JOPS

Java Operator Overloading Plugin

Originally JOPS stood for "Java Opcodes", but that didn't make sense anymore, so now it stands for Java Operator Overloading Plugin.

I know I know, it should be called JOOP instead, but I like JOPS better. Oh yeah, the 'S' stands for Syntactic Sugar Edition.

How to use

• add @OperatorOverloading annotation to the class with overloaded operators
• overload the operators with the following C++ syntax:

@OperatorOverloading
public class Bla {       
    public Bla operator+(Bla b) {
        return ...//something..or nothing
    }                 
}

• ...
• write some code, and behold:

public class BlaTest {       
    public static void main(String[]args) {
        Bla a = new Bla();
        Bla b = new Bla();
        Bla c = a + b;
        System.out.println("operator overloading banzai!");
    }                     
}

Currently only the following single operand operators are supported:

1. operator+
2. operator-
3. operator*
4. operator/
5. operator+=
6. operator-=
7. operator*=
8. operator/=

How to build/compile

Maven

• include the jops_plugin as a dependency(we need this for the @OperatorOverloading annotation)

<dependencies>
    <dependency>
        <groupId>io.github.blackbeard334</groupId>
        <artifactId>jops_plugin</artifactId>
        <version>${jops_plugin.version}</version>
    </dependency> 
</dependencies>

• next you need to add the jops_plugin as a compiler arg, and as a dependency for the maven-compiler_plugin

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.8.1</version>
            <configuration>
                <source>11</source>
                <target>11</target>
                <compilerArgs>
                    <arg>-Xplugin:JOPSPlugin</arg>
                </compilerArgs>
            </configuration>
            <dependencies>
                <dependency>
                    <groupId>io.github.blackbeard334</groupId>
                    <artifactId>jops_plugin</artifactId>
                    <version>${jops_plugin.version}</version>
                </dependency>
            </dependencies>
        </plugin>
    </plugins>
</build>

Mavenless

• javac -cp /path/jops -Xplugin:JOPSPlugin HelloWorld.java
  1. first we need to include the jops_plugin in the classpath -cp /path/jops
  2. then we tell the compiler that we want to use the jops_plugin with the -Xplugin:JOPSPlugin switch
  3. enjoy...

References

• The Hitchhiker's Guide to javac
• Java Compiler API - Compile Code to a File and Load it using Default Class Loader
• ANNOTATION PROCESSING 101
• Extending Java and Javac
• Creating a Java Compiler Plugin
• Parser for C and Objective-C.