Java tutorial
/* * Copyright 2008 Google Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); you may not * use this file except in compliance with the License. You may obtain a copy of * the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations under * the License. */ package org.gwtproject.gwt.worker.linker; import com.google.gwt.core.ext.LinkerContext; import com.google.gwt.core.ext.TreeLogger; import com.google.gwt.core.ext.UnableToCompleteException; import com.google.gwt.core.ext.linker.Artifact; import com.google.gwt.core.ext.linker.ArtifactSet; import com.google.gwt.core.ext.linker.CompilationResult; import com.google.gwt.core.ext.linker.EmittedArtifact; import com.google.gwt.core.ext.linker.LinkerOrder; import com.google.gwt.core.ext.linker.LinkerOrder.Order; import com.google.gwt.core.ext.linker.Shardable; import com.google.gwt.core.ext.linker.Transferable; import com.google.gwt.core.ext.linker.impl.SelectionScriptLinker; import com.google.gwt.dev.About; import com.google.gwt.dev.util.DefaultTextOutput; import java.util.ArrayList; import java.util.Collection; import java.util.Set; /** * A Linker for producing a single JavaScript file from a GWT module. The use of * this Linker requires that the module has exactly one distinct compilation * result. * * Customized to support worker linker. See //#worker comments */ @LinkerOrder(Order.PRIMARY) @Shardable public class SingleScriptLinker extends SelectionScriptLinker { @Override public String getDescription() { return "Single Script"; } @Transferable protected static class Script extends Artifact<Script> { private static final long serialVersionUID = -8385802388145548029L; private final String javaScript; private final String strongName; public Script(String strongName, String javaScript) { super(SingleScriptLinker.class); this.strongName = strongName; this.javaScript = javaScript; } @Override public int compareToComparableArtifact(Script that) { int res = strongName.compareTo(that.strongName); if (res == 0) { res = javaScript.compareTo(that.javaScript); } return res; } @Override public Class<Script> getComparableArtifactType() { return Script.class; } public String getJavaScript() { return javaScript; } public String getStrongName() { return strongName; } @Override public int hashCode() { return strongName.hashCode() ^ javaScript.hashCode(); } @Override public String toString() { return "Script " + strongName; } } @Override protected Collection<Artifact<?>> doEmitCompilation(TreeLogger logger, LinkerContext context, CompilationResult result, ArtifactSet artifacts) throws UnableToCompleteException { String[] js = result.getJavaScript(); if (js.length != 1) { logger.branch(TreeLogger.ERROR, getMultiFragmentWarningMessage(), null); throw new UnableToCompleteException(); } Collection<Artifact<?>> toReturn = new ArrayList<Artifact<?>>(); toReturn.add(new Script(result.getStrongName(), js[0])); toReturn.addAll(emitSelectionInformation(result.getStrongName(), result)); return toReturn; } @Override protected EmittedArtifact emitSelectionScript(TreeLogger logger, LinkerContext context, ArtifactSet artifacts) throws UnableToCompleteException { // Find the single Script result Set<Script> results = artifacts.find(Script.class); ensureSinglePermutation(logger, context, results); Script result = results.iterator().next(); DefaultTextOutput out = new DefaultTextOutput(true); // Emit the selection script. String bootstrap = generateSelectionScript(logger, context, artifacts); bootstrap = context.optimizeJavaScript(logger, bootstrap); out.print(bootstrap); out.newlineOpt(); // Emit the module's JS a closure. out.print("(function () {"); out.newlineOpt(); out.print("var $gwt_version = \"" + About.getGwtVersionNum() + "\";"); out.newlineOpt(); defineJsWndAndDoc(out); out.print("var $moduleName, $moduleBase;"); out.newlineOpt(); out.print("var $stats = $wnd.__gwtStatsEvent ? function(a) {$wnd.__gwtStatsEvent(a)} : null;"); out.newlineOpt(); out.print("var $strongName = '" + result.getStrongName() + "';"); out.newlineOpt(); out.print(result.getJavaScript()); // Generate the call to tell the bootstrap code that we're ready to go. out.newlineOpt(); out.print("if (" + context.getModuleFunctionName() + ") " + context.getModuleFunctionName() + ".onScriptLoad(gwtOnLoad);"); out.newlineOpt(); out.print("})();"); out.newlineOpt(); return emitString(logger, out.toString(), context.getModuleName() + getCompilationExtension(logger, context)); } //#worker used so it's possible to override @Override protected String getCompilationExtension(TreeLogger logger, LinkerContext context) throws UnableToCompleteException { return ".nocache.js"; } /** * Unimplemented. Normally required by * {@link #doEmitCompilation(TreeLogger, LinkerContext, CompilationResult, ArtifactSet)}. */ @Override protected String getModulePrefix(TreeLogger logger, LinkerContext context, String strongName) throws UnableToCompleteException { throw new UnableToCompleteException(); } /** * Unimplemented. Normally required by * {@link #doEmitCompilation(TreeLogger, LinkerContext, CompilationResult, ArtifactSet)}. */ @Override protected String getModuleSuffix(TreeLogger logger, LinkerContext context) throws UnableToCompleteException { throw new UnableToCompleteException(); } @Override protected String getSelectionScriptTemplate(TreeLogger logger, LinkerContext context) throws UnableToCompleteException { return "com/google/gwt/core/linker/SingleScriptTemplate.js"; } //#worker: refactored out to be able to customize the message protected String getMultiFragmentWarningMessage() { return "The module must not have multiple fragments when using the " + getDescription() + " Linker."; } //#worker: refactored out to be able to customize creation of $wnd and $doc protected void defineJsWndAndDoc(DefaultTextOutput out) { out.print("var $wnd = window;"); out.newlineOpt(); out.print("var $doc = $wnd.document;"); out.newlineOpt(); } //#worker: refactored out to be able to print helper message what may have //caused multiply permutations protected void ensureSinglePermutation(TreeLogger logger, LinkerContext context, Set<Script> results) throws UnableToCompleteException { if (results.size() != 1) { logger.log(TreeLogger.ERROR, "The module must have exactly one distinct" + " permutation when using the " + getDescription() + " Linker; found " + results.size(), null); throw new UnableToCompleteException(); } } }