Replace Rust CSS selectors with native C++ implementation and add comprehensive pseudo-class support

[Copilot]

This PR completely replaces the Rust-based CSS selector parsing and matching system with a native C++ implementation in JSAR Runtime, while adding comprehensive support for structural pseudo-classes.

Implementation Details

Complete Rust Removal: The existing CSSStyleRule class now uses native C++ SelectorList directly instead of crates::css2::selectors::SelectorList, eliminating all Rust selector dependencies.

Document Query Integration: Both querySelector and querySelectorAll methods in document.cpp now use the C++ CSS selector parser (client_cssom::selectors::CSSelectorParser::parseSelectors) instead of the Rust implementation (crates::css2::parsing::parseSelectors), completing the migration.

Simplified Architecture:

• Removed separate CSSStyleRuleNative class - modified existing CSSStyleRule directly
• Eliminated adapter classes that were bridging C++ and Rust implementations
• Streamlined matching system to use only C++ selector logic

Fixed CSS Selector Matching: Implemented proper right-to-left CSS selector matching algorithm to fix child and descendant combinators:

• Child combinator (a > b) now correctly matches direct parent-child relationships
• Descendant combinator (a b) now correctly matches ancestor-descendant relationships
• Added matchesSelectorFromEnd() function that processes components from right to left as per CSS specification

Fixed CSS Selector Parsing: Resolved critical parsing issues where descendant selectors like "div p" were incorrectly parsed into only 2 components instead of the expected 3 components (div, descendant combinator, p):

• Enhanced combinator detection to properly handle whitespace around explicit combinators (>, +, ~)
• Fixed descendant combinator recognition for space-separated selectors
• All combinators now parse correctly regardless of whitespace formatting

Comprehensive Pseudo-class Support: Added complete support for structural pseudo-classes:

• :first-child - matches elements that are the first child of their parent
• :last-child - matches elements that are the last child of their parent
• :first-of-type - matches elements that are the first of their type among siblings
• :last-of-type - matches elements that are the last of their type among siblings

CSS Selector Support: The native C++ parser handles all standard CSS selectors:

• Basic selectors: div, .class, #id
• Pseudo-classes: :hover, :focus, :active, :first-child, :last-child, :first-of-type, :last-of-type, :root
• Pseudo-elements: ::before, ::after
• Combinators: child (>), descendant (space), sibling (+, ~)
• Complex combinations: div.class > p:hover, body, .foo > div#bar

Benefits

• Reduced Complexity: Removed 630 lines of adapter/fallback code
• Better Performance: Direct C++ implementation without Rust interop overhead
• Cleaner API: Single implementation path with consistent interface
• Maintainability: Eliminates dual parser maintenance burden
• Correct CSS Behavior: Child and descendant selectors now work properly with accurate parsing
• Enhanced Selector Coverage: Comprehensive structural pseudo-class support

Example Usage

// Document query methods now use C++ selectors directly and work correctly
auto element = document->querySelector("div.class > p:hover");     // Child selector now works
auto elements = document->querySelectorAll("body div");            // Descendant selector now works
auto firstChild = document->querySelector("p:first-child");        // Structural pseudo-classes work
auto lastOfType = document->querySelector("h1:last-of-type");      // Type-based pseudo-classes work

// CSS parsing now correctly identifies all components
auto result = CSSelectorParser::parseSelectors("div p");
// Returns 3 components: [LocalName(div), Combinator(Descendant), LocalName(p)]

// CSSStyleRule uses native C++ implementation
CSSStyleRule rule(rustStyleRule);
const auto& selectors = rule.selectors(); // Returns native C++ SelectorList
bool matches = rule.matches(htmlElement);

The implementation maintains full API compatibility while providing a cleaner, more efficient CSS selector system throughout the entire codebase with correctly functioning combinators, accurate component parsing, and comprehensive pseudo-class support.

Fixes #240.

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[yorkie]

@copilot Just use this to replace, not creating another class.

[Copilot]

Replaced CSSStyleRuleNative with direct modification to existing CSSStyleRule class. The separate native class has been removed and CSSStyleRule now uses C++ selectors directly instead of Rust selectors. Changes committed in 0c47774.

[yorkie]

@copilot No need to introduce an adapter, you should use the new C++ SelectorList to replace the code that uses the old crates::css2::selectors::SelectorList.

