# CSV Parser

A Flex/Bison-based CSV parser that can handle various CSV formats including quoted fields, empty fields, and escaped characters.

## Project Structure

```
sa-parse/
├── .gitignore          # Ignore build artifacts and temporary files
├── build.sh            # Build script for easy compilation
├── meson.build         # Meson build configuration
├── README.md           # This file
├── src/                # Source code directory
│   ├── csv.l           # Flex lexer specification
│   └── csv.y           # Bison parser specification
└── tests/              # Test files and documentation
    ├── README.md       # Test documentation
    ├── test.csv        # Basic test case
    ├── complex.csv     # Complex field content test
    ├── quotes.csv      # Quote handling test
    ├── empty_fields.csv # Empty field handling test
    ├── header_only.csv # Header-only file test
    └── empty.csv       # Empty file test
```

## Features

- **RFC 4180 CSV Parsing**: Handles standard CSV format
- **Quoted Field Support**: Properly processes quoted fields with commas and quotes
- **Empty Field Handling**: Correctly parses empty fields in any position
- **Memory Safe**: Conservative memory management with proper error handling
- **Robust Error Reporting**: Line number and context information for parse errors

## Building

### Quick Build (Recommended)
```bash
./build.sh
```

### Manual Build
```bash
cd src
yacc -d csv.y      # Generate parser
flex csv.l         # Generate lexer  
gcc -o csv_parser y.tab.c lex.yy.c -ll
```

### Meson Build
```bash
meson setup builddir
meson compile -C builddir
```

## Usage

```bash
# Parse from file
./src/csv_parser < tests/test.csv

# Parse from stdin
echo "name,age,city
John,25,Boston" | ./src/csv_parser

# Test various formats
./src/csv_parser < tests/complex.csv
./src/csv_parser < tests/empty_fields.csv
```

## Output Format

The parser outputs structured information about the CSV content:

```
Header: [field1], [field2], [field3]
Record 1: [value1], [value2], [value3]
Record 2: [value4], [value5], [value6]
```

## Testing

See `tests/README.md` for detailed information about test cases and expected behavior.

## Implementation Notes

- Built with Flex 2.6+ and Bison 3.0+
- Uses conservative memory management approach
- Handles both CRLF and LF line endings
- Supports files with or without headers
- Gracefully handles malformed input with informative error messages

## Recent Improvements

- Fixed buffer overflow vulnerabilities in lexer
- Added proper memory allocation failure handling
- Enhanced error checking in semantic actions
- Improved memory leak prevention
- Added comprehensive test suite