special case literals

src/parse/read/expression.js

@@ -1,18 +1,28 @@
 import { parseExpressionAt } from 'acorn';
 
+const literals = {
+	true: true,
+	false: false,
+	null: null
+};
+
 export default function readExpression ( parser ) {
 	const start = parser.index;
 
-	parser.index = start;
-
-	try {
-		const node = parseExpressionAt( parser.template, parser.index );
-		parser.index = node.end;
-
-		return node;
-	} catch ( err ) {
 	const name = parser.readUntil( /\s*}}/ );
 	if ( name && /^[a-z]+$/.test( name ) ) {
+		const end = start + name.length;
+
+		if ( name in literals ) {
+			return {
+				type: 'Literal',
+				start,
+				end,
+				value: literals[ name ],
+				raw: name
+			};
+		}
+
 		return {
 			type: 'Identifier',
 			start,
@@ -20,6 +30,15 @@ export default function readExpression ( parser ) {
 			name
 		};
 	}
+
+	parser.index = start;
+
+	try {
+		const node = parseExpressionAt( parser.template, parser.index );
+		parser.index = node.end;
+
+		return node;
+	} catch ( err ) {
 		parser.acornError( err );
 	}
 }