Refactor directive parsing for code reuse

This removes the copy-pasta for directive parsing and removes the need for special if-else cases for each directive.

src/parse/read/directives.ts

@@ -2,6 +2,65 @@ import { parseExpressionAt } from 'acorn';
 import repeat from '../../utils/repeat';
 import { Parser } from '../index';
 
+const DIRECTIVES = {
+	Ref: {
+		names: [ 'ref' ],
+		attribute(start, end, type, name) {
+			return { start, end, type, name };
+		}
+	},
+
+	EventHandler: {
+		names: [ 'on' ],
+		allowedExpressionTypes: [ 'CallExpression' ],
+	},
+
+	Binding: {
+		names: [ '', 'bind' ],
+		allowedExpressionTypes: [ 'Identifier', 'MemberExpression' ],
+		attribute(start, end, type, name, expression, directiveName) {
+			let value;
+
+			// :foo is shorthand for foo='{{foo}}'
+			if (!directiveName) {
+				const valueStart = start + 1;
+				const valueEnd = start + name.length;
+				type = 'Attribute';
+				value = getShorthandValue(start + 1, name);
+			} else {
+				value = expression || {
+					type: 'Identifier',
+					start: start + 5,
+					end,
+					name,
+				};
+			}
+
+			return { start, end, type, name, value };
+		},
+	},
+
+	Transition: {
+		names: [ 'in', 'out', 'transition' ],
+		allowedExpressionTypes: [ 'ObjectExpression' ],
+		attribute(start, end, type, name, expression, directiveName) {
+			return {
+				start, end, type, name, expression,
+				intro: directiveName === 'in' || directiveName === 'transition',
+				outro: directiveName === 'out' || directiveName === 'transition',
+			}
+		},
+	},
+};
+
+
+const lookupByName = {};
+
+Object.keys(DIRECTIVES).forEach(name => {
+	const directive = DIRECTIVES[name];
+	directive.names.forEach(type => lookupByName[type] = name);
+});
+
 function readExpression(parser: Parser, start: number, quoteMark: string|null) {
 	let str = '';
 	let escaped = false;
@@ -24,7 +83,7 @@ function readExpression(parser: Parser, start: number, quoteMark: string|null) {
 			} else {
 				str += char;
 			}
-		} else if (/\s/.test(char)) {
+		} else if (/[\s\r\n\/>]/.test(char)) {
 			break;
 		} else {
 			str += char;
@@ -42,125 +101,70 @@ function readExpression(parser: Parser, start: number, quoteMark: string|null) {
 	return expression;
 }
 
-export function readEventHandlerDirective(
+export function readDirective(
 	parser: Parser,
 	start: number,
-	name: string,
+	attrName: string
-	hasValue: boolean
 ) {
-	let expression;
+	const [ directiveName, name ] = attrName.split(':');
+	if (name === undefined) return; // No colon in the name
 	
-	if (hasValue) {
+	const type = lookupByName[directiveName];
-		const quoteMark = parser.eat(`'`) ? `'` : parser.eat(`"`) ? `"` : null;
+	if (!type) return; // not a registered directive
 	
-		const expressionStart = parser.index;
+	const directive = DIRECTIVES[type];
-
+	let expression = null;
-		expression = readExpression(parser, expressionStart, quoteMark);
-
-		if (expression.type !== 'CallExpression') {
-			parser.error(`Expected call expression`, expressionStart);
-		}
-	}
-
-	return {
-		start,
-		end: parser.index,
-		type: 'EventHandler',
-		name,
-		expression,
-	};
-}
-
-export function readBindingDirective(
-	parser: Parser,
-	start: number,
-	name: string
-) {
-	let value;
 
 	if (parser.eat('=')) {
 		const quoteMark = parser.eat(`'`) ? `'` : parser.eat(`"`) ? `"` : null;
 
-		const a = parser.index;
+		const expressionStart = parser.index;
 
 		if (parser.eat('{{')) {
-			let message = 'bound values should not be wrapped';
+			let message = 'directive values should not be wrapped';
-			const b = parser.template.indexOf('}}', a);
+			const expressionEnd = parser.template.indexOf('}}', expressionStart);
-			if (b !== -1) {
+			if (expressionEnd !== -1) {
-				const value = parser.template.slice(parser.index, b);
+				const value = parser.template.slice(parser.index, expressionEnd);
 				message += ` — use '${value}', not '{{${value}}}'`;
 			}
 
-			parser.error(message, a);
+			parser.error(message, expressionStart);
 		}
 
-		// this is a bit of a hack so that we can give Acorn something parseable
+		expression = readExpression(parser, expressionStart, quoteMark);
-		let b;
+		if (directive.allowedExpressionTypes.indexOf(expression.type) === -1) {
-		if (quoteMark) {
+			parser.error(`Expected ${directive.allowedExpressionTypes.join(' or ')}`, expressionStart);
-			b = parser.index = parser.template.indexOf(quoteMark, parser.index);
-		} else {
-			parser.readUntil(/[\s\r\n\/>]/);
-			b = parser.index;
 		}
-
-		const source = repeat(' ', a) + parser.template.slice(a, b);
-		value = parseExpressionAt(source, a, { ecmaVersion: 9 });
-
-		if (value.type !== 'Identifier' && value.type !== 'MemberExpression') {
-			parser.error(`Cannot bind to rvalue`, value.start);
 	}
 
