Java tool to transform React JSX into Javascript

JSXTransformer.java

import org.mozilla.javascript.Context;
import org.mozilla.javascript.Function;
import org.mozilla.javascript.NativeObject;
import org.mozilla.javascript.Scriptable;
import org.mozilla.javascript.commonjs.module.Require;
import org.mozilla.javascript.commonjs.module.RequireBuilder;
import org.mozilla.javascript.commonjs.module.provider.SoftCachingModuleScriptProvider;
import org.mozilla.javascript.commonjs.module.provider.UrlModuleSourceProvider;

import java.io.File;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 *
 * Depends on Mozilla Rhino. Does not work with the JRE built-in version
 * 
 * <dependency>
 *   <groupId>org.mozilla</groupId>
 *   <artifactId>rhino</artifactId>
 *   <version>1.7R4</version>
 * </dependency>
 */
public class JSXTransformer {
// ------------------------------ FIELDS ------------------------------

    private List<String> modulePaths;
    private String jsxTransformerJS;
    private Context ctx;
    private Scriptable exports;
    private Scriptable topLevelScope;
    private Function transform;

// --------------------------- main() method ---------------------------

    public static void main(String args[]) throws URISyntaxException {
        JSXTransformer jsxTransformer = new JSXTransformer();
        //Using the CDN does not work
        //jsxTransformer.setModulePaths(Arrays.asList("http://fb.me/"));
        jsxTransformer.setModulePaths(Arrays.asList("public"));
        jsxTransformer.setJsxTransformerJS("JSXTransformer-0.10.0.js");
        jsxTransformer.init();
        String js = jsxTransformer.transform("/** @jsx React.DOM */ React.renderComponent(<h1>Hello, world!</h1>,document.getElementById('example'));");
        System.out.println("js = " + js);
    }

    public void setModulePaths(List<String> modulePaths) {
        this.modulePaths = modulePaths;
    }

    public void setJsxTransformerJS(String jsxTransformerJS) {
        this.jsxTransformerJS = jsxTransformerJS;
    }

    public void init() throws URISyntaxException {
        ctx = Context.enter();
        try {
            RequireBuilder builder = new RequireBuilder();
            builder.setModuleScriptProvider(new SoftCachingModuleScriptProvider(
                    new UrlModuleSourceProvider(buildModulePaths(), null)
            ));

            topLevelScope = ctx.initStandardObjects();
            Require require = builder.createRequire(ctx, topLevelScope);

            exports = require.requireMain(ctx, jsxTransformerJS);
            transform = (Function) exports.get("transform", topLevelScope);
        } finally {
            Context.exit();
        }
    }

    //mostly copied from org.mozilla.javascript.tools.shell.Global.installRequire()
    private List<URI> buildModulePaths() throws URISyntaxException {
        List<URI> uris = new ArrayList<URI>(modulePaths.size());
        for (String path : modulePaths) {
            try {
                URI uri = new URI(path);
                if (!uri.isAbsolute()) {
                    // call resolve("") to canonify the path
                    uri = new File(path).toURI().resolve("");
                }
                if (!uri.toString().endsWith("/")) {
                    // make sure URI always terminates with slash to
                    // avoid loading from unintended locations
                    uri = new URI(uri + "/");
                }
                uris.add(uri);
            } catch (URISyntaxException usx) {
                throw new RuntimeException(usx);
            }
        }
        return uris;
    }

    public String transform(String jsx) {
        Context.enter();
        try {
            NativeObject result = (NativeObject) transform.call(ctx, topLevelScope, exports, new String[]{jsx});
            return result.get("code").toString();
        } finally {
            Context.exit();
        }
    }
}

JSXTransformerPlugin.java

package plugins.jsxtransformer;

import av.common.controllers.JSXTransformer;
import play.Application;
import play.Plugin;
import play.api.templates.Html;

import java.net.URISyntaxException;

/**
 * application.conf should look like this
 *
 * <pre>{@code
 * JSXTransformer.modulePaths=["public/"]
 * JSXTransformer.JS="JSXTransformer-0.10.0.js"
 * } </pre>
 *
 * play.plugins should look like this
 *
 * <pre>{@code
 * 1000:plugins.jsxtransformer.JSXTransformerPlugin
 * } </pre>
 *
 *
 * Use this plugin from your Scala templates like this
 *
 * <pre>{@code
 * <script>
 *      &#064;plugins.jsxtransformer.JSXTransformerPlugin.transform{
 *          React.renderComponent(
 *              <h1>Hello, world!</h1>,
 *              document.getElementById('example')
 *          );
 *      }
 * </script>
 * } </pre>
 */
public class JSXTransformerPlugin extends Plugin{
// ------------------------------ FIELDS ------------------------------

    private static JSXTransformer transformer;
    private final Application application;

// -------------------------- STATIC METHODS --------------------------

    public static String transform(String jsx) {
        return transformer.transform("/**@jsx React.DOM */" + jsx);
    }

    public static Html transform(Html jsx) {
        return Html.apply(transform(jsx.body()));
    }

// --------------------------- CONSTRUCTORS ---------------------------

    public JSXTransformerPlugin(Application application) {
        this.application = application;
    }

// ------------------------ CANONICAL METHODS ------------------------

    @Override
    public void onStart() {
        if (transformer == null) {
            JSXTransformer instance = new JSXTransformer();
            instance.setModulePaths(application.configuration().getStringList("JSXTransformer.modulePaths"));
            instance.setJsxTransformerJS(application.configuration().getString("JSXTransformer.JS"));
            try {
                instance.init();
                transformer = instance;
                super.onStart();
            } catch (URISyntaxException e) {
                e.printStackTrace();
            }
        }
    }
}

Thank you for this! I have based a grails jsx asset pipeline plugin partly on your work. Thumbsup for publishing this!

https://github.com/balsamiq/jsx-grails-asset-pipeline