[feat] |important modifier for style directive (#7489)

* important modifier for style directive

* docs

* Exclude third param if false
third param for set_style is optional

* Remove unused test

Runtime test doesn't work because of weird behaviour of computed style
the puppeteer test should cover it

* remove unnecessary test

Co-authored-by: tanhauhau <[email protected]>

Author: gtm-nayan

site/content/docs/03-template-syntax.md

@@ -874,6 +874,9 @@ The `style:` directive provides a shorthand for setting multiple styles on an el
 
 <!-- Multiple styles can be included -->
 <div style:color style:width="12rem" style:background-color={darkMode ? "black" : "white"}>...</div>
+
+<!-- Styles can be marked as important -->
+<div style:color|important="red">...</div>
 ```
 
 ---

src/compiler/compile/compiler_errors.ts

@@ -281,5 +281,9 @@ export default {
 	invalid_component_style_directive: {
 		code: 'invalid-component-style-directive',
 		message: 'Style directives cannot be used on components'
-	}
+	},
+	invalid_style_directive_modifier: (valid: string) => ({
+		code: 'invalid-style-directive-modifier',
+		message: `Valid modifiers for style directives are: ${valid}`
+	})
 };

src/compiler/compile/nodes/StyleDirective.ts

@@ -1,20 +1,42 @@
 import { TemplateNode } from '../../interfaces';
+import list from '../../utils/list';
+import compiler_errors from '../compiler_errors';
 import Component from '../Component';
 import { nodes_to_template_literal } from '../utils/nodes_to_template_literal';
 import Expression from './shared/Expression';
 import Node from './shared/Node';
 import TemplateScope from './shared/TemplateScope';
 
+const valid_modifiers = new Set(['important']);
+
 export default class StyleDirective extends Node {
 	type: 'StyleDirective';
 	name: string;
+	modifiers: Set<string>;
 	expression: Expression;
 	should_cache: boolean;
 
-	constructor(component: Component, parent: Node, scope: TemplateScope, info: TemplateNode) {
+	constructor(
+		component: Component,
+		parent: Node,
+		scope: TemplateScope,
+		info: TemplateNode
+	) {
 		super(component, parent, scope, info);
 
 		this.name = info.name;
+		this.modifiers = new Set(info.modifiers);
+
+		for (const modifier of this.modifiers) {
+			if (!valid_modifiers.has(modifier)) {
+				component.error(
+					this,
+					compiler_errors.invalid_style_directive_modifier(
+						list([...valid_modifiers])
+					)
+				);
+			}
+		}
 
 		// Convert the value array to an expression so it's easier to handle
 		// the StyleDirective going forward.
@@ -34,6 +56,9 @@ export default class StyleDirective extends Node {
 			this.expression = new Expression(component, this, scope, raw_expression);
 			this.should_cache = raw_expression.expressions.length > 0;
 		}
+	}
 
+	get important() {
+		return this.modifiers.has('important');
 	}
 }

src/compiler/compile/render_dom/wrappers/Element/index.ts

@@ -1100,7 +1100,7 @@ export default class ElementWrapper extends Wrapper {
 	add_styles(block: Block) {
 		const has_spread = this.node.attributes.some(attr => attr.is_spread);
 		this.node.styles.forEach((style_directive) => {
-			const { name, expression, should_cache } = style_directive;
+			const { name, expression, should_cache, important } = style_directive;
 
 			const snippet = expression.manipulate(block);
 			let cached_snippet: Identifier | undefined;
@@ -1109,7 +1109,7 @@ export default class ElementWrapper extends Wrapper {
 				block.add_variable(cached_snippet, snippet);
 			}
 
-			const updater = b`@set_style(${this.var}, "${name}", ${should_cache ? cached_snippet : snippet}, false)`;
