Refactor CSS node types with reusable type builders

[bartveneman]

Summary

This refactor introduces reusable type builders (Toggle, WithClone, and Leaf) to reduce duplication across ~40 CSS node type definitions. These are pure type-level utilities that compile away entirely, improving maintainability without runtime cost.

Key Changes

• Added Toggle<HasKey, ValueKey, T> type: A discriminated union pattern for optional fields gated by boolean flags (e.g., has_prelude / prelude). Replaces repeated inline union patterns throughout the file.

• Added WithClone<T> type: Wraps a node type to add a clone() method with proper return type inference (ToPlain<T>). Eliminates repetitive clone method declarations.

• Added Leaf<Type, Name, Extra> type: Combines CSSNode, type tag, and optional extra fields for leaf nodes (nodes without children). Significantly reduces boilerplate for simple node types.

• Refactored all node type definitions to use these builders:

  • Structural nodes: StyleSheet, Rule, Atrule, Declaration, Selector, SelectorList, Block, Comment, Raw
  • Value nodes: Identifier, Number, Dimension, String, Hash, Function, Operator, Parenthesis, Url, UnicodeRange, Value
  • Selector nodes: TypeSelector, ClassSelector, IdSelector, AttributeSelector, PseudoClassSelector, PseudoElementSelector, Combinator, UniversalSelector, NestingSelector, NthSelector, NthOfSelector, LangSelector
  • At-rule prelude nodes: AtrulePrelude, MediaQuery, MediaFeature, MediaType, ContainerQuery, SupportsQuery, SupportsDeclaration, LayerName, PreludeSelectorList, PreludeOperator, FeatureRange

Implementation Details

• The Toggle type replaces verbose union patterns like ({ readonly has_X: true } & { readonly X: T }) | ({ readonly has_X: false } & { readonly X: null }) with a single, reusable construct.
• BlockChild now uses Toggle for its has_next / next_sibling pattern.
• All type definitions maintain identical semantics and exported interfaces—this is purely a refactoring for code clarity and maintainability.
• The builders are documented with JSDoc comments explaining their purpose and usage.

https://claude.ai/code/session_01FuvCERnifYS6ggHAXMwVkD

[github-actions]

⚠️ Duplicate Dependencies (found: 35, threshold: 1)

