Incremental Parsing Overview
Incremental parsing is Sipha’s core strength. It allows you to efficiently update your parse tree when code changes, rather than re-parsing everything from scratch.
Why Incremental Parsing?
In interactive applications like IDEs, users edit code frequently. Traditional parsers re-parse the entire file on every change, which can be slow for large files. Incremental parsing:
- Reuses unchanged subtrees from previous parses
- Only re-parses affected regions instead of the entire file
- Maintains parse caches for fast updates
- Scales to large codebases efficiently
This makes Sipha perfect for building language servers, IDEs, and other tools that need to parse code as users type.
Benefits
Performance
Incremental parsing provides significant performance improvements:
- Fast updates: Only re-parse changed regions
- Memory efficient: Shared tree representation
- Scalable: Handles large files efficiently
- IDE-ready: Designed for interactive editing scenarios
User Experience
For interactive applications, incremental parsing means:
- Responsive editing: No lag when typing
- Real-time feedback: Errors and diagnostics update instantly
- Smooth experience: Large files don’t slow down the editor
How It Works (High Level)
- Initial parse: Parse the entire file and cache results
- Edit detection: Identify which regions changed
- Node reuse: Find unchanged subtrees from previous parse
- Incremental re-parse: Only re-parse affected regions
- Tree reconstruction: Combine reused nodes with new parse results
Current Status
Incremental parsing is fully implemented with complete node reuse and cache management:
- ✅ Node reuse: Unchanged subtrees are automatically identified and reused
- ✅ Cache population: Parse results are cached for future reuse
- ✅ Affected range computation: Only affected regions are re-parsed
- ✅ Smart invalidation: Cache entries are invalidated based on edit locations
The parser automatically integrates reusable nodes from previous parses, providing significant performance improvements for interactive editing scenarios.
When to Use Incremental Parsing
Use incremental parsing when:
- Building language servers or IDEs
- Creating interactive code editors
- Building tools that need real-time syntax analysis
- Parsing large files that change frequently
- Providing live error checking and diagnostics
For batch parsing (one-time parsing of files), regular parsing is sufficient and may be faster due to less overhead.
Next Steps
- Learn How It Works for detailed implementation
- See Usage for API examples
- Read Implementation Details for advanced topics