Partial restoration of TypeCheckSimp to work with new SymTable

2 files changed, 352 insertions, 351 deletions

diff --git a/Typecheck.java b/Typecheck.java
index cf86389..4c43709 100644
--- a/Typecheck.java
+++ b/Typecheck.java
@@ -26,18 +26,18 @@ public class Typecheck {
             root.accept(new SymTableTopDown<Void>(), symt);
             PrintFilter.print("===================================================", true);
 
-            // TypeCheckSimp ts = new TypeCheckSimp();
-            // TypeInstance res = root.accept(ts, symt);
+            TypeCheckSimp ts = new TypeCheckSimp();
+            TypeInstance res = root.accept(ts, symt);
 
-            // // Ugly code not to be inspired from: "my" way of storing
-            // // type info / typecheck property: if some of my internal
-            // // structure is empty, then things don't typecheck for
-            // // me. This is specific to my own implementation.
-            // // if (res != null && res.type_array.size() > 0)
-            // if (res.get_type() != TypeEnum.ERROR)
-            //     System.out.println("Program type checked successfully");
-            // else
-            //     System.out.println("Type error");
+            // Ugly code not to be inspired from: "my" way of storing
+            // type info / typecheck property: if some of my internal
+            // structure is empty, then things don't typecheck for
+            // me. This is specific to my own implementation.
+            // if (res != null && res.type_array.size() > 0)
+            if (res.getType() != TypeEnum.ERROR)
+                System.out.println("Program type checked successfully");
+            else
+                System.out.println("Type error");
         }
         catch (ParseException e) {
             System.out.println(e.toString());
diff --git a/typecheck/library/TypeCheckSimp.java b/typecheck/library/TypeCheckSimp.java
index 59ee69b..b3a9ca3 100644
--- a/typecheck/library/TypeCheckSimp.java
+++ b/typecheck/library/TypeCheckSimp.java
@@ -10,11 +10,11 @@ import java.util.*;
  * Provides default methods which visit each node in the tree in depth-first
  * order.  Your visitors may extend this class.
  */
-public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,AbstractInstance>> {
+public class TypeCheckSimp extends GJDepthFirst<TypeInstance,SymbolTable> {
 
     private int offset;
 
-    private void printNode(Node n, HashMap<String,AbstractInstance> argu, boolean enter, TypeEnum consensus) {
+    private void printNode(Node n, SymbolTable symt, boolean enter, TypeEnum consensus) {
         for (int i=0; i < this.offset; ++i)
             PrintFilter.print(".", false);
         if (enter)
@@ -31,36 +31,36 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
         PrintFilter.print("", true);
     }
 
-    public TypeInstance visit(NodeList n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(NodeList n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
         TypeInstance ret = new TypeInstance(null, TypeEnum.CHECK);
         int _count=0;
         for ( Enumeration<Node> e = n.elements(); e.hasMoreElements(); ) {
-            TypeInstance node = e.nextElement().accept(this,argu);
-            e.nextElement().accept(this,argu);
-            if (node.get_type() == TypeEnum.ERROR)
+            TypeInstance node = e.nextElement().accept(this,symt);
+            e.nextElement().accept(this,symt);
+            if (node.getType() == TypeEnum.ERROR)
                 ret = node;
             _count++;
         }
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
 
-    public TypeInstance visit(NodeListOptional n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(NodeListOptional n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
         TypeInstance ret;
         if ( n.present() ) {
             ret = new TypeInstance(null, TypeEnum.CHECK);
             int _count=0;
             for ( Enumeration<Node> e = n.elements(); e.hasMoreElements(); ) {
-                TypeInstance node = e.nextElement().accept(this,argu);
-                if (node.get_type() == TypeEnum.ERROR)
+                TypeInstance node = e.nextElement().accept(this,symt);
+                if (node.getType() == TypeEnum.ERROR)
                     ret = node;
                 _count++;
             }
@@ -68,47 +68,47 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
         else
             ret = new TypeInstance(null, TypeEnum.CHECK);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
 
     // FIXME
-    public TypeInstance visit(NodeOptional n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(NodeOptional n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
         TypeInstance ret;
 
         if ( n.present() )
-            ret = n.node.accept(this,argu);
+            ret = n.node.accept(this,symt);
         else
             ret = new TypeInstance(null, TypeEnum.CHECK);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
 