📦 Package	📋 Versions
tinybench	2 versions root@ @vitest/coverage-v8@4.1.9 vitest@4.1.9 tinybench@2.9.0 root@ tinybench@6.0.2
@babel/helper-validator-identifier	2 versions root@ @vitest/coverage-v8@4.1.9 magicast@0.5.2 @babel/parser@7.29.3 @babel/types@7.29.0 @babel/helper-validator-identifier@7.28.5 root@ tsdown@0.22.3 ... @babel/parser@8.0.0 @babel/types@8.0.0 @babel/helper-validator-identifier@8.0.2
js-tokens	2 versions root@ @vitest/coverage-v8@4.1.9 ast-v8-to-istanbul@1.0.0 js-tokens@10.0.0 root@ tailwindcss@2.2.19 cosmiconfig@7.1.0 parse-json@5.2.0 @babel/code-frame@7.27.1 js-tokens@4.0.0
@babel/parser	2 versions root@ @vitest/coverage-v8@4.1.9 magicast@0.5.2 @babel/parser@7.29.3 root@ tsdown@0.22.3 rolldown-plugin-dts@0.26.0 @babel/generator@8.0.0 @babel/parser@8.0.0
@babel/types	2 versions root@ @vitest/coverage-v8@4.1.9 magicast@0.5.2 @babel/parser@7.29.3 @babel/types@7.29.0 root@ tsdown@0.22.3 rolldown-plugin-dts@0.26.0 @babel/generator@8.0.0 @babel/parser@8.0.0 @babel/types@8.0.0
@babel/helper-string-parser	2 versions root@ @vitest/coverage-v8@4.1.9 magicast@0.5.2 @babel/parser@7.29.3 @babel/types@7.29.0 @babel/helper-string-parser@7.27.1 root@ tsdown@0.22.3 ... @babel/parser@8.0.0 @babel/types@8.0.0 @babel/helper-string-parser@8.0.0
@emnapi/core	3 versions root@ @vitest/coverage-v8@4.1.9 ... rolldown@1.0.3 @rolldown/binding-wasm32-wasi@1.0.3 @emnapi/core@1.10.0 root@ knip@6.18.0 oxc-resolver@11.21.3 @oxc-resolver/binding-wasm32-wasi@11.21.3 @emnapi/core@1.11.0 root@ knip@6.18.0 oxc-parser@0.137.0 @oxc-parser/binding-wasm32-wasi@0.137.0 @emnapi/core@1.11.1
@emnapi/wasi-threads	2 versions root@ @vitest/coverage-v8@4.1.9 ... @rolldown/binding-wasm32-wasi@1.0.3 @emnapi/core@1.10.0 @emnapi/wasi-threads@1.2.1 root@ knip@6.18.0 oxc-parser@0.137.0 @oxc-parser/binding-wasm32-wasi@0.137.0 @emnapi/core@1.11.1 @emnapi/wasi-threads@1.2.2
@emnapi/runtime	3 versions root@ @vitest/coverage-v8@4.1.9 ... rolldown@1.0.3 @rolldown/binding-wasm32-wasi@1.0.3 @emnapi/runtime@1.10.0 root@ knip@6.18.0 oxc-resolver@11.21.3 @oxc-resolver/binding-wasm32-wasi@11.21.3 @emnapi/runtime@1.11.0 root@ knip@6.18.0 oxc-parser@0.137.0 @oxc-parser/binding-wasm32-wasi@0.137.0 @emnapi/runtime@1.11.1
@rolldown/binding-wasm32-wasi	2 versions root@ @vitest/coverage-v8@4.1.9 ... vite@8.0.16 rolldown@1.0.3 @rolldown/binding-wasm32-wasi@1.0.3 root@ tsdown@0.22.3 rolldown@1.1.2 @rolldown/binding-wasm32-wasi@1.1.2
obug	2 versions root@ @vitest/coverage-v8@4.1.9 obug@2.1.1 root@ tsdown@0.22.3 obug@2.1.3
picomatch	2 versions root@ tailwindcss@2.2.19 chokidar@3.6.0 anymatch@3.1.3 picomatch@2.3.2 root@ @vitest/coverage-v8@4.1.9 vitest@4.1.9 @vitest/mocker@4.1.9 vite@8.0.16 picomatch@4.0.4
postcss-value-parser	2 versions root@ tailwindcss@2.2.19 reduce-css-calc@2.1.8 postcss-value-parser@3.3.1 root@ tailwindcss@2.2.19 autoprefixer@10.4.23 postcss-value-parser@4.2.0
glob-parent	2 versions root@ tailwindcss@2.2.19 chokidar@3.6.0 glob-parent@5.1.2 root@ tailwindcss@2.2.19 glob-parent@6.0.2
yaml	2 versions root@ tailwindcss@2.2.19 cosmiconfig@7.1.0 yaml@1.10.3 root@ @vitest/coverage-v8@4.1.9 vitest@4.1.9 @vitest/mocker@4.1.9 vite@8.0.16 yaml@2.9.0
is-arrayish	2 versions root@ tailwindcss@2.2.19 cosmiconfig@7.1.0 parse-json@5.2.0 error-ex@1.3.4 is-arrayish@0.2.1 root@ tailwindcss@2.2.19 color@4.2.3 color-string@1.9.1 simple-swizzle@0.2.4 is-arrayish@0.3.4
get-tsconfig	2 versions root@ knip@6.18.0 get-tsconfig@4.14.0 root@ tsdown@0.22.3 rolldown-plugin-dts@0.26.0 get-tsconfig@5.0.0-beta.5
semver	2 versions root@ @vitest/coverage-v8@4.1.9 istanbul-lib-report@3.0.1 make-dir@4.0.0 semver@7.8.0 root@ tsdown@0.22.3 semver@7.8.5
