Remove empty expression statements from the output.

[cycript.git] / Replace.cpp

diff --git a/Replace.cpp b/Replace.cpp
index b41aac1d959ed7133164e0b93b51d91e59c88382..f51d2234e2232f35b83cc79918715fc4ab82b823 100644 (file)
--- a/Replace.cpp
+++ b/Replace.cpp
@@ -1,48 +1,29 @@
-/* Cycript - Inlining/Optimizing JavaScript Compiler
- * Copyright (C) 2009  Jay Freeman (saurik)
+/* Cycript - Optimizing JavaScript Compiler/Runtime
+ * Copyright (C) 2009-2010  Jay Freeman (saurik)

 */
 
 */
 

-/* Modified BSD License {{{ */
+/* GNU Lesser General Public License, Version 3 {{{ */

 /*
 /*

- *        Redistribution and use in source and binary
- * forms, with or without modification, are permitted
- * provided that the following conditions are met:
+ * Cycript is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Lesser General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or (at your
+ * option) any later version.

  *
  *

- * 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.
- * 3. The name of the author may not be used to endorse
- *    or promote products derived from this software
- *    without specific prior written permission.
+ * Cycript 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 Lesser General Public
+ * License for more details.

  *
  *

- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 THE AUTHOR 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.
-*/
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Cycript.  If not, see <http://www.gnu.org/licenses/>.
+**/

 /* }}} */
 
 #include "Parser.hpp"
 /* }}} */
 
 #include "Parser.hpp"

+#include "Replace.hpp"

 
 #include <iomanip>
 
 
 #include <iomanip>
 

-#include "Replace.hpp"
-

 CYExpression *CYAdd::Replace(CYContext &context) {
     CYInfix::Replace(context);
 
 CYExpression *CYAdd::Replace(CYContext &context) {
     CYInfix::Replace(context);
 


@@ -56,11 +37,11 @@ CYExpression *CYAdd::Replace(CYContext &context) {
         if (lhs == NULL) {
             lhs = lhp->String(context);
             if (lhs == NULL)
         if (lhs == NULL) {
             lhs = lhp->String(context);
             if (lhs == NULL)

-                return NULL;
+                return this;

         } else if (rhs == NULL) {
             rhs = rhp->String(context);
             if (rhs == NULL)
         } else if (rhs == NULL) {
             rhs = rhp->String(context);
             if (rhs == NULL)

-                return NULL;
+                return this;

         }
 
         return lhs->Concat(context, rhs);
         }
 
         return lhs->Concat(context, rhs);


@@ -70,7 +51,7 @@ CYExpression *CYAdd::Replace(CYContext &context) {
         if (CYNumber *rhn = rhp->Number(context))
             return $D(lhn->Value() + rhn->Value());
 
         if (CYNumber *rhn = rhp->Number(context))
             return $D(lhn->Value() + rhn->Value());
 

-    return NULL;
+    return this;

 }
 
 CYExpression *CYAddressOf::Replace(CYContext &context) {
 }
 
 CYExpression *CYAddressOf::Replace(CYContext &context) {


@@ -85,7 +66,7 @@ void CYArgument::Replace(CYContext &context) { $T()
 
 CYExpression *CYArray::Replace(CYContext &context) {
     elements_->Replace(context);
 
 CYExpression *CYArray::Replace(CYContext &context) {
     elements_->Replace(context);

-    return NULL;
+    return this;

 }
 
 CYExpression *CYArrayComprehension::Replace(CYContext &context) {
 }
 
 CYExpression *CYArrayComprehension::Replace(CYContext &context) {


@@ -101,42 +82,62 @@ CYExpression *CYArrayComprehension::Replace(CYContext &context) {
 CYExpression *CYAssignment::Replace(CYContext &context) {
     context.Replace(lhs_);
     context.Replace(rhs_);
 CYExpression *CYAssignment::Replace(CYContext &context) {
     context.Replace(lhs_);
     context.Replace(rhs_);

-    return NULL;
+    return this;

 }
 
 CYStatement *CYBlock::Replace(CYContext &context) {
 }
 
 CYStatement *CYBlock::Replace(CYContext &context) {

-    statements_ = statements_->ReplaceAll(context);
-    return NULL;
+    context.ReplaceAll(statements_);
+    if (statements_ == NULL)
+        return $ CYEmpty();
+    return this;

