Tiny Interpreter (Pratt Parser)

A tiny expression interpreter built in C99 using a Pratt parser. It reads single-digit arithmetic expressions (only + - * / are supported), tokenises them, builds an AST, and evaluates the result. Parenthesis are also handled. Example:

clc> (3 + 4) * 2
= 14
clc> 6/2+1
= 4

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Building & Running

From the project root:

make        # compiles into build/main
make run    # runs the interpreter

Or simply after compiling:

./build/main

Project Structure

src/
  intf/      # Public headers
    lexer.h
    parser.h
  impl/      # Implementations
    lexer.c  # Tokenises input strings
    parser.c # Pratt parser + AST construction
    main.c   # REPL loop

• Lexer: Converts input text into a stream of tokens (T_NUM, T_PLUS, T_LPAREN, etc.)
• Parser: Implements Pratt’s top-down operator-precedence algorithm. Builds an Expr tree representing the expression.
• Evaluator: Walks the AST and computes the final numeric result.