A compiler for the Pico programming language, implementing the front-end phases of compilation: Scanner, Syntax Analyzer, and Semantic Analyzer.

Course: Compiler Construction 1
Date: October 31, 2025
Development Team:

• Muhammad Rouhan (22k-4577)
• Moiz-ul-Haq (22k-4587)
• Huzefa Tayyab
• Sarim Shah

Pico is a strongly-typed, imperative programming language designed as a minimal, Pascal-like dialect. It enforces a clear separation between variable declarations and executable statements and is case-insensitive.

• INTEGER: 32-bit signed integer
• REAL: 32-bit floating-point number
• BOOLEAN: Logical values (TRUE/FALSE)

A Pico program follows this structure:

PROGRAM program_name;
VAR
  variable1 : TYPE;
  variable2 : TYPE;
BEGIN
  statement1;
  statement2;
END.

PROGRAM, VAR, BEGIN, END, PROCEDURE, INTEGER, REAL, BOOLEAN, IF, THEN, ELSE, WHILE, DO, TRUE, FALSE, WRITELN, AND, OR, NOT

• Assignment: :=
• Arithmetic: +, -, *, /
• Comparison: =, <>, <, >, <=, >=
• Logical: AND, OR, NOT

• Variable declarations in a single VAR block
• Control flow: IF-THEN-ELSE, WHILE-DO
• Procedures: PROCEDURE name; BEGIN ... END;
• Input/Output: WRITELN(expression)
• Comments: (* ... *)

make

This will create the executable at bin/pico_compiler.

mkdir build
cd build
cmake ..
make

The executable will be in the build directory.

g++ -std=c++17 -Wall -Wextra -O2 -Iinclude src/*.cpp -o pico_compiler

./bin/pico_compiler <source_file.pico>

Or with make:

make run FILE=examples/test.pico

PROGRAM example;
VAR
  counter : INTEGER;
  flag : BOOLEAN;
  value : REAL;
BEGIN
  counter := 10;
  flag := TRUE;
  value := 3.14;
  IF counter > 5 THEN
    WRITELN(counter);
  WHILE counter > 0 DO
    counter := counter - 1;
END.

• Tokenizes the source code
• Handles case-insensitive input
• Generates a stream of tokens for the parser

• Analyzes the token stream against the Context-Free Grammar (CFG)
• Constructs an Abstract Syntax Tree (AST) representing the program structure

• Traverses the AST to ensure semantic correctness
• Performs type checking
• Validates scope (ensuring variables are declared before use)

.
├── include/
│   ├── token.h          # Token definitions
│   ├── ast.h            # Abstract Syntax Tree nodes
│   ├── scanner.h        # Lexical analyzer
│   ├── parser.h         # Syntax analyzer
│   └── semantic_analyzer.h  # Semantic analyzer
├── src/
│   ├── main.cpp         # Main driver program
│   ├── token.cpp        # Token utilities
│   ├── scanner.cpp      # Scanner implementation
│   ├── parser.cpp       # Parser implementation
│   ├── ast.cpp          # AST node implementations
│   └── semantic_analyzer.cpp  # Semantic analyzer implementation
├── examples/            # Example Pico programs
├── Makefile             # Build configuration
├── CMakeLists.txt       # CMake build configuration
└── README.md            # This file

The compiler reports errors at three levels:

1. Lexical Errors: Invalid tokens or characters
2. Syntax Errors: Grammar violations
3. Semantic Errors: Type mismatches, undeclared variables, etc.

All errors include line and column numbers for easy debugging.

This project is developed for educational purposes as part of the Compiler Construction course.