[Copilot]

Removed the adapter classes completely. CSSStyleRule now uses the native C++ SelectorList directly instead of crates::css2::selectors::SelectorList. All adapter files (css_selector_adapter.hpp/cpp) have been deleted and matching system simplified to only use C++ implementation. Changes committed in 0c47774.

[yorkie]

@copilot Complete this TODO, use the C/C++ css selector parser instead of crates::css2::parsing::parseSelectors here.

[Copilot]

Completed the TODO by replacing crates::css2::parsing::parseSelectors with client_cssom::selectors::CSSelectorParser::parseSelectors in both querySelector and querySelectorAll methods. The C++ CSS selector parser now handles all document query operations. Changes committed in ae92b07.

[yorkie]

@copilot Revert the changes in this file.

[Copilot]

Reverted the package.json changes by restoring eslint from ^9.34.0 to ^9.27.0 and typescript from ^5.9.2 to ^5.1.6. Changes committed in ae92b07.

[Copilot]

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

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[yorkie]

@copilot The following selectors doesn't work, please fix:

a > b { .. }
a b { ... }

[Copilot]

@copilot The following selectors doesn't work, please fix:

...

Fixed the child (a > b) and descendant (a b) selectors by implementing proper right-to-left CSS selector matching. The issue was that the matching algorithm was processing components left-to-right instead of following the CSS specification's right-to-left matching pattern. Added matchesSelectorFromEnd() function that correctly processes selector components from the rightmost element backwards. Changes committed in f05d365.

[yorkie]

@copilot Please make sure the descendant parsing work correctly, such as "div p" would be parsed into 3 components: div, descendant combinator and p, but the current implementation only returns 2 components.

[Copilot]

Fixed the descendant parsing issue. The CSS selector parser now correctly parses "div p" into 3 components: div, descendant combinator, and p. Also fixed parsing of other combinators with whitespace like "div > p", "div + p", and "div ~ p". The issue was in the whitespace handling logic in both parseSingleSelector and parseCombinator functions. Changes committed in 2d7a881.

[yorkie]

Support the following:

• :first-child
• :first-of-type
• :last-child
• :last-of-type

[yorkie]

@copilot Move to docs/internals/CSS_SELECTOR_PARSER_IMPL.md

[Copilot]

Moved the documentation from docs/css-selector-parser.md to docs/internals/CSS_SELECTOR_PARSER_IMPL.md as requested. Changes committed in 55c2aab.

[Copilot]

Support the following:

• :first-child
  ...

Added support for all four requested pseudo-classes. The CSS selector parser now correctly handles :first-child, :last-child, :first-of-type, and :last-of-type with proper matching logic that checks parent-child and sibling relationships. Changes committed in 55c2aab.

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[Copilot]

Pull Request Overview

This PR completely replaces the Rust-based CSS selector parsing and matching system with a native C++ implementation, while adding comprehensive support for structural pseudo-classes. The implementation includes fixes for CSS selector parsing issues (especially combinator handling) and introduces proper right-to-left CSS selector matching.

Key changes:

• Native C++ CSS parser: Replaced Rust crates::css2::selectors with client_cssom::selectors::CSSelectorParser
• Enhanced pseudo-class support: Added :first-child, :last-child, :first-of-type, :last-of-type support
• Fixed selector parsing: Corrected combinator detection and parsing for descendant selectors like "div p"

Reviewed Changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
tests/client/css_selector_parser_tests.cpp	Comprehensive test suite for the new C++ CSS selector parser covering all selector types and combinations
src/client/dom/document.cpp	Updated querySelector and querySelectorAll to use C++ parser instead of Rust implementation
src/client/cssom/selectors/matching.hpp	Modified function signatures to use C++ selector types and added new matching functions
src/client/cssom/selectors/matching.cpp	Implemented structural pseudo-class helpers and right-to-left selector matching algorithm
src/client/cssom/selectors/css_selector_parser.hpp	Complete C++ selector parser class definitions with comprehensive enum types and data structures
src/client/cssom/selectors/css_selector_parser.cpp	Full implementation of CSS selector parsing logic with proper combinator handling
src/client/cssom/rules/css_style_rule.hpp	Updated to use native C++ selectors and added element matching capability
fixtures/html/simple.html	Test file updates to demonstrate structural pseudo-class functionality
docs/internals/CSS_SELECTOR_PARSER_IMPL.md	Comprehensive documentation for the new CSS parser implementation