From 33bce408390dd8360f34ca97d374c3c17af419af Mon Sep 17 00:00:00 2001
From: Rich-Harris <richard.a.harris@gmail.com>
Date: Wed, 26 Apr 2017 14:33:44 -0400
Subject: [PATCH] allow parameter-less transitions

---
 src/generators/dom/Block.js                   |  3 --
 .../dom/visitors/Element/Transition.js        | 16 ++++----
 src/parse/read/directives.js                  | 22 ++++++-----
 src/parse/state/tag.js                        |  1 -
 .../transition-intro-no-params/input.html     |  1 +
 .../transition-intro-no-params/output.json    | 37 +++++++++++++++++++
 6 files changed, 59 insertions(+), 21 deletions(-)
 create mode 100644 test/parser/samples/transition-intro-no-params/input.html
 create mode 100644 test/parser/samples/transition-intro-no-params/output.json

diff --git a/src/generators/dom/Block.js b/src/generators/dom/Block.js
index e79423c55a..8c6bbec667 100644
--- a/src/generators/dom/Block.js
+++ b/src/generators/dom/Block.js
@@ -33,9 +33,6 @@ export default class Block {
 		this.variables = new Map();
 		this.getUniqueName = this.generator.getUniqueNameMaker( options.params );
 
-		this.intros = [];
-		this.outros = [];
-
 		// unique names
 		this.component = this.getUniqueName( 'component' );
 		this.target = this.getUniqueName( 'target' );
diff --git a/src/generators/dom/visitors/Element/Transition.js b/src/generators/dom/visitors/Element/Transition.js
index 9b9957d4a6..50f7534979 100644
--- a/src/generators/dom/visitors/Element/Transition.js
+++ b/src/generators/dom/visitors/Element/Transition.js
@@ -5,12 +5,12 @@ export default function visitTransition ( generator, block, state, node, attribu
 
 	block.addVariable( name );
 
+	const snippet = attribute.expression ? block.contextualise( attribute.expression ).snippet : '{}';
+	const fn = `${generator.alias( 'template' )}.transitions.${attribute.name}`; // TODO add built-in transitions?
+
 	if ( attribute.intro ) {
 		generator.hasIntroTransitions = true;
 
-		const { snippet } = block.contextualise( attribute.expression );
-		const fn = `${generator.alias( 'template' )}.transitions.${attribute.name}`; // TODO add built-in transitions?
-
 		block.builders.create.addBlock( deindent`
 			${block.component}._renderHooks.push({
 				fn: function () {
@@ -22,9 +22,9 @@ export default function visitTransition ( generator, block, state, node, attribu
 		` );
 	}
 
-	( attribute.intro ? block.intros : block.outros ).push({
-		node: state.name,
-		transition: attribute.name,
-		params: block.contextualise( attribute.expression ).snippet
-	});
+	if ( attribute.outro ) {
+		generator.hasOutroTransitions = true;
+
+		throw new Error( 'TODO' );
+	}
 }
\ No newline at end of file
diff --git a/src/parse/read/directives.js b/src/parse/read/directives.js
index 9cc09392d7..32e86a0a4d 100644
--- a/src/parse/read/directives.js
+++ b/src/parse/read/directives.js
@@ -131,18 +131,22 @@ export function readBindingDirective ( parser, start, name ) {
 }
 
 export function readTransitionDirective ( parser, start, name, type ) {
-	const quoteMark = (
-		parser.eat( `'` ) ? `'` :
-		parser.eat( `"` ) ? `"` :
-		null
-	);
+	let expression = null;
 
-	const expressionStart = parser.index;
+	if ( parser.eat( '=' ) ) {
+		const quoteMark = (
+			parser.eat( `'` ) ? `'` :
+			parser.eat( `"` ) ? `"` :
+			null
+		);
 
-	const expression = readExpression( parser, expressionStart, quoteMark );
+		const expressionStart = parser.index;
+
+		expression = readExpression( parser, expressionStart, quoteMark );
 
-	if ( expression.type !== 'ObjectExpression' ) {
-		parser.error( `Expected object expression`, expressionStart );
+		if ( expression.type !== 'ObjectExpression' ) {
+			parser.error( `Expected object expression`, expressionStart );
+		}
 	}
 
 	return {
diff --git a/src/parse/state/tag.js b/src/parse/state/tag.js
index 901b250833..475043f311 100644
--- a/src/parse/state/tag.js
+++ b/src/parse/state/tag.js
@@ -255,7 +255,6 @@ function readAttribute ( parser, uniqueNames ) {
 
 	const match = /^(in|out|transition):/.exec( name );
 	if ( match ) {
-		parser.eat( '=', true );
 		return readTransitionDirective( parser, start, name.slice( match[0].length ), match[1] );
 	}
 
diff --git a/test/parser/samples/transition-intro-no-params/input.html b/test/parser/samples/transition-intro-no-params/input.html
new file mode 100644
index 0000000000..e5e4171434
--- /dev/null
+++ b/test/parser/samples/transition-intro-no-params/input.html
@@ -0,0 +1 @@
+<div in:fade>fades in</div>
\ No newline at end of file
diff --git a/test/parser/samples/transition-intro-no-params/output.json b/test/parser/samples/transition-intro-no-params/output.json
new file mode 100644
index 0000000000..ae1f76a3bc
--- /dev/null
+++ b/test/parser/samples/transition-intro-no-params/output.json
@@ -0,0 +1,37 @@
+{
+	"hash": 1535528483,
+	"html": {
+		"start": 0,
+		"end": 27,
+		"type": "Fragment",
+		"children": [
+			{
+				"start": 0,
+				"end": 27,
+				"type": "Element",
+				"name": "div",
+				"attributes": [
+					{
+						"start": 5,
+						"end": 12,
+						"type": "Transition",
+						"name": "fade",
+						"intro": true,
+						"outro": false,
+						"expression": null
+					}
+				],
+				"children": [
+					{
+						"start": 13,
+						"end": 21,
+						"type": "Text",
+						"data": "fades in"
+					}
+				]
+			}
+		]
+	},
+	"css": null,
+	"js": null
+}
\ No newline at end of file