C Syntax Checker

This is a C syntax checker built using Flex and Bison. It parses C code and reports any syntax errors found.

Features

• Parses a subset of the C language, including:
  • Variable declarations (including pointers)
  • Function declarations and definitions
  • Structs, unions, and typedefs
  • Expressions and statements
  • Control flow structures (if, else, for, while, do-while, switch, case, default, break, continue, return)
• Detailed error reporting with line and column numbers, and a caret pointing to the error location.
• Reports multiple errors in a single pass.
• Color-coded output for better readability.
• Comprehensive test suite.

Requirements

• flex
• bison
• gcc or clang
• make

Building and Running

Building

You can build the parser by following these steps:

1. Generate the parser and tokenizer C code from the Bison and Flex files:

   bison -d parser.y
   flex -o tokenizer.c tokenizer.l

   This will create parser.c, parser.h, and tokenizer.c.

2. Compile the generated C files and create the executable:

   gcc -o parser parser.c tokenizer.c

   This will create the parser executable.

Running

To check the syntax of a C file, run the parser executable with the file as an argument:

./parser path/to/your/file.c

Example:

./parser tests/comprehensive_test.c

If the file has no syntax errors, the program will exit silently with a status code of 0. If there are syntax errors, they will be printed to standard error, and the program will exit with a non-zero status code.

Running on Different Operating Systems

This project is built using standard tools that are available on most Unix-like operating systems, including Linux and macOS.

Linux:

The build and run instructions above should work without any modifications. You may need to install the required tools first. On Debian-based distributions (like Ubuntu), you can do this with:

sudo apt-get update
sudo apt-get install flex bison build-essential

macOS:

The build and run instructions above should work without any modifications. You may need to install the required tools first. You can do this using Homebrew:

brew install flex bison

Xcode Command Line Tools are also required, which can be installed with:

xcode-select --install

Windows:

To build and run this project on Windows, you will need to use a Unix-like environment such as Windows Subsystem for Linux (WSL) or MinGW/MSYS2. Once you have set up one of these environments, you can follow the Linux instructions to install the required tools and build the project.

Test Suite

The tests/ directory contains a suite of C files to test the syntax checker.

• comprehensive_test.c: A large file that includes a variety of valid C constructs.
• error_test.c: A file with a variety of syntax errors to test the error reporting.
• expressions.c: Tests for various expressions.
• loops.c: Tests for loop structures.
• selection.c: Tests for selection statements.
• pointers.c: Tests for pointer declarations and usage.
• structs_unions.c: Tests for struct and union declarations.
• typedefs.c: Tests for typedef declarations.

You can run the tests by passing any of these files to the parser.

Error Reporting

The syntax checker provides detailed error messages, including:

• The file name, line number, and column number of the error.
• The line of code where the error occurred.
• A caret (^) pointing to the exact location of the error.
• A descriptive message about the error.

Example of error output:

tests/error_test.c:4:2: error: expected ';' before 'int'
  int y = 20
  ^
1 error(s) found.

Future Improvements

• Support for more C language features (e.g., enums, preprocessor directives).
• Improved error recovery.
• Integration with a language server for real-time syntax checking in an IDE.

License

This project is licensed under the MIT License.