Functions 10

src/jlox/interpreter.d

@@ -106,7 +106,7 @@ class Interpreter : Stmt.Visitor!void, Expr.Visitor!TValue {
 		evaluate(stmt.expression);
 	}
 	void visit(Stmt.Function stmt){
-		LoxFunction func = new LoxFunction(stmt);
+		LoxFunction func = new LoxFunction(stmt, environment);
 		environment.define(stmt.name.lexeme, TValue.cal(func));
 	}
 	void visit(Stmt.If stmt){

src/jlox/loxfunction.d

@@ -10,11 +10,15 @@ import jlox.util;
 
 class LoxFunction : LoxCallable{
 	private Stmt.Function declaration;
+	private Environment closure;
 	mixin defaultCtor;
+	invariant{
+		assert(declaration && closure);
+	}
 	
 	int arity() => declaration.params.length.to!int;
 	TValue call(Interpreter interpreter, TValue[] arguments){
-		Environment environment = new Environment(interpreter.globals);
+		Environment environment = new Environment(closure);
 		foreach(i; 0 .. declaration.params.length)
 			environment.define(declaration.params[i].lexeme, arguments[i]);
 		try{

test/all.d

@@ -17,5 +17,6 @@ void main(){
 	}
 	assert([ "./lox", "test/fib21.lox" ].execute.output == fib(6765));
 	assert([ "./lox", "test/fib10.lox" ].execute.output == fib(34));
+	assert([ "./lox", "test/closure.lox" ].execute.output == "1\n2\n");
 }
 

test/closure.lox

@@ -0,0 +1,13 @@
+
+fun makeCounter(){
+	var i = 0;
+	fun counter(){
+		return i = i + 1;
+	}
+	return counter;
+}
+
+var counter = makeCounter();
+print counter(); // "1".
+print counter(); // "2".
+