fixed "this" bugs

Author: minirop

environment.php

@@ -48,7 +48,7 @@ public function get(Token $name)
 			return $this->enclosing->get($name);
 		}
 
-		throw new ParseError("Undef ".$name->literal);
+		throw new RuntimeError($name, "Undefined variable '".$name->literal."'.");
 	}
 
 	public function assign(Token $name, $value)
@@ -65,6 +65,6 @@ public function assign(Token $name, $value)
 			return;
 		}
 
-		throw new ParseError("Undef ".$name->literal);
+		throw new RuntimeError($name, "Undefined variable '".$name->literal."'.");
 	}
 }

interpreter.php

@@ -76,11 +76,6 @@ private function setLocal(Expr $expr, $value)
 		$this->locals[] = [$expr, $value];
 	}
 
-	public function print(Expr $expr)
-	{
-		echo "lol\n";
-	}
-
 	public function visitAssignExpr(AssignExpr $expr)
 	{
 		$value = $this->evaluate($expr->value);
@@ -219,7 +214,7 @@ public function visitSuperExpr(SuperExpr $expr)
 
 	public function visitThisExpr(ThisExpr $expr)
 	{
-		return lookUpVariable($expr->keyword, $expr);
+		return $this->lookUpVariable($expr->keyword, $expr);
 	}
 
 	public function visitUnaryExpr(UnaryExpr $expr)

resolver.php

@@ -114,7 +114,7 @@ public function visitClassStmt(ClassStmt $stmt)
 		$this->currentClass = TYPE_CLASS;
 
 		$this->beginScope();
-		$this->scopes[count($this->scopes)]["this"] = true;
+		$this->scopes[count($this->scopes) - 1]["this"] = true;
 
 		foreach ($stmt->methods as $method)
 		{

scanner.php

@@ -193,7 +193,6 @@ private function identifier()
 		if (isset(self::$keywords[$str]))
 		{
 			$type = self::$keywords[$str];
-			$str = null;
 		}
 
 		$this->addToken($type, $str);

std/clock.php

@@ -12,4 +12,9 @@ public function call(\Interpreter $interpreter, array $arguments)
 	{
 		return time();
 	}
+
+	public function __tostring()
+	{
+		return 'Std\Clock';
+	}
 }