use destructuring syntax for computed props in v2 mode - fixes #1069

src/generators/Generator.ts

@@ -84,6 +84,7 @@ export default class Generator {
 	source: string;
 	name: string;
 	options: CompileOptions;
+	v2: boolean;
 
 	customElement: CustomElementOptions;
 	tag: string;
@@ -132,6 +133,8 @@ export default class Generator {
 		stats.start('compile');
 		this.stats = stats;
 
+		this.v2 = options.parser === 'v2';
+
 		this.ast = clone(parsed);
 
 		this.parsed = parsed;
@@ -575,10 +578,10 @@ export default class Generator {
 						const key = getName(prop.key);
 						const value = prop.value;
 
-						const deps = value.params.map(
-							(param: Node) =>
-								param.type === 'AssignmentPattern' ? param.left.name : param.name
-						);
+						const deps = this.v2
+							? value.params[0].properties.map(prop => prop.key.name)
+							: value.params.map(param => param.type === 'AssignmentPattern' ? param.left.name : param.name);
+
 						deps.forEach(dep => {
 							this.expectedProperties.add(dep);
 						});

src/generators/dom/index.ts

@@ -99,9 +99,11 @@ export default function dom(
 
 			const condition = `${deps.map(dep => `changed.${dep}`).join(' || ')}`;
 
-			const statement = `if (this._differs(state.${key}, (state.${key} = %computed-${key}(${deps
-				.map(dep => `state.${dep}`)
-				.join(', ')})))) changed.${key} = true;`;
+			const call = generator.v2
+				? `%computed-${key}(state)`
+				: `%computed-${key}(${deps.map(dep => `state.${dep}`).join(', ')})`;
+
+			const statement = `if (this._differs(state.${key}, (state.${key} = ${call}))) changed.${key} = true;`;
 
 			computationBuilder.addConditional(condition, statement);
 		});

src/validate/index.ts

@@ -10,6 +10,7 @@ import { Node, Parsed, CompileOptions, Warning } from '../interfaces';
 export class Validator {
 	readonly source: string;
 	readonly filename: string;
+	readonly v2: boolean;
 
 	options: CompileOptions;
 	onwarn: ({}) => void;
@@ -38,6 +39,7 @@ export class Validator {
 		this.filename = options.filename;
 		this.onwarn = options.onwarn;
 		this.options = options;
+		this.v2 = options.parser === 'v2';
 
 		this.namespace = null;
 		this.defaultExport = null;
@@ -96,7 +98,7 @@ export default function validate(
 	stylesheet: Stylesheet,
 	options: CompileOptions
 ) {
-	const { onwarn, onerror, name, filename, store, dev } = options;
+	const { onwarn, onerror, name, filename, store, dev, parser } = options;
 
 	try {
 		if (name && !/^[a-zA-Z_$][a-zA-Z_$0-9]*$/.test(name)) {
@@ -119,7 +121,8 @@ export default function validate(
 			name,
 			filename,
 			store,
-			dev
+			dev,
+			parser
 		});
 
 		if (parsed.js) {

src/validate/js/propValidators/computed.ts

@@ -7,6 +7,7 @@ import { Validator } from '../../index';
 import { Node } from '../../../interfaces';
 import walkThroughTopFunctionScope from '../../../utils/walkThroughTopFunctionScope';
 import isThisGetCallExpression from '../../../utils/isThisGetCallExpression';
+import validCalleeObjects from '../../../utils/validCalleeObjects';
 
 const isFunctionExpression = new Set([
 	'FunctionExpression',
@@ -74,19 +75,37 @@ export default function computed(validator: Validator, prop: Node) {
 			});
 		}
 
-		params.forEach((param: Node) => {
-			const valid =
-				param.type === 'Identifier' ||
-				(param.type === 'AssignmentPattern' &&
-					param.left.type === 'Identifier');
-
-			if (!valid) {
-				// TODO change this for v2
-				validator.error(param, {
+		if (validator.v2) {
+			if (params.length > 1) {
+				validator.error(computation.value, {
 					code: `invalid-computed-arguments`,
-					message: `Computed properties cannot use destructuring in function parameters`
+					message: `Computed properties must take a single argument`
 				});
 			}
-		});
+
+			const param = params[0];
+			if (param.type !== 'ObjectPattern') {
+				// TODO in v2, allow the entire object to be passed in
+				validator.error(computation.value, {
+					code: `invalid-computed-argument`,
+					message: `Computed property argument must be a destructured object pattern`
+				});
+			}
+		} else {
+			params.forEach((param: Node) => {
+				const valid =
+					param.type === 'Identifier' ||
+					(param.type === 'AssignmentPattern' &&
+						param.left.type === 'Identifier');
+
+				if (!valid) {
+					// TODO change this for v2
+					validator.error(param, {
+						code: `invalid-computed-arguments`,
+						message: `Computed properties cannot use destructuring in function parameters`
+					});
+				}
+			});
+		}
 	});
 }

test/js/samples/dev-warning-missing-data-computed/_actual-bundle-v2.js

@@ -226,7 +226,7 @@ var protoDev = {
 
 /* generated by Svelte vX.Y.Z */
 
-function bar(foo) {
+function bar({ foo }) {
 	return foo * 2;
 }
 
@@ -291,7 +291,7 @@ SvelteComponent.prototype._checkReadOnly = function _checkReadOnly(newState) {
 