-    public TypeInstance visit(NodeSequence n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(NodeSequence n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
         TypeInstance ret = new TypeInstance(null, TypeEnum.CHECK);
         int _count=0;
         for ( Enumeration<Node> e = n.elements(); e.hasMoreElements(); ) {
-            TypeInstance node = e.nextElement().accept(this,argu);
-            if (node.get_type() == TypeEnum.ERROR)
+            TypeInstance node = e.nextElement().accept(this,symt);
+            if (node.getType() == TypeEnum.ERROR)
                 ret = node;
             _count++;
         }
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
 
-    public TypeInstance visit(NodeToken n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(NodeToken n, SymbolTable symt) {
         // A fixed string token. '⌣'
         for (int i=0; i < this.offset; ++i)
             PrintFilter.print(".", false);
@@ -127,15 +127,15 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f1 -> ( TypeDeclaration() )*
      * f2 -> <EOF>
      */
-    public TypeInstance visit(Goal n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(Goal n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        TypeInstance ret = n.f0.accept(this, argu);
-        n.f1.accept(this, argu);
-        n.f2.accept(this, argu);
+        TypeInstance ret = n.f0.accept(this, symt);
+        n.f1.accept(this, symt);
+        n.f2.accept(this, symt);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -160,30 +160,30 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f16 -> "}"
      * f17 -> "}"
      */
-    public TypeInstance visit(MainClass n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(MainClass n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
-
-        n.f0.accept(this, argu);
-        TypeInstance name = n.f1.accept(this, argu);
-        n.f2.accept(this, argu);
-        n.f3.accept(this, argu);
-        n.f4.accept(this, argu);
-        n.f5.accept(this, argu);
-        n.f6.accept(this, argu);
-        n.f7.accept(this, argu);
-        n.f8.accept(this, argu);
-        n.f9.accept(this, argu);
-        n.f10.accept(this, argu);
-        // TypeInstance args = n.f11.accept(this, argu); // FIXME Type in the main class declaration uses an illegal minijava type?
-        n.f12.accept(this, argu);
-        n.f13.accept(this, argu);
-        TypeInstance var_dec = n.f14.accept(this, argu);
-        TypeInstance stmt = n.f15.accept(this, argu);
-        n.f16.accept(this, argu);
-        n.f17.accept(this, argu);
-
-        this.printNode(n, argu, false, stmt.get_type());
+        this.printNode(n, symt, true, null);
+
+        n.f0.accept(this, symt);
+        TypeInstance name = n.f1.accept(this, symt);
+        n.f2.accept(this, symt);
+        n.f3.accept(this, symt);
+        n.f4.accept(this, symt);
+        n.f5.accept(this, symt);
+        n.f6.accept(this, symt);
+        n.f7.accept(this, symt);
+        n.f8.accept(this, symt);
+        n.f9.accept(this, symt);
+        n.f10.accept(this, symt);
+        // TypeInstance args = n.f11.accept(this, symt); // FIXME Type in the main class declaration uses an illegal minijava type?
+        n.f12.accept(this, symt);
+        n.f13.accept(this, symt);
+        TypeInstance var_dec = n.f14.accept(this, symt);
+        TypeInstance stmt = n.f15.accept(this, symt);
+        n.f16.accept(this, symt);
+        n.f17.accept(this, symt);
+
+        this.printNode(n, symt, false, stmt.getType());
         --this.offset;
         return stmt;
     }
@@ -192,13 +192,13 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f0 -> ClassDeclaration()
      *     | ClassExtendsDeclaration()
      */
-    public TypeInstance visit(TypeDeclaration n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(TypeDeclaration n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        TypeInstance ret = n.f0.accept(this, argu);
+        TypeInstance ret = n.f0.accept(this, symt);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -211,23 +211,23 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f4 -> ( MethodDeclaration() )*
      * f5 -> "}"
      */
-    public TypeInstance visit(ClassDeclaration n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(ClassDeclaration n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
-
-        n.f0.accept(this, argu);
-        TypeInstance id = n.f1.accept(this, argu);
-        n.f2.accept(this, argu);
-        TypeInstance vars = n.f3.accept(this, argu);
-        TypeInstance mehs = n.f4.accept(this, argu);
-        n.f5.accept(this, argu);
-        TypeInstance ret = (id.get_type() == TypeEnum.classname &&
-                            vars.has_checked() &&
-                            mehs.has_checked()) ?
+        this.printNode(n, symt, true, null);
+
+        n.f0.accept(this, symt);
+        TypeInstance id = n.f1.accept(this, symt);
+        n.f2.accept(this, symt);
+        TypeInstance vars = n.f3.accept(this, symt);
+        TypeInstance mehs = n.f4.accept(this, symt);
+        n.f5.accept(this, symt);
+        TypeInstance ret = (id.getType() == TypeEnum.classname &&
+                            vars.hasChecked() &&
+                            mehs.hasChecked()) ?
             new TypeInstance(null, TypeEnum.CHECK) :
             new TypeInstance(null, TypeEnum.ERROR);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -242,25 +242,25 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f6 -> ( MethodDeclaration() )*
      * f7 -> "}"
      */
-    public TypeInstance visit(ClassExtendsDeclaration n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(ClassExtendsDeclaration n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
-
-        n.f0.accept(this, argu);
-        TypeInstance id = n.f1.accept(this, argu);
-        n.f2.accept(this, argu);
-        TypeInstance ext = n.f3.accept(this, argu);
-        n.f4.accept(this, argu);