+			const updater = b`@set_style(${this.var}, "${name}", ${should_cache ? cached_snippet : snippet}, ${important ? 1 : null})`;
 
 			block.chunks.hydrate.push(updater);
 

src/compiler/compile/render_ssr/handlers/Element.ts

@@ -44,7 +44,10 @@ export default function (node: Element, renderer: Renderer, options: RenderOptio
 		class_expression_list.reduce((lhs, rhs) => x`${lhs} + ' ' + ${rhs}`);
 
 	const style_expression_list = node.styles.map(style_directive => {
-		const { name, expression: { node: expression } } = style_directive;
+		let { name, important, expression: { node: expression } } = style_directive;
+		if (important) {
+			expression = x`${expression} + ' !important'`;
+		}
 		return p`"${name}": ${expression}`;
 	});
 

src/compiler/parse/state/tag.ts

@@ -395,6 +395,7 @@ function read_attribute(parser: Parser, unique_names: Set<string>) {
 				end,
 				type,
 				name: directive_name,
+				modifiers,
 				value
 			};
 		}

test/parser/samples/attribute-style-directive-modifiers/input.svelte

@@ -0,0 +1 @@
+<div style:color|important={myColor}></div>

test/parser/samples/attribute-style-directive-modifiers/output.json

@@ -0,0 +1,50 @@
+{
+	"html": {
+		"start": 0,
+		"end": 43,
+		"type": "Fragment",
+		"children": [
+			{
+				"start": 0,
+				"end": 43,
+				"type": "Element",
+				"name": "div",
+				"attributes": [
+					{
+						"start": 5,
+						"end": 36,
+						"type": "StyleDirective",
+						"name": "color",
+						"modifiers": [
+							"important"
+						],
+						"value": [
+							{
+								"start": 27,
+								"end": 36,
+								"type": "MustacheTag",
+								"expression": {
+									"type": "Identifier",
+									"start": 28,
+									"end": 35,
+									"loc": {
+										"start": {
+											"line": 1,
+											"column": 28
+										},
+										"end": {
+											"line": 1,
+											"column": 35
+										}
+									},
+									"name": "myColor"
+								}
+							}
+						]
+					}
+				],
+				"children": []
+			}
+		]
+	}
+}

test/parser/samples/attribute-style-directive-shorthand/output.json

@@ -15,11 +15,12 @@
 						"end": 16,
 						"type": "StyleDirective",
 						"name": "color",
+						"modifiers": [],
 						"value": true
 					}
 				],
 				"children": []
 			}
 		]
 	}
-}
+}

test/parser/samples/attribute-style-directive-string/output.json

@@ -15,6 +15,7 @@
 						"end": 22,
 						"type": "StyleDirective",
 						"name": "color",
+						"modifiers": [],
 						"value": [
 							{
 								"start": 18,
@@ -45,6 +46,7 @@
 						"start": 35,
 						"end": 52,
 						"type": "StyleDirective",
+						"modifiers": [],
 						"name": "color",
 						"value": [
 							{
@@ -77,6 +79,7 @@
 						"end": 80,
 						"type": "StyleDirective",
 						"name": "color",
+						"modifiers": [],
 						"value": [
 							{
 								"start": 77,
@@ -108,6 +111,7 @@
 						"end": 120,
 						"type": "StyleDirective",
 						"name": "color",
+						"modifiers": [],
 						"value": [
 							{
 								"start": 106,
@@ -160,6 +164,7 @@
 						"end": 160,
 						"type": "StyleDirective",
 						"name": "color",
+						"modifiers": [],
 						"value": [
 							{
 								"start": 146,
@@ -212,6 +217,7 @@
 						"end": 198,
 						"type": "StyleDirective",
 						"name": "color",
+						"modifiers": [],
 						"value": [
 							{
 								"start": 185,
@@ -264,6 +270,7 @@
 						"end": 245,
 						"type": "StyleDirective",
 						"name": "color",
+						"modifiers": [],
 						"value": [
 							{
 								"start": 223,
@@ -352,4 +359,4 @@
 			}
 		]
 	}
-}
+}