Merge pull request #434 from sveltejs/gh-424-alt

Treat literals as special cases when parsing

src/parse/read/expression.js

@@ -1,10 +1,28 @@
 import { parseExpressionAt } from 'acorn';
 
+const literals = new Map([
+	[ 'true', true ],
+	[ 'false', false ],
+	[ 'null', null ]
+]);
+
 export default function readExpression ( parser ) {
 	const start = parser.index;
 
 	const name = parser.readUntil( /\s*}}/ );
 	if ( name && /^[a-z]+$/.test( name ) ) {
+		const end = start + name.length;
+
+		if ( literals.has( name ) ) {
+			return {
+				type: 'Literal',
+				start,
+				end,
+				value: literals.get( name ),
+				raw: name
+			};
+		}
+
 		return {
 			type: 'Identifier',
 			start,

test/generator/samples/attribute-prefer-expression/_config.js

@@ -0,0 +1,19 @@
+export default {
+	'skip-ssr': true,
+
+	data: {
+		foo: false
+	},
+
+	test ( assert, component, target ) {
+		const inputs = target.querySelectorAll( 'input' );
+
+		assert.ok( inputs[0].checked );
+		assert.ok( !inputs[1].checked );
+
+		component.set( { foo: true } );
+
+		assert.ok( !inputs[0].checked );
+		assert.ok( inputs[1].checked );
+	}
+};

test/generator/samples/attribute-prefer-expression/main.html

@@ -0,0 +1,2 @@
+<input type='radio' bind:group='foo' value='{{false}}'>
+<input type='radio' bind:group='foo' value='{{true}}'>