From a0be43fc10f28843e7a477d0c5354ea5e82b3140 Mon Sep 17 00:00:00 2001
From: "Jay Freeman (saurik)" <saurik@saurik.com>
Date: Fri, 8 Jun 2012 15:22:30 -0700
Subject: [PATCH] Correctly defer this-resolution on ECMA6 fat-arrows.

---
 Cycript.yy.in |  2 +-
 Output.cpp    |  4 ++++
 Parser.hpp    | 42 ++++++++++++++++++++++++++++++++++++++++++
 Replace.cpp   | 18 ++++++++++++++++++
 4 files changed, 65 insertions(+), 1 deletion(-)

diff --git a/Cycript.yy.in b/Cycript.yy.in
index e735597..cd63aec 100644
--- a/Cycript.yy.in
+++ b/Cycript.yy.in
@@ -1288,7 +1288,7 @@ FunctionBody
 /* }}} */
 /* 13.2 Arrow Function Definitions {{{ */
 ArrowFunction
-    : LexSetRegExp ArrowParameters "=>" LexNoBrace ConciseBody { $$ = CYNew CYFunctionExpression(NULL, $2, $5); }
+    : LexSetRegExp ArrowParameters "=>" LexNoBrace ConciseBody { $$ = CYNew CYFatArrow($2, $5); }
     ;
 
 ArrowParameters
diff --git a/Output.cpp b/Output.cpp
index b4f82ed..1feff42 100644
--- a/Output.cpp
+++ b/Output.cpp
@@ -336,6 +336,10 @@ void CYExpression::Output(CYOutput &out, unsigned precedence, CYFlags flags) con
         Output(out, flags);
 }
 
+void CYFatArrow::Output(CYOutput &out, CYFlags flags) const {
+    out << '(' << parameters_ << ')' << ' ' << "=>" << ' ' << code_;
+}
+
 void CYFinally::Output(CYOutput &out) const {
     out << ' ' << "finally" << ' ' << code_;
 }
diff --git a/Parser.hpp b/Parser.hpp
index c26e6d2..afb2c66 100644
--- a/Parser.hpp
+++ b/Parser.hpp
@@ -350,11 +350,14 @@ struct CYProgram :
 };
 
 struct CYNonLocal;
+struct CYThisScope;
 
 struct CYContext {
     CYOptions &options_;
 
     CYScope *scope_;
+    CYThisScope *this_;
+
     CYIdentifierUsageVector rename_;
 
     CYNonLocal *nonlocal_;
@@ -364,6 +367,7 @@ struct CYContext {
     CYContext(CYOptions &options) :
         options_(options),
         scope_(NULL),
+        this_(NULL),
         nonlocal_(NULL),
         nextlocal_(NULL),
         unique_(0)
@@ -414,6 +418,25 @@ struct CYNonLocal {
     }
 };
 
+struct CYThisScope :
+    CYNext<CYThisScope>
+{
+    CYIdentifier *identifier_;
+
+    CYThisScope() :
+        identifier_(NULL)
+    {
+    }
+
+    CYIdentifier *Identifier(CYContext &context) {
+        if (next_ != NULL)
+            return next_->Identifier(context);
+        if (identifier_ == NULL)
+            identifier_ = context.Unique();
+        return identifier_;
+    }
+};
+
 struct CYBlock :
     CYStatement,
     CYThing
@@ -1482,7 +1505,9 @@ struct CYFunction {
     CYIdentifier *name_;
     CYFunctionParameter *parameters_;
     CYBlock code_;
+
     CYNonLocal *nonlocal_;
+    CYThisScope this_;
 
     CYFunction(CYIdentifier *name, CYFunctionParameter *parameters, CYStatement *statements) :
         name_(name),
@@ -1517,6 +1542,23 @@ struct CYFunctionExpression :
     virtual void Output(CYOutput &out, CYFlags flags) const;
 };
 
+// XXX: this should derive from CYAnonymousFunction
+struct CYFatArrow :
+    CYFunction,
+    CYExpression
+{
+    CYFatArrow(CYFunctionParameter *parameters, CYStatement *statements) :
+        CYFunction(NULL, parameters, statements)
+    {
+    }
+
+    CYPrecedence(0)
+    CYRightHand(false)
+
+    virtual CYExpression *Replace(CYContext &context);
+    virtual void Output(CYOutput &out, CYFlags flags) const;
+};
+
 // XXX: this should derive from CYAnonymousFunctionExpression
 struct CYRubyProc :
     CYFunctionExpression
diff --git a/Replace.cpp b/Replace.cpp
index 3e06308..acf4d51 100644
--- a/Replace.cpp
+++ b/Replace.cpp
@@ -330,6 +330,12 @@ CYString *CYFalse::String(CYContext &context) {
     return $S("false");
 }
 
+CYExpression *CYFatArrow::Replace(CYContext &context) {
+    CYFunctionExpression *function($ CYFunctionExpression(NULL, parameters_, code_));
+    function->this_.SetNext(context.this_);
+    return function;
+}
+
 void CYFinally::Replace(CYContext &context) { $T()
     code_.Replace(context);
 }
@@ -411,6 +417,9 @@ void CYFunction::Replace_(CYContext &context, bool outer) {
     if (outer)
         Inject(context);
 
+    CYThisScope *_this(context.this_);
+    context.this_ = CYGetLast(&this_);
+
     CYNonLocal *nonlocal(context.nonlocal_);
     CYNonLocal *nextlocal(context.nextlocal_);
 
@@ -432,12 +441,19 @@ void CYFunction::Replace_(CYContext &context, bool outer) {
     parameters_->Replace(context, code_);
     code_.Replace(context);
 
+    if (CYIdentifier *identifier = this_.identifier_)
+        code_.statements_ = $$->*
+            $ CYVar($L1($ CYDeclaration(identifier, $ CYThis())))->*
+            code_.statements_;
+
     if (localize)
         context.NonLocal(code_.statements_);
 
     context.nextlocal_ = nextlocal;
     context.nonlocal_ = nonlocal;
 
+    context.this_ = _this;
+
     scope.Close();
 }
 
@@ -806,6 +822,8 @@ CYStatement *CYSwitch::Replace(CYContext &context) {
 }
 
 CYExpression *CYThis::Replace(CYContext &context) {
+    if (context.this_ != NULL)
+        return $V(context.this_->Identifier(context));
     return this;
 }
 
-- 
2.47.2