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| 1 | +use biome_analyze::{ |
| 2 | + Ast, Rule, RuleDiagnostic, RuleSource, context::RuleContext, declare_lint_rule, |
| 3 | +}; |
| 4 | +use biome_console::markup; |
| 5 | +use biome_diagnostics::Severity; |
| 6 | +use biome_html_syntax::{ |
| 7 | + HtmlElement, HtmlSyntaxKind, HtmlSyntaxNode, T, element_ext::AnyHtmlTagElement, |
| 8 | +}; |
| 9 | +use biome_languages::HtmlFileSource; |
| 10 | +use biome_parser::{TokenSet, token_set}; |
| 11 | +use biome_rowan::{AstNode, TextRange}; |
| 12 | +use biome_rule_options::no_misplaced_list_elements::NoMisplacedListElementsOptions; |
| 13 | + |
| 14 | +declare_lint_rule! { |
| 15 | + /// Require `<li>` elements with an HTML element parent to be children of `<ul>`, `<ol>`, or `<menu>`. |
| 16 | + /// |
| 17 | + /// List items need a list container to define their relationship to the other items. |
| 18 | + /// Placing a list item outside a list container produces invalid HTML. |
| 19 | + /// |
| 20 | + /// The parent is the element the item is rendered into. List items that aren't inside |
| 21 | + /// any element in the file are ignored, because the file may be rendered inside a list |
| 22 | + /// somewhere else, for example as a component. Items directly inside a <template> element are also |
| 23 | + /// ignored, because the template's content is inserted by a script, not rendered in place. |
| 24 | + /// Items whose parent is a component are also ignored, |
| 25 | + /// because the element a component renders is unknown. |
| 26 | + /// |
| 27 | + /// In Svelte, control blocks such as `{#if}` and `{#each}`, as well as `<svelte:boundary>`, |
| 28 | + /// `<svelte:fragment>`, and `<slot>`, are skipped when finding the parent, while items |
| 29 | + /// inside snippets, `<svelte:element>`, and other Svelte special elements are ignored. |
| 30 | + /// |
| 31 | + /// In Vue, `<template>` elements with a `v-if`, `v-else-if`, `v-else`, or `v-for` |
| 32 | + /// directive, `<transition>`, `<keep-alive>`, `<suspense>`, and `<slot>` are looked |
| 33 | + /// through to find the parent. Items directly inside the component's top-level |
| 34 | + /// `<template>`, and items inside `<component>`, `<transition-group>`, or `<teleport>`, |
| 35 | + /// are ignored. |
| 36 | + /// |
| 37 | + /// In Astro, fragments and `<slot>` are looked through to find the parent. Markup inside |
| 38 | + /// a `{...}` expression is checked separately from the markup around it, so an item in |
| 39 | + /// an expression is only compared with elements in the same expression. For example, |
| 40 | + /// `<div>{items.map((item) => <li>{item}</li>)}</div>` isn't reported, because the |
| 41 | + /// `<div>` is outside the expression. |
| 42 | + /// |
| 43 | + /// ## Examples |
| 44 | + /// |
| 45 | + /// ### Invalid |
| 46 | + /// |
| 47 | + /// ```html,expect_diagnostic |
| 48 | + /// <div><li>Item</li></div> |
| 49 | + /// ``` |
| 50 | + /// |
| 51 | + /// ```html,expect_diagnostic |
| 52 | + /// <ul><div><li>Item</li></div></ul> |
| 53 | + /// ``` |
| 54 | + /// |
| 55 | + /// ```svelte,expect_diagnostic |
| 56 | + /// <div> |
| 57 | + /// {#each items as item} |
| 58 | + /// <li>{item}</li> |
| 59 | + /// {/each} |
| 60 | + /// </div> |
| 61 | + /// ``` |
| 62 | + /// |
| 63 | + /// ```astro,expect_diagnostic |
| 64 | + /// <div> |
| 65 | + /// <> |
| 66 | + /// <li>Item</li> |
| 67 | + /// </> |
| 68 | + /// </div> |
| 69 | + /// ``` |
| 70 | + /// |
| 71 | + /// ### Valid |
| 72 | + /// |
| 73 | + /// ```html |
| 74 | + /// <ul><li>Item</li></ul> |
| 75 | + /// <ol><li>Item</li></ol> |
