runtime lexical/dynamic toggling

src/Interp/ExpressionInterp.js

@@ -12,6 +12,8 @@ import {
  applyClosure,
 } from '../Closure';
 
+import Options from '../Options';
+
 import { interp as statementInterp } from './StatementInterp';
 
 const interp = (exp, env) => {
@@ -52,7 +54,7 @@ const interp = (exp, env) => {
  const closure = interp(callee, env);
  const vals = rawArgs.map((obj) => interp(obj, env));
 
- return applyClosure(interp, closure, vals, env);
+ return applyClosure(interp, closure, vals, env, Options.isLexical);
  }
 
  case 'UnaryExpression': {

src/Interp/__tests__/ExpressionInterp-test.js

@@ -1,8 +1,11 @@
 'use strict';
 
 jest.unmock('../../Parser')
- .unmock('../ExpressionInterp').unmock('../StatementInterp')
- .unmock('../../Environment').unmock('../../Closure');
+ .unmock('../ExpressionInterp')
+ .unmock('../StatementInterp')
+ .unmock('../../Environment')
+ .unmock('../../Closure')
+ .unmock('../../Options');
 
 const { interp } = require('../ExpressionInterp');
 const { parse } = require('../../Parser');
@@ -11,7 +14,8 @@ const {
  extendEnv,
 } = require('../../Environment');
 
-import { makeClosure } from '../../Closure';
+const { makeClosure } = require('../../Closure');
+const Options = require('../../Options').default;
 
 const parseAndgetExp = (code) => parse(code).body[0].expression;
 
@@ -205,6 +209,34 @@ describe('Interp', () => {
  })());
  });
 
+ it('should support dynamic scope', () => {
+ Options.isLexical = false;
+
+ expect(interpExp(`(() => {
+ const adder = (x) => (y) => x + y;
+ const x = 100;
+ const add3ButActuallyAdd100 = adder(3);
+ return add3ButActuallyAdd100(5);
+ })()`)).toBe(100 + 5);
+
+ expect(interpExp(`(() => {
+ const adder = (x) => (y) => x + y;
+ const x = 100;
+ const add3ButActuallyAdd100 = adder(3);
+ return add3ButActuallyAdd100(5);
+ })()`)).toBe(100 + 5);
+
+ expect(interpExp(`(() => {
+ const x = 100;
+ const y = 200;
+ const adder = (x) => (y) => x + y;
+ const add3 = adder(3);
+ return add3(39);
+ })()`)).toBe(100 + 39);
+
+ Options.isLexical = true;
+ });
+
 
  // it('IfStatement', () => {
  // expect(interpExp(`(() => {

src/Options.js

@@ -0,0 +1,9 @@
+/*
+ * This guy allows us to toggle the lexical/dynamic behavior at runtime.
+ */
+
+const Options = {
+ isLexical: true,
+};
+
+export default Options;