/*
* 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 com.google.gwt.core.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.ArtifactSet;
import com.google.gwt.core.ext.linker.CompilationResult;
import com.google.gwt.core.ext.linker.ConfigurationProperty;
import com.google.gwt.core.ext.linker.EmittedArtifact;
import com.google.gwt.core.ext.linker.LinkerOrder;
import com.google.gwt.core.ext.linker.StatementRanges;
import com.google.gwt.core.ext.linker.LinkerOrder.Order;
import com.google.gwt.core.ext.linker.impl.HostedModeLinker;
import com.google.gwt.core.ext.linker.impl.SelectionScriptLinker;
import com.google.gwt.dev.About;
import com.google.gwt.dev.util.DefaultTextOutput;
import com.google.gwt.dev.util.Util;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import java.util.SortedSet;
/**
* Implements the canonical GWT bootstrap sequence that loads the GWT module in
* a separate iframe.
*/
@LinkerOrder(Order.PRIMARY)
public class IFrameLinker extends SelectionScriptLinker {
/**
* This string is inserted between script chunks. It is made default access
* for testing.
*/
static final String SCRIPT_CHUNK_SEPARATOR = "--></script>\n<script><!--\n";
/**
* A configuration property indicating how large each script tag should be.
*/
private static final String CHUNK_SIZE_PROPERTY = "iframe.linker.script.chunk.size";
/**
* Split a JavaScript string into multiple chunks, at statement boundaries.
* Insert and end-script tag and a start-script tag in between each chunk.
* This method is made default access for testing.
*
* @param ranges Describes where the statements are located within the
* JavaScript code. If <code>null</code>, then return <code>js</code>
* unchanged.
* @param js The JavaScript code to be split up.
* @param charsPerChunk The number of characters to be put in each script tag
*/
static String splitPrimaryJavaScript(StatementRanges ranges, String js,
int charsPerChunk) {
if (charsPerChunk < 0 || ranges == null) {
return js;
}
StringBuilder sb = new StringBuilder();
int bytesInCurrentTag = 0;
for (int i = 0; i < ranges.numStatements(); i++) {
int start = ranges.start(i);
int end = ranges.end(i);
int length = end - start;
if (bytesInCurrentTag > 0 && bytesInCurrentTag + length > charsPerChunk) {
if (lastChar(sb) != '\n') {
sb.append('\n');
}
sb.append(SCRIPT_CHUNK_SEPARATOR);
bytesInCurrentTag = 0;
}
if (bytesInCurrentTag > 0) {
char lastChar = lastChar(sb);
if (lastChar != '\n' && lastChar != ';' && lastChar != '}') {
/*
* Make sure this statement has a separator from the last one.
*/
sb.append(";");
}
}
sb.append(js, start, end);
bytesInCurrentTag += length;
}
return sb.toString();
}
private static char lastChar(StringBuilder sb) {
return sb.charAt(sb.length() - 1);
}
@Override
public String getDescription() {
return "Standard";
}
@Override
public ArtifactSet link(TreeLogger logger, LinkerContext context,
ArtifactSet artifacts) throws UnableToCompleteException {
ArtifactSet toReturn = super.link(logger, context, artifacts);
try {
// Add hosted mode iframe contents
// TODO move this into own impl package if HostedModeLinker goes away
URL resource = HostedModeLinker.class.getResource("hosted.html");
if (resource == null) {
logger.log(TreeLogger.ERROR,
"Unable to find support resource 'hosted.html'");
throw new UnableToCompleteException();
}
final URLConnection connection = resource.openConnection();
// TODO: extract URLArtifact class?
EmittedArtifact hostedHtml = new EmittedArtifact(IFrameLinker.class,
"hosted.html") {
@Override
public InputStream getContents(TreeLogger logger)
throws UnableToCompleteException {
try {
return connection.getInputStream();
} catch (IOException e) {
logger.log(TreeLogger.ERROR, "Unable to copy support resource", e);
throw new UnableToCompleteException();
}
}
@Override
public long getLastModified() {
return connection.getLastModified();
}
};
toReturn.add(hostedHtml);
} catch (IOException e) {
logger.log(TreeLogger.ERROR, "Unable to copy support resource", e);
throw new UnableToCompleteException();
}
return toReturn;
}
/**
* This implementation divides the code of the initial fragment into multiple
* script tags. These chunked script tags loads faster on Firefox even when
* the data is cached. Additionally, having the script tags separated means
* that the early ones can be evaluated before the later ones have finished
* downloading. As a result of this parallelism, the overall time to get the
* JavaScript downloaded and evaluated can lower.
*/
@Override
protected byte[] generatePrimaryFragment(TreeLogger logger,
LinkerContext context, CompilationResult result, String[] js)
throws UnableToCompleteException {
StringBuffer b = new StringBuffer();
b.append(getModulePrefix(logger, context, result.getStrongName(), js.length));
b.append(splitPrimaryJavaScript(result.getStatementRanges()[0], js[0],
charsPerChunk(context, logger)));
b.append(getModuleSuffix(logger, context));
return Util.getBytes(b.toString());
}
@Override
protected String getCompilationExtension(TreeLogger logger,
LinkerContext context) {
return ".cache.html";
}
/**
* Returns the subdirectory name to be used by getModulPrefix when requesting
* a runAsync module. The default implementation returns the value of
* FRAGMENT_SUDBIR. This has been factored out for test cases.
