From 47d3daf9a5275e35492e7b3552cfc62838234fff Mon Sep 17 00:00:00 2001
From: Rich-Harris <richard.a.harris@gmail.com>
Date: Thu, 29 Dec 2016 07:56:54 -0500
Subject: [PATCH] statically analyse LogicalExpression nodes (#1061)

---
 src/ast/nodes/LogicalExpression.js            | 19 +++++++++++++++++++
 src/ast/nodes/index.js                        |  2 ++
 test/form/skips-dead-branches-i/_config.js    |  2 +-
 test/form/skips-dead-branches-j/_config.js    |  3 +++
 .../skips-dead-branches-j/_expected/amd.js    |  7 +++++++
 .../skips-dead-branches-j/_expected/cjs.js    |  5 +++++
 .../skips-dead-branches-j/_expected/es.js     |  3 +++
 .../skips-dead-branches-j/_expected/iife.js   |  8 ++++++++
 .../skips-dead-branches-j/_expected/umd.js    | 11 +++++++++++
 test/form/skips-dead-branches-j/main.js       |  5 +++++
 10 files changed, 64 insertions(+), 1 deletion(-)
 create mode 100644 src/ast/nodes/LogicalExpression.js
 create mode 100644 test/form/skips-dead-branches-j/_config.js
 create mode 100644 test/form/skips-dead-branches-j/_expected/amd.js
 create mode 100644 test/form/skips-dead-branches-j/_expected/cjs.js
 create mode 100644 test/form/skips-dead-branches-j/_expected/es.js
 create mode 100644 test/form/skips-dead-branches-j/_expected/iife.js
 create mode 100644 test/form/skips-dead-branches-j/_expected/umd.js
 create mode 100644 test/form/skips-dead-branches-j/main.js

diff --git a/src/ast/nodes/LogicalExpression.js b/src/ast/nodes/LogicalExpression.js
new file mode 100644
index 0000000..4f81d3b
--- /dev/null
+++ b/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 );
+	}
+}
diff --git a/src/ast/nodes/index.js b/src/ast/nodes/index.js
index 1c3ba4c..2c59ee4 100644
--- a/src/ast/nodes/index.js
+++ b/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,
diff --git a/test/form/skips-dead-branches-i/_config.js b/test/form/skips-dead-branches-i/_config.js
index 85e8fbe..95aa942 100644
--- a/test/form/skips-dead-branches-i/_config.js
+++ b/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)'
 };
diff --git a/test/form/skips-dead-branches-j/_config.js b/test/form/skips-dead-branches-j/_config.js
new file mode 100644
index 0000000..b9abe10
--- /dev/null
+++ b/test/form/skips-dead-branches-j/_config.js
@@ -0,0 +1,3 @@
+module.exports = {
+	description: 'skips a dead branch (j)'
+};
diff --git a/test/form/skips-dead-branches-j/_expected/amd.js b/test/form/skips-dead-branches-j/_expected/amd.js
new file mode 100644
index 0000000..9ee9589
--- /dev/null
+++ b/test/form/skips-dead-branches-j/_expected/amd.js
@@ -0,0 +1,7 @@
+define(function () { 'use strict';
+
+	{
+		console.log( 'true' );
+	}
+
+});
diff --git a/test/form/skips-dead-branches-j/_expected/cjs.js b/test/form/skips-dead-branches-j/_expected/cjs.js
new file mode 100644
index 0000000..f71d9f9
--- /dev/null
+++ b/test/form/skips-dead-branches-j/_expected/cjs.js
@@ -0,0 +1,5 @@
+'use strict';
+
+{
+	console.log( 'true' );
+}
diff --git a/test/form/skips-dead-branches-j/_expected/es.js b/test/form/skips-dead-branches-j/_expected/es.js
new file mode 100644
index 0000000..bbd290a
--- /dev/null
+++ b/test/form/skips-dead-branches-j/_expected/es.js
@@ -0,0 +1,3 @@
+{
+	console.log( 'true' );
+}
diff --git a/test/form/skips-dead-branches-j/_expected/iife.js b/test/form/skips-dead-branches-j/_expected/iife.js
new file mode 100644
index 0000000..c506520
--- /dev/null
+++ b/test/form/skips-dead-branches-j/_expected/iife.js
@@ -0,0 +1,8 @@
+(function () {
+	'use strict';
+
+	{
+		console.log( 'true' );
+	}
+
+}());
diff --git a/test/form/skips-dead-branches-j/_expected/umd.js b/test/form/skips-dead-branches-j/_expected/umd.js
new file mode 100644
index 0000000..2f6e70a
--- /dev/null
+++ b/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' );
+	}
+
+})));
diff --git a/test/form/skips-dead-branches-j/main.js b/test/form/skips-dead-branches-j/main.js
new file mode 100644
index 0000000..afc8c67
--- /dev/null
+++ b/test/form/skips-dead-branches-j/main.js
@@ -0,0 +1,5 @@
+if ( true && true ) {
+	console.log( 'true' );
+} else {
+	console.log( 'false' );
+}