 }
 
 CYStatement *CYBreak::Replace(CYContext &context) {
 }
 
 CYStatement *CYBreak::Replace(CYContext &context) {

-    return NULL;
+    return this;
+}
+
+CYExpression *CYCall::AddArgument(CYContext &context, CYExpression *value) {
+    CYArgument **argument(&arguments_);
+    while (*argument != NULL)
+        argument = &(*argument)->next_;
+    *argument = $ CYArgument(value);
+    return this;

 }
 
 CYExpression *CYCall::Replace(CYContext &context) {
     context.Replace(function_);
     arguments_->Replace(context);
 }
 
 CYExpression *CYCall::Replace(CYContext &context) {
     context.Replace(function_);
     arguments_->Replace(context);

-    return NULL;
+    return this;

 }
 
 namespace cy {
 namespace Syntax {
 
 void Catch::Replace(CYContext &context) { $T()
 }
 
 namespace cy {
 namespace Syntax {
 
 void Catch::Replace(CYContext &context) { $T()

+    CYScope scope(CYScopeCatch, context, code_.statements_);
+
+    context.Replace(name_);
+    context.scope_->Declare(context, name_, CYIdentifierCatch);
+

     code_.Replace(context);
     code_.Replace(context);

+    scope.Close();

 }
 
 } }
 
 void CYClause::Replace(CYContext &context) { $T()
     context.Replace(case_);
 }
 
 } }
 
 void CYClause::Replace(CYContext &context) { $T()
     context.Replace(case_);

-    statements_ = statements_->ReplaceAll(context);
+    context.ReplaceAll(statements_);

     next_->Replace(context);
 }
 
     next_->Replace(context);
 }
 

+CYStatement *CYComment::Replace(CYContext &context) {
+    return this;
+}
+

 CYExpression *CYCompound::Replace(CYContext &context) {
 CYExpression *CYCompound::Replace(CYContext &context) {

-    expressions_ = expressions_->ReplaceAll(context);
-    return NULL;
+    context.ReplaceAll(expressions_);
+    return this;

 }
 
 CYFunctionParameter *CYComprehension::Parameters(CYContext &context) const { $T(NULL)
 }
 
 CYFunctionParameter *CYComprehension::Parameters(CYContext &context) const { $T(NULL)


@@ -156,39 +157,77 @@ CYExpression *CYCondition::Replace(CYContext &context) {
     context.Replace(test_);
     context.Replace(true_);
     context.Replace(false_);
     context.Replace(test_);
     context.Replace(true_);
     context.Replace(false_);

-    return NULL;
+    return this;
+}
+
+void CYContext::NonLocal(CYStatement *&statements) {
+    CYContext &context(*this);
+
+    if (nextlocal_ != NULL && nextlocal_->identifier_ != NULL) {
+        CYIdentifier *cye($I("$cye")->Replace(context));
+        CYIdentifier *unique(nextlocal_->identifier_->Replace(context));
+
+        CYStatement *declare(
+            $ CYVar($L1($L(unique, $ CYObject()))));
+
+        cy::Syntax::Catch *rescue(
+            $ cy::Syntax::Catch(cye, $$->*
+                $ CYIf($ CYIdentical($M($V(cye), $S("$cyk")), $V(unique)), $$->*
+                    $ CYReturn($M($V(cye), $S("$cyv"))))->*
+                $ cy::Syntax::Throw($V(cye))));
+
+        context.Replace(declare);
+        rescue->Replace(context);
+
+        statements = $$->*
+            declare->*
+            $ cy::Syntax::Try(statements, rescue, NULL);
+    }
+}
+
+CYIdentifier *CYContext::Unique() {
+    return $ CYIdentifier(apr_psprintf($pool, "$cy%u", unique_++));

 }
 
 CYStatement *CYContinue::Replace(CYContext &context) {
 }
 
 CYStatement *CYContinue::Replace(CYContext &context) {

-    return NULL;
+    return this;

 }
 
 }
 

-CYExpression *CYDeclaration::ForEachIn(CYContext &context) {
-    return $ CYVariable(identifier_);
+CYAssignment *CYDeclaration::Assignment(CYContext &context) {
+    CYExpression *variable(Replace(context));
+    return initialiser_ == NULL ? NULL : $ CYAssign(variable, initialiser_);

 }
 
 }
 

-void CYDeclaration::Replace(CYContext &context) {
-    context.Replace(initialiser_);
+CYStatement *CYDeclaration::ForEachIn(CYContext &context, CYExpression *value) {
+    return $ CYVar($L1($L(identifier_, value)));
+}
+
+CYExpression *CYDeclaration::Replace(CYContext &context) {
+    context.Replace(identifier_);
+    context.scope_->Declare(context, identifier_, CYIdentifierVariable);
+    return $V(identifier_);