| 76 | + /// <menu><li>Item</li></menu> |
| 77 | + /// ``` |
| 78 | + /// |
| 79 | + /// ```vue |
| 80 | + /// <template> |
| 81 | + /// <li>Item rendered in a list elsewhere</li> |
| 82 | + /// </template> |
| 83 | + /// ``` |
| 84 | + /// |
| 85 | + /// ```svelte |
| 86 | + /// {#snippet item()} |
| 87 | + /// <li>Item</li> |
| 88 | + /// {/snippet} |
| 89 | + /// ``` |
| 90 | + /// |
| 91 | + /// ```astro |
| 92 | + /// <ul> |
| 93 | + /// <> |
| 94 | + /// <li>Item</li> |
| 95 | + /// </> |
| 96 | + /// </ul> |
| 97 | + /// ``` |
| 98 | + /// |
| 99 | + pub NoMisplacedListElements { |
| 100 | + version: "next", |
| 101 | + name: "noMisplacedListElements", |
| 102 | + language: "html", |
| 103 | + recommended: true, |
| 104 | + severity: Severity::Error, |
| 105 | + sources: &[RuleSource::HtmlEslint("require-li-container").inspired()], |
| 106 | + } |
| 107 | +} |
| 108 | + |
| 109 | +const LIST_CONTAINERS: TokenSet<HtmlSyntaxKind> = token_set![T![ul], T![ol], T![menu]]; |
| 110 | +const SVELTE_CONTROL_BLOCK_KINDS: TokenSet<HtmlSyntaxKind> = token_set![ |
| 111 | + HtmlSyntaxKind::SVELTE_IF_BLOCK, |
| 112 | + HtmlSyntaxKind::SVELTE_IF_OPENING_BLOCK, |
| 113 | + HtmlSyntaxKind::SVELTE_ELSE_IF_CLAUSE_LIST, |
| 114 | + HtmlSyntaxKind::SVELTE_ELSE_IF_CLAUSE, |
| 115 | + HtmlSyntaxKind::SVELTE_ELSE_CLAUSE, |
| 116 | + HtmlSyntaxKind::SVELTE_EACH_BLOCK, |
| 117 | + HtmlSyntaxKind::SVELTE_AWAIT_BLOCK, |
| 118 | + HtmlSyntaxKind::SVELTE_AWAIT_OPENING_BLOCK, |
| 119 | + HtmlSyntaxKind::SVELTE_AWAIT_THEN_BLOCK, |
| 120 | + HtmlSyntaxKind::SVELTE_AWAIT_CATCH_BLOCK, |
| 121 | + HtmlSyntaxKind::SVELTE_AWAIT_CLAUSES_LIST, |
| 122 | + HtmlSyntaxKind::SVELTE_KEY_BLOCK, |
| 123 | +]; |
| 124 | + |
| 125 | +impl Rule for NoMisplacedListElements { |
| 126 | + type Query = Ast<AnyHtmlTagElement>; |
| 127 | + type State = TextRange; |
| 128 | + type Signals = Option<Self::State>; |
| 129 | + type Options = NoMisplacedListElementsOptions; |
| 130 | + |
| 131 | + fn run(ctx: &RuleContext<Self>) -> Self::Signals { |
| 132 | + let node = ctx.query(); |
| 133 | + if node.tag_name_kind() != Some(T![li]) { |
| 134 | + return None; |
| 135 | + } |
| 136 | + |
| 137 | + let element = match node { |
| 138 | + AnyHtmlTagElement::HtmlOpeningElement(opening) => opening.syntax().parent()?, |
| 139 | + AnyHtmlTagElement::HtmlSelfClosingElement(element) => element.syntax().clone(), |
| 140 | + }; |
| 141 | + let parent = rendered_parent(&element, ctx.source_type::<HtmlFileSource>())?; |
| 142 | + let parent_kind = parent.tag_name_kind()?; |
| 143 | + if LIST_CONTAINERS.contains(parent_kind) { |
| 144 | + return None; |
| 145 | + } |
| 146 | + |
| 147 | + Some(node.syntax().text_trimmed_range()) |
| 148 | + } |
| 149 | + |
| 150 | + fn diagnostic(_ctx: &RuleContext<Self>, range: &Self::State) -> Option<RuleDiagnostic> { |
| 151 | + Some( |
| 152 | + RuleDiagnostic::new( |
| 153 | + rule_category!(), |
| 154 | + *range, |
| 155 | + markup! { |
| 156 | + "This "<Emphasis>"<li>"</Emphasis>" element is outside a list container." |
| 157 | + }, |
| 158 | + ) |
| 159 | + .note("List items need a list container to form a valid HTML list.") |
| 160 | + .note(markup! { |
| 161 | + "Make this element a direct child of "<Emphasis>"<ul>"</Emphasis>", "<Emphasis>"<ol>"</Emphasis>", or "<Emphasis>"<menu>"</Emphasis>"." |
| 162 | + }), |
| 163 | + ) |
| 164 | + } |
| 165 | +} |
| 166 | + |
| 167 | +/// Returns the opening tag of the element that `element` is rendered into. |
| 168 | +/// |
| 169 | +/// Returns `None` when the element has no parent element, or when the parent does not |
| 170 | +/// determine where its children are rendered. See [`ParentRole`]. |
