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/*
 * 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.dev.javac;

import com.google.gwt.core.ext.TreeLogger;
import com.google.gwt.dev.asm.ClassReader;
import com.google.gwt.dev.asm.MethodVisitor;
import com.google.gwt.dev.asm.Opcodes;
import com.google.gwt.dev.javac.asmbridge.EmptyVisitor;
import com.google.gwt.dev.jjs.ast.JDeclaredType;
import com.google.gwt.dev.jjs.ast.JProgram;
import com.google.gwt.dev.util.DiskCache;
import com.google.gwt.dev.util.Util;
import com.google.gwt.dev.util.collect.HashMap;

import org.eclipse.jdt.core.compiler.CategorizedProblem;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.Serializable;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.regex.Pattern;

/**
 * Encapsulates the state of a single active compilation unit in a particular
 * module. State is accumulated throughout the life cycle of the containing
 * module and may be invalidated at certain times and recomputed.
 */
public abstract class CompilationUnit implements Serializable {

  /**
   * Encapsulates the functionality to find all nested classes of this class
   * that have compiler-generated names. All class bytes are loaded from the
   * disk and then analyzed using ASM.
   */
  static class GeneratedClassnameFinder {
    private static class AnonymousClassVisitor extends EmptyVisitor {
      /*
       * array of classNames of inner clases that aren't synthetic classes.
       */
      List classNames = new ArrayList();

      int expectCode;
      int sawCode;

      public AnonymousClassVisitor() {

        this.mv = new MethodVisitor(Opcodes.ASM4, this.mv) {
          @Override
          public void visitCode() {
            ++sawCode;
          }
        };
      }
      public List getInnerClassNames() {
        return classNames;
      }

      /**
       * Return whether or not the class file visited was well-formed.
       * Currently, this only checks that all non-abstract, non-native methods
       * have a Code attribute.
       */
      public boolean isWellFormed() {
        return expectCode == sawCode;
      }

      @Override
      public void visitInnerClass(String name, String outerName, String innerName, int access) {
        if ((access & Opcodes.ACC_SYNTHETIC) == 0) {
          classNames.add(name);
        }
      }

      @Override
      public MethodVisitor visitMethod(int access, String name, String desc, String signature,
                                                              String[] exceptions) {
        if ((access & (Opcodes.ACC_ABSTRACT | Opcodes.ACC_NATIVE)) == 0) {
          ++expectCode;
        }
        return super.visitMethod(access, name, desc, signature, exceptions);
      }
    }

    private final List classesToScan;
    private final TreeLogger logger;
    private final String mainClass;
    private String mainUrlBase = null;

    GeneratedClassnameFinder(TreeLogger logger, String mainClass) {
      assert mainClass != null;
      this.mainClass = mainClass;
      classesToScan = new ArrayList();
      classesToScan.add(mainClass);
      this.logger = logger;
    }

    List getClassNames() {
      // using a list because presumably there will not be many generated
      // classes
      List allGeneratedClasses = new ArrayList();
      for (int i = 0; i < classesToScan.size(); i++) {
        String lookupName = classesToScan.get(i);
        byte classBytes[] = getClassBytes(lookupName);
        if (classBytes == null) {
          /*
           * Weird case: javac might generate a name and reference the class in
           * the bytecode but decide later that the class is unnecessary. In the
           * bytecode, a null is passed for the class.
           */
          continue;
        }

        AnonymousClassVisitor cv = new AnonymousClassVisitor();
        new ClassReader(classBytes).accept(cv, 0);
        if (!cv.isWellFormed()) {
          /*
           * Weird case #2: As of OpenJDK 7, javac in the above case now does
           * generate a class file, but an incomplete one that fails to load
           * with a ClassFormatError "Absent Code attribute in method that
           * is not native or abstract in class file" error.
           */
          continue;
        }

        /*
         * Add the class to the list only if it can be loaded to get around the
         * javac weirdness issue where javac refers a class but does not
         * generate it.
         */
        if (isClassnameGenerated(lookupName) && !allGeneratedClasses.contains(lookupName)) {
          allGeneratedClasses.add(lookupName);
        }
        List innerClasses = cv.getInnerClassNames();
        for (String innerClass : innerClasses) {
          // The innerClass has to be an inner class of the lookupName
          if (!innerClass.startsWith(mainClass + "$")) {
            continue;
          }
          /*
           * TODO (amitmanjhi): consider making this a Set if necessary for
           * performance
           */
          // add the class to classes
          if (!classesToScan.contains(innerClass)) {
            classesToScan.add(innerClass);
          }
        }
      }
      Collections.sort(allGeneratedClasses, new GeneratedClassnameComparator());
      return allGeneratedClasses;
    }