 }
 
 CYProperty *CYDeclarations::Property(CYContext &context) { $T(NULL)
     return $ CYProperty(declaration_->identifier_, declaration_->initialiser_ ?: $U, next_->Property(context));
 }
 
 }
 
 CYProperty *CYDeclarations::Property(CYContext &context) { $T(NULL)
     return $ CYProperty(declaration_->identifier_, declaration_->initialiser_ ?: $U, next_->Property(context));
 }
 

-void CYDeclarations::Replace(CYContext &context) { $T()
-    declaration_->Replace(context);
-    next_->Replace(context);
+CYCompound *CYDeclarations::Replace(CYContext &context) {
+    CYCompound *compound(next_ == NULL ? $ CYCompound() : next_->Replace(context));
+    if (CYAssignment *assignment = declaration_->Assignment(context))
+        compound->AddPrev(assignment);
+    return compound;

 }
 
 CYExpression *CYDirectMember::Replace(CYContext &context) {
     Replace_(context);
 }
 
 CYExpression *CYDirectMember::Replace(CYContext &context) {
     Replace_(context);

-    return NULL;
+    return this;

 }
 
 CYStatement *CYDoWhile::Replace(CYContext &context) {
     context.Replace(test_);
     context.Replace(code_);
 }
 
 CYStatement *CYDoWhile::Replace(CYContext &context) {
     context.Replace(test_);
     context.Replace(code_);

-    return NULL;
+    return this;

 }
 
 void CYElement::Replace(CYContext &context) { $T()
 }
 
 void CYElement::Replace(CYContext &context) { $T()


@@ -196,33 +235,44 @@ void CYElement::Replace(CYContext &context) { $T()
     next_->Replace(context);
 }
 
     next_->Replace(context);
 }
 

-CYStatement *CYEmpty::Replace(CYContext &context) {
-    return NULL;
+CYStatement *CYEmpty::Collapse(CYContext &context) {
+    return next_;

 }
 
 }
 

-CYStatement *CYExpress::Replace(CYContext &context) {
-    context.Replace(expression_);
+CYStatement *CYEmpty::Replace(CYContext &context) {

     return NULL;
 }
 
     return NULL;
 }
 

-CYExpression *CYExpression::ClassName(CYContext &context, bool object) {
+CYStatement *CYExpress::Collapse(CYContext &context) {
+    if (CYExpress *express = dynamic_cast<CYExpress *>(next_)) {
+        CYCompound *next(dynamic_cast<CYCompound *>(express->expression_));
+        if (next == NULL)
+            next = $ CYCompound(express->expression_);
+        next->AddPrev(expression_);
+        expression_ = next;
+        SetNext(express->next_);
+    }
+

     return this;
 }
 
     return this;
 }
 

-CYExpression *CYExpression::ForEachIn(CYContext &context) {
+CYStatement *CYExpress::Replace(CYContext &context) {
+    context.Replace(expression_);
+    if (expression_ == NULL)
+        return $ CYEmpty();

     return this;
 }
 
     return this;
 }
 

-CYExpression *CYExpression::ReplaceAll(CYContext &context) { $T(NULL)
-    CYExpression *replace(this);
-    context.Replace(replace);
+CYExpression *CYExpression::AddArgument(CYContext &context, CYExpression *value) {
+    return $C1(this, value);
+}

 
 

-    if (CYExpression *next = next_->ReplaceAll(context))
-        replace->SetNext(next);
-    else
-        replace->SetNext(next_);
+CYExpression *CYExpression::ClassName(CYContext &context, bool object) {
+    return this;
+}

 
 

-    return replace;
+CYStatement *CYExpression::ForEachIn(CYContext &context, CYExpression *value) {
+    return $E($ CYAssign(this, value));

 }
 
 CYNumber *CYFalse::Number(CYContext &context) {
 }
 
 CYNumber *CYFalse::Number(CYContext &context) {


@@ -238,18 +288,19 @@ void CYFinally::Replace(CYContext &context) { $T()
 }
 
 CYStatement *CYFor::Replace(CYContext &context) {
 }
 
 CYStatement *CYFor::Replace(CYContext &context) {

-    // XXX: initialiser_
+    context.Replace(initialiser_);

     context.Replace(test_);
     context.Replace(increment_);
     context.Replace(code_);
     context.Replace(test_);
     context.Replace(increment_);
     context.Replace(code_);

