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Google XML Pages (GXP) is a templating system used to generate XML/SGML markup (most often HTML).
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/*
* Copyright (C) 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.gxp.base.dynamic;
import com.google.common.base.Charsets;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.google.common.collect.Sets;
import com.google.common.io.CharStreams;
import com.google.common.io.ByteStreams;
import com.google.gxp.base.GxpTemplate;
import com.google.gxp.compiler.Compiler;
import com.google.gxp.compiler.Configuration;
import com.google.gxp.compiler.InvalidConfigException;
import com.google.gxp.compiler.alerts.AlertPolicy;
import com.google.gxp.compiler.alerts.AlertSet;
import com.google.gxp.compiler.fs.FileRef;
import com.google.gxp.compiler.fs.FileSystem;
import com.google.gxp.compiler.fs.InMemoryFileSystem;
import com.google.gxp.compiler.fs.JavaFileManagerImpl;
import com.google.gxp.compiler.fs.JavaFileRef;
import com.google.gxp.compiler.fs.SystemFileSystem;
import javax.tools.Diagnostic;
import javax.tools.DiagnosticCollector;
import javax.tools.JavaCompiler;
import javax.tools.JavaFileManager;
import javax.tools.JavaFileObject;
import javax.tools.StandardLocation;
import javax.tools.ToolProvider;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.ProtectionDomain;
import java.util.Collections;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* Base class for all GxpTemplates that compile their source .gxp at runtime.
*/
public class StubGxpTemplate extends GxpTemplate {
// system filesystem
// can be changed for testing
protected static FileSystem systemFS = SystemFileSystem.INSTANCE;
public static void setSystemFileSystem(FileSystem systemFS) {
StubGxpTemplate.systemFS = systemFS;
}
public static void setJavaCompiler(JavaCompiler javaCompiler) {
StubGxpTemplate.javaCompiler = javaCompiler;
}
protected static FileRef parseFilename(String filename) {
return systemFS.parseFilename(filename);
}
protected static Set parseFilenames(String... filenames) {
Set fileRefs = Sets.newHashSet();
for (String filename : filenames) {
fileRefs.add(parseFilename(filename));
}
return fileRefs;
}
// java compiler
// can be changed for testing
private static JavaCompiler javaCompiler = ToolProvider.getSystemJavaCompiler();
/**
* Reconstruct an {@code AlertPolicy} that has been serialized to a byte array.
*/
protected static AlertPolicy createAlertPolicy(byte[] bytes) {
try {
ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
ObjectInputStream ois = new ObjectInputStream(bais);
return (AlertPolicy) ois.readObject();
} catch (ClassNotFoundException e) {
throw new RuntimeException(e);
} catch (IOException e) {
throw new RuntimeException(e);
}
}
protected static FileRef compileGxp(InMemoryFileSystem outFs,
Set srcGxps,
Set srcSchemas,
Set srcPaths,
String javaBase,
long compilationVersion,
AlertPolicy alertPolicy)
throws GxpCompilationException {
String javaFile = javaBase + compilationVersion + ".java";
Configuration configuration = new RuntimeConfiguration(systemFS, outFs, srcGxps, srcSchemas,
srcPaths, javaFile, compilationVersion,
alertPolicy);
try {
// Perform GXP Compilation
AlertSet alertSet = new Compiler(configuration).call();
// check for gxp compilation errors
if (alertSet.hasErrors(alertPolicy)) {
throw new GxpCompilationException.Gxp(alertPolicy, alertSet);
}
} catch (InvalidConfigException e) {
throw new GxpCompilationException.Throw(e);
}
return outFs.parseFilename(javaFile);
}
protected static Map compileJava(InMemoryFileSystem outFs,
String classBase,
final long compilationVersion) {
// compile java
DiagnosticCollector diagnosticCollector
= new DiagnosticCollector();
JavaFileManager javaFileManager
= new JavaFileManagerImpl(javaCompiler.getStandardFileManager(diagnosticCollector,
Locale.US,
Charsets.US_ASCII),
outFs);
String className = classBase + compilationVersion;
try {
JavaFileObject compilationUnit = javaFileManager.getJavaFileForInput(
StandardLocation.SOURCE_PATH, className, JavaFileObject.Kind.SOURCE);
Iterable compilationUnits = ImmutableList.of(compilationUnit);
javaCompiler.getTask(null, javaFileManager, diagnosticCollector,
null, null, compilationUnits).call();
List> diagnostics =
filterErrors(diagnosticCollector.getDiagnostics());
if (!diagnostics.isEmpty()) {
throw new GxpCompilationException.Java(diagnostics);
}
List classFiles = Lists.newArrayList();
for (FileRef fileRef : outFs.getManifest()) {
if (fileRef.getKind().equals(JavaFileObject.Kind.CLASS)) {
String outputClassName = javaFileManager.inferBinaryName(StandardLocation.CLASS_OUTPUT,
new JavaFileRef(fileRef));
if (outputClassName.equals(className) || outputClassName.startsWith(className + "$")) {
classFiles.add(ByteStreams.toByteArray(fileRef.openInputStream()));
}
}
}
// A single java compile can generate many .class files due to inner classes, and it
// is difficult to know what order to load them in to avoid NoClassDefFoundErrors,
// so what we do is go through the whole list attempting to load them all, keeping
// track of which ones file with NoClassDefFoundError. Then we loop and try again.
