decaf-lang/decaf-in-scala

The Decaf compiler, written in Scala

The Decaf Compiler, in Scala

Decaf is a Java-like, but much smaller programming language mainly for educational purpose. We now have at least three different implementations of the compiler in Java, Scala and Rust. Since the standard language has quite a limited set of language features, students are welcome to add their own new features.

Getting Started

This project requires JDK 12, because the package decaf.lowlevel is shared with Java's.

Other dependencies will be automatically downloaded from the maven central repository by the build script.

Build

Type standard sbt commands after you launch the REPL with sbt.

To compile, type:

sbt:decaf-in-scala> compile

To build a standalone jar, type:

sbt:decaf-in-scala> assembly

To start a scala REPL, type:

sbt:decaf-in-scala> console

Or, import the project in IDEA and use sbt plugin, if available.

Run

In sbt console, type:

sbt:decaf-in-scala> run --help

to show the usage help. Or you first build a standalone jar and run it in CLI.

Possible targets/tasks are:

• PA1: parse source code and output the pretty printed tree, or error messages
• PA2: type check and output the pretty printed scopes, or error messages
• PA3: generate TAC (three-address code), dump it to a .tac file, and then output the execution result using our built-in simulator
• PA3-JVM: generate JVM bytecode
• PA4: currently same with PA3, will be reserved for students to do a bunch of optimizations on TAC
• PA5: (default target) allocate registers and emit assembly code, currently we are using a very brute-force algorithm and only generates MIPS assembly code (with pseudo-ops, and no delayed branches)

To run the MIPS assembly code, you may need spim, a MIPS32 simulator. For Mac OS users, simply install spim with brew install spim and run with spim -file your_file.s.

decaf-in-scala's Issues

decaf程序没有任何class时编译器会崩溃

在 DecafParser.g4 中，topLevel 的产生式是 classDef*，而 Parser.scala 中 visitTopLevel 时将 TopLevel 的位置设置为 classes.head 的位置，产生 NoSuchElementException。