scope CSS sibling combinators (#5427)

Author: tanhauhau

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Unreleased
 
 * Add `|nonpassive` event modifier, explicitly passing `passive: false` ([#2068](https://github.com/sveltejs/svelte/issues/2068))
+* Scope CSS selectors with `~` and `+` combinators ([#3104](https://github.com/sveltejs/svelte/issues/3104))
 * Fix keyed `{#each}` not reacting to key changing ([#5444](https://github.com/sveltejs/svelte/issues/5444))
 * Fix destructuring into store values ([#5449](https://github.com/sveltejs/svelte/issues/5449))
 * Fix erroneous `missing-declaration` warning with `use:obj.method` ([#5451](https://github.com/sveltejs/svelte/issues/5451))

src/compiler/compile/Component.ts

@@ -29,6 +29,7 @@ import add_to_set from './utils/add_to_set';
 import check_graph_for_cycles from './utils/check_graph_for_cycles';
 import { print, x, b } from 'code-red';
 import { is_reserved_keyword } from './utils/reserved_keywords';
+import Element from './nodes/Element';
 
 interface ComponentOptions {
 	namespace?: string;
@@ -85,6 +86,7 @@ export default class Component {
 	file: string;
 	locate: (c: number) => { line: number; column: number };
 
+	elements: Element[] = [];
 	stylesheet: Stylesheet;
 
 	aliases: Map<string, Identifier> = new Map();
@@ -171,8 +173,8 @@ export default class Component {
 
 		this.walk_instance_js_post_template();
 
+		this.elements.forEach(element => this.stylesheet.apply(element));
 		if (!compile_options.customElement) this.stylesheet.reify();
-
 		this.stylesheet.warn_on_unused_selectors(this);
 	}
 
@@ -221,6 +223,10 @@ export default class Component {
 		return this.aliases.get(name);
 	}
 
+	apply_stylesheet(element: Element) {
+		this.elements.push(element);
+	}
+
 	global(name: string) {
 		const alias = this.alias(name);
 		this.globals.set(name, alias);

src/compiler/compile/css/Selector.ts

@@ -4,12 +4,20 @@ import { gather_possible_values, UNKNOWN } from './gather_possible_values';
 import { CssNode } from './interfaces';
 import Component from '../Component';
 import Element from '../nodes/Element';
+import { INode } from '../nodes/interfaces';
+import EachBlock from '../nodes/EachBlock';
+import IfBlock from '../nodes/IfBlock';
+import AwaitBlock from '../nodes/AwaitBlock';
 
 enum BlockAppliesToNode {
 	NotPossible,
 	Possible,
 	UnknownSelectorType
 }
+enum NodeExist {
+	Probably = 1,
+	Definitely = 2,
+}
 
 const whitelist_attribute_selector = new Map([
 	['details', new Set(['open'])]
@@ -39,10 +47,10 @@ export default class Selector {
 		this.used = this.local_blocks.length === 0;
 	}
 
-	apply(node: Element, stack: Element[]) {
+	apply(node: Element) {
 		const to_encapsulate: any[] = [];
 
-		apply_selector(this.local_blocks.slice(), node, stack.slice(), to_encapsulate);
+		apply_selector(this.local_blocks.slice(), node, to_encapsulate);
 
 		if (to_encapsulate.length > 0) {
 			to_encapsulate.forEach(({ node, block }) => {
@@ -149,7 +157,7 @@ export default class Selector {
 	}
 }
 
-function apply_selector(blocks: Block[], node: Element, stack: Element[], to_encapsulate: any[]): boolean {
+function apply_selector(blocks: Block[], node: Element, to_encapsulate: any[]): boolean {
 	const block = blocks.pop();
 	if (!block) return false;
 
@@ -162,7 +170,7 @@ function apply_selector(blocks: Block[], node: Element, stack: Element[], to_enc
 			return false;
 
 		case BlockAppliesToNode.UnknownSelectorType:
-			// bail. TODO figure out what these could be
+		// bail. TODO figure out what these could be
 			to_encapsulate.push({ node, block });
 			return true;
 	}
@@ -174,9 +182,10 @@ function apply_selector(blocks: Block[], node: Element, stack: Element[], to_enc
 					continue;
 				}
 