// This should eventually work no matter what order the files come in.
//
// We have an additional check to make sure that at least one file is loaded each
// time through the loop to prevent infinite looping.
//
// I'm not entirely happy with this scheme, but it's the best I can come up with
// for now.
int oldCount, newCount;
do {
oldCount = classFiles.size();
classFiles = defineClasses(classFiles);
newCount = classFiles.size();
} while (newCount != 0 && newCount != oldCount);
// get the main class generated durring this compile
Class c = Class.forName(className);
// get methods
return getMethodMap(c);
} catch (GxpCompilationException e) {
throw e;
} catch (Throwable e) {
throw new GxpCompilationException.Throw(e);
}
}
protected static Map getMethodMap(Class c) {
Map map = Maps.newHashMap();
for (Method method : c.getMethods()) {
map.put(method.getName(), method);
}
return map;
}
private static List defineClasses(List classFiles)
throws Throwable {
List failures = Lists.newArrayList();
for (byte[] classFile : classFiles) {
try {
defineClass(classFile);
} catch (NoClassDefFoundError e) {
failures.add(classFile);
}
}
return failures;
}
// TODO(harryh): Consider strategies for detecting and generating an error
// when, at runtime, two parameters of the same type but different
// names are swapped. Name mangling of the method name with a
// parameters name list might be a good way to do this.
protected static Object exec(Map methods, String function,
Object[] args) throws Throwable {
try {
return methods.get(function).invoke(null, args);
} catch (InvocationTargetException e) {
throw e.getCause();
} catch (IllegalArgumentException e) {
throw new GxpCompilationException.GxpParamChange(e);
} catch (Exception e) {
throw new GxpCompilationException.Throw(e);
}
}
protected static T execNoExceptions(Map methods,
String function,
Object[] args) {
try {
@SuppressWarnings("unchecked")
T result = (T)exec(methods, function, args);
return result;
} catch (Error e) {
throw e;
} catch (RuntimeException e) {
throw e;
} catch (Throwable t) {
throw new GxpCompilationException.Throw(t);
}
}
/**
* @return a filtered list of {@code Diagnostic}s that only contains
* errors.
*/
private static List> filterErrors(
List> diagnostics) {
List> newList = Lists.newArrayList();
for (Diagnostic diagnostic : diagnostics) {
if (diagnostic.getKind().equals(Diagnostic.Kind.ERROR)) {
newList.add(diagnostic);
}
}
return Collections.unmodifiableList(newList);
}
private static final Method DEFINE_CLASS =
AccessController.doPrivileged(new PrivilegedAction() {
public Method run() {
try {
Class loader = ClassLoader.class;
Method m = loader.getDeclaredMethod("defineClass",
new
Class[]{ String.class,
byte[].class,
Integer.TYPE,
Integer.TYPE,
ProtectionDomain.class });
m.setAccessible(true);
return m;
} catch (NoSuchMethodException e) {
throw new RuntimeException();
}
}
});
private static final ProtectionDomain PROTECTION_DOMAIN =
StubGxpTemplate.class.getProtectionDomain();
/**
* Define a class using the SystemClassLoader so that the class has access to
* package private items in its java package.
*/
private static Class defineClass(byte[] classFile)
throws Throwable {
Object[] args = new Object[]{ null, classFile,
new Integer(0), new Integer(classFile.length),
PROTECTION_DOMAIN };
try {
return (Class) DEFINE_CLASS.invoke(ClassLoader.getSystemClassLoader(), args);
} catch (InvocationTargetException e) {
throw e.getCause();
}
}
/**
* The pattern for a line directive; 1->file 2->line 3->col.
*/
private final static Pattern LINE_DIRECTIVE = Pattern.compile("^.* // (.*): L(\\d*), C(\\d*)$");
/**
* Examine each element of the stack trace that belongs to this throwable
* looking for a filename that matches the source file for this template.
* If we find a match, rewrite the filename and line number. The line number
* is based on line # comments in the source file.
*/
protected static void rewriteStackTraceElements(Throwable throwable, FileRef sourceFile) {
try {
if (sourceFile != null) {
String sourceFileName = sourceFile.getName().substring(1).replace('/', '.');
StackTraceElement[] stackTrace = throwable.getStackTrace();
for (int i = 0; i < stackTrace.length; i++) {
if (sourceFileName.equals(stackTrace[i].getFileName())) {
// get source name
String[] parts = sourceFileName.split("[\\.\\$]");
String sourceName = parts[parts.length-3] + ".gxp";
// get source line
String line = CharStreams
.readLines(sourceFile.openReader(Charsets.UTF_8))
.get(stackTrace[i].getLineNumber() - 1);
Matcher m = LINE_DIRECTIVE.matcher(line);
int sourceLine = m.find() ? Integer.valueOf(m.group(2)) : -1;
// fix class name
String className = stackTrace[i].getClassName().split("\\$")[0];
stackTrace[i] = new StackTraceElement(className,
stackTrace[i].getMethodName(),
sourceName,
sourceLine);
throwable.setStackTrace(stackTrace);
return;
}
}
}
} catch (Exception e) {
throw new AssertionError(e);
}
}
}