# "Nicht Haskel 2.0" Java Compiler

Realisation of a subset of the Java Standard Compiler in the course Compiler Construction of the 4th semester Computer Science at the Duale Hochschule Stuttgart (Horb).

This project aims to provide a simplified version of the Java compiler, focusing on key language features and demonstrating the principles of compiler construction.

## Realised Java syntax

- **Data types**: `int`, `boolean`, `char`
- **Access modifier**: `public`, `protected`, `private`
- **Operators**: `=` `+` `-` `*` `%` `/` `>` `<` `>=` `<=` `==` `!=` `!` `&&` `||` `++` `--`
- **Keywords**: `class`, `this`, `while`, `do`, `if`, `else`, `for`, `return`, `new`, `switch`, `case`, `break`, `default`, `:`
- **Statements**:
    - `if` ... `if else` ... `else`;
    - `while` ... ;
    - `do` ... `while`;
    - `for`;
    - `switch` ... `case` ... ;
- **Comments**:
    - Single line: `// comment`
    - Multi-line: `/* comment */`
- **Further functions**:
    - All methods are overloadable
    - High maintainability and expandability through implementation of the visitor pattern
    - Logging Input and Outputs
    - Error Handling in the Semantic Check

## Project Structure

```plain
src/
└── main/
    ├── java/
    │   ├── ast/              -> Defining the structure of the AST
    │   ├── bytecode/         -> Generate Java bytecode
    │   ├── main/             -> Running the compiler
    │   ├── parser/
    │   │   ├── astBuilder/   -> Builder creating the AST
    │   │   ├── generated/    -> Antlr generated grammar
    │   │   └── grammar/      -> Antlr grammar
    │   ├── semantic/         -> Running the semantic check
    │   └── visitor/          -> Visitor interface
    └── resources/
test/
└── java/
  │ ├── main/                 -> Running E2E tests 
  │ ├── parser/               -> Performs tests on the parser
  │ ├── semantic/             -> Performs tests on the semantic check
  └── resources/              -> Ressources for running the Tests
```

## Class-Diagramm AST

![AST Diagramm](ast.png)

## Distribution of the realisation

### i22030 & i22035

Parser:
- Grammar -> (src/main/java/parser/grammar)
- Scanner 
- Parser
- Abstract Syntax Tree (AST) -> (src/main/java/ast)
- AstBuilder -> (src/main/java/parser/astBuilder)

Parser tests:
- ParserTests -> (src/test/java/parser)
- TestCases -> (src/test/resources/input/singeFeatureTests)

Other:
- Documentation -> (README.md)
- Ast Class-Diagramm -> (ast.png) 
- PowerPoint

### i22005
Semantic check:
- Set all types and check whether types have been used correctly
- Contexts -> (src/main/java/semantic/context)
- Exceptions Handling -> (src/main/java/semantic/exceptions)

Semantic Tests:
- Typing and Type checking -> (src/test/java/semantic/EndToTypedAstTest)
- Exception and feature test -> (src/test/resources/input/typedAstExceptionsTests)

### i22007
Bytecode generation:
- Complete bytecode generation -> (src/mein/java/bytecode)

### i22011
Tests and execution:
- Makefile
- Running Compiler -> (src/main/main)
- Running E2E tests -> (src/test/main)
- Typing and Type checking -> (src/test/java/semantic/EndToTypedAstTest)



## Used Tools

- [Maven 4.0](https://maven.apache.org/index.html)
  - Used for automating the build process and managing dependencies.
- [ANTLR4 v.13.1](https://www.antlr.org/)
  - Used to parse the input Java code into the Abstract Syntax Tree.