Add configurable SQL comment removal feature

[sufleR]

Summary

This PR introduces a comprehensive SQL comment removal system that addresses #20. The feature allows developers to configure how and when SQL comments are removed from queries, providing flexibility for different use cases (debugging, logging, production).

Key Features

• Configurable removal strategies (config.remove_comments):

  • :none - Don't remove any comments
  • :oneline - Remove only single-line comments (--)
  • :multiline - Remove only multi-line comments (/* */)
  • :all - Remove both types (default)

• Configurable scope (config.remove_comments_from):

  • :none - Don't remove comments anywhere
  • :prepared_for_logs - Remove comments only in prepared_for_logs method
  • :all - Remove comments from all queries (default)

• SQL Standard Compliance:

  • Follows SQL-92 comment syntax
  • Supports all major databases (PostgreSQL, MySQL, Oracle, SQL Server, SQLite)
  • Preserves comments within quoted strings:
    • Single quotes: '-- not a comment'
    • Double quotes: "-- not a comment"
    • Dollar quotes (PostgreSQL): $$-- not a comment$$, $tag$-- not a comment$tag$

• Edge Case Handling:

  • SQL-style escaped quotes ('', "")
  • Backslash-escaped quotes (\', \")
  • Comments without trailing newlines
  • Inline comments
  • Multiple comments of different types
  • Comments containing quote characters

Implementation Approach

State Machine Pattern

This implementation uses a state machine approach rather than complex regex for several reasons:

1. Easier to Debug: Character-by-character processing with clear state tracking
2. Better Edge Case Handling: Tracks multiple quote types simultaneously
3. Maintainable: Easy to understand and extend
4. Reliable: Handles nested quote types correctly

Architecture

• CommentRemover Service Class (lib/sql_query/comment_remover.rb):

  • Implements state machine for comment removal
  • Handles all quote types and escape sequences
  • SQL-92 standard compliant

• Config Class Extraction (lib/sql_query/config.rb):

  • Extracted to separate file for better organization
  • Added should_comments_be_removed?(for_logs:) method for clean logic
  • Reduces SqlQuery class complexity

• Integration Points:

  • SqlQuery#sql - Applies removal based on configuration
  • SqlQuery#prepared_for_logs - Applies removal based on configuration
  • SqlQuery#apply_comment_removal - Helper method with clean logic

Testing

• 78 total test examples, 0 failures
• 98.38% code coverage
• CommentRemover unit tests: 32 examples covering all scenarios
• Integration tests: 10 examples for configuration combinations
• Config tests: 12 examples for configuration behavior
• Test fixtures: 5 SQL templates with various comment scenarios
• RuboCop compliant: All style checks pass

Documentation

• CHANGELOG.md: Updated with feature description
• README.md: Added configuration examples and detailed option descriptions

Default Behavior

By default, both comment types are removed from all queries:

SqlQuery.configure do |config|
  config.remove_comments = :all        # Remove both -- and /* */
  config.remove_comments_from = :all   # From both sql() and prepared_for_logs()
end

Migration Path

This is a backwards-compatible addition:

• Default behavior removes comments (improves log readability)
• Can be disabled by setting config.remove_comments = :none
• Can be scoped to only logs with config.remove_comments_from = :prepared_for_logs

Test Plan

• All existing tests pass
• New unit tests for CommentRemover service
• New integration tests for configuration scenarios
• Config class tests
• RuboCop compliance verified
• Manual testing with various SQL patterns

Addresses #20