Transpile using Babel

This is pretty slow right now, but works as a proof-of-concept.

worldedit-core/build.gradle.kts

@@ -31,7 +31,7 @@ dependencies {
     "compile"(project(":worldedit-libs:core"))
     "compile"("de.schlichtherle:truezip:6.8.3")
     "compile"("net.java.truevfs:truevfs-profile-default_2.13:0.12.1")
-    "compile"("org.mozilla:rhino:1.7.11")
+    "compile"("org.mozilla:rhino-runtime:1.7.12")
     "compile"("org.yaml:snakeyaml:1.23")
     "compile"("com.google.guava:guava:21.0")
     "compile"("com.google.code.findbugs:jsr305:3.0.2")

worldedit-core/src/main/java/com/sk89q/worldedit/scripting/RhinoCraftScriptEngine.java

@@ -19,7 +19,10 @@
 
 package com.sk89q.worldedit.scripting;
 
+import com.google.common.io.CharStreams;
 import com.sk89q.worldedit.WorldEditException;
+import com.sk89q.worldedit.scripting.compat.BabelScriptTranspiler;
+import com.sk89q.worldedit.scripting.compat.ScriptTranspiler;
 import org.mozilla.javascript.Context;
 import org.mozilla.javascript.ImporterTopLevel;
 import org.mozilla.javascript.JavaScriptException;
@@ -28,11 +31,13 @@ import org.mozilla.javascript.Scriptable;
 import org.mozilla.javascript.ScriptableObject;
 import org.mozilla.javascript.WrappedException;
 
+import javax.script.ScriptException;
+import java.io.StringReader;
 import java.util.Map;
 
-import javax.script.ScriptException;
-
 public class RhinoCraftScriptEngine implements CraftScriptEngine {
+
+    private static final ScriptTranspiler TRANSPILER = new BabelScriptTranspiler();
     private int timeLimit;
 
     @Override
@@ -48,6 +53,7 @@ public class RhinoCraftScriptEngine implements CraftScriptEngine {
     @Override
     public Object evaluate(String script, String filename, Map<String, Object> args)
             throws ScriptException, Throwable {
+        String transpiled = CharStreams.toString(TRANSPILER.transpile(new StringReader(script)));
         RhinoContextFactory factory = new RhinoContextFactory(timeLimit);
         Context cx = factory.enterContext();
         cx.setClassShutter(new MinecraftHidingClassShutter());
@@ -59,7 +65,7 @@ public class RhinoCraftScriptEngine implements CraftScriptEngine {
                     Context.javaToJS(entry.getValue(), scope));
         }
         try {
-            return cx.evaluateString(scope, script, filename, 1, null);
+            return cx.evaluateString(scope, transpiled, filename, 1, null);
         } catch (Error e) {
             throw new ScriptException(e.getMessage());
         } catch (RhinoException e) {

worldedit-core/src/main/java/com/sk89q/worldedit/scripting/compat/BabelScriptTranspiler.java

@@ -0,0 +1,83 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldedit.scripting.compat;
+
+import com.google.common.io.CharStreams;
+import org.mozilla.javascript.Context;
+import org.mozilla.javascript.ContextFactory;
+import org.mozilla.javascript.Function;
+import org.mozilla.javascript.Scriptable;
+
+import java.io.IOException;
+import java.io.Reader;
+import java.io.StringReader;
+import java.util.concurrent.TimeUnit;
+
+public class BabelScriptTranspiler implements ScriptTranspiler {
+
+    private static final RemoteScript BABEL = new RemoteScript(
+        "https://unpkg.com/@babel/standalone@7.9/babel.min.js",
+        "babel.min.js",
+        new RemoteScript(
+            "https://unpkg.com/core-js-bundle@3.6.5/index.js",
+            "core-js-bundle.js"
+        ),
+        new RemoteScript(
+            "https://unpkg.com/regenerator-runtime@0.13.5/runtime.js",
+            "regenerator-runtime.js"
+        )
+    );
+
+    private final ContextFactory contextFactory = new ContextFactory() {
+        @Override
+        protected Context makeContext() {
+            Context context = super.makeContext();
+            context.setLanguageVersion(Context.VERSION_ES6);
+            return context;
+        }
+    };
+    private final Function executeBabel;
+
+    public BabelScriptTranspiler() {
+        Scriptable babel = BABEL.getScope();
+        executeBabel = contextFactory.call(ctx -> {
+            ctx.setOptimizationLevel(9);
+            String execBabelSource = "function(source) {\n" +
+                "return Babel.transform(source, { presets: ['env'] }).code;\n" +
+                "}\n";
+            return ctx.compileFunction(
+                babel, execBabelSource, "<execute-babel>", 1, null
+            );
+        });
+    }
+
+    @Override
+    public Reader transpile(Reader script) throws IOException {
+        long startTranspile = System.nanoTime();
+        Scriptable babel = BABEL.getScope();
+        String source = CharStreams.toString(script);
+        String result = (String) contextFactory.call(ctx ->
+            executeBabel.call(ctx, babel, null, new Object[] { source })
+        );
+        System.err.println(result);
+        System.err.println("Took " + TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startTranspile));
+        return new StringReader(result);
+    }
+}