-        TypeInstance vars = n.f5.accept(this, argu);
-        TypeInstance mehs = n.f6.accept(this, argu);
-        n.f7.accept(this, argu);
-        TypeInstance ret = (id.get_type() == TypeEnum.classname &&
-                            vars.has_checked() &&
-                            mehs.has_checked()) ?
+        this.printNode(n, symt, true, null);
+
+        n.f0.accept(this, symt);
+        TypeInstance id = n.f1.accept(this, symt);
+        n.f2.accept(this, symt);
+        TypeInstance ext = n.f3.accept(this, symt);
+        n.f4.accept(this, symt);
+        TypeInstance vars = n.f5.accept(this, symt);
+        TypeInstance mehs = n.f6.accept(this, symt);
+        n.f7.accept(this, symt);
+        TypeInstance ret = (id.getType() == TypeEnum.classname &&
+                            vars.hasChecked() &&
+                            mehs.hasChecked()) ?
             new TypeInstance(null, TypeEnum.CHECK) :
             new TypeInstance(null, TypeEnum.ERROR);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -271,15 +271,15 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f1 -> Identifier()
      * f2 -> ";"
      */
-    public TypeInstance visit(VarDeclaration n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(VarDeclaration n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        TypeInstance ret = n.f0.accept(this, argu);
-        n.f1.accept(this, argu);
-        n.f2.accept(this, argu);
+        TypeInstance ret = n.f0.accept(this, symt);
+        n.f1.accept(this, symt);
+        n.f2.accept(this, symt);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -300,29 +300,29 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f11 -> ";"
      * f12 -> "}"
      */
-    public TypeInstance visit(MethodDeclaration n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(MethodDeclaration n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
-
-        n.f0.accept(this, argu);
-        TypeInstance ret_type = n.f1.accept(this, argu);
-        n.f2.accept(this, argu);
-        n.f3.accept(this, argu);
-        n.f4.accept(this, argu);
-        n.f5.accept(this, argu);
-        n.f6.accept(this, argu);
-        n.f7.accept(this, argu);
-        TypeInstance stmt = n.f8.accept(this, argu);
-        n.f9.accept(this, argu);
-        TypeInstance retur = n.f10.accept(this, argu);
-        n.f11.accept(this, argu);
-        n.f12.accept(this, argu);
-        TypeInstance ret = (stmt.same_type(ret_type) &&
-                            stmt.has_checked()) ?
+        this.printNode(n, symt, true, null);
+
+        n.f0.accept(this, symt);
+        TypeInstance ret_type = n.f1.accept(this, symt);
+        n.f2.accept(this, symt);
+        n.f3.accept(this, symt);
+        n.f4.accept(this, symt);
+        n.f5.accept(this, symt);
+        n.f6.accept(this, symt);
+        n.f7.accept(this, symt);
+        TypeInstance stmt = n.f8.accept(this, symt);
+        n.f9.accept(this, symt);
+        TypeInstance retur = n.f10.accept(this, symt);
+        n.f11.accept(this, symt);
+        n.f12.accept(this, symt);
+        TypeInstance ret = (stmt.sameType(ret_type) &&
+                            stmt.hasChecked()) ?
             new TypeInstance(null, TypeEnum.CHECK) :
             new TypeInstance(null, TypeEnum.ERROR);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -331,19 +331,19 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f0 -> FormalParameter()
      * f1 -> ( FormalParameterRest() )*
      */
-    public TypeInstance visit(FormalParameterList n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(FormalParameterList n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
         TypeInstance _ret=null;
-        TypeInstance para1 = n.f0.accept(this, argu);
-        TypeInstance parar = n.f1.accept(this, argu);
-        TypeInstance ret = (para1.has_checked() &&
-                            parar.has_checked()) ?
+        TypeInstance para1 = n.f0.accept(this, symt);
+        TypeInstance parar = n.f1.accept(this, symt);
+        TypeInstance ret = (para1.hasChecked() &&
+                            parar.hasChecked()) ?
             new TypeInstance(null, TypeEnum.CHECK) :
             new TypeInstance(null, TypeEnum.ERROR);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -352,14 +352,14 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f0 -> Type()
      * f1 -> Identifier()
      */
-    public TypeInstance visit(FormalParameter n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(FormalParameter n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        TypeInstance ret = n.f0.accept(this, argu);
-        n.f1.accept(this, argu);
+        TypeInstance ret = n.f0.accept(this, symt);
+        n.f1.accept(this, symt);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -368,14 +368,14 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f0 -> ","
      * f1 -> FormalParameter()
      */
-    public TypeInstance visit(FormalParameterRest n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(FormalParameterRest n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        n.f0.accept(this, argu);
-        TypeInstance ret = n.f1.accept(this, argu);
+        n.f0.accept(this, symt);
+        TypeInstance ret = n.f1.accept(this, symt);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -386,13 +386,13 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      *     | IntegerType()
      *     | Identifier()
      */
-    public TypeInstance visit(Type n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(Type n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        TypeInstance ret = n.f0.accept(this, argu);
+        TypeInstance ret = n.f0.accept(this, symt);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -402,13 +402,13 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f1 -> "["
      * f2 -> "]"
      */