-    return NULL;
+    return this;

 }
 
 CYStatement *CYForIn::Replace(CYContext &context) {
 }
 
 CYStatement *CYForIn::Replace(CYContext &context) {

-    // XXX: initialiser_
+    // XXX: this actually might need a prefix statement
+    context.Replace(initialiser_);

     context.Replace(set_);
     context.Replace(code_);
     context.Replace(set_);
     context.Replace(code_);

-    return NULL;
+    return this;

 }
 
 CYFunctionParameter *CYForInComprehension::Parameter(CYContext &context) const {
 }
 
 CYFunctionParameter *CYForInComprehension::Parameter(CYContext &context) const {


@@ -257,15 +308,15 @@ CYFunctionParameter *CYForInComprehension::Parameter(CYContext &context) const {
 }
 
 CYStatement *CYForInComprehension::Replace(CYContext &context, CYStatement *statement) const {
 }
 
 CYStatement *CYForInComprehension::Replace(CYContext &context, CYStatement *statement) const {

-    return $ CYForIn($ CYVariable(name_), set_, CYComprehension::Replace(context, statement));
+    return $ CYForIn($V(name_), set_, CYComprehension::Replace(context, statement));

 }
 
 CYStatement *CYForEachIn::Replace(CYContext &context) {
 }
 
 CYStatement *CYForEachIn::Replace(CYContext &context) {

-    CYVariable *cys($V("$cys")), *cyt($V("$cyt"));
+    CYIdentifier *cys($I("$cys")), *cyt($I("$cyt"));

 
 

-    return $ CYLet($L2($L($I("$cys"), set_), $L($I("$cyt"))), $$->*
-        $ CYForIn(cyt, cys, $ CYBlock($$->*
-            $E($ CYAssign(initialiser_->ForEachIn(context), $M(cys, cyt)))->*
+    return $ CYLet($L2($L(cys, set_), $L(cyt)), $$->*
+        $ CYForIn($V(cyt), $V(cys), $ CYBlock($$->*
+            initialiser_->ForEachIn(context, $M($V(cys), $V(cyt)))->*

             code_
         ))
     );
             code_
         ))
     );


@@ -276,36 +327,88 @@ CYFunctionParameter *CYForEachInComprehension::Parameter(CYContext &context) con
 }
 
 CYStatement *CYForEachInComprehension::Replace(CYContext &context, CYStatement *statement) const {
 }
 
 CYStatement *CYForEachInComprehension::Replace(CYContext &context, CYStatement *statement) const {

-    CYVariable *cys($V("$cys")), *name($ CYVariable(name_));
+    CYIdentifier *cys($I("cys"));

 
     return $E($C0($F(NULL, $P1("$cys"), $$->*
 
     return $E($C0($F(NULL, $P1("$cys"), $$->*

-        $E($ CYAssign(cys, set_))->*
-        $ CYForIn(name, cys, $ CYBlock($$->*
-            $E($ CYAssign(name, $M(cys, name)))->*
+        $E($ CYAssign($V(cys), set_))->*
+        $ CYForIn($V(name_), $V(cys), $ CYBlock($$->*
+            $E($ CYAssign($V(name_), $M($V(cys), $V(name_))))->*

             CYComprehension::Replace(context, statement)
         ))
     )));
 }
 
             CYComprehension::Replace(context, statement)
         ))
     )));
 }
 

-void CYFunction::Replace_(CYContext &context) {
+void CYFunction::Inject(CYContext &context) {
+    context.Replace(name_);
+    context.scope_->Declare(context, name_, CYIdentifierOther);
+}
+
+void CYFunction::Replace_(CYContext &context, bool outer) {
+    if (outer)
+        Inject(context);
+
+    CYScope scope(CYScopeFunction, context, code_.statements_);
+
+    CYNonLocal *nonlocal(context.nonlocal_);
+    CYNonLocal *nextlocal(context.nextlocal_);
+
+    bool localize;
+    if (nonlocal_ != NULL) {
+        localize = false;
+        context.nonlocal_ = nonlocal_;
+    } else {
+        localize = true;
+        nonlocal_ = $ CYNonLocal();
+        context.nextlocal_ = nonlocal_;
+    }
+
+    if (!outer && name_ != NULL)
+        Inject(context);
+
+    if (parameters_ != NULL)
+        parameters_ = parameters_->Replace(context, code_);
+

     code_.Replace(context);
     code_.Replace(context);

