Parser of EO as an External Java Library

@yegor256
30 Aug 2022
comments

EO parser is written in ANTLR4, Java, and XSL. It is packaged as a multi-module Maven project, in objectionary/eo GitHub repository. In order to compile an EO program to Java you may either use our Maven plugin or our eoc command line toolkit. Moreover, you can also use our parser programmatically in order to generate XMIR from EO. Here is how you do it in your Java/Kotlin/Clojure/Groovy/etc. project.

First you need to put this dependency into compile scope (make sure you use the latest version):

<dependency>
  <groupId>org.eolang</groupId>
  <artifactId>eo-parser</artifactId>
  <version>0.27.2</version>
</dependency>

Then, you need Xsline too (again, check the latest version here):

<dependency>
  <groupId>com.yegor256</groupId>
  <artifactId>xsline</artifactId>
  <version>0.11.0</version>
</dependency>

Finally, you need Cactoos and jcabi-xml:

<dependency>
  <groupId>org.cactoos</groupId>
  <artifactId>cactoos</artifactId>
  <version>0.54.0</version>
</dependency>
<dependency>
  <groupId>com.jcabi</groupId>
  <artifactId>jcabi-xml</artifactId>
  <version>0.25.3</version>
</dependency>

Now, you are ready to parse a EO program to XMIR:

import java.io.ByteArrayOutputStream;
import org.eolang.parser.Syntax;
import org.cactoos.io.InputOf;
import org.cactoos.io.OutputTo;
import com.jcabi.xml.XML;

ByteArrayOutputStream baos = new ByteArrayOutputStream();
new Syntax(
  "foo", // just a name to be put into XMIR
  new InputOf(Paths.get("test/foo.eo")),
  new OutputTo(baos)
).parse();
XML xmir = new XMLDocument(baos.toByteArray());

You can also parse it from a String: just give it to the constructor of InputOf.

Then, you can send this XMIR through a default “train” of optimizing XSL stylesheets:

import com.jcabi.xml.XML;
import com.yegor256.xsline.Xsline;
import org.eolang.parser.ParsingTrain;

XML after = new Xsline(new ParsingTrain()).pass(xmir);

If you want to add a few extra XSL stylesheets to the train, here is how:

XML after = new Xsline(
  new TrClasspath<>(
    new ParsingTrain()
    "/org/eolang/parser/add-refs.xsl",
    "/org/foo/simple.xsl"
  ).back()
).pass(xmir);

Here, /org/eolang/parser/add-refs.xsl is the XSL file available in classpath thanks to the eo-parser.jar, while /org/foo/simple.xsl is the XSL you have in your own project in src/main/resources/org/foo/simple.xml.

If, instead of adding XSL stylesheets to the default collection, you want to use your own set of XSL stylesheets, do this (mind the usage of empty()):

XML after = new Xsline(
  new TrClasspath<>(
    new ParsingTrain().empty(),
    "/org/eolang/parser/add-refs.xsl",
    "/org/foo/simple.xsl"
  ).back()
).pass(xmir);

That’s it :)