-    public TypeInstance visit(ArrayType n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(ArrayType n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
         TypeInstance ret = new TypeInstance(null, TypeEnum.intarray);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -416,13 +416,13 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
     /**
      * f0 -> "boolean"
      */
-    public TypeInstance visit(BooleanType n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(BooleanType n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
         TypeInstance ret = new TypeInstance(null, TypeEnum.bool);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -430,13 +430,13 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
     /**
      * f0 -> "int"
      */
-    public TypeInstance visit(IntegerType n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(IntegerType n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
         TypeInstance ret =      new TypeInstance(null, TypeEnum.integer);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -449,13 +449,13 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      *     | WhileStatement()
      *     | PrintStatement()
      */
-    public TypeInstance visit(Statement n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(Statement n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        TypeInstance ret =      n.f0.accept(this, argu);
+        TypeInstance ret =      n.f0.accept(this, symt);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -465,15 +465,15 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f1 -> ( Statement() )*
      * f2 -> "}"
      */
-    public TypeInstance visit(Block n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(Block n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        n.f0.accept(this, argu);
-        TypeInstance ret = n.f1.accept(this, argu);
-        n.f2.accept(this, argu);
+        n.f0.accept(this, symt);
+        TypeInstance ret = n.f1.accept(this, symt);
+        n.f2.accept(this, symt);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -488,19 +488,19 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f2 -> Expression()
      * f3 -> ";"
      */
-    public TypeInstance visit(AssignmentStatement n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(AssignmentStatement n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        TypeInstance lhs = n.f0.accept(this, argu);
-        n.f1.accept(this, argu);
-        TypeInstance rhs = n.f2.accept(this, argu);
-        n.f3.accept(this, argu);
-        TypeInstance ret = (lhs.same_type(rhs)) ?
+        TypeInstance lhs = n.f0.accept(this, symt);
+        n.f1.accept(this, symt);
+        TypeInstance rhs = n.f2.accept(this, symt);
+        n.f3.accept(this, symt);
+        TypeInstance ret = (lhs.sameType(rhs)) ?
             new TypeInstance(null, TypeEnum.CHECK) :
             new TypeInstance(null, TypeEnum.ERROR);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -517,24 +517,24 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f5 -> Expression()
      * f6 -> ";"
      */
-    public TypeInstance visit(ArrayAssignmentStatement n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(ArrayAssignmentStatement n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
-
-        TypeInstance id = n.f0.accept(this, argu);
-        n.f1.accept(this, argu);
-        TypeInstance index = n.f2.accept(this, argu);
-        n.f3.accept(this, argu);
-        n.f4.accept(this, argu);
-        TypeInstance value = n.f5.accept(this, argu);
-        n.f6.accept(this, argu);
-        TypeInstance ret =      (id.get_type() == TypeEnum.intarray &&
-                                 index.get_type() == TypeEnum.integer &&
-                                 value.get_type() == TypeEnum.integer) ?
+        this.printNode(n, symt, true, null);
+
+        TypeInstance id = n.f0.accept(this, symt);
+        n.f1.accept(this, symt);
+        TypeInstance index = n.f2.accept(this, symt);
+        n.f3.accept(this, symt);
+        n.f4.accept(this, symt);
+        TypeInstance value = n.f5.accept(this, symt);
+        n.f6.accept(this, symt);
+        TypeInstance ret =      (id.getType() == TypeEnum.intarray &&
+                                 index.getType() == TypeEnum.integer &&
+                                 value.getType() == TypeEnum.integer) ?
             new TypeInstance(null, TypeEnum.CHECK) :
             new TypeInstance(null, TypeEnum.ERROR);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -550,24 +550,24 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f5 -> "else"
      * f6 -> Statement()
      */
-    public TypeInstance visit(IfStatement n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(IfStatement n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
-
-        n.f0.accept(this, argu);
-        n.f1.accept(this, argu);
-        TypeInstance expr = n.f2.accept(this, argu);
-        n.f3.accept(this, argu);
-        TypeInstance stmt1 = n.f4.accept(this, argu);
-        n.f5.accept(this, argu);
-        TypeInstance stmt2 = n.f6.accept(this, argu);
-        TypeInstance ret = (expr.get_type() == TypeEnum.bool &&
-                            stmt1.get_type() == stmt2.get_type() &&
-                            stmt1.has_checked()) ?
+        this.printNode(n, symt, true, null);
+
+        n.f0.accept(this, symt);
+        n.f1.accept(this, symt);
+        TypeInstance expr = n.f2.accept(this, symt);
+        n.f3.accept(this, symt);
+        TypeInstance stmt1 = n.f4.accept(this, symt);
+        n.f5.accept(this, symt);
+        TypeInstance stmt2 = n.f6.accept(this, symt);
+        TypeInstance ret = (expr.getType() == TypeEnum.bool &&
+                            stmt1.getType() == stmt2.getType() &&
+                            stmt1.hasChecked()) ?
             new TypeInstance(null, TypeEnum.CHECK) :
             new TypeInstance(null, TypeEnum.ERROR);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
 