+
+    if (localize)
+        context.NonLocal(code_.statements_);
+
+    context.nextlocal_ = nextlocal;
+    context.nonlocal_ = nonlocal;
+
+    scope.Close();

 }
 
 CYExpression *CYFunctionExpression::Replace(CYContext &context) {
 }
 
 CYExpression *CYFunctionExpression::Replace(CYContext &context) {

-    Replace_(context);
-    return NULL;
+    Replace_(context, false);
+    return this;
+}
+
+CYFunctionParameter *CYFunctionParameter::Replace(CYContext &context, CYBlock &code) {
+    context.Replace(name_);
+    context.scope_->Declare(context, name_, CYIdentifierArgument);
+    if (next_ != NULL)
+        next_ = next_->Replace(context, code);
+    return this;

 }
 
 CYStatement *CYFunctionStatement::Replace(CYContext &context) {
 }
 
 CYStatement *CYFunctionStatement::Replace(CYContext &context) {

-    Replace_(context);
-    return NULL;
+    Replace_(context, true);
+    return this;
+}
+
+CYIdentifier *CYIdentifier::Replace(CYContext &context) {
+    if (replace_ != NULL && replace_ != this)
+        return replace_->Replace(context);
+    replace_ = context.scope_->Lookup(context, this);
+    return replace_;

 }
 
 CYStatement *CYIf::Replace(CYContext &context) {
     context.Replace(test_);
     context.Replace(true_);
     context.Replace(false_);
 }
 
 CYStatement *CYIf::Replace(CYContext &context) {
     context.Replace(test_);
     context.Replace(true_);
     context.Replace(false_);

-    return NULL;
+    return this;

 }
 
 CYFunctionParameter *CYIfComprehension::Parameter(CYContext &context) const {
 }
 
 CYFunctionParameter *CYIfComprehension::Parameter(CYContext &context) const {


@@ -329,12 +432,12 @@ CYExpression *CYIndirectMember::Replace(CYContext &context) {
 CYExpression *CYInfix::Replace(CYContext &context) {
     context.Replace(lhs_);
     context.Replace(rhs_);
 CYExpression *CYInfix::Replace(CYContext &context) {
     context.Replace(lhs_);
     context.Replace(rhs_);

-    return NULL;
+    return this;

 }
 
 CYStatement *CYLabel::Replace(CYContext &context) {
     context.Replace(statement_);
 }
 
 CYStatement *CYLabel::Replace(CYContext &context) {
     context.Replace(statement_);

-    return NULL;
+    return this;

 }
 
 CYStatement *CYLet::Replace(CYContext &context) {
 }
 
 CYStatement *CYLet::Replace(CYContext &context) {


@@ -346,12 +449,22 @@ void CYMember::Replace_(CYContext &context) {
     context.Replace(property_);
 }
 
     context.Replace(property_);
 }
 

-CYExpression *CYNew::Replace(CYContext &context) {
+namespace cy {
+namespace Syntax {
+
+CYExpression *New::AddArgument(CYContext &context, CYExpression *value) {
+    CYSetLast(arguments_, $ CYArgument(value));
+    return this;
+}
+
+CYExpression *New::Replace(CYContext &context) {

     context.Replace(constructor_);
     arguments_->Replace(context);
     context.Replace(constructor_);
     arguments_->Replace(context);

-    return NULL;
+    return this;

 }
 
 }
 

+} }
+

 CYNumber *CYNull::Number(CYContext &context) {
     return $D(0);
 }
 CYNumber *CYNull::Number(CYContext &context) {
     return $D(0);
 }


@@ -366,26 +479,109 @@ CYNumber *CYNumber::Number(CYContext &context) {
 
 CYString *CYNumber::String(CYContext &context) {
     // XXX: there is a precise algorithm for this
 
 CYString *CYNumber::String(CYContext &context) {
     // XXX: there is a precise algorithm for this

-    return $S(apr_psprintf(context.pool_, "%.17g", Value()));
+    return $S(apr_psprintf($pool, "%.17g", Value()));

 }
 
 CYExpression *CYObject::Replace(CYContext &context) {
     properties_->Replace(context);
 }
 
 CYExpression *CYObject::Replace(CYContext &context) {
     properties_->Replace(context);