    /*
     * Load classBytes from disk. Check if the classBytes are loaded from the
     * same location as the location of the mainClass.
     */
    private byte[] getClassBytes(String slashedName) {
      URL url = Thread.currentThread().getContextClassLoader().getResource(slashedName + ".class");
      if (url == null) {
        if (logger.isLoggable(TreeLogger.DEBUG)) {
          logger.log(TreeLogger.DEBUG, "Unable to find " + slashedName + " on the classPath");
        }
        return null;
      }
      String urlStr = url.toExternalForm();
      if (slashedName.equals(mainClass)) {
        // initialize the mainUrlBase for later use.
        mainUrlBase = urlStr.substring(0, urlStr.lastIndexOf('/'));
      } else {
        assert mainUrlBase != null;
        if (!mainUrlBase.equals(urlStr.substring(0, urlStr.lastIndexOf('/')))) {
          if (logger.isLoggable(TreeLogger.DEBUG)) {
            logger.log(TreeLogger.DEBUG, "Found " + slashedName + " at " + urlStr
                + " The base location is different from  that of " + mainUrlBase + " Not loading");
          }
          return null;
        }
      }

      // url != null, we found it on the class path.
      try {
        URLConnection conn = url.openConnection();
        return Util.readURLConnectionAsBytes(conn);
      } catch (IOException ignored) {
        if (logger.isLoggable(TreeLogger.DEBUG)) {
          logger.log(TreeLogger.DEBUG, "Unable to load " + urlStr + ", in trying to load "
              + slashedName);
        }
        // Fall through.
      }
      return null;
    }
  }

  protected static final DiskCache diskCache = DiskCache.INSTANCE;

  public static final Comparator COMPARATOR = new Comparator() {
    @Override
    public int compare(CompilationUnit o1, CompilationUnit o2) {
      return o1.getResourcePath().compareTo(o2.getResourcePath());
    }
  };

  private static final Pattern GENERATED_CLASSNAME_PATTERN = Pattern.compile(".+\\$\\d.*");

  /**
   * Checks if the class names is generated. Accepts any classes whose names
   * match .+$\d.* (handling named classes within anonymous classes and multiple
   * named classes of the same name in a class, but in different methods).
   * Checks if the class or any of its enclosing classes are anonymous or
   * synthetic.
   * 

* If new compilers have different conventions for anonymous and synthetic * classes, this code needs to be updated. *