 SvelteComponent.prototype._recompute = function _recompute(changed, state) {
 	if (changed.foo) {
-		if (this._differs(state.bar, (state.bar = bar(state.foo)))) changed.bar = true;
+		if (this._differs(state.bar, (state.bar = bar(state)))) changed.bar = true;
 	}
 };
 

test/js/samples/dev-warning-missing-data-computed/expected-bundle-v2.js

@@ -226,7 +226,7 @@ var protoDev = {
 
 /* generated by Svelte vX.Y.Z */
 
-function bar(foo) {
+function bar({ foo }) {
 	return foo * 2;
 }
 
@@ -291,7 +291,7 @@ SvelteComponent.prototype._checkReadOnly = function _checkReadOnly(newState) {
 
 SvelteComponent.prototype._recompute = function _recompute(changed, state) {
 	if (changed.foo) {
-		if (this._differs(state.bar, (state.bar = bar(state.foo)))) changed.bar = true;
+		if (this._differs(state.bar, (state.bar = bar(state)))) changed.bar = true;
 	}
 };
 

test/js/samples/dev-warning-missing-data-computed/expected-v2.js

@@ -1,7 +1,7 @@
 /* generated by Svelte vX.Y.Z */
 import { appendNode, assign, createElement, createText, detachNode, init, insertNode, noop, protoDev } from "svelte/shared.js";
 
-function bar(foo) {
+function bar({ foo }) {
 	return foo * 2;
 }
 
@@ -66,7 +66,7 @@ SvelteComponent.prototype._checkReadOnly = function _checkReadOnly(newState) {
 
 SvelteComponent.prototype._recompute = function _recompute(changed, state) {
 	if (changed.foo) {
-		if (this._differs(state.bar, (state.bar = bar(state.foo)))) changed.bar = true;
+		if (this._differs(state.bar, (state.bar = bar(state)))) changed.bar = true;
 	}
 }
 export default SvelteComponent;

test/js/samples/dev-warning-missing-data-computed/input-v2.html

@@ -6,7 +6,7 @@
 <script>
 	export default {
 		computed: {
-			bar: foo => foo * 2
+			bar: ({ foo }) => foo * 2
 		}
 	};
 </script>

test/runtime/samples/computed-function/main-v2.html

@@ -0,0 +1,20 @@
+<p>{scale(x)}</p>
+
+<script>
+	export default {
+		data: () => ({
+			x: 5,
+			domain: [ 0, 10 ],
+			range: [ 0, 100 ]
+		}),
+
+		computed: {
+			scale: ({ domain, range }) => {
+				return num => {
+					const t = domain[0] + ( num - domain[0] ) / ( domain[1] - domain[0] );
+					return range[0] + t * ( range[1] - range[0] );
+				}
+			}
+		}
+	};
+</script>

test/runtime/samples/computed-values-deconflicted/main-v2.html

@@ -0,0 +1,14 @@
+<span>{state}</span>
+
+<script>
+	export default {
+		data() {
+			return {
+				x: 'waiting'
+			};
+		},
+		computed: {
+			state: ({ x }) => x
+		}
+	};
+</script>

test/runtime/samples/computed-values-default/main-v2.html

@@ -0,0 +1,9 @@
+<p>{foo}</p>
+
+<script>
+	export default {
+		computed: {
+			foo: ({ a = 1 }) => a * 2
+		}
+	};
+</script>

test/runtime/samples/computed-values-function-dependency/main-v2.html

@@ -0,0 +1,28 @@
+<p>{x}</p>
+
+<script>
+	let _x;
+
+	function getX () {
+		return _x;
+	}
+
+	export default {
+		data () {
+			return {
+				y: 1
+			};
+		},
+
+		computed: {
+			xGetter ({ y }) {
+				_x = y * 2;
+				return getX;
+			},
+
+			x ({ xGetter }) {
+				return xGetter();
+			}
+		}
+	};
+</script>

test/runtime/samples/computed-values/main-v2.html

@@ -0,0 +1,16 @@
+<p>{a} + {b} = {c}</p>
+<p>{c} * {c} = {cSquared}</p>
+
+<script>
+	export default {
+		data: () => ({
+			a: 1,
+			b: 2
+		}),
+
+		computed: {
+			c: ({ a, b }) => a + b,
+			cSquared: ({ c }) => c * c
+		}
+	};
+</script>