C to Python Translator

Jialong Wu, Yishujie Zhao and Shuwei Huang

Introduction

A C to Python translator 🤖 based on Lex/Yacc.

Course project for Principles of Assembly and Compilation, instructed by Prof. Wang.

For details, see our report and slides (in Chinese).

Features 🔥

Basic Syntax of C

Support:

• Variable and literal
• Arithmetic and logical expression
• Conditional and loop statements
• One-dimensional array
• Function

Not support:

• Pointer and reference
• continue and break
• do-while statement
• Conditions like if (a) (must be if (a!=0))

Library Functions

Standard library functions, including:

• scanf
• printf
• atoi
• strlen

Their Python equivalents are implemented in utils.py.

Semantic Error Handling

Detect and report semantic errors, including:

• Redefinition of variables, arrays and functions
• Undefined identifiers

All semantic errors will be accumulated and reported in the end of compilation.

Scope check and renaming for variables

We maintain a symbol table in order to do scope check and renaming of variables. For details, have a try to compile examples/test.c.

Environment

Ubuntu 16.04+ with Lex, Yacc, and Python 3.7

Usage

make clean
make
./parser [Input C File]
python out.py

The default input file is in.c and results will be written to out.py.

Examples

There are more examples in src/examples:

• calc/calc.c: Expression evaluation
• aplusb.c: A+B Problem & HelloWorld
• factorial.c: Solving factorial
• palindrome.c: Palindrome Validation
• special.c: Example for semantic errors
• test.c: Example for variables renaming

For details, please refer to our report.

References

• Write text parsers with yacc and lex – IBM Developer
• Writing Your Own Toy Compiler Using Flex, Bison and LLVM (gnuu.org)
• re — Regular expression operations — Python 3.9.1 documentation