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Lexer Generator

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Expert skill for generating and hand-writing lexers using DFA-based, table-driven, and recursive approaches

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Lexer Generator Skill

Overview

Expert skill for generating and hand-writing lexers using various approaches including DFA-based lexers, table-driven lexers, and hand-written recursive lexers.

Capabilities

  • Generate lexer from regular expression specifications
  • Implement maximal munch tokenization
  • Handle Unicode character classes and normalization
  • Implement efficient keyword recognition (tries, perfect hashing)
  • Support incremental/resumable lexing for IDE integration
  • Generate lexer tables and state machines
  • Handle lexer modes and contexts (e.g., string interpolation)
  • Implement error recovery with skip-to-next strategies

Target Processes

  • lexer-implementation.js
  • language-grammar-design.js
  • lsp-server-implementation.js
  • repl-development.js

Dependencies

  • Flex-like generators
  • RE2/Hyperscan libraries

Usage Guidelines

  1. Token Definition: Start by defining the complete set of tokens with their regex patterns
  2. Maximal Munch: Always implement maximal munch to handle ambiguous token boundaries
  3. Unicode Support: Consider Unicode normalization forms and character classes from the start
  4. Error Recovery: Implement skip-to-next-valid strategies for robust error handling
  5. Performance: Use table-driven approaches for large token sets, hand-written for simple lexers

Output Schema

{
  "type": "object",
  "properties": {
    "tokens": {
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "name": { "type": "string" },
          "pattern": { "type": "string" },
          "priority": { "type": "integer" }
        }
      }
    },
    "lexerType": {
      "type": "string",
      "enum": ["dfa", "table-driven", "hand-written"]
    },
    "generatedFiles": {
      "type": "array",
      "items": { "type": "string" }
    }
  }
}