@@ -582,21 +582,21 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f3 -> ")"
      * f4 -> Statement()
      */
-    public TypeInstance visit(WhileStatement n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(WhileStatement n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
-
-        n.f0.accept(this, argu);
-        n.f1.accept(this, argu);
-        TypeInstance expr = n.f2.accept(this, argu);
-        n.f3.accept(this, argu);
-        TypeInstance stmt = n.f4.accept(this, argu);
-        TypeInstance ret = (expr.get_type() == TypeEnum.bool &&
-                            stmt.has_checked()) ?
+        this.printNode(n, symt, true, null);
+
+        n.f0.accept(this, symt);
+        n.f1.accept(this, symt);
+        TypeInstance expr = n.f2.accept(this, symt);
+        n.f3.accept(this, symt);
+        TypeInstance stmt = n.f4.accept(this, symt);
+        TypeInstance ret = (expr.getType() == TypeEnum.bool &&
+                            stmt.hasChecked()) ?
             new TypeInstance(null, TypeEnum.CHECK) :
             new TypeInstance(null, TypeEnum.ERROR);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -610,20 +610,20 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f3 -> ")"
      * f4 -> ";"
      */
-    public TypeInstance visit(PrintStatement n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(PrintStatement n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
-
-        n.f0.accept(this, argu);
-        n.f1.accept(this, argu);
-        TypeInstance ret = n.f2.accept(this, argu);
-        n.f3.accept(this, argu);
-        n.f4.accept(this, argu);
-        ret = (ret.get_type() == TypeEnum.integer) ?
+        this.printNode(n, symt, true, null);
+
+        n.f0.accept(this, symt);
+        n.f1.accept(this, symt);
+        TypeInstance ret = n.f2.accept(this, symt);
+        n.f3.accept(this, symt);
+        n.f4.accept(this, symt);
+        ret = (ret.getType() == TypeEnum.integer) ?
             new TypeInstance(null, TypeEnum.CHECK) :
             new TypeInstance(null, TypeEnum.ERROR);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -639,13 +639,13 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      *     | MessageSend()
      *     | PrimaryExpression()
      */
-    public TypeInstance visit(Expression n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(Expression n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        TypeInstance ret = n.f0.accept(this, argu);
+        TypeInstance ret = n.f0.accept(this, symt);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -657,19 +657,19 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f1 -> "&&"
      * f2 -> PrimaryExpression()
      */
-    public TypeInstance visit(AndExpression n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(AndExpression n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        TypeInstance oper1 = n.f0.accept(this, argu);
-        n.f1.accept(this, argu);
-        TypeInstance oper2 = n.f2.accept(this, argu);
-        TypeInstance ret = (oper1.get_type() == TypeEnum.bool &&
-                            oper2.get_type() == TypeEnum.bool) ?
+        TypeInstance oper1 = n.f0.accept(this, symt);
+        n.f1.accept(this, symt);
+        TypeInstance oper2 = n.f2.accept(this, symt);
+        TypeInstance ret = (oper1.getType() == TypeEnum.bool &&
+                            oper2.getType() == TypeEnum.bool) ?
             new TypeInstance(null, TypeEnum.bool) :
             new TypeInstance(null, TypeEnum.ERROR);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -681,19 +681,19 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f1 -> "<"
      * f2 -> PrimaryExpression()
      */
-    public TypeInstance visit(CompareExpression n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(CompareExpression n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        TypeInstance oper1 = n.f0.accept(this, argu);
-        n.f1.accept(this, argu);
-        TypeInstance oper2 = n.f2.accept(this, argu);
-        TypeInstance ret = (oper1.get_type() == TypeEnum.integer &&
-                            oper2.get_type() == TypeEnum.integer) ?
+        TypeInstance oper1 = n.f0.accept(this, symt);
+        n.f1.accept(this, symt);
+        TypeInstance oper2 = n.f2.accept(this, symt);
+        TypeInstance ret = (oper1.getType() == TypeEnum.integer &&
+                            oper2.getType() == TypeEnum.integer) ?
             new TypeInstance(null, TypeEnum.bool) :
