Error Handling Overview

Sipha provides comprehensive error handling with configurable error recovery strategies. This section covers error types, recovery mechanisms, and best practices for handling errors in your parsers.

Overview

Sipha’s error handling system is designed to:

• Provide detailed error information with precise source locations
• Recover from errors gracefully to continue parsing
• Support rich diagnostics with context and suggestions (via diagnostics feature)
• Distinguish between errors and warnings for different severity levels

Error Handling Flow

flowchart TD
    Start[Parse Input] --> Parse[Parser Processes Tokens]
    Parse --> Error{Error<br/>Encountered?}
    Error -->|No| Success[Parse Success]
    Error -->|Yes| Recover{Recovery<br/>Enabled?}
    Recover -->|Yes| Attempt[Attempt Recovery]
    Recover -->|No| Fail[Report Error]
    Attempt --> Success2[Continue Parsing]
    Attempt --> Fail2[Recovery Failed]
    Success --> Result[Return ParseResult]
    Success2 --> Result
    Fail --> Result
    Fail2 --> Result
    
    style Success fill:#c8e6c9,color:#000000
    style Success2 fill:#c8e6c9,color:#000000
    style Fail fill:#ffccbc,color:#000000
    style Fail2 fill:#ffccbc,color:#000000
    style Result fill:#e1f5ff,color:#000000

Key Concepts

Errors vs Warnings

• Errors: Prevent successful parsing or indicate syntax violations
• Warnings: Non-fatal issues that don’t prevent parsing

Error Recovery

Sipha parsers can automatically recover from errors to continue parsing, which is essential for:

• IDEs: Providing real-time feedback as users type
• Language Servers: Maintaining parse state despite errors
• Interactive Tools: Allowing partial parsing results

Rich Diagnostics

With the diagnostics feature enabled, errors include:

• Source code snippets
• Highlighted error locations
• Suggestions and hints
• Related code locations

What’s Covered

This section covers:

• Error Types: Understanding ParseError, LexerError, and ParseWarning
• Working with Errors: Checking, reporting, and extracting error information
• Error Recovery: Configuring and understanding error recovery strategies
• Rich Diagnostics: Using miette for beautiful error reporting
• Best Practices: Guidelines and common patterns

Quick Start

The most basic error handling:

use sipha::backend::ll::{LlParser, LlConfig};
use sipha::backend::ParserBackend;

let result = parser.parse(&tokens, entry_point);

// Always check for errors
if !result.errors.is_empty() {
    for error in &result.errors {
        eprintln!("Error: {}", error);
    }
    return Err("Parsing failed".into());
}

// Check for warnings
for warning in &result.warnings {
    eprintln!("Warning: {}", warning.message);
}

Next Steps

• Learn about Error Types to understand what errors you might encounter
• See Working with Errors for practical error handling patterns
• Explore Error Recovery to configure recovery strategies