worldedit-core/src/main/java/com/sk89q/worldedit/scripting/compat/RemoteScript.java

@@ -0,0 +1,120 @@
+package com.sk89q.worldedit.scripting.compat;
+
+import com.google.common.collect.ImmutableList;
+import com.sk89q.worldedit.WorldEdit;
+import com.sk89q.worldedit.util.net.HttpRequest;
+import org.mozilla.javascript.Context;
+import org.mozilla.javascript.ContextFactory;
+import org.mozilla.javascript.Scriptable;
+import org.mozilla.javascript.ScriptableObject;
+import org.mozilla.javascript.TopLevel;
+
+import java.io.IOException;
+import java.io.Reader;
+import java.io.UncheckedIOException;
+import java.net.URL;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.List;
+
+import static com.google.common.base.Preconditions.checkState;
+
+public class RemoteScript {
+
+    private static final int MAX_REDIRECTS = 100;
+
+
+    private final ContextFactory contextFactory = new ContextFactory() {
+        @Override
+        protected boolean hasFeature(Context cx, int featureIndex) {
+            if (featureIndex == Context.FEATURE_OLD_UNDEF_NULL_THIS) {
+                return true;
+            }
+            return super.hasFeature(cx, featureIndex);
+        }
+
+        @Override
+        protected Context makeContext() {
+            Context context = super.makeContext();
+            context.setLanguageVersion(Context.VERSION_ES6);
+            return context;
+        }
+    };
+    private final Path cacheDir = WorldEdit.getInstance()
+        .getWorkingDirectoryFile("craftscripts/.cache").toPath();
+    private final URL source;
+    private final String cacheFileName;
+    private final Path cachePath;
+    private final List<RemoteScript> dependencies;
+
+    private volatile Scriptable cachedScope;
+
+    public RemoteScript(String source, String cacheFileName, RemoteScript... dependencies) {
+        this.source = HttpRequest.url(source);
+        this.cacheFileName = cacheFileName;
+        this.cachePath = cacheDir.resolve(cacheFileName);
+        this.dependencies = ImmutableList.copyOf(dependencies);
+    }
+
+    private synchronized void ensureCached() throws IOException {
+        if (!Files.exists(cacheDir)) {
+            Files.createDirectories(cacheDir);
+        }
+        if (!Files.exists(cachePath)) {
+            boolean downloadedBabel = false;
+            int redirects = 0;
+            URL url = source;
+            while (redirects < MAX_REDIRECTS && !downloadedBabel) {
+                try (HttpRequest request = HttpRequest.get(url)) {
+                    request.execute();
+                    request.expectResponseCode(200, 301, 302);
+                    if (request.getResponseCode() > 300) {
+                        redirects++;
+                        url = HttpRequest.url(request.getSingleHeaderValue("Location"));
+                        continue;
+                    }
+                    request.saveContent(cachePath.toFile());
+                    downloadedBabel = true;
+                }
+            }
+            checkState(downloadedBabel, "Too many redirects following: %s", url);
+            checkState(Files.exists(cachePath), "Failed to actually download %s", cacheFileName);
+        }
+    }
+
+    protected synchronized void loadIntoScope(Context ctx, Scriptable scope) {
+        try {
+            ensureCached();
+            try (Reader reader = Files.newBufferedReader(cachePath)) {
+                ctx.evaluateReader(scope, reader, cacheFileName, 1, null);
+            }
+        } catch (IOException e) {
+            throw new UncheckedIOException(e);
+        }
+    }
+
+    /**
+     * Get a scope that the script has been evaluated in.
+     *
+     * @return the scope
+     */
+    public synchronized Scriptable getScope() {
+        if (cachedScope != null) {
+            return cachedScope;
+        }
+
+        // parse + execute standalone script to load it into the scope
+        cachedScope = contextFactory.call(ctx -> {
+            ScriptableObject scriptable = new TopLevel();
+            Scriptable newScope = ctx.initStandardObjects(scriptable);
+            ctx.setOptimizationLevel(9);
+            for (RemoteScript dependency : dependencies) {
+                dependency.loadIntoScope(ctx, newScope);
+            }
+            loadIntoScope(ctx, newScope);
+            return newScope;
+        });
+
+        return cachedScope;
+    }
+}