             new TypeInstance(null, TypeEnum.ERROR);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -705,19 +705,19 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f1 -> "+"
      * f2 -> PrimaryExpression()
      */
-    public TypeInstance visit(PlusExpression n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(PlusExpression n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        TypeInstance oper1 = n.f0.accept(this, argu);
-        n.f1.accept(this, argu);
-        TypeInstance oper2 = n.f2.accept(this, argu);
-        TypeInstance ret = (oper1.get_type() == TypeEnum.integer &&
-                            oper2.get_type() == TypeEnum.integer) ?
+        TypeInstance oper1 = n.f0.accept(this, symt);
+        n.f1.accept(this, symt);
+        TypeInstance oper2 = n.f2.accept(this, symt);
+        TypeInstance ret = (oper1.getType() == TypeEnum.integer &&
+                            oper2.getType() == TypeEnum.integer) ?
             new TypeInstance(null, TypeEnum.integer) :
             new TypeInstance(null, TypeEnum.ERROR);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -729,19 +729,19 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f1 -> "-"
      * f2 -> PrimaryExpression()
      */
-    public TypeInstance visit(MinusExpression n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(MinusExpression n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        TypeInstance oper1 = n.f0.accept(this, argu);
-        n.f1.accept(this, argu);
-        TypeInstance oper2 = n.f2.accept(this, argu);
-        TypeInstance ret = (oper1.get_type() == TypeEnum.integer &&
-                            oper2.get_type() == TypeEnum.integer) ?
+        TypeInstance oper1 = n.f0.accept(this, symt);
+        n.f1.accept(this, symt);
+        TypeInstance oper2 = n.f2.accept(this, symt);
+        TypeInstance ret = (oper1.getType() == TypeEnum.integer &&
+                            oper2.getType() == TypeEnum.integer) ?
             new TypeInstance(null, TypeEnum.integer) :
             new TypeInstance(null, TypeEnum.ERROR);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -753,19 +753,19 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f1 -> "*"
      * f2 -> PrimaryExpression()
      */
-    public TypeInstance visit(TimesExpression n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(TimesExpression n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        TypeInstance oper1 = n.f0.accept(this, argu);
-        n.f1.accept(this, argu);
-        TypeInstance oper2 = n.f2.accept(this, argu);
-        TypeInstance ret = (oper1.get_type() == TypeEnum.integer &&
-                            oper2.get_type() == TypeEnum.integer) ?
+        TypeInstance oper1 = n.f0.accept(this, symt);
+        n.f1.accept(this, symt);
+        TypeInstance oper2 = n.f2.accept(this, symt);
+        TypeInstance ret = (oper1.getType() == TypeEnum.integer &&
+                            oper2.getType() == TypeEnum.integer) ?
             new TypeInstance(null, TypeEnum.integer) :
             new TypeInstance(null, TypeEnum.ERROR);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -779,20 +779,20 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f2 -> PrimaryExpression()
      * f3 -> "]"
      */
-    public TypeInstance visit(ArrayLookup n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(ArrayLookup n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
-
-        TypeInstance array = n.f0.accept(this, argu);
-        n.f1.accept(this, argu);
-        TypeInstance index = n.f2.accept(this, argu);
-        n.f3.accept(this, argu);
-        TypeInstance ret = (array.get_type() == TypeEnum.intarray &&
-                            index.get_type() == TypeEnum.integer) ?
+        this.printNode(n, symt, true, null);
+
+        TypeInstance array = n.f0.accept(this, symt);
+        n.f1.accept(this, symt);
+        TypeInstance index = n.f2.accept(this, symt);
+        n.f3.accept(this, symt);
+        TypeInstance ret = (array.getType() == TypeEnum.intarray &&
+                            index.getType() == TypeEnum.integer) ?
             new TypeInstance(null, TypeEnum.integer) :
             new TypeInstance(null, TypeEnum.ERROR);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -804,17 +804,17 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f1 -> "."
      * f2 -> "length"
      */
-    public TypeInstance visit(ArrayLength n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(ArrayLength n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        TypeInstance ret = n.f0.accept(this, argu);
-        n.f1.accept(this, argu);
