Merge pull request #1195 from rollup/gh-1061

statically analyse LogicalExpression nodes

src/ast/nodes/LogicalExpression.js

@@ -0,0 +1,19 @@
+import Node from '../Node.js';
+import { UNKNOWN } from '../values.js';
+
+const operators = {
+	'&&': ( left, right ) => left && right,
+	'||': ( left, right ) => left || right
+};
+
+export default class LogicalExpression extends Node {
+	getValue () {
+		const leftValue = this.left.getValue();
+		if ( leftValue === UNKNOWN ) return UNKNOWN;
+
+		const rightValue = this.right.getValue();
+		if ( rightValue === UNKNOWN ) return UNKNOWN;
+
+		return operators[ this.operator ]( leftValue, rightValue );
+	}
+}

src/ast/nodes/index.js

@@ -21,6 +21,7 @@ import Identifier from './Identifier.js';
 import IfStatement from './IfStatement.js';
 import ImportDeclaration from './ImportDeclaration.js';
 import Literal from './Literal.js';
+import LogicalExpression from './LogicalExpression.js';
 import MemberExpression from './MemberExpression.js';
 import NewExpression from './NewExpression.js';
 import ObjectExpression from './ObjectExpression.js';
@@ -59,6 +60,7 @@ export default {
 	IfStatement,
 	ImportDeclaration,
 	Literal,
+	LogicalExpression,
 	MemberExpression,
 	NewExpression,
 	ObjectExpression,

test/form/skips-dead-branches-i/_config.js

@@ -1,3 +1,3 @@
 module.exports = {
-	description: 'skips a dead branch (h)'
+	description: 'skips a dead branch (i)'
 };

test/form/skips-dead-branches-j/_config.js

@@ -0,0 +1,3 @@
+module.exports = {
+	description: 'skips a dead branch (j)'
+};

test/form/skips-dead-branches-j/_expected/amd.js

@@ -0,0 +1,7 @@
+define(function () { 'use strict';
+
+	{
+		console.log( 'true' );
+	}
+
+});

test/form/skips-dead-branches-j/_expected/cjs.js

@@ -0,0 +1,5 @@
+'use strict';
+
+{
+	console.log( 'true' );
+}

test/form/skips-dead-branches-j/_expected/es.js

@@ -0,0 +1,3 @@
+{
+	console.log( 'true' );
+}

test/form/skips-dead-branches-j/_expected/iife.js

@@ -0,0 +1,8 @@
+(function () {
+	'use strict';
+
+	{
+		console.log( 'true' );
+	}
+
+}());

test/form/skips-dead-branches-j/_expected/umd.js

@@ -0,0 +1,11 @@
+(function (global, factory) {
+	typeof exports === 'object' && typeof module !== 'undefined' ? factory() :
+	typeof define === 'function' && define.amd ? define(factory) :
+	(factory());
+}(this, (function () { 'use strict';
+
+	{
+		console.log( 'true' );
+	}
+
+})));

test/form/skips-dead-branches-j/main.js

@@ -0,0 +1,5 @@
+if ( true && true ) {
+	console.log( 'true' );
+} else {
+	console.log( 'false' );
+}