension::Parameter(CYContext &context) const {
 387     return NULL;
 388 }
 389
 390 CYStatement *CYIfComprehension::Replace(CYContext &context, CYStatement *statement) const {
 391     return $ CYIf(test_, CYComprehension::Replace(context, statement));
 392 }
 393
 394 CYExpression *CYIndirect::Replace(CYContext &context) {
 395     CYPrefix::Replace(context);
 396     return $M(rhs_, $S("$cyi"));
 397 }
 398
 399 CYExpression *CYIndirectMember::Replace(CYContext &context) {
 400     Replace_(context);
 401     return $M($ CYIndirect(object_), property_);
 402 }
 403
 404 CYExpression *CYInfix::Replace(CYContext &context) {
 405     context.Replace(lhs_);
 406     context.Replace(rhs_);
 407     return this;
 408 }
 409
 410 CYStatement *CYLabel::Replace(CYContext &context) {
 411     context.Replace(statement_);
 412     return this;
 413 }
 414
 415 CYStatement *CYLet::Replace(CYContext &context) {
 416     return $ CYWith($ CYObject(declarations_->Property(context)), &code_);
 417 }
 418
 419 void CYMember::Replace_(CYContext &context) {
 420     context.Replace(object_);
 421     context.Replace(property_);
 422 }
 423
 424 CYExpression *CYNew::Replace(CYContext &context) {
 425     context.Replace(constructor_);
 426     arguments_->Replace(context);
 427     return this;
 428 }
 429
 430 CYNumber *CYNull::Number(CYContext &context) {
 431     return $D(0);
 432 }
 433
 434 CYString *CYNull::String(CYContext &context) {
 435     return $S("null");
 436 }
 437
 438 CYNumber *CYNumber::Number(CYContext &context) {
 439     return this;
 440 }
 441
 442 CYString *CYNumber::String(CYContext &context) {
 443     // XXX: there is a precise algorithm for this
 444     return $S(apr_psprintf(context.pool_, "%.17g", Value()));
 445 }
 446
 447 CYExpression *CYObject::Replace(CYContext &context) {
 448     properties_->Replace(context);
 449     return this;
 450 }
 451
 452 CYExpression *CYPostfix::Replace(CYContext &context) {
 453     context.Replace(lhs_);
 454     return this;
 455 }
 456
 457 CYExpression *CYPrefix::Replace(CYContext &context) {
 458     context.Replace(rhs_);
 459     return this;
 460 }
 461
 462 // XXX: this is evil evil black magic. don't ask, don't tell... don't believe!
 463 #define MappingSet "0etnirsoalfucdphmgyvbxTwSNECAFjDLkMOIBPqzRH$_WXUVGYKQJZ"
 464 //#define MappingSet "0abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ$_"
 465
 466 namespace {
 467     struct IdentifierUsageLess :
 468         std::binary_function<CYIdentifier *, CYIdentifier *, bool>
 469     {
 470         _finline bool operator ()(CYIdentifier *lhs, CYIdentifier *rhs) const {
 471             if (lhs->usage_ != rhs->usage_)
 472                 return lhs->usage_ > rhs->usage_;
 473             return lhs < rhs;
 474         }
 475     };
 476
 477     typedef std::set<CYIdentifier *, IdentifierUsageLess> IdentifierUsages;
 478 }
 479
 480 void CYProgram::Replace(CYContext &context) {
 481     parent_ = context.scope_;
 482     CYProgram *program(context.program_);
 483
 484     context.scope_ = this;
 485     context.program_ = this;
 486
 487     statements_ = statements_->ReplaceAll(context);
 488
 489     context.scope_ = parent_;
 490     context.program_ = program;
 491     Scope(context, statements_);
 492
 493     size_t offset(0);
 494
 495     CYCStringSet external;
 496     for (CYIdentifierValueSet::const_iterator i(identifiers_.begin()); i != identifiers_.end(); ++i)
 497         external.insert((*i)->Word());
 498
 499     IdentifierUsages usages;
 500
 501     if (offset < rename_.size())
 502         for (CYIdentifier *i(rename_[offset].identifier_); i != NULL; i = i->next_)
 503             usages.insert(i);
 504
 505     // XXX: totalling the probable occurrences and sorting by them would improve the result
 506     for (CYIdentifierUsageVector::const_iterator i(rename_.begin()); i != rename_.end(); ++i, ++offset) {
 507         //std::cout << *i << ":" << (*i)->offset_ << std::endl;
 508
 509         const char *name;
 510
