scripthon-tool

Scripthon is a DSL to describe the Java source pattern (code snippet) which might be recognised by the searching algorithm traversing the Java AST.

To execute, run:

./gradlew clean fatJar && java -jar scripthon-tool/build/libs/scripthon-tool-all-0.1.2.jar

To execute tests:

./gradlew test

First motivation example:

Consider the Java source as follows:

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello world!");
    }
}

This sample could be found by teh following Scripthon code:

Meth()

Unfortunately, this will find a lot of miscellaneous results. With Scripthon, we can search only methods named with a certain name:

Meth(Name="main")

Moreover, we want just the public and static ones:

Meth(Name="main"; Rest=[public, static])

Even more, the most specific searching criteria for the main method are:

Meth(Name="main"; Rest=[public, static]; Ret=void; ParNum=1;ParTypes=[String[]]; ParNames=["args"])

With Scripthon, we can define a method call inside the main method:

Meth(Name="main"; Rest=[public, static])
    MethCall(Name="System.out.println";Params=["args"])

Scripthon supports also a block of the code description. We can define the block properties in the following way:

Class(Name="HelloWorld")
    Meth(Name="main")
        Block(StmtNum=1;Order=false)

Again, this example corresponds to the Hello, World! example. There is one statement inside the main method, and the order of statements does not matter.

Another interesting Scripthon's keyword is the word Any. It is useful for an indefinite searching, i.e. the searched statements can include anything or be empty. To describe the code above, we can write:

Meth(Name="main")
    Any()

But the desired code can look like this:

public static void main (String[] args) {
    int i = 1;
    i++;
    System.out.println(args);
}

And we can find this by the following script:

Meth(Name="main")
    Any()
    MethCall(Name="System.out.println")

There are several more keywords supported by Scripthon. For example, Init() for a variable initialization, Loop() for a common loop, etc. Finally, with the presented examples, it is easy to find a singleton in the code:

Class() class
    Block(Order=false;Consecutive=false)
        Meth(Name=class.Name;Rest=private)
            MethCall(Ret=class.Name;Rest=[public, static])

The only unmentioned parameter here is the "Consecutive" parameter. It means that the statements inside the block must not be consecutive, they just need to be contained somewhere in the given block.