Make more AST properties optional in return types

node/ast.d.ts

@@ -7025,7 +7025,7 @@ export interface ImportRule {
   /**
    * A media query.
    */
-  media: MediaList;
+  media?: MediaList;
   /**
    * An optional `supports()` condition.
    */
@@ -7050,7 +7050,7 @@ export interface StyleRule<D = Declaration> {
   /**
    * Nested rules within the style rule.
    */
-  rules: Rule<D>[];
+  rules?: Rule<D>[];
   /**
    * The selectors for the style rule.
    */
@@ -7065,11 +7065,11 @@ export interface DeclarationBlock<D = Declaration> {
   /**
    * A list of normal declarations in the block.
    */
-  declarations: D[];
+  declarations?: D[];
   /**
    * A list of `!important` declarations in the block.
    */
-  importantDeclarations: D[];
+  importantDeclarations?: D[];
 }
 /**
  * A CSS [`<position>`](https://www.w3.org/TR/css3-values/#position) value, as used in the `background-position` property, gradients, masks, etc.

node/index.d.ts

@@ -1,4 +1,4 @@
-import type { Angle, CssColor, Rule, CustomProperty, EnvironmentVariable, Function, Image, LengthValue, MediaQuery, Declaration, Ratio, Resolution, Selector, SupportsCondition, Time, Token, TokenOrValue, UnknownAtRule, Url, Variable } from './ast';
+import type { Angle, CssColor, Rule, CustomProperty, EnvironmentVariable, Function, Image, LengthValue, MediaQuery, Declaration, Ratio, Resolution, Selector, SupportsCondition, Time, Token, TokenOrValue, UnknownAtRule, Url, Variable, StyleRule, DeclarationBlock } from './ast';
 import type { Targets } from './targets';
 
 export * from './ast';
@@ -69,9 +69,14 @@ type ReturnedDeclaration = Declaration | {
 
 type FindByType<Union, Name> = Union extends { type: Name } ? Union : never;
 type ReturnedRule = Rule<ReturnedDeclaration>;
-type RuleVisitor<R = Rule> = ((rule: R) => ReturnedRule | ReturnedRule[] | void);
+type RequiredValue<Rule> = Rule extends { value: object }
+  ? Rule['value'] extends StyleRule
+  ? Rule & { value: Required<StyleRule> & { declarations: Required<DeclarationBlock> } }
+  : Rule & { value: Required<Rule['value']> }
+  : Rule;
+type RuleVisitor<R = RequiredValue<Rule>> = ((rule: R) => ReturnedRule | ReturnedRule[] | void);
 type MappedRuleVisitors = {
-  [Name in Exclude<Rule['type'], 'unknown' | 'custom'>]?: RuleVisitor<FindByType<Rule, Name>>;
+  [Name in Exclude<Rule['type'], 'unknown' | 'custom'>]?: RuleVisitor<RequiredValue<FindByType<Rule, Name>>>;
 }
 
 type UnknownVisitors = {

node/test/visitor.test.mjs

@@ -658,17 +658,8 @@ test('hover media query', () => {
 test('momentum scrolling', () => {
   // Similar to https://github.com/yunusga/postcss-momentum-scrolling
   let visitOverflow = decl => [decl, {
-    property: 'custom',
-    value: {
-      name: '-webkit-overflow-scrolling',
-      value: [{
-        type: 'token',
-        value: {
-          type: 'ident',
-          value: 'touch'
-        }
-      }]
-    }
+    property: '-webkit-overflow-scrolling',
+    raw: 'touch'
   }];
 
   let res = transform({
@@ -836,7 +827,6 @@ test('returning string values', () => {
           return {
             type: 'style',
             value: {
-              rules: [],
               loc: rule.loc,
               selectors: [
                 [{ type: 'universal' }]
@@ -864,8 +854,7 @@ test('returning string values', () => {
                     property: '-webkit-animation',
                     raw: '3s cubic-bezier(0.25, 0.1, 0.25, 1) foo'
                   }
-                ],
-                importantDeclarations: [],
+                ]
               }
             }
           }

src/declaration.rs

@@ -54,9 +54,10 @@ use cssparser::*;
 #[cfg_attr(feature = "jsonschema", derive(schemars::JsonSchema))]
 pub struct DeclarationBlock<'i> {
   /// A list of `!important` declarations in the block.
-  #[cfg_attr(feature = "serde", serde(borrow))]
+  #[cfg_attr(feature = "serde", serde(borrow, default))]
   pub important_declarations: Vec<Property<'i>>,
   /// A list of normal declarations in the block.
+  #[cfg_attr(feature = "serde", serde(default))]
   pub declarations: Vec<Property<'i>>,
 }
 

src/media_query.rs

@@ -23,7 +23,7 @@ use std::collections::{HashMap, HashSet};
 use crate::serialization::ValueWrapper;
 
 /// A [media query list](https://drafts.csswg.org/mediaqueries/#mq-list).
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, Default)]
 #[cfg_attr(feature = "visitor", derive(Visit), visit(visit_media_list, MEDIA_QUERIES))]
 #[cfg_attr(feature = "into_owned", derive(lightningcss_derive::IntoOwned))]
 #[cfg_attr(

src/rules/import.rs

@@ -30,6 +30,7 @@ pub struct ImportRule<'i> {
   /// An optional `supports()` condition.
   pub supports: Option<SupportsCondition<'i>>,
   /// A media query.
+  #[cfg_attr(feature = "serde", serde(default))]
   pub media: MediaList<'i>,
   /// The location of the rule in the source file.
   #[cfg_attr(feature = "visitor", skip_visit)]

src/rules/mod.rs

@@ -388,7 +388,7 @@ impl<'i, T: ToCss> ToCss for CssRule<'i, T> {
 }
 
 /// A list of CSS rules.
-#[derive(Debug, PartialEq, Clone)]
+#[derive(Debug, PartialEq, Clone, Default)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize), serde(transparent))]
 #[cfg_attr(feature = "jsonschema", derive(schemars::JsonSchema))]
 pub struct CssRuleList<'i, R = DefaultAtRule>(

src/rules/style.rs

@@ -36,12 +36,17 @@ pub struct StyleRule<'i, R = DefaultAtRule> {
   /// The declarations within the style rule.
   pub declarations: DeclarationBlock<'i>,
   /// Nested rules within the style rule.
+  #[cfg_attr(feature = "serde", serde(default = "default_rule_list::<R>"))]
   pub rules: CssRuleList<'i, R>,
   /// The location of the rule in the source file.
   #[cfg_attr(feature = "visitor", skip_visit)]
   pub loc: Location,
 }
 
+fn default_rule_list<'i, R>() -> CssRuleList<'i, R> {
+  CssRuleList(Vec::new())
+}
+
 impl<'i, T> StyleRule<'i, T> {
   pub(crate) fn minify(
     &mut self,