 511         if (context.options_.verbose_)
 512             name = apr_psprintf(context.pool_, "$%"APR_SIZE_T_FMT"", offset);
 513         else {
 514             char id[8];
 515             id[7] = '\0';
 516
 517           id:
 518             unsigned position(7), local(offset + 1);
 519
 520             do {
 521                 unsigned index(local % (sizeof(MappingSet) - 1));
 522                 local /= sizeof(MappingSet) - 1;
 523                 id[--position] = MappingSet[index];
 524             } while (local != 0);
 525
 526             if (external.find(id + position) != external.end()) {
 527                 ++offset;
 528                 goto id;
 529             }
 530
 531             name = apr_pstrmemdup(context.pool_, id + position, 7 - position);
 532             // XXX: at some point, this could become a keyword
 533         }
 534
 535         for (CYIdentifier *identifier(i->identifier_); identifier != NULL; identifier = identifier->next_)
 536             identifier->Set(name);
 537     }
 538 }
 539
 540 void CYProperty::Replace(CYContext &context) { $T()
 541     context.Replace(value_);
 542     next_->Replace(context);
 543 }
 544
 545 CYStatement *CYReturn::Replace(CYContext &context) {
 546     context.Replace(value_);
 547     return this;
 548 }
 549
 550 void CYScope::Declare(CYContext &context, CYIdentifier *identifier, CYIdentifierFlags flags) {
 551     internal_.insert(CYIdentifierAddressFlagsMap::value_type(identifier, flags));
 552 }
 553
 554 CYIdentifier *CYScope::Lookup(CYContext &context, CYIdentifier *identifier) {
 555     std::pair<CYIdentifierValueSet::iterator, bool> insert(identifiers_.insert(identifier));
 556     return *insert.first;
 557 }
 558
 559 void CYScope::Merge(CYContext &context, CYIdentifier *identifier) {
 560     std::pair<CYIdentifierValueSet::iterator, bool> insert(identifiers_.insert(identifier));
 561     if (!insert.second) {
 562         if ((*insert.first)->offset_ < identifier->offset_)
 563             (*insert.first)->offset_ = identifier->offset_;
 564         identifier->replace_ = *insert.first;
 565         (*insert.first)->usage_ += identifier->usage_ + 1;
 566     }
 567 }
 568
 569 namespace {
 570     struct IdentifierOffset {
 571         size_t offset_;
 572         CYIdentifierFlags flags_;
 573         size_t usage_;
 574         CYIdentifier *identifier_;
 575
 576         IdentifierOffset(CYIdentifier *identifier, CYIdentifierFlags flags) :
 577             offset_(identifier->offset_),
 578             flags_(flags),
 579             usage_(identifier->usage_),
 580             identifier_(identifier)
 581         {
 582         }
 583     };
 584
 585     struct IdentifierOffsetLess :
 586         std::binary_function<const IdentifierOffset &, const IdentifierOffset &, bool>
 587     {
 588         _finline bool operator ()(const IdentifierOffset &lhs, const IdentifierOffset &rhs) const {
 589             if (lhs.offset_ != rhs.offset_)
 590                 return lhs.offset_ < rhs.offset_;
 591             if (lhs.flags_ != rhs.flags_)
 592                 return lhs.flags_ < rhs.flags_;
 593             /*if (lhs.usage_ != rhs.usage_)
 594                 return lhs.usage_ > rhs.usage_;*/
 595             return lhs.identifier_ < rhs.identifier_;
 596         }
 597     };
 598
 599     typedef std::set<IdentifierOffset, IdentifierOffsetLess> IdentifierOffsets;
 600 }
 601
 602 void CYScope::Scope(CYContext &context, CYStatement *&statements) {
 603     CYDeclarations *last(NULL), *curr(NULL);
 604     CYProgram *program(context.program_);
 605
 606     IdentifierOffsets offsets;
 607
 608     for (CYIdentifierAddressFlagsMap::const_iterator i(internal_.begin()); i != internal_.end(); ++i)
 609         if (program != NULL && i->second != CYIdentifierMagic)
 610             offsets.insert(IdentifierOffset(i->first, i->second));
 611
 612     size_t offset(0);
 613
 614     for (IdentifierOffsets::const_iterator i(offsets.begin()); i != offsets.end(); ++i) {
