Add function calls

1 files changed, 27 insertions, 3 deletions

diff --git a/src/com/craftinginterpreters/lox/Interpreter.java b/src/com/craftinginterpreters/lox/Interpreter.java
index f752e77..407c537 100644
--- a/src/com/craftinginterpreters/lox/Interpreter.java
+++ b/src/com/craftinginterpreters/lox/Interpreter.java
@@ -4,7 +4,23 @@ import java.util.ArrayList;
 import java.util.List;
 
 class Interpreter implements Expr.Visitor<Object>, Stmt.Visitor<Void> {
-    private Environment environment = new Environment();
+    final Environment globals = new Environment();
+    private Environment environment = globals;
+
+    Interpreter() {
+        globals.define("clock", new LoxCallable() {
+                @Override
+                public int arity() { return 0; }
+
+                @Override
+                public Object call(Interpreter interpreter, List<Object> arguments) {
+                    return (double)System.currentTimeMillis() / 1000.0;
+                }
+
+                @Override
+                public String toString() { return "<native fn>"; }
+            });
+    }
 
     @Override
     public Object visitLiteralExpr(Expr.Literal expr) {
@@ -105,7 +121,7 @@ class Interpreter implements Expr.Visitor<Object>, Stmt.Visitor<Void> {
         stmt.accept(this);
     }
 
-    private void executeBlock(List<Stmt> statements, Environment environment) {
+    public void executeBlock(List<Stmt> statements, Environment environment) {
         Environment previous = this.environment;
 
         try {
@@ -132,6 +148,13 @@ class Interpreter implements Expr.Visitor<Object>, Stmt.Visitor<Void> {
     }
 
     @Override
+    public Void visitFunctionStmt(Stmt.Function stmt) {
+        LoxFunction function = new LoxFunction(stmt);
+        environment.define(stmt.name.lexeme, function);
+        return null;
+    }
+
+    @Override
     public Void visitIfStmt(Stmt.If stmt) {
         if (isTruthy(evaluate(stmt.condition))) {
             execute(stmt.thenBranch);
@@ -238,7 +261,8 @@ class Interpreter implements Expr.Visitor<Object>, Stmt.Visitor<Void> {
 
         LoxCallable function = (LoxCallable) callee;
         if (arguments.size() != function.arity()) {
-            throw new RuntimeError(expr.paren, "Expected " + function.arity() + " arguments but got " + arguments.size() + ".");
+            throw new RuntimeError(expr.paren,
+                    "Expected " + function.arity() + " arguments but got " + arguments.size() + ".");
         }
 
         return function.call(this, arguments);