-				for (const stack_node of stack) {
-					if (block_might_apply_to_node(ancestor_block, stack_node) !== BlockAppliesToNode.NotPossible) {
-						to_encapsulate.push({ node: stack_node, block: ancestor_block });
+				let parent = node;
+				while (parent = get_element_parent(parent)) {
+					if (block_might_apply_to_node(ancestor_block, parent) !== BlockAppliesToNode.NotPossible) {
+						to_encapsulate.push({ node: parent, block: ancestor_block });
 					}
 				}
 
@@ -193,12 +202,22 @@ function apply_selector(blocks: Block[], node: Element, stack: Element[], to_enc
 
 			return false;
 		} else if (block.combinator.name === '>') {
-			if (apply_selector(blocks, stack.pop(), stack, to_encapsulate)) {
+			if (apply_selector(blocks, get_element_parent(node), to_encapsulate)) {
 				to_encapsulate.push({ node, block });
 				return true;
 			}
 
 			return false;
+		} else if (block.combinator.name === '+' || block.combinator.name === '~') {
+			const siblings = get_possible_element_siblings(node, block.combinator.name === '+');
+			let has_match = false;
+			for (const possible_sibling of siblings.keys()) {
+				if (apply_selector(blocks.slice(), possible_sibling, to_encapsulate)) {
+					to_encapsulate.push({ node, block });
+					has_match = true;
+				}
+			}
+			return has_match;
 		}
 
 		// TODO other combinators
@@ -376,6 +395,158 @@ function unquote(value: CssNode) {
 	return str;
 }
 