-    return NULL;
+    return this;
+}
+
+CYFunctionParameter *CYOptionalFunctionParameter::Replace(CYContext &context, CYBlock &code) {
+    CYFunctionParameter *parameter($ CYFunctionParameter(name_, next_));
+    parameter = parameter->Replace(context, code);
+    context.Replace(initializer_);
+
+    CYVariable *name($V(name_));
+    code.AddPrev($ CYIf($ CYIdentical($ CYTypeOf(name), $S("undefined")), $$->*
+        $E($ CYAssign(name, initializer_))
+    ));
+
+    return parameter;

 }
 
 CYExpression *CYPostfix::Replace(CYContext &context) {
     context.Replace(lhs_);
 }
 
 CYExpression *CYPostfix::Replace(CYContext &context) {
     context.Replace(lhs_);

-    return NULL;
+    return this;

 }
 
 CYExpression *CYPrefix::Replace(CYContext &context) {
     context.Replace(rhs_);
 }
 
 CYExpression *CYPrefix::Replace(CYContext &context) {
     context.Replace(rhs_);

-    return NULL;
+    return this;
+}
+
+// XXX: this is evil evil black magic. don't ask, don't tell... don't believe!
+#define MappingSet "0etnirsoalfucdphmgyvbxTwSNECAFjDLkMOIBPqzRH$_WXUVGYKQJZ"
+//#define MappingSet "0abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ$_"
+
+namespace {
+    struct IdentifierUsageLess :
+        std::binary_function<CYIdentifier *, CYIdentifier *, bool>
+    {
+        _finline bool operator ()(CYIdentifier *lhs, CYIdentifier *rhs) const {
+            if (lhs->usage_ != rhs->usage_)
+                return lhs->usage_ > rhs->usage_;
+            return lhs < rhs;
+        }
+    };
+
+    typedef std::set<CYIdentifier *, IdentifierUsageLess> IdentifierUsages;

 }
 
 void CYProgram::Replace(CYContext &context) {
 }
 
 void CYProgram::Replace(CYContext &context) {

-    statements_ = statements_->ReplaceAll(context);
+    CYScope scope(CYScopeProgram, context, statements_);
+
+    context.nextlocal_ = $ CYNonLocal();
+    context.ReplaceAll(statements_);
+    context.NonLocal(statements_);
+
+    scope.Close();
+
+    size_t offset(0);
+
+    CYCStringSet external;
+    for (CYIdentifierValueSet::const_iterator i(scope.identifiers_.begin()); i != scope.identifiers_.end(); ++i)
+        external.insert((*i)->Word());
+
+    IdentifierUsages usages;
+
+    if (offset < context.rename_.size())
+        CYForEach (i, context.rename_[offset].identifier_)
+            usages.insert(i);
+
+    // XXX: totalling the probable occurrences and sorting by them would improve the result
+    for (CYIdentifierUsageVector::const_iterator i(context.rename_.begin()); i != context.rename_.end(); ++i, ++offset) {
+        //std::cout << *i << ":" << (*i)->offset_ << std::endl;
+
+        const char *name;
+
+        if (context.options_.verbose_)
+            name = apr_psprintf($pool, "$%"APR_SIZE_T_FMT"", offset);
+        else {
+            char id[8];
+            id[7] = '\0';
+
+          id:
+            unsigned position(7), local(offset + 1);
+
+            do {
+                unsigned index(local % (sizeof(MappingSet) - 1));
+                local /= sizeof(MappingSet) - 1;
+                id[--position] = MappingSet[index];
+            } while (local != 0);
+
+            if (external.find(id + position) != external.end()) {
+                ++offset;
+                goto id;
+            }
+
+            name = apr_pstrmemdup($pool, id + position, 7 - position);
+            // XXX: at some point, this could become a keyword
+        }
+
+        CYForEach (identifier, i->identifier_)
+            identifier->Set(name);
+    }

 }
 
 void CYProperty::Replace(CYContext &context) { $T()
 }
 
 void CYProperty::Replace(CYContext &context) { $T()


@@ -394,25 +590,157 @@ void CYProperty::Replace(CYContext &context) { $T()
 }
 
 CYStatement *CYReturn::Replace(CYContext &context) {
 }
 
 CYStatement *CYReturn::Replace(CYContext &context) {

+    if (context.nonlocal_ != NULL) {
+        CYProperty *value(value_ == NULL ? NULL : $ CYProperty($S("$cyv"), value_));
+        return $ cy::Syntax::Throw($ CYObject(
+            $ CYProperty($S("$cyk"), $V(context.nonlocal_->Target(context)), value)
+        ));
+    }
+

     context.Replace(value_);
     context.Replace(value_);