 615         if (i->flags_ == CYIdentifierVariable) {
 616             CYDeclarations *next($ CYDeclarations($ CYDeclaration(i->identifier_)));
 617             if (last == NULL)
 618                 last = next;
 619             if (curr != NULL)
 620                 curr->SetNext(next);
 621             curr = next;
 622         }
 623
 624         if (offset < i->offset_)
 625             offset = i->offset_;
 626         if (program->rename_.size() <= offset)
 627             program->rename_.resize(offset + 1);
 628
 629         CYIdentifierUsage &rename(program->rename_[offset++]);
 630         i->identifier_->SetNext(rename.identifier_);
 631         rename.identifier_ = i->identifier_;
 632         rename.usage_ += i->identifier_->usage_ + 1;
 633     }
 634
 635     if (last != NULL) {
 636         CYVar *var($ CYVar(last));
 637         var->SetNext(statements);
 638         statements = var;
 639     }
 640
 641     for (CYIdentifierValueSet::const_iterator i(identifiers_.begin()); i != identifiers_.end(); ++i)
 642         if (internal_.find(*i) == internal_.end()) {
 643             //std::cout << *i << '=' << offset << std::endl;
 644             if ((*i)->offset_ < offset)
 645                 (*i)->offset_ = offset;
 646             parent_->Merge(context, *i);
 647         }
 648 }
 649
 650 CYStatement *CYStatement::Collapse(CYContext &context) {
 651     return this;
 652 }
 653
 654 CYStatement *CYStatement::ReplaceAll(CYContext &context) { $T(NULL)
 655     CYStatement *replace(this);
 656     context.Replace(replace);
 657     replace->SetNext(next_->ReplaceAll(context));
 658     return replace->Collapse(context);
 659 }
 660
 661 CYString *CYString::Concat(CYContext &context, CYString *rhs) const {
 662     size_t size(size_ + rhs->size_);
 663     char *value(new(context.pool_) char[size + 1]);
 664     memcpy(value, value_, size_);
 665     memcpy(value + size_, rhs->value_, rhs->size_);
 666     value[size] = '\0';
 667     return $S(value, size);
 668 }
 669
 670 CYNumber *CYString::Number(CYContext &context) {
 671     // XXX: there is a precise algorithm for this
 672     return NULL;
 673 }
 674
 675 CYString *CYString::String(CYContext &context) {
 676     return this;
 677 }
 678
 679 CYStatement *CYSwitch::Replace(CYContext &context) {
 680     context.Replace(value_);
 681     clauses_->Replace(context);
 682     return this;
 683 }
 684
 685 CYExpression *CYThis::Replace(CYContext &context) {
 686     return this;
 687 }
 688
 689 namespace cy {
 690 namespace Syntax {
 691
 692 CYStatement *Throw::Replace(CYContext &context) {
 693     context.Replace(value_);
 694     return this;
 695 }
 696
 697 } }
 698
 699 CYExpression *CYTrivial::Replace(CYContext &context) {
 700     return this;
 701 }
 702
 703 CYNumber *CYTrue::Number(CYContext &context) {
 704     return $D(1);
 705 }
 706
 707 CYString *CYTrue::String(CYContext &context) {
 708     return $S("true");
 709 }
 710
 711 namespace cy {
 712 namespace Syntax {
 713
 714 CYStatement *Try::Replace(CYContext &context) {
 715     code_.Replace(context);
 716     catch_->Replace(context);
 717     finally_->Replace(context);
 718     return this;
 719 }
 720
 721 } }
 722
 723 CYStatement *CYVar::Replace(CYContext &context) {
 724     return $E(declarations_->Replace(context));
 725 }
 726
 727 CYExpression *CYVariable::Replace(CYContext &context) {
 728     name_ = name_->Replace(context);
 729     return this;
 730 }
 731
 732 CYStatement *CYWhile::Replace(CYContext &context) {
 733     context.Replace(test_);
 734     context.Replace(code_);
 735     return this;
 736 }
 737
 738 CYStatement *CYWith::Replace(CYContext &context) {
 739     context.Replace(scope_);
 740     context.Replace(code_);
 741     return this;
 742 }
 743
 744 CYExpression *CYWord::ClassName(CYContext &context, bool object) {
 745     CYString *name($S(this));
 746     if (object)
 747         return $C1($V("objc_getClass"), name);
 748     else
 749         return name;
 750 }