@oxc-project/types	2 versions root@ @vitest/coverage-v8@4.1.9 ... vite@8.0.16 rolldown@1.0.3 @oxc-project/types@0.133.0 root@ knip@6.18.0 oxc-parser@0.137.0 @oxc-project/types@0.137.0
rolldown	2 versions root@ @vitest/coverage-v8@4.1.9 vitest@4.1.9 @vitest/mocker@4.1.9 vite@8.0.16 rolldown@1.0.3 root@ tsdown@0.22.3 rolldown@1.1.2
@rolldown/binding-android-arm64	2 versions root@ @vitest/coverage-v8@4.1.9 ... vite@8.0.16 rolldown@1.0.3 @rolldown/binding-android-arm64@1.0.3 root@ tsdown@0.22.3 rolldown@1.1.2 @rolldown/binding-android-arm64@1.1.2
@rolldown/binding-darwin-arm64	2 versions root@ @vitest/coverage-v8@4.1.9 ... vite@8.0.16 rolldown@1.0.3 @rolldown/binding-darwin-arm64@1.0.3 root@ tsdown@0.22.3 rolldown@1.1.2 @rolldown/binding-darwin-arm64@1.1.2
@rolldown/binding-darwin-x64	2 versions root@ @vitest/coverage-v8@4.1.9 ... vite@8.0.16 rolldown@1.0.3 @rolldown/binding-darwin-x64@1.0.3 root@ tsdown@0.22.3 rolldown@1.1.2 @rolldown/binding-darwin-x64@1.1.2
@rolldown/binding-freebsd-x64	2 versions root@ @vitest/coverage-v8@4.1.9 ... vite@8.0.16 rolldown@1.0.3 @rolldown/binding-freebsd-x64@1.0.3 root@ tsdown@0.22.3 rolldown@1.1.2 @rolldown/binding-freebsd-x64@1.1.2
@rolldown/binding-linux-arm-gnueabihf	2 versions root@ @vitest/coverage-v8@4.1.9 ... vite@8.0.16 rolldown@1.0.3 @rolldown/binding-linux-arm-gnueabihf@1.0.3 root@ tsdown@0.22.3 rolldown@1.1.2 @rolldown/binding-linux-arm-gnueabihf@1.1.2
@rolldown/binding-linux-arm64-gnu	2 versions root@ @vitest/coverage-v8@4.1.9 ... vite@8.0.16 rolldown@1.0.3 @rolldown/binding-linux-arm64-gnu@1.0.3 root@ tsdown@0.22.3 rolldown@1.1.2 @rolldown/binding-linux-arm64-gnu@1.1.2
@rolldown/binding-linux-arm64-musl	2 versions root@ @vitest/coverage-v8@4.1.9 ... vite@8.0.16 rolldown@1.0.3 @rolldown/binding-linux-arm64-musl@1.0.3 root@ tsdown@0.22.3 rolldown@1.1.2 @rolldown/binding-linux-arm64-musl@1.1.2
@rolldown/binding-linux-ppc64-gnu	2 versions root@ @vitest/coverage-v8@4.1.9 ... vite@8.0.16 rolldown@1.0.3 @rolldown/binding-linux-ppc64-gnu@1.0.3 root@ tsdown@0.22.3 rolldown@1.1.2 @rolldown/binding-linux-ppc64-gnu@1.1.2
@rolldown/binding-linux-s390x-gnu	2 versions root@ @vitest/coverage-v8@4.1.9 ... vite@8.0.16 rolldown@1.0.3 @rolldown/binding-linux-s390x-gnu@1.0.3 root@ tsdown@0.22.3 rolldown@1.1.2 @rolldown/binding-linux-s390x-gnu@1.1.2
@rolldown/binding-linux-x64-gnu	2 versions root@ @vitest/coverage-v8@4.1.9 ... vite@8.0.16 rolldown@1.0.3 @rolldown/binding-linux-x64-gnu@1.0.3 root@ tsdown@0.22.3 rolldown@1.1.2 @rolldown/binding-linux-x64-gnu@1.1.2
@rolldown/binding-linux-x64-musl	2 versions root@ @vitest/coverage-v8@4.1.9 ... vite@8.0.16 rolldown@1.0.3 @rolldown/binding-linux-x64-musl@1.0.3 root@ tsdown@0.22.3 rolldown@1.1.2 @rolldown/binding-linux-x64-musl@1.1.2
@rolldown/binding-openharmony-arm64	2 versions root@ @vitest/coverage-v8@4.1.9 ... vite@8.0.16 rolldown@1.0.3 @rolldown/binding-openharmony-arm64@1.0.3 root@ tsdown@0.22.3 rolldown@1.1.2 @rolldown/binding-openharmony-arm64@1.1.2
@rolldown/binding-win32-arm64-msvc	2 versions root@ @vitest/coverage-v8@4.1.9 ... vite@8.0.16 rolldown@1.0.3 @rolldown/binding-win32-arm64-msvc@1.0.3 root@ tsdown@0.22.3 rolldown@1.1.2 @rolldown/binding-win32-arm64-msvc@1.1.2
@rolldown/binding-win32-x64-msvc	2 versions root@ @vitest/coverage-v8@4.1.9 ... vite@8.0.16 rolldown@1.0.3 @rolldown/binding-win32-x64-msvc@1.0.3 root@ tsdown@0.22.3 rolldown@1.1.2 @rolldown/binding-win32-x64-msvc@1.1.2
tinyexec	2 versions root@ @vitest/coverage-v8@4.1.9 vitest@4.1.9 tinyexec@1.1.2 root@ tsdown@0.22.3 tinyexec@1.2.4

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🎉 Package Size Decrease

📦 Package	📏 Base Size	📏 Source Size	📈 Size Change
@projectwallace/css-parser	41 kB	41 kB	-69 B