MiniPascal Compiler

A compiler for MiniPascal, a custom, simplified Pascal-like programming language. Implemented from scratch in C++ (std=c++17) using Flex for lexical analysis and Bison for syntax analysis. This project implements all the core phases of compiler design, from tokenizing to generating executable assembly for a custom stack-based virtual machine.

Current Status (as of June 18, 2025)

The compiler is now functionally complete. All major phases have been implemented, allowing the compiler to process MiniPascal source code with complex features—including nested subprograms, local/global scopes, arrays, and function/procedure overloading—and generate executable assembly.

• Lexical & Syntax Analysis: The frontend correctly tokenizes source code and builds a valid Abstract Syntax Tree (AST).
• Semantic Analysis: The semantic analyzer correctly validates the AST for scope resolution, type checking (including INTEGER, REAL, BOOLEAN, and ARRAY types), and declaration verification. It now fully supports overload resolution for subprograms.
• Code Generation: The backend successfully traverses the semantically-validated AST and generates correct, executable assembly code for the target stack-based Virtual Machine.

All major language features have been implemented and tested, including full subprogram support (procedures and functions with overloading) and built-in I/O.

Key Features of MiniPascal Supported

The compiler currently supports the following MiniPascal language features:

• Program Structure: PROGRAM ... BEGIN ... END.
• Declarations:
  • VAR: For both global and local variables.
  • Data Types: INTEGER, REAL, BOOLEAN.
  • ARRAY [low..high] OF standard_type: One-dimensional arrays with support for variable indices.
• Subprograms:
  • PROCEDURE Name(params); local_vars; BEGIN ... END;
  • FUNCTION Name(params) : return_type; local_vars; BEGIN ... RETURN value; END;
  • Function & Procedure Overloading: Subprograms with the same name are differentiated by their parameter signatures.
  • Correct handling of parameters, local variables, and global variables.
  • Support for recursive function calls.
• Statements:
  • Assignment: variable := expression;
  • Compound: BEGIN ... END;
  • Procedure Calls: ProcName; or ProcName(arg1, arg2);
  • Conditional: IF condition THEN statement ELSE statement;
  • Looping: WHILE condition DO statement;
  • Function Return: RETURN expression;
• Expressions:
  • Arithmetic: +, -, *, / (real division), div (integer division).
  • Relational: =, <>, <, <=, >, >=.
  • Logical: AND, OR, NOT.
  • Parentheses for grouping with correct operator precedence.
• Literals: Integer, Real, Boolean (TRUE, FALSE), String (e.g., 'Hello').
• Built-in I/O: write, writeln, read, readln.

Target Virtual Machine

The compiler targets a custom stack-based virtual machine.

• Architecture: It uses separate stacks for execution and calls, with gp (global pointer) and fp (frame pointer) registers to manage variable scopes.
• Instruction Set: The generator produces text-based assembly code (e.g., pushi, storeg, alloc, jump, call) that the VM executes directly.

Technologies Used

• C++: (Standard: C++17) for the AST, semantic analysis, code generator, and main compiler logic.
• GNU Flex: For lexical analysis (scanner generation).
• GNU Bison: For syntax analysis (parser generation).
• GNU Make: For building the project.
• Development Environment: MinGW64 on Windows.

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Project Lead: Tarek