-        n.f2.accept(this, argu);
-        ret = (ret.get_type() == TypeEnum.intarray) ? new TypeInstance(null, TypeEnum.integer) :
+        TypeInstance ret = n.f0.accept(this, symt);
+        n.f1.accept(this, symt);
+        n.f2.accept(this, symt);
+        ret = (ret.getType() == TypeEnum.intarray) ? new TypeInstance(null, TypeEnum.integer) :
             new TypeInstance(null, TypeEnum.ERROR);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -830,16 +830,16 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f4 -> ( ExpressionList() )?
      * f5 -> ")"
      */
-    public TypeInstance visit(MessageSend n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(MessageSend n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
-
-        n.f0.accept(this, argu);
-        n.f1.accept(this, argu);
-        n.f2.accept(this, argu);
-        n.f3.accept(this, argu);
-        n.f4.accept(this, argu);
-        n.f5.accept(this, argu);
+        this.printNode(n, symt, true, null);
+
+        n.f0.accept(this, symt);
+        n.f1.accept(this, symt);
+        n.f2.accept(this, symt);
+        n.f3.accept(this, symt);
+        n.f4.accept(this, symt);
+        n.f5.accept(this, symt);
         --this.offset;
         return new TypeInstance(null, TypeEnum.ERROR);
     }
@@ -849,18 +849,18 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f0 -> Expression()
      * f1 -> ( ExpressionRest() )*
      */
-    public TypeInstance visit(ExpressionList n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(ExpressionList n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        TypeInstance expr1 = n.f0.accept(this, argu);
-        TypeInstance exprr =  n.f1.accept(this, argu);
-        TypeInstance ret = (expr1.has_checked() &&
-                            exprr.has_checked()) ?
+        TypeInstance expr1 = n.f0.accept(this, symt);
+        TypeInstance exprr =  n.f1.accept(this, symt);
+        TypeInstance ret = (expr1.hasChecked() &&
+                            exprr.hasChecked()) ?
             new TypeInstance(null, TypeEnum.CHECK) :
             new TypeInstance(null, TypeEnum.ERROR);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -869,14 +869,14 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f0 -> ","
      * f1 -> Expression()
      */
-    public TypeInstance visit(ExpressionRest n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(ExpressionRest n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        n.f0.accept(this, argu);
-        TypeInstance ret = n.f1.accept(this, argu);
+        n.f0.accept(this, symt);
+        TypeInstance ret = n.f1.accept(this, symt);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -892,13 +892,13 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      *     | NotExpression()
      *     | BracketExpression()
      */
-    public TypeInstance visit(PrimaryExpression n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(PrimaryExpression n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        TypeInstance ret = n.f0.accept(this, argu);
+        TypeInstance ret = n.f0.accept(this, symt);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -909,11 +909,11 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      *
      * f0 -> <INTEGER_LITERAL>
      */
-    public TypeInstance visit(IntegerLiteral n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(IntegerLiteral n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        this.printNode(n, argu, false, TypeEnum.integer);
+        this.printNode(n, symt, false, TypeEnum.integer);
         --this.offset;
         return new TypeInstance(null, TypeEnum.integer);
     }
@@ -923,11 +923,11 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      *
      * f0 -> "true"
      */
-    public TypeInstance visit(TrueLiteral n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(TrueLiteral n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        this.printNode(n, argu, false, TypeEnum.bool);
+        this.printNode(n, symt, false, TypeEnum.bool);
         --this.offset;
         return new TypeInstance(null, TypeEnum.bool);
     }
@@ -937,11 +937,11 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      *
      * f0 -> "false"
      */
-    public TypeInstance visit(FalseLiteral n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(FalseLiteral n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        this.printNode(n, argu, false, TypeEnum.bool);
+        this.printNode(n, symt, false, TypeEnum.bool);
         --this.offset;
