From d1af35f0f5094fb8d2bd9b098d964df72f9197e2 Mon Sep 17 00:00:00 2001
From: Danny Yoo <dyoo@cs.wpi.edu>
Date: Tue, 8 Mar 2011 17:27:43 -0500
Subject: [PATCH] fixed bug with lexical scoping.

---
 compile.rkt         | 21 ++++++++++-----------
 lexical-env.rkt     | 36 +++++++++++++++++-------------------
 lexical-structs.rkt | 14 ++++++++------
 test-compiler.rkt   |  4 ++--
 4 files changed, 37 insertions(+), 38 deletions(-)

diff --git a/compile.rkt b/compile.rkt
index 9255156..dc6314e 100644
--- a/compile.rkt
+++ b/compile.rkt
@@ -120,7 +120,8 @@
 (: lexical-environment-pop-depth (CompileTimeEnvironment Linkage -> Natural))
 ;; Computes how much of the environment we need to pop.
 (define (lexical-environment-pop-depth cenv linkage)
-  (cond
+  (length cenv)
+  #;(cond
     [(empty? cenv)
      0]
     [else
@@ -128,14 +129,12 @@
            (cond
              [(Prefix? entry)
               (+ 1 (lexical-environment-pop-depth (rest cenv) linkage))]
-             [(FunctionExtension? entry)
-              (length (FunctionExtension-names entry))]
-             [(LocalExtension? entry)
-              (+ (length (LocalExtension-names entry))
-                 (lexical-environment-pop-depth (rest cenv) linkage))]
-             [(TemporaryExtension? entry)
-              (+ (TemporaryExtension-n entry)
-                 (lexical-environment-pop-depth (rest cenv) linkage))]))]))
+             [(symbol? entry)
+              (cond
+              (+ 1 (lexical-environment-pop-depth (rest cenv) linkage)))]
+             [(eq? entry #f)
+              (+ 1 (lexical-environment-pop-depth (rest cenv) linkage))]))]))
+
 
 
 
@@ -274,9 +273,9 @@
 (define (compile-lambda-body exp cenv lexical-references proc-entry)
   (let*: ([formals : (Listof Symbol) (Lam-parameters exp)]
           [extended-cenv : CompileTimeEnvironment 
-                         (extend-lexical-environment 
+                         (extend-lexical-environment/names
                           '() 
-                          (make-FunctionExtension formals))]
+                          formals)]
           [extended-cenv : CompileTimeEnvironment 
                          (lexical-references->compile-time-environment 
                           lexical-references cenv extended-cenv)])
diff --git a/lexical-env.rkt b/lexical-env.rkt
index dcb9477..8521a85 100644
--- a/lexical-env.rkt
+++ b/lexical-env.rkt
@@ -6,6 +6,7 @@
          "sets.rkt")
 (provide find-variable 
          extend-lexical-environment
+         extend-lexical-environment/names
          extend-lexical-environment/placeholders
          collect-lexical-references
          lexical-references->compile-time-environment)
@@ -35,25 +36,16 @@
                           [else
                            (loop (rest cenv) (add1 depth))])]
                    
-                   [(FunctionExtension? elt)
-                    (let: ([index : (U #f Natural) (list-index name (FunctionExtension-names elt))])
-                          (cond
-                            [(boolean? index)
-                             (loop (rest cenv) (+ depth (length (FunctionExtension-names elt))))]
-                            [else
-                             (make-LocalAddress (+ depth index))]))]
+                   [(symbol? elt)
+                    (cond
+                      [(eq? elt name)
+                       (make-LocalAddress depth)]
+                      [else
+                       (loop (rest cenv) (add1 depth))])]
                    
-                   [(LocalExtension? elt)
-                    (let: ([index : (U #f Natural) (list-index name (LocalExtension-names elt))])
-                          (cond 
-                            [(boolean? index)
-                             (loop (rest cenv) (+ depth (length (LocalExtension-names elt))))]
-                            [else
-                             (make-LocalAddress (+ depth index))]))]
+                   [(eq? elt #f)
+                    (loop (rest cenv) (add1 depth))]))])))
 
-                   [(TemporaryExtension? elt)
-                    (loop (rest cenv) 
-                          (+ depth (TemporaryExtension-n elt)))]))])))
 
 (: list-index (All (A) A (Listof A) -> (U #f Natural)))
 (define (list-index x l)
@@ -75,12 +67,18 @@
   (cons extension cenv))
 
 
+
+(: extend-lexical-environment/names (CompileTimeEnvironment (Listof Symbol) -> CompileTimeEnvironment))
+(define (extend-lexical-environment/names cenv names)
+  (append names cenv))
+
+
 (: extend-lexical-environment/placeholders
    (CompileTimeEnvironment Natural -> CompileTimeEnvironment))
 ;; Add placeholders to the lexical environment (This represents what happens during procedure application.)
 (define (extend-lexical-environment/placeholders cenv n)
-  (cons (make-TemporaryExtension n)
-        cenv))
+  (append (build-list n (lambda: ([i : Natural]) #f))
+          cenv))
   
 
 
diff --git a/lexical-structs.rkt b/lexical-structs.rkt
index dc27a49..ef01bdc 100644
--- a/lexical-structs.rkt
+++ b/lexical-structs.rkt
@@ -11,20 +11,22 @@
 (define-struct: Prefix ([names : (Listof Symbol)])
   #:transparent)
 
-(define-struct: FunctionExtension ([names : (Listof Symbol)])
+#;(define-struct: FunctionExtension ([names : (Listof Symbol)])
   #:transparent)
 
-(define-struct: LocalExtension ([names : (Listof Symbol)])
+#;(define-struct: LocalExtension ([names : (Listof Symbol)])
   #:transparent)
 
-(define-struct: TemporaryExtension ([n : Natural])
+#;(define-struct: TemporaryExtension ([n : Natural])
   #:transparent)
 
 
 (define-type CompileTimeEnvironmentEntry (U Prefix ;; a prefix
-                                            FunctionExtension
-                                            LocalExtension
-                                            TemporaryExtension))
+                                            Symbol
+                                            False
+                                            #;FunctionExtension
+                                            #;LocalExtension
+                                            #;TemporaryExtension))
 
 
 ;; A compile-time environment is a (listof (listof symbol)).
diff --git a/test-compiler.rkt b/test-compiler.rkt
index e090423..64e96a4 100644
--- a/test-compiler.rkt
+++ b/test-compiler.rkt
@@ -282,8 +282,8 @@
                       (* x acc))
                     1
                     '(1 2 3 4 5 6 7 8 9 10)))
-      (* 1 2 3 4 5 6 7 8 9 10)
-      #:debug? #t)
+      (* 1 2 3 4 5 6 7 8 9 10))
+