-    return NULL;
+    return this;
+}
+
+CYExpression *CYRubyBlock::Replace(CYContext &context) {
+    // XXX: this needs to do something much more epic to handle return
+    return call_->AddArgument(context, proc_->Replace(context));

 }
 
 }
 

-CYStatement *CYStatement::ReplaceAll(CYContext &context) { $T(NULL)
-    CYStatement *replace(this);
-    context.Replace(replace);
+CYExpression *CYRubyProc::Replace(CYContext &context) {
+    CYFunctionExpression *function($ CYFunctionExpression(NULL, parameters_, code_));
+    function->nonlocal_ = context.nextlocal_;
+    return function;
+}
+
+CYScope::CYScope(CYScopeType type, CYContext &context, CYStatement *&statements) :
+    type_(type),
+    context_(context),
+    statements_(statements),
+    parent_(context.scope_)
+{
+    context_.scope_ = this;
+}

 
 

-    if (CYStatement *next = next_->ReplaceAll(context))
-        replace->SetNext(next);
+CYScope::~CYScope() {
+}
+
+void CYScope::Close() {
+    context_.scope_ = parent_;
+    Scope(context_, statements_);
+}
+
+void CYScope::Declare(CYContext &context, CYIdentifier *identifier, CYIdentifierFlags flags) {
+    if (type_ == CYScopeCatch && flags != CYIdentifierCatch)
+        parent_->Declare(context, identifier, flags);

     else
     else

-        replace->SetNext(next_);
+        internal_.insert(CYIdentifierAddressFlagsMap::value_type(identifier, flags));
+}

 
 

-    return replace;
+CYIdentifier *CYScope::Lookup(CYContext &context, CYIdentifier *identifier) {
+    std::pair<CYIdentifierValueSet::iterator, bool> insert(identifiers_.insert(identifier));
+    return *insert.first;
+}
+
+void CYScope::Merge(CYContext &context, CYIdentifier *identifier) {
+    std::pair<CYIdentifierValueSet::iterator, bool> insert(identifiers_.insert(identifier));
+    if (!insert.second) {
+        if ((*insert.first)->offset_ < identifier->offset_)
+            (*insert.first)->offset_ = identifier->offset_;
+        identifier->replace_ = *insert.first;
+        (*insert.first)->usage_ += identifier->usage_ + 1;
+    }
+}
+
+namespace {
+    struct IdentifierOffset {
+        size_t offset_;
+        CYIdentifierFlags flags_;
+        size_t usage_;
+        CYIdentifier *identifier_;
+
+        IdentifierOffset(CYIdentifier *identifier, CYIdentifierFlags flags) :
+            offset_(identifier->offset_),
+            flags_(flags),
+            usage_(identifier->usage_),
+            identifier_(identifier)
+        {
+        }
+    };
+
+    struct IdentifierOffsetLess :
+        std::binary_function<const IdentifierOffset &, const IdentifierOffset &, bool>
+    {
+        _finline bool operator ()(const IdentifierOffset &lhs, const IdentifierOffset &rhs) const {
+            if (lhs.offset_ != rhs.offset_)
+                return lhs.offset_ < rhs.offset_;
+            if (lhs.flags_ != rhs.flags_)
+                return lhs.flags_ < rhs.flags_;
+            /*if (lhs.usage_ != rhs.usage_)
+                return lhs.usage_ < rhs.usage_;*/
+            return lhs.identifier_ < rhs.identifier_;
+        }
+    };
+
+    typedef std::set<IdentifierOffset, IdentifierOffsetLess> IdentifierOffsets;
+}
+
+void CYScope::Scope(CYContext &context, CYStatement *&statements) {
+    if (parent_ == NULL)
+        return;
+
+    CYDeclarations *last(NULL), *curr(NULL);
+
+    IdentifierOffsets offsets;
+
+    for (CYIdentifierAddressFlagsMap::const_iterator i(internal_.begin()); i != internal_.end(); ++i)
+        if (i->second != CYIdentifierMagic)
+            offsets.insert(IdentifierOffset(i->first, i->second));
+
+    size_t offset(0);
+
+    for (IdentifierOffsets::const_iterator i(offsets.begin()); i != offsets.end(); ++i) {
+        if (i->flags_ == CYIdentifierVariable) {
+            CYDeclarations *next($ CYDeclarations($ CYDeclaration(i->identifier_)));
+            if (last == NULL)
+                last = next;
+            if (curr != NULL)
+                curr->SetNext(next);
+            curr = next;
+        }
+
+        if (offset < i->offset_)
+            offset = i->offset_;
+        if (context.rename_.size() <= offset)
+            context.rename_.resize(offset + 1);
+
+        CYIdentifierUsage &rename(context.rename_[offset++]);
+        i->identifier_->SetNext(rename.identifier_);
+        rename.identifier_ = i->identifier_;
+        rename.usage_ += i->identifier_->usage_ + 1;
+    }
+
+    if (last != NULL) {
+        CYVar *var($ CYVar(last));
+        var->SetNext(statements);
+        statements = var;
+    }
+
+    for (CYIdentifierValueSet::const_iterator i(identifiers_.begin()); i != identifiers_.end(); ++i)
+        if (internal_.find(*i) == internal_.end()) {
+            //std::cout << *i << '=' << offset << std::endl;
+            if ((*i)->offset_ < offset)
+                (*i)->offset_ = offset;
+            parent_->Merge(context, *i);
+        }
+}
+
+CYStatement *CYStatement::Collapse(CYContext &context) {
+    return this;