         return new TypeInstance(null, TypeEnum.bool);
     }
@@ -952,16 +952,17 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      *
      * f0 -> <IDENTIFIER>
      */
-    public TypeInstance visit(Identifier n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(Identifier n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        TypeInstance ret = (argu.get(n.f0.tokenImage) != null) ?
-            new TypeInstance(argu.get(n.f0.tokenImage).get_name(),
-                             argu.get(n.f0.tokenImage).get_type()) :
+        TypeInstance type;
+        TypeInstance ret = ((type = symt.getType(n.f0.tokenImage)) != null) ?
+            new TypeInstance(type.getName(),
+                             type.getType()) :
             new TypeInstance(null, TypeEnum.ERROR);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -972,14 +973,14 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      *
      * f0 -> "this"
      */
-    public TypeInstance visit(ThisExpression n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(ThisExpression n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        n.f0.accept(this, argu);
+        n.f0.accept(this, symt);
         TypeInstance ret = new TypeInstance(null, TypeEnum.CHECK);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -993,19 +994,19 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f3 -> Expression()
      * f4 -> "]"
      */
-    public TypeInstance visit(ArrayAllocationExpression n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(ArrayAllocationExpression n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
-
-        n.f0.accept(this, argu);
-        n.f1.accept(this, argu);
-        n.f2.accept(this, argu);
-        TypeInstance ret = n.f3.accept(this, argu);
-        n.f4.accept(this, argu);
-        ret = (ret.get_type() == TypeEnum.integer) ? new TypeInstance(null, TypeEnum.intarray) :
+        this.printNode(n, symt, true, null);
+
+        n.f0.accept(this, symt);
+        n.f1.accept(this, symt);
+        n.f2.accept(this, symt);
+        TypeInstance ret = n.f3.accept(this, symt);
+        n.f4.accept(this, symt);
+        ret = (ret.getType() == TypeEnum.integer) ? new TypeInstance(null, TypeEnum.intarray) :
             new TypeInstance(null, TypeEnum.ERROR);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -1019,16 +1020,16 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f2 -> "("
      * f3 -> ")"
      */
-    public TypeInstance visit(AllocationExpression n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(AllocationExpression n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        n.f0.accept(this, argu);
-        TypeInstance ret = n.f1.accept(this, argu);
-        n.f2.accept(this, argu);
-        n.f3.accept(this, argu);
+        n.f0.accept(this, symt);
+        TypeInstance ret = n.f1.accept(this, symt);
+        n.f2.accept(this, symt);
+        n.f3.accept(this, symt);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }
@@ -1039,16 +1040,16 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f0 -> "!"
      * f1 -> Expression()
      */
-    public TypeInstance visit(NotExpression n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(NotExpression n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        n.f0.accept(this, argu);
-        TypeInstance ret = n.f1.accept(this, argu);
+        n.f0.accept(this, symt);
+        TypeInstance ret = n.f1.accept(this, symt);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
-        return (ret.get_type() == TypeEnum.bool) ? ret : new TypeInstance(null, TypeEnum.ERROR);
+        return (ret.getType() == TypeEnum.bool) ? ret : new TypeInstance(null, TypeEnum.ERROR);
     }
 
     /**
@@ -1058,15 +1059,15 @@ public class TypeCheckSimp extends GJDepthFirst<TypeInstance,HashMap<String,Abst
      * f1 -> Expression()
      * f2 -> ")"
      */
-    public TypeInstance visit(BracketExpression n, HashMap<String,AbstractInstance> argu) {
+    public TypeInstance visit(BracketExpression n, SymbolTable symt) {
         ++this.offset;
-        this.printNode(n, argu, true, null);
+        this.printNode(n, symt, true, null);
 
-        n.f0.accept(this, argu);
-        TypeInstance ret = n.f1.accept(this, argu);
-        n.f2.accept(this, argu);
+        n.f0.accept(this, symt);
+        TypeInstance ret = n.f1.accept(this, symt);
+        n.f2.accept(this, symt);
 
-        this.printNode(n, argu, false, ret.get_type());
+        this.printNode(n, symt, false, ret.getType());
         --this.offset;
         return ret;
     }