# e-Knife: Java edition

e-Knife is a program slicer for Java programs based on the Expression Dependence Graph (EDG).

You can also try this project through [the online demo](https://mist.dsic.upv.es/e-knife-java/).

This project consists of three modules:

* e-Knife: the frontend for the EDG, which implements the necessary tools to slice Java programs.
* EDG: the generic library that implements the graph and slicing techniques.
* Miscellaneous: various shared utilities.

## Compilation

Requirements: Java JDK ≥ 11 and Maven.

Download this project, then open a terminal inside the extracted folder and compile it with the following command:

```bash
mvn package
```

You'll find a file named `e-Knife-...-jar-with-dependencies.jar` inside the `e-Knife/target/` folder.

## Usage

Requirements: Java JRE ≥ 11.

Download the `.jar` file from the releases page or compile the project.

You'll probably want to generate slices, so you should run e-Knife. Run it without args
to obtain a list and explanation of arguments.

```
java -jar path/to/eknife.jar
```

There are 5 mandatory parameters. If one of them is missing the program will do nothing and print a help prompt.
- `-ip <file>`: the file to be sliced.
- `-li <number>`: the line where the slicing criterion is located.
- `-na <name>`: the variable of the slicing criterion.
- `-oc <number>`: the occurrence of the variable in the line (use 1 unless it appears more than one).
- `-op <file>`: the file where the slice should be saved.

For example, to slice `Example.java` with the slicing criterion `11, sum` and save the slice
to `ExampleSliced.java`, you can use the following command:

```
java -jar path/to/eknife.jar -ip Example.java -li 11 -na sum -oc 1 -op ExampleSliced.java
```

### View the sliced graph

To produce a graph, you must specify the optional argument `-pdf <file>`.

In non-trivial programs, the graph can be too complicated to be useful.
You can either:

1. Use the corresponding options to show/hide certain types of arcs (e.g., `-summary`, `-allarcs`, `-control`...).
2. Output the graph to a dot file using `-dot <file>`, and then manually delete unwanted arcs and/or
   use an interactive graphviz viewer, such as [XDot][xdot].

[xdot]: https://github.com/jrfonseca/xdot.py

## Import into an IDE

In most Java IDEs you'll find an option to import an existing Maven project, and
thus load the project structure and settings from the `pom.xml` files.

Otherwise, you can treat each folder (EDG, e-Knife and Miscellanea) as a
separate module, with the following dependencies:

* e-Knife requires EDG and Miscellanea.
* EDG requires Miscellanea.
* Miscellanea has no dependencies.

## License

This project is licensed under GNU Affero Public License (Version 3.0).

You should have received a copy of the GNU Affero Public License along with this program.
If not, see https://www.gnu.org/licenses.