coverage passed!

src/main/java/chocopy/pa2/TypeChecker.java

@@ -53,7 +53,10 @@ public class TypeChecker extends AbstractNodeAnalyzer<SymbolType> {
     public SymbolType analyze(Program program) {
         if(isBuildingSym) {
             sym.put("object", OBJECT_TYPE);
-            sym.put("print", new FuncType(new ArrayList<ValueType>(Arrays.asList(OBJECT_TYPE)), NONE_TYPE));
+            sym.put("print", new FuncType(Arrays.asList(OBJECT_TYPE), NONE_TYPE));
+            // sym.put("len", new FuncType(Arrays.asList(new ListValueType(OBJECT_TYPE)), INT_TYPE));
+            // SILLY FUCKING EXAMPLE PROGRAM SAYS: len(object). OK OK OK I'll DO IT.
+            sym.put("len", new FuncType(Arrays.asList(OBJECT_TYPE), INT_TYPE));
         }
 
         for (Declaration decl : program.declarations) {
@@ -375,7 +378,6 @@ public class TypeChecker extends AbstractNodeAnalyzer<SymbolType> {
                 // fallthrough: do left-right match check.
             case "==":
             case "!=":
-            case "is":
                 if(!left_type.equals(right_type)) {
                     if(left_type.isListType() && right_type.isListType()) {
                         System.out.println("debug: left_type=" + left_type.toString() + ", right=" + right_type.toString());
@@ -385,6 +387,8 @@ public class TypeChecker extends AbstractNodeAnalyzer<SymbolType> {
                     err(node, "Syntax Error: binary operator operand type mismatch: left=" + left_type.toString() + ", right=" + right_type.toString());
                 }
                 break;
+            case "is":
+                break;
             default:
                 err(node, "Syntax Error: binary operator operand type not supported.");
                 return OBJECT_TYPE;
@@ -629,20 +633,25 @@ public class TypeChecker extends AbstractNodeAnalyzer<SymbolType> {
             return true;
         if(from.equals(EMPTY_TYPE)) from = new ListValueType(NONE_TYPE);
         if(to.equals(EMPTY_TYPE)) to = new ListValueType(NONE_TYPE);
-        if(!from.isListType() || !to.isListType())  {
-            // Cast class to parent
-            if(from instanceof ClassValueType && to instanceof ClassValueType) {
-                if(_typeConvertible_calcClassInheritChainCommonNode((ClassValueType) from, (ClassValueType) to).equals(to))
-                    return true; // Can cast from->to
-            }
-            return from.equals(to);
+
+        if(from.isListType() && to.isListType()) {
+            // Convert list to list:
+            ListValueType lsFrom = (ListValueType) from, lsTo =  (ListValueType) to;
+            if(lsFrom.elementType == null || lsFrom.elementType.equals(NONE_TYPE))
+                return true;
+            return typeConvertible(lsFrom.elementType, lsTo.elementType);
         }
 
-        // Convert list to list:
-        ListValueType lsFrom = (ListValueType) from, lsTo =  (ListValueType) to;
-        if(lsFrom.elementType == null || lsFrom.elementType.equals(NONE_TYPE))
-            return true;
-        return typeConvertible(lsFrom.elementType, lsTo.elementType);
+        if(from.equals(STR_TYPE) && to.isListType()) {
+            // STR -> [STR, ...], so len(list) works to len(str).
+            return typeConvertible(from, ((ListValueType) to).elementType);
+        }
+        // Cast class to parent
+        if(from instanceof ClassValueType && to instanceof ClassValueType) {
+            if(_typeConvertible_calcClassInheritChainCommonNode((ClassValueType) from, (ClassValueType) to).equals(to))
+                return true; // Can cast from->to
+        }
+        return from.equals(to);
     }
     private ClassValueType _typeConvertible_calcClassInheritChainCommonNode(ClassValueType l, ClassValueType r) {
         int l_depth = 1, r_depth = 1;