* * @param className name of the class to be checked. * @return true iff class or any of its enclosing classes are anonymous or * synthetic. */ @Deprecated public static boolean isClassnameGenerated(String className) { return GENERATED_CLASSNAME_PATTERN.matcher(className).matches(); } /** * Map from the className in javac to the className in jdt. String represents * the part of className after the compilation unit name. Emma-specific. */ private transient Map anonymousClassMap = null; /** * Returns the unit as an instance of {@link CachedCompilationUnit}, making a * copy if necessary. */ public abstract CachedCompilationUnit asCachedCompilationUnit(); @Deprecated public final boolean constructAnonymousClassMappings(TreeLogger logger) { /* * Check if the unit has one or more classes with generated names. 'javac' * below refers to the compiler that was used to compile the java files on * disk. Returns true if our heuristic for constructing the anonymous class * mappings worked. */ anonymousClassMap = new HashMap(); for (String topLevelClass : getTopLevelClasses()) { // Generate a mapping for each top-level class separately List javacClasses = new GeneratedClassnameFinder(logger, topLevelClass).getClassNames(); List jdtClasses = getJdtClassNames(topLevelClass); if (javacClasses.size() != jdtClasses.size()) { anonymousClassMap = Collections.emptyMap(); return false; } int size = javacClasses.size(); for (int i = 0; i < size; i++) { if (!javacClasses.get(i).equals(jdtClasses.get(i))) { anonymousClassMap.put(javacClasses.get(i), jdtClasses.get(i)); } } } return true; } @Deprecated public final boolean createdClassMapping() { return anonymousClassMap != null; } /** * Overridden to finalize; always returns object identity. */ @Override public final boolean equals(Object obj) { return super.equals(obj); } @Deprecated public final Map getAnonymousClassMap() { /* * Return an empty map so that class-rewriter does not need to check for * null. A null value indicates that anonymousClassMap was never created * which is the case for many units. An example is a class containing jsni * units but no inner classes. */ if (anonymousClassMap == null) { return Collections.emptyMap(); } return anonymousClassMap; } /** * Returns all contained classes. */ public abstract Collection getCompiledClasses(); public abstract List getJsniMethods(); /** * Returns the last modified time of the compilation unit. */ public abstract long getLastModified(); /** * @return a way to lookup method argument names for this compilation unit. */ public abstract MethodArgNamesLookup getMethodArgs(); /** * This is the resource location from the classpath or some deterministic * virtual location (in the case of generators or mock data) where the source * for this unit originated. This should be unique for each unit compiled to * create a module. * * @see com.google.gwt.dev.resource.Resource#getLocation() */ public abstract String getResourceLocation(); /** * Returns the full abstract path of the resource. If a resource has been * re-rooted, this path should include any path prefix that was stripped. * * @see com.google.gwt.dev.resource.Resource#getPath() * @see com.google.gwt.dev.resource.Resource#getPathPrefix() */ public abstract String getResourcePath(); /** * Returns the fully-qualified name of the top level public type. */ public abstract String getTypeName(); /** * Returns the GWT AST types in this unit. */ public List getTypes() { try { byte[] bytes = getTypesSerialized(); ObjectInputStream ois = new ObjectInputStream(new ByteArrayInputStream(bytes)); return JProgram.deserializeTypes(ois); } catch (IOException e) { throw new RuntimeException("Unexpected IOException on in-memory stream", e); } catch (ClassNotFoundException e) { throw new RuntimeException("Unexpected error deserializing AST for '" + getTypeName() + "'", e); } } /** * Returns the GWT AST types in this unit in serialized form. */ public abstract byte[] getTypesSerialized(); @Deprecated public final boolean hasAnonymousClasses() { for (CompiledClass cc : getCompiledClasses()) { if (isAnonymousClass(cc)) { return true; } } return false; } /** * Overridden to finalize; always returns identity hash code. */ @Override public final int hashCode() { return super.hashCode(); } /** * Returns true if this unit had errors. */ public abstract boolean isError(); /** * Returns true if this unit was generated by a * {@link com.google.gwt.core.ext.Generator}. */ @Deprecated public abstract boolean isGenerated(); /** * * @return true if the Compilation Unit is from a super-source. */ @Deprecated public abstract boolean isSuperSource(); /** * Overridden to finalize; always returns {@link #getResourceLocation()}. */ @Override public final String toString() { return getResourceLocation(); } /** * The canonical serialized form of a CompilatinUnit is * {@link CachedCompilationUnit}. */ protected final Object writeReplace() { return asCachedCompilationUnit(); } /** * Returns the content ID for the source with which this unit was compiled. */ abstract ContentId getContentId(); /** * The set of dependencies on other classes. */ abstract Dependencies getDependencies(); abstract CategorizedProblem[] getProblems(); private List getJdtClassNames(String topLevelClass) { List classNames = new ArrayList(); for (CompiledClass cc : getCompiledClasses()) { if (isAnonymousClass(cc) && cc.getInternalName().startsWith(topLevelClass + "$")) { classNames.add(cc.getInternalName()); } } Collections.sort(classNames, new GeneratedClassnameComparator()); return classNames; } private List getTopLevelClasses() { List topLevelClasses = new ArrayList(); for (CompiledClass cc : getCompiledClasses()) { if (cc.getEnclosingClass() == null) { topLevelClasses.add(cc.getInternalName()); } } return topLevelClasses; } /** * TODO(amitmanjhi): what is the difference between an anonymous and local * class for our purposes? All our unit tests pass whether or not we do the * additional {@link #isClassnameGenerated} check. We either need to find the * real difference and add a unit test, or else simply this. */ private boolean isAnonymousClass(CompiledClass cc) { return cc.isLocal() && isClassnameGenerated(cc.getInternalName()); } }




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