Programming Language Syntax Validator

A syntax validator built using Python and PLY (Python Lex-Yacc) that performs lexical analysis and parsing for a simple programming language. The project tokenizes source code, validates it against predefined grammar rules, and reports syntax errors.

Features

• Lexical analysis using PLY Lex
• Parsing using Context-Free Grammar (CFG)
• Variable declaration validation (int, float, char)
• Assignment statement parsing
• Arithmetic expression parsing
• Conditional statement (if-else) support
• do-while loop parsing
• Syntax error detection and reporting

Tech Stack

• Python
• PLY (Python Lex-Yacc)

Grammar Supported

The parser supports:

• Variable declarations
• Variable assignments
• Arithmetic expressions
• if / if-else statements
• do-while loops
• Relational conditions

Example:

int x = 10;
float y = 20;

if (x < 20) {
    x = x + 1;
}

do {
    x = x + 1;
} while (x < 30);

Project Structure

.
├── lexer.py          # Lexical analyzer
├── parser.py         # Grammar rules and parser
├── input.txt         # Sample input program
└── README.md

How It Works

1. The lexer scans the source code and converts it into tokens.
2. The parser processes the token stream using Context-Free Grammar rules.
3. Valid programs are accepted by the parser.
4. Invalid syntax is detected and reported with descriptive error messages.

Learning Outcomes

• Lexical analysis
• Parsing techniques
• Context-Free Grammars (CFG)
• Compiler design fundamentals
• Syntax validation using PLY

Future Improvements

• Symbol table implementation
• Semantic analysis
• Type checking
• Support for functions and arrays
• Intermediate code generation