-		parser.allowWhitespace();
+	if (directive.attribute) {
-
+		return directive.attribute(start, parser.index, type, name, expression, directiveName);
-		if (quoteMark) {
-			parser.eat(quoteMark, true);
-		}
 	} else {
-		// shorthand – bind:foo equivalent to bind:foo='foo'
-		value = {
-			type: 'Identifier',
-			start: start + 5,
-			end: parser.index,
-			name,
-		};
-	}
-
 		return {
 			start,
 			end: parser.index,
-		type: 'Binding',
+			type: type,
 			name,
-		value,
+			expression,
 		};
 	}
+}
 
-export function readTransitionDirective(
-	parser: Parser,
-	start: number,
-	name: string,
-	type: string
-) {
-	let expression = null;
-
-	if (parser.eat('=')) {
-		const quoteMark = parser.eat(`'`) ? `'` : parser.eat(`"`) ? `"` : null;
-
-		const expressionStart = parser.index;
 
-		expression = readExpression(parser, expressionStart, quoteMark);
+function getShorthandValue(start: number, name: string) {
+	const end = start + name.length;
 
-		if (expression.type !== 'ObjectExpression') {
+	return [
-			parser.error(`Expected object expression`, expressionStart);
+		{
-		}
+			type: 'AttributeShorthand',
-	}
-
-	return {
 			start,
-		end: parser.index,
+			end,
-		type: 'Transition',
+			expression: {
+				type: 'Identifier',
+				start,
+				end,
 				name,
-		intro: type === 'in' || type === 'transition',
+			},
-		outro: type === 'out' || type === 'transition',
+		},
-		expression,
+	];
-	};
 }

src/parse/state/tag.ts

@@ -1,11 +1,7 @@
 import readExpression from '../read/expression';
 import readScript from '../read/script';
 import readStyle from '../read/style';
-import {
+import { readDirective } from '../read/directives';
-	readEventHandlerDirective,
-	readBindingDirective,
-	readTransitionDirective,
-} from '../read/directives';
 import { trimStart, trimEnd } from '../../utils/trim';
 import { decodeCharacterReferences } from '../utils/html';
 import isVoidElementName from '../../utils/isVoidElementName';
@@ -303,42 +299,10 @@ function readAttribute(parser: Parser, uniqueNames: Set<string>) {
 
 	parser.allowWhitespace();
 
-	if (/^on:/.test(name)) {
+	const attribute = readDirective(parser, start, name);
-		return readEventHandlerDirective(parser, start, name.slice(3), parser.eat('='));
+	if (attribute) return attribute;
-	}
-
-	if (/^bind:/.test(name)) {
-		return readBindingDirective(parser, start, name.slice(5));
-	}
-
-	if (/^ref:/.test(name)) {
-		return {
-			start,
-			end: parser.index,
-			type: 'Ref',
-			name: name.slice(4),
-		};
-	}
-
-	const match = /^(in|out|transition):/.exec(name);
-	if (match) {
-		return readTransitionDirective(
-			parser,
-			start,
-			name.slice(match[0].length),
-			match[1]
-		);
-	}
-
-	let value;
 
-	// :foo is shorthand for foo='{{foo}}'
+	let value = parser.eat('=') ? readAttributeValue(parser) : true;
-	if (/^:\w+$/.test(name)) {
-		name = name.slice(1);
-		value = getShorthandValue(start + 1, name);
-	} else {
-		value = parser.eat('=') ? readAttributeValue(parser) : true;
-	}
 
 	return {
 		start,
@@ -364,24 +328,6 @@ function readAttributeValue(parser: Parser) {
 	return value;
 }
 
-function getShorthandValue(start: number, name: string) {
-	const end = start + name.length;
-
-	return [
-		{
-			type: 'AttributeShorthand',
-			start,
-			end,
-			expression: {
-				type: 'Identifier',
-				start,
-				end,
-				name,
-			},
-		},
-	];
-}
-
 function readSequence(parser: Parser, done: () => boolean) {
 	let currentChunk: Node = {
 		start: parser.index,

test/parser/samples/error-binding-mustaches/error.json

@@ -1,5 +1,5 @@
 {
-	"message": "bound values should not be wrapped — use 'foo', not '{{foo}}'",
+	"message": "directive values should not be wrapped — use 'foo', not '{{foo}}'",
 	"loc": {
 		"line": 1,
 		"column": 19

test/parser/samples/error-binding-rvalue/error.json

@@ -1,5 +1,5 @@
 {
-	"message": "Cannot bind to rvalue",
+	"message": "Expected Identifier or MemberExpression",
 	"pos": 19,
 	"loc": {
 		"line": 1,

test/parser/samples/error-event-handler/error.json

@@ -1,5 +1,5 @@
 {
-	"message": "Expected call expression",
+	"message": "Expected CallExpression",
 	"loc": {
 		"line": 1,
 		"column": 15