+function get_element_parent(node: Element): Element | null {
+	let parent: INode = node;
+	while ((parent = parent.parent) && parent.type !== 'Element');
+	return parent as Element | null;
+}
+
+function get_possible_element_siblings(node: INode, adjacent_only: boolean): Map<Element, NodeExist> {
+	const result: Map<Element, NodeExist> = new Map();
+	let prev: INode = node;
+	while (prev = prev.prev) {
+		if (prev.type === 'Element') {
+			if (!prev.attributes.find(attr => attr.name.toLowerCase() === 'slot')) {
+				result.set(prev, NodeExist.Definitely);
+			}
+
+			if (adjacent_only) {
+				break;
+			}
+		} else if (prev.type === 'EachBlock' || prev.type === 'IfBlock' || prev.type === 'AwaitBlock') {
+			const possible_last_child = get_possible_last_child(prev, adjacent_only);
+
+			add_to_map(possible_last_child, result);
+			if (adjacent_only && has_definite_elements(possible_last_child)) {
+				return result;
+			}
+		}
+	}
+
+	if (!prev || !adjacent_only) {
+		let parent: INode = node;
+		let skip_each_for_last_child = node.type === 'ElseBlock';
+		while ((parent = parent.parent) && (parent.type === 'EachBlock' || parent.type === 'IfBlock' || parent.type === 'ElseBlock' || parent.type === 'AwaitBlock')) {
+			const possible_siblings = get_possible_element_siblings(parent, adjacent_only);
+			add_to_map(possible_siblings, result);
+			
+			if (parent.type === 'EachBlock') {
+				// first child of each block can select the last child of each block as previous sibling
+				if (skip_each_for_last_child) {
+					skip_each_for_last_child = false;
+				} else {
+					add_to_map(get_possible_last_child(parent, adjacent_only), result);
+				}
+			} else if (parent.type === 'ElseBlock') {
+				skip_each_for_last_child = true;
+				parent = parent.parent;
+			}
+
+			if (adjacent_only && has_definite_elements(possible_siblings)) {
+				break;
+			}
+		}
+	}
+
+	return result;
+}
+
+function get_possible_last_child(block: EachBlock | IfBlock | AwaitBlock, adjacent_only: boolean): Map<Element, NodeExist> {
+	const result: Map<Element, NodeExist> = new Map();
+
+	if (block.type === 'EachBlock') {
+		const each_result: Map<Element, NodeExist> = loop_child(block.children, adjacent_only);
+		const else_result: Map<Element, NodeExist> = block.else ? loop_child(block.else.children, adjacent_only) : new Map();
+		
+		const not_exhaustive = !has_definite_elements(else_result);
+
+		if (not_exhaustive) {
+			mark_as_probably(each_result);
+			mark_as_probably(else_result);
+		}
+		add_to_map(each_result, result);
+		add_to_map(else_result, result);
+	} else if (block.type === 'IfBlock') {
+		const if_result: Map<Element, NodeExist> = loop_child(block.children, adjacent_only);
+		const else_result: Map<Element, NodeExist> = block.else ? loop_child(block.else.children, adjacent_only) : new Map();
+
+		const not_exhaustive = !has_definite_elements(if_result) || !has_definite_elements(else_result);
+
+		if (not_exhaustive) {
+			mark_as_probably(if_result);
+			mark_as_probably(else_result);
+		}
+
+		add_to_map(if_result, result);
+		add_to_map(else_result, result);
+	} else if (block.type === 'AwaitBlock') {
+		const pending_result: Map<Element, NodeExist> = block.pending ? loop_child(block.pending.children, adjacent_only) : new Map();
+		const then_result: Map<Element, NodeExist> = block.then ? loop_child(block.then.children, adjacent_only) : new Map();
+		const catch_result: Map<Element, NodeExist> = block.catch ? loop_child(block.catch.children, adjacent_only) : new Map();
+
+		const not_exhaustive = !has_definite_elements(pending_result) || !has_definite_elements(then_result) || !has_definite_elements(catch_result);
+
+		if (not_exhaustive) {
+			mark_as_probably(pending_result);
+			mark_as_probably(then_result);
+			mark_as_probably(catch_result);
+		}
+
+		add_to_map(pending_result, result);
+		add_to_map(then_result, result);
+		add_to_map(catch_result, result);
+	}
+
+	return result;
+}
+
+function has_definite_elements(result: Map<Element, NodeExist>): boolean {
+	if (result.size === 0) return false;
+	for (const exist of result.values()) {
+		if (exist === NodeExist.Definitely) {
+			return true;
+		}
+	}
+	return false;
+}
+
+function add_to_map(from: Map<Element, NodeExist>, to: Map<Element, NodeExist>) {
+	from.forEach((exist, element) => {
+		to.set(element, higher_existance(exist, to.get(element)));
+	});
+}
+
+function higher_existance(exist1: NodeExist | null, exist2: NodeExist | null): NodeExist {
+	if (exist1 === undefined || exist2 === undefined) return exist1 || exist2;
+	return exist1 > exist2 ? exist1 : exist2;
+}
+
+function mark_as_probably(result: Map<Element, NodeExist>) {
+	for (const key of result.keys()) {
+		result.set(key, NodeExist.Probably);
+	}
+}
+
+function loop_child(children: INode[], adjacent_only: boolean) {
+	const result: Map<Element, NodeExist> = new Map();
+	for (let i = children.length - 1; i >= 0; i--) {
+		const child = children[i];
+		if (child.type === 'Element') {
+			result.set(child, NodeExist.Definitely);
+			if (adjacent_only) {
+				break;
+			}
+		} else if (child.type === 'EachBlock' || child.type === 'IfBlock' || child.type === 'AwaitBlock') {
+			const child_result = get_possible_last_child(child, adjacent_only);
+			add_to_map(child_result, result);
+			if (adjacent_only && has_definite_elements(child_result)) {
+				break;
+			}
+		}
+	}
+	return result;
+}
+
 class Block {
 	global: boolean;
 	combinator: CssNode;

src/compiler/compile/css/Stylesheet.ts

@@ -2,7 +2,7 @@ import MagicString from 'magic-string';
 import { walk } from 'estree-walker';
 import Selector from './Selector';
 import Element from '../nodes/Element';
-import { Ast, TemplateNode } from '../../interfaces';
+import { Ast } from '../../interfaces';
 import Component from '../Component';
 import { CssNode } from './interfaces';
 import hash from "../utils/hash";
@@ -51,8 +51,8 @@ class Rule {
 		this.declarations = node.block.children.map((node: CssNode) => new Declaration(node));
 	}
 