worldedit-core/src/main/java/com/sk89q/worldedit/scripting/compat/ScriptTranspiler.java

@@ -0,0 +1,38 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldedit.scripting.compat;
+
+import java.io.IOException;
+import java.io.Reader;
+
+/**
+ * Transpile a script from one (version) of a language to another.
+ */
+public interface ScriptTranspiler {
+
+    /**
+     * Given input {@code script}, return the transpiled script.
+     *
+     * @param script the script to transpile
+     * @return the new script
+     */
+    Reader transpile(Reader script) throws IOException;
+
+}

worldedit-core/src/main/java/com/sk89q/worldedit/util/net/HttpRequest.java

@@ -43,6 +43,8 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
+import static com.google.common.base.Preconditions.checkState;
+
 public class HttpRequest implements Closeable {
 
     private static final int CONNECT_TIMEOUT = 1000 * 5;
@@ -200,6 +202,13 @@ public class HttpRequest implements Closeable {
         return conn.getResponseCode();
     }
 
+    public String getSingleHeaderValue(String header) {
+        checkState(conn != null, "No connection has been made");
+
+        // maybe we should check for multi-header?
+        return conn.getHeaderField(header);
+    }
+
     /**
      * Get the input stream.
      *
@@ -214,9 +223,8 @@ public class HttpRequest implements Closeable {
      *
      * @return the buffered response
      * @throws java.io.IOException  on I/O error
-     * @throws InterruptedException on interruption
      */
-    public BufferedResponse returnContent() throws IOException, InterruptedException {
+    public BufferedResponse returnContent() throws IOException {
         if (inputStream == null) {
             throw new IllegalArgumentException("No input stream available");
         }
@@ -239,9 +247,8 @@ public class HttpRequest implements Closeable {
      * @param file the file
      * @return this object
      * @throws java.io.IOException  on I/O error
-     * @throws InterruptedException on interruption
      */
-    public HttpRequest saveContent(File file) throws IOException, InterruptedException {
+    public HttpRequest saveContent(File file) throws IOException {
         Closer closer = Closer.create();
 
         try {
@@ -262,9 +269,8 @@ public class HttpRequest implements Closeable {
      * @param out the output stream
      * @return this object
      * @throws java.io.IOException  on I/O error
-     * @throws InterruptedException on interruption
      */
-    public HttpRequest saveContent(OutputStream out) throws IOException, InterruptedException {
+    public HttpRequest saveContent(OutputStream out) throws IOException {
         BufferedInputStream bis;
 
         try {

worldedit-forge/build.gradle.kts

@@ -88,10 +88,10 @@ tasks.named<ShadowJar>("shadowJar") {
         include(dependency("org.apache.logging.log4j:log4j-slf4j-impl"))
         include(dependency("de.schlichtherle:truezip"))
         include(dependency("net.java.truevfs:truevfs-profile-default_2.13"))
-        include(dependency("org.mozilla:rhino"))
+        include(dependency("org.mozilla:rhino-runtime"))
     }
     minimize {
-        exclude(dependency("org.mozilla:rhino"))
+        exclude(dependency("org.mozilla:rhino-runtime"))
     }
 }