BUILD ON THE POLYGLOT COMPILER FRAMEWORK

MIHAL BRUMBULLI

7th Workshop “SEERE” Montenegro-Risan 9-14 September 2007

SimJ Programming Language

Introduction

Goal: “Build a new programming language”

For beginners Redable & Easy code No complexity Basic functionality (found in beginners programming text

books)

For compiler design Basic functionality (not too complex) Most important data types Very similiar to Java (not an exact copy of it) Implemented in a compiler framework

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Polytechnic University of Tirana M. Brumbulli

Polyglot Compiler Framework

An extensible Java compiler toolkit designed for experimentation with new language extensions.

The base polyglot compiler is a mostly-complete Java front end. It parses, performs semantic checking on Java source code

and outputs Java source code. Its power consists in doing so on other languages source

codes.

The AST is translated into a Java AST and the existing code is output into a Java source file which can then be compiled with javac.

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Polytechnic University of Tirana M. Brumbulli

Framework Architecture

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Language Extensions

An extension is a source-to-source compiler that accepts a program written in a language extension and translates it to Java source code.

The first step in compilation is parsing input source code to produce an AST. Polyglot includes an extensible parser generator, PPG,

which allows the implementer to define the syntax of the language extension as a set of changes to the base grammar for Java.

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Language Extentions cont...

The second step consist in a set of passes that transform the produced AST in a JavaAST. The pass scheduler selects passes to run over the AST

of a single source file in an order defined by the extension.

Each compilation pass, if successful, rewrites the AST, producing a new AST that is the input to the next pass.

Finally, a Java compiler such as javac is invoked to compile the Java code to bytecode.

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SimJ Language

Is a simplified version of the Java programming language. Not just a reduced copy of Java (MiniJava).

Simple Java like program structure. Not some simple, command like instructions (J0) .

Two possible targets: Beginners with no experience in programming. Compiler construction.

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SimJ Language cont...

Classes, Methods, ...

Data types boolean – true or false int – integers char – characters string – sequence of characters int[] – array of integers

Control flow if else for while switch

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JavaJava SimJSimJ

public class A {

public static void main(String[] args) {

try {

BufferedReader reader = new BufferedReader(new InputStreamReader (System.in));

System.out.print(“Your name:”);

String name = reader.readLine();

System.out.print(“\nHello, ”+name+ “!”);

}

catch (IOException ioexeption) {

System.out.println(ioexeption);

}

}

}

class A {

main() {

print(“Your name:”);

string name = readLine();

print(“\nHello, ”+name+“!”);

}

}

SimJ vs Java

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Implementation

The design process of SimJ includes the following tasks: Syntactic differences between SimJ and Java are defined

based on the Java grammar: polyglot/ext/jl/parse/java12.cup.

Any new AST nodes that SimJ requires are defined based on the existing Java nodes found in: polyglot.ast and polyglot.ext.jl.ast .

Semantic differences between SimJ and Java are defined.

Translation from SimJ to Java is defined. The translation produces a legal Java program that can be compiled by javac.

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Implementation cont...

Resulting packages are: ext.simj.ast

AST nodes specific to SimJ language. ext.simj.extension

New extension and delegate objects specific to SimJ. ext.simj.types

Type objects and typing judgments specific to SimJ. ext.simj.visit

Visitors specific to SimJ. ext.simj.parse

The parser and lexer for the SimJ language.

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Conclusions

SimJ is a simple programming language that improves the learning of programming basic structures. the existing approaches did not fully address the

problem of a simplified Java like structured language and that is not only a reduced copy of it.

Simplicity of SimJ is principally gained by hiding some of the Java object-orientation syntax in the usage of basic statements. This improves the understandability of the code,

making it less confusing and definitely more easy to learn.

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Conclusions cont...

Polyglot Framework is an effective and easy way to produce compilers for Java-like languages like SimJ. It offers the possibility to generate a base skeleton for new

language extensions on witch we can add the desired specifications.

SimJ is a simplified version of the Java programming language that is not only a reduced copy of it. SimJ could be used by beginners that want to learn Java but

don’t know anything about programming. It is also a good choice for learning compiler design

because of its well defined and easy to implement structure.

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MIHAL BRUMBULLI

THANK YOU!