*/
protected String getFragmentSubdir() {
return FRAGMENT_SUBDIR;
}
@Override
protected String getModulePrefix(TreeLogger logger, LinkerContext context,
String strongName) {
return getModulePrefix(context, strongName, true);
}
@Override
protected String getModulePrefix(TreeLogger logger, LinkerContext context,
String strongName, int numFragments) {
return getModulePrefix(context, strongName, numFragments > 1);
}
@Override
protected String getModuleSuffix(TreeLogger logger, LinkerContext context) {
DefaultTextOutput out = new DefaultTextOutput(context.isOutputCompact());
out.print("$stats && $stats({moduleName:'" + context.getModuleName()
+ "',sessionId:$sessionId"
+ ",subSystem:'startup',evtGroup:'moduleStartup'"
+ ",millis:(new Date()).getTime(),type:'moduleEvalEnd'});");
// Generate the call to tell the bootstrap code that we're ready to go.
out.newlineOpt();
out.print("if ($wnd." + context.getModuleFunctionName() + ") $wnd."
+ context.getModuleFunctionName() + ".onScriptLoad();");
out.newline();
out.print("--></script></body></html>");
out.newlineOpt();
return out.toString();
}
@Override
protected String getSelectionScriptTemplate(TreeLogger logger,
LinkerContext context) {
return "com/google/gwt/core/linker/IFrameTemplate.js";
}
protected String modifyPrimaryJavaScript(String js) {
return js;
}
/**
* Extract via {@link #CHUNK_SIZE_PROPERTY} the number of characters to be
* included in each script tag.
*/
private int charsPerChunk(LinkerContext context, TreeLogger logger)
throws UnableToCompleteException {
SortedSet<ConfigurationProperty> configProps = context.getConfigurationProperties();
for (ConfigurationProperty prop : configProps) {
if (prop.getName().equals(CHUNK_SIZE_PROPERTY)) {
return Integer.parseInt(prop.getValues().get(0));
}
}
logger.log(TreeLogger.ERROR, "Unable to find configuration property "
+ CHUNK_SIZE_PROPERTY);
throw new UnableToCompleteException();
}
/**
* This is the real implementation of <code>getModulePrefix</code> for this
* linker. The other versions forward to this one.
*/
private String getModulePrefix(LinkerContext context, String strongName,
boolean supportRunAsync) {
DefaultTextOutput out = new DefaultTextOutput(context.isOutputCompact());
out.print("<html>");
out.newlineOpt();
// Setup the well-known variables.
out.print("<head><script>");
out.newlineOpt();
out.print("var $gwt_version = \"" + About.getGwtVersionNum() + "\";");
out.newlineOpt();
out.print("var $wnd = parent;");
out.newlineOpt();
out.print("var $doc = $wnd.document;");
out.newlineOpt();
out.print("var $moduleName, $moduleBase;");
out.newlineOpt();
out.print("var $strongName = '" + strongName + "';");
out.newlineOpt();
if (supportRunAsync) {
out.print("function __gwtStartLoadingFragment(frag) {");
out.indentIn();
out.newlineOpt();
out.print(" return $moduleBase + '" + getFragmentSubdir()
+ "/' + $strongName + '/' + frag + '" + FRAGMENT_EXTENSION + "';");
out.indentOut();
out.newlineOpt();
out.print("};");
out.newlineOpt();
out.print("function __gwtInstallCode(code) {");
/*
* Use a script tag on all platforms, for simplicity. It would be cleaner
* to use window.eval, but at the time of writing that only reliably works
* on Firefox. It would also be cleaner to use window.execScript on
* platforms that support it (IE and Chrome). However, trying this causes
* IE 6 (and possibly others) to emit "error 80020101", apparently due to
* something objectionable in the compiler's output JavaScript.
*/
out.indentIn();
out.newlineOpt();
out.print("var head = document.getElementsByTagName('head').item(0);");
out.newlineOpt();
out.print("var script = document.createElement('script');");
out.newlineOpt();
out.print("script.type = 'text/javascript';");
out.newlineOpt();
out.print("script.text = code;");
out.newlineOpt();
out.print("head.appendChild(script);");
out.indentOut();
out.newlineOpt();
out.print("};");
out.newlineOpt();
}
out.print("var $stats = $wnd.__gwtStatsEvent ? function(a) {return $wnd.__gwtStatsEvent(a);} : null,");
out.newlineOpt();
out.print("$sessionId = $wnd.__gwtStatsSessionId ? $wnd.__gwtStatsSessionId : null;");
out.newlineOpt();
out.print("$stats && $stats({moduleName:'" + context.getModuleName()
+ "',sessionId:$sessionId"
+ ",subSystem:'startup',evtGroup:'moduleStartup'"
+ ",millis:(new Date()).getTime(),type:'moduleEvalStart'});");
out.newlineOpt();
out.print("</script></head>");
out.newlineOpt();
out.print("<body>");
out.newlineOpt();
// Begin a script block inside the body. It's commented out so that the
// browser won't mistake strings containing "<script>" for actual script.
out.print("<script><!--");
out.newline();
return out.toString();
}
}