-	apply(node: Element, stack: Element[]) {
-		this.selectors.forEach(selector => selector.apply(node, stack)); // TODO move the logic in here?
+	apply(node: Element) {
+		this.selectors.forEach(selector => selector.apply(node)); // TODO move the logic in here?
 	}
 
 	is_used(dev: boolean) {
@@ -162,10 +162,10 @@ class Atrule {
 		this.declarations = [];
 	}
 
-	apply(node: Element, stack: Element[]) {
+	apply(node: Element) {
 		if (this.node.name === 'media' || this.node.name === 'supports') {
 			this.children.forEach(child => {
-				child.apply(node, stack);
+				child.apply(node);
 			});
 		}
 
@@ -364,15 +364,9 @@ export default class Stylesheet {
 	apply(node: Element) {
 		if (!this.has_styles) return;
 
-		const stack: Element[] = [];
-		let parent: TemplateNode = node;
-		while (parent = parent.parent) {
-			if (parent.type === 'Element') stack.unshift(parent as Element);
-		}
-
 		for (let i = 0; i < this.children.length; i += 1) {
 			const child = this.children[i];
-			child.apply(node, stack);
+			child.apply(node);
 		}
 	}
 

src/compiler/compile/nodes/Element.ts

@@ -16,6 +16,7 @@ import list from '../../utils/list';
 import Let from './Let';
 import TemplateScope from './shared/TemplateScope';
 import { INode } from './interfaces';
+import Component from '../Component';
 
 const svg = /^(?:altGlyph|altGlyphDef|altGlyphItem|animate|animateColor|animateMotion|animateTransform|circle|clipPath|color-profile|cursor|defs|desc|discard|ellipse|feBlend|feColorMatrix|feComponentTransfer|feComposite|feConvolveMatrix|feDiffuseLighting|feDisplacementMap|feDistantLight|feDropShadow|feFlood|feFuncA|feFuncB|feFuncG|feFuncR|feGaussianBlur|feImage|feMerge|feMergeNode|feMorphology|feOffset|fePointLight|feSpecularLighting|feSpotLight|feTile|feTurbulence|filter|font|font-face|font-face-format|font-face-name|font-face-src|font-face-uri|foreignObject|g|glyph|glyphRef|hatch|hatchpath|hkern|image|line|linearGradient|marker|mask|mesh|meshgradient|meshpatch|meshrow|metadata|missing-glyph|mpath|path|pattern|polygon|polyline|radialGradient|rect|set|solidcolor|stop|svg|switch|symbol|text|textPath|tref|tspan|unknown|use|view|vkern)$/;
 
@@ -124,7 +125,7 @@ export default class Element extends Node {
 	namespace: string;
 	needs_manual_style_scoping: boolean;
 
-	constructor(component, parent, scope, info: any) {
+	constructor(component: Component, parent, scope, info: any) {
 		super(component, parent, scope, info);
 		this.name = info.name;
 
@@ -185,7 +186,7 @@ export default class Element extends Node {
 
 				case 'Attribute':
 				case 'Spread':
-					// special case
+				// special case
 					if (node.name === 'xmlns') this.namespace = node.value[0].data;
 
 					this.attributes.push(new Attribute(component, this, scope, node));
@@ -236,7 +237,7 @@ export default class Element extends Node {
 
 		this.validate();
 
-		component.stylesheet.apply(this);
+		component.apply_stylesheet(this);
 	}
 
 	validate() {

test/css/samples/general-siblings-combinator-await-not-exhaustive/_config.js

@@ -0,0 +1,3 @@
+export default {
+	warnings: []
+};

test/css/samples/general-siblings-combinator-await-not-exhaustive/expected.css

@@ -0,0 +1,4 @@
+<div class="a svelte-xyz"></div>
+<div class="d svelte-xyz"></div>
+<div class="f svelte-xyz"></div>
+<div class="h svelte-xyz"></div>