| 171 | +fn rendered_parent( |
| 172 | + element: &HtmlSyntaxNode, |
| 173 | + source_type: &HtmlFileSource, |
| 174 | +) -> Option<AnyHtmlTagElement> { |
| 175 | + for ancestor in element.ancestors().skip(1) { |
| 176 | + let kind = ancestor.kind(); |
| 177 | + if kind == HtmlSyntaxKind::HTML_ELEMENT_LIST |
| 178 | + || kind == HtmlSyntaxKind::ASTRO_FRAGMENT |
| 179 | + || (source_type.is_svelte() && SVELTE_CONTROL_BLOCK_KINDS.contains(kind)) |
| 180 | + { |
| 181 | + continue; |
| 182 | + } |
| 183 | + |
| 184 | + let parent = HtmlElement::cast(ancestor)?; |
| 185 | + let opening = AnyHtmlTagElement::from(parent.opening_element().ok()?); |
| 186 | + match ParentRole::of(&opening, source_type) { |
| 187 | + ParentRole::Element => return Some(opening), |
| 188 | + ParentRole::Transparent => {} |
| 189 | + ParentRole::Unknown => return None, |
| 190 | + } |
| 191 | + } |
| 192 | + None |
| 193 | +} |
| 194 | + |
| 195 | +/// How a parent element relates to the element its children are rendered into. |
| 196 | +enum ParentRole { |
| 197 | + /// The parent is the element its children are rendered into. |
| 198 | + Element, |
| 199 | + /// The parent renders its children in its own place, so they are rendered into the |
| 200 | + /// nearest enclosing element. |
| 201 | + Transparent, |
| 202 | + /// The element the children are rendered into can't be determined. |
| 203 | + Unknown, |
| 204 | +} |
| 205 | + |
| 206 | +impl ParentRole { |
| 207 | + fn of(opening: &AnyHtmlTagElement, source_type: &HtmlFileSource) -> Self { |
| 208 | + if source_type.is_svelte() && opening.is_svelte_special_element() { |
| 209 | + return match opening.tag_name().as_ref().map(|name| name.text()) { |
| 210 | + Some("svelte:boundary" | "svelte:fragment") => Self::Transparent, |
| 211 | + _ => Self::Unknown, |
| 212 | + }; |
| 213 | + } |
| 214 | + |
| 215 | + if source_type.is_vue() { |
| 216 | + match opening.tag_name().as_ref().map(|name| name.text()) { |
| 217 | + Some("transition" | "keep-alive" | "suspense") => return Self::Transparent, |
| 218 | + Some("component" | "transition-group" | "teleport") => return Self::Unknown, |
| 219 | + _ => {} |
| 220 | + } |
| 221 | + } |
| 222 | + |
| 223 | + match opening.tag_name_kind() { |
| 224 | + // Vue renders the content of a `<template>` with a control flow directive in |
| 225 | + // place of the template. |
| 226 | + Some(T![template]) |
| 227 | + if source_type.is_vue() && has_vue_control_flow_directive(opening) => |
| 228 | + { |
| 229 | + Self::Transparent |
| 230 | + } |
| 231 | + // The content of a native `<template>` is inserted by a script, which decides |
| 232 | + // where it is rendered. |
| 233 | + Some(T![template]) => Self::Unknown, |
| 234 | + Some(T![slot]) |
| 235 | + if source_type.is_vue() || source_type.is_svelte() || source_type.is_astro() => |
| 236 | + { |
| 237 | + Self::Transparent |
| 238 | + } |
| 239 | + Some(_) => Self::Element, |
| 240 | + None => Self::Unknown, |
| 241 | + } |
| 242 | + } |
| 243 | +} |
| 244 | + |
| 245 | +fn has_vue_control_flow_directive(opening: &AnyHtmlTagElement) -> bool { |
| 246 | + opening.attributes().into_iter().any(|attribute| { |
| 247 | + attribute |
| 248 | + .as_any_vue_directive() |
| 249 | + .and_then(|directive| directive.as_vue_directive()) |
| 250 | + .and_then(|directive| directive.name_token().ok()) |
| 251 | + .is_some_and(|name| { |
| 252 | + matches!( |
| 253 | + name.text_trimmed(), |
| 254 | + "v-if" | "v-else-if" | "v-else" | "v-for" |
| 255 | + ) |
| 256 | + }) |
| 257 | + }) |
| 258 | +} |
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