Background

To support advanced CSS features and improve maintainability, a general-purpose CSS Tokenizer and Parser should be introduced under cssom/parsers.

Requirements

• Tokenizer: Implement a tokenizer for CSS that can tokenize input for both stylesheets and inline style declarations.
• Parser: Implement a general parser that can:
  • Parse an entire CSS stylesheet.
  • Parse a single style declaration (e.g., from a style attribute).

Stylesheet Parsing

• The parser should support the following rule types:
  • StyleRule (standard style rules)
  • KeyframeRule (for @keyframes)
  • FontFaceRule (for @font-face)
  • MediaRule (for @media)
  • ImportRule (for @import)

Single Style Declaration Parsing

• Should parse style declarations into a map/object of key/value pairs for use with inline styles or style attributes.
• Only key/value extraction is required for declarations.

Acceptance Criteria

• Tokenizer covers all valid CSS tokens used in the above rule types and declarations.
• Parser correctly parses complete stylesheets with the listed rule types.
• Parser can parse a single style declaration into key/value pairs.
• Unit tests for both tokenizer and parser (stylesheet + declaration cases).

References

• CSS Syntax Module Level 3
• MDN CSSOM Reference

This feature will lay the groundwork for more robust CSS support throughout the engine.