Basic Lexer Implementation

Your Task

Implement a lexer that tokenizes a subset of C code.

Requirements

1. Create a Lexer struct containing:

   • Source code string
   • Current position
   • Line and column tracking

2. Implement these functions:

   • lexer_create(const char* source): Initialize lexer state
   • lexer_destroy(Lexer* lexer): Clean up resources
   • lexer_next_token(Lexer* lexer): Return the next token
   • lexer_peek(Lexer* lexer): Look at next token without consuming

3. Handle these token types:

   • Single-character: + - * / ( ) { } ; ,
   • Two-character: == != <= >= && ||
   • Numbers: Integer literals (e.g., 42, 0, 123)
   • Identifiers: [a-zA-Z_][a-zA-Z0-9_]*
   • Keywords: int, return, if, else, while

4. Skip whitespace and single-line comments (//)

Success Criteria

• Correctly tokenizes: int main() { return 42; }
• Reports line/column for each token
• Handles end-of-file gracefully