 }
 
 CYString *CYString::Concat(CYContext &context, CYString *rhs) const {
     size_t size(size_ + rhs->size_);
 }
 
 CYString *CYString::Concat(CYContext &context, CYString *rhs) const {
     size_t size(size_ + rhs->size_);

-    char *value(new(context.pool_) char[size + 1]);
+    char *value($ char[size + 1]);

     memcpy(value, value_, size_);
     memcpy(value + size_, rhs->value_, rhs->size_);
     value[size] = '\0';
     memcpy(value, value_, size_);
     memcpy(value + size_, rhs->value_, rhs->size_);
     value[size] = '\0';


@@ -431,11 +759,11 @@ CYString *CYString::String(CYContext &context) {
 CYStatement *CYSwitch::Replace(CYContext &context) {
     context.Replace(value_);
     clauses_->Replace(context);
 CYStatement *CYSwitch::Replace(CYContext &context) {
     context.Replace(value_);
     clauses_->Replace(context);

-    return NULL;
+    return this;

 }
 
 CYExpression *CYThis::Replace(CYContext &context) {
 }
 
 CYExpression *CYThis::Replace(CYContext &context) {

-    return NULL;
+    return this;

 }
 
 namespace cy {
 }
 
 namespace cy {


@@ -443,13 +771,13 @@ namespace Syntax {
 
 CYStatement *Throw::Replace(CYContext &context) {
     context.Replace(value_);
 
 CYStatement *Throw::Replace(CYContext &context) {
     context.Replace(value_);

-    return NULL;
+    return this;

 }
 
 } }
 
 CYExpression *CYTrivial::Replace(CYContext &context) {
 }
 
 } }
 
 CYExpression *CYTrivial::Replace(CYContext &context) {

-    return NULL;
+    return this;

 }
 
 CYNumber *CYTrue::Number(CYContext &context) {
 }
 
 CYNumber *CYTrue::Number(CYContext &context) {


@@ -467,30 +795,30 @@ CYStatement *Try::Replace(CYContext &context) {
     code_.Replace(context);
     catch_->Replace(context);
     finally_->Replace(context);
     code_.Replace(context);
     catch_->Replace(context);
     finally_->Replace(context);

-    return NULL;
+    return this;

 }
 
 } }
 
 CYStatement *CYVar::Replace(CYContext &context) {
 }
 
 } }
 
 CYStatement *CYVar::Replace(CYContext &context) {

-    declarations_->Replace(context);
-    return NULL;
+    return $E(declarations_->Replace(context));

 }
 
 CYExpression *CYVariable::Replace(CYContext &context) {
 }
 
 CYExpression *CYVariable::Replace(CYContext &context) {

-    return NULL;
+    context.Replace(name_);
+    return this;

 }
 
 CYStatement *CYWhile::Replace(CYContext &context) {
     context.Replace(test_);
     context.Replace(code_);
 }
 
 CYStatement *CYWhile::Replace(CYContext &context) {
     context.Replace(test_);
     context.Replace(code_);

-    return NULL;
+    return this;

 }
 
 CYStatement *CYWith::Replace(CYContext &context) {
     context.Replace(scope_);
     context.Replace(code_);
 }
 
 CYStatement *CYWith::Replace(CYContext &context) {
     context.Replace(scope_);
     context.Replace(code_);

-    return NULL;
+    return this;

 }
 
 CYExpression *CYWord::ClassName(CYContext &context, bool object) {
 }
 
 CYExpression *CYWord::ClassName(CYContext &context, bool object) {