DebuggerUtils.java

/*
 * Copyright 2012 Dart project authors.
 * 
 * Licensed under the Eclipse Public License v1.0 (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.eclipse.org/legal/epl-v10.html
 * 
 * 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.dart.tools.debug.core.util;

import com.google.common.io.CharStreams;
import com.google.common.io.Closeables;

import org.eclipse.core.resources.IFile;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.debug.core.DebugException;
import org.eclipse.debug.core.model.IStackFrame;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.util.Arrays;
import java.util.List;

/**
 * This class contains static utility methods for use by the debugger.
 */
public class DebuggerUtils {

  /**
   * Returns whether the given frame needs some additional disambiguating information from its two
   * surrounding frames.
   * 
   * @param frame
   * @return
   * @throws DebugException
   */
  public static boolean areSiblingNamesUnique(IExceptionStackFrame frame) throws DebugException {
    List<IStackFrame> frames = Arrays.asList(frame.getThread().getStackFrames());

    int index = frames.indexOf(frame);

    if (index == -1) {
      return true;
    }

    if (index > 0) {
      IExceptionStackFrame other = (IExceptionStackFrame) frames.get(index - 1);

      if (needsDisambiguating(other, frame)) {
        return false;
      }
    }

    if ((index + 1) < frames.size()) {
      IExceptionStackFrame other = (IExceptionStackFrame) frames.get(index + 1);

      if (needsDisambiguating(frame, other)) {
        return false;
      }
    }

    return true;
  }

  /**
   * The names of private fields are mangled by the VM.
   * <p>
   * _foo@652376 ==> _foo
   * <p>
   * Also, remove "set:" and "get:", as these are artifacts of the VM implementation.
   * <p>
   * e.x., Cat.get:color() ==> Cat.color()
   * 
   * @param name
   * @return
   */
  public static String demangleVmName(String name) {
    if (name == null) {
      return null;
    }

    int atIndex = name.indexOf('@');

    while (atIndex != -1) {
      // check for _foo@76876.bar (or _Process@14117cc4._reportError@14117cc4)
      int endIndex = name.indexOf('.', atIndex);

      if (endIndex == -1) {
        name = name.substring(0, atIndex);
      } else {
        name = name.substring(0, atIndex) + name.substring(endIndex);
      }

      atIndex = name.indexOf('@');
    }

    // Also remove the trailing '.' for default constructors.
    if (name.endsWith(".")) {
      name = name.substring(0, name.length() - 1);
    }

    // remove "set:" and "get:"
    // Cat.get:color() ==> Cat.color()
    if (name.indexOf(".set:") != -1) {
      int index = name.indexOf(".set:");
      name = name.substring(0, index + 1) + name.substring(index + 5);
    }

    if (name.indexOf(".get:") != -1) {
      int index = name.indexOf(".get:");
      name = name.substring(0, index + 1) + name.substring(index + 5);
    }

    return name;
  }

  public static String extractFileLine(IFile file, int lineNumber) {
    if (file == null) {
      return null;
    }

    try {
      return extractFileLine(file.getContents(), file.getCharset(), lineNumber);
    } catch (CoreException ce) {

    }

    return null;
  }

  public static String extractFileLine(InputStream contents, String charset, int lineNumber) {
    if (contents == null) {
      return null;
    }

    try {
      Reader r = charset != null ? new InputStreamReader(contents, charset)
          : new InputStreamReader(contents);

      List<String> lines = CharStreams.readLines(r);
      Closeables.close(r, true);

      if (lineNumber >= 0 && lineNumber < lines.size()) {
        String lineStr = lines.get(lineNumber).trim();

        return lineStr.length() == 0 ? null : lineStr;
      }
    } catch (IOException ioe) {

    }

    return null;
  }

  public static boolean isInternalMethodName(String methodName) {
    return methodName.startsWith("Object._noSuchMethod@");
  }

  /**
   * @return whether the given debugger symbol name represents a private symbol
   */
  public static boolean isPrivateName(String name) {
    // These are special names generated by dart2js.
    if (name.startsWith("$.") || name.startsWith("$$.")) {
      return false;
    }

    // A private top-level method (_foo()).
    if (name.startsWith("_")) {
      return true;
    }

    // A private static or instance method (i.e Foo._bar()).
    return name.indexOf("._") != -1;
  }

  public static String printString(String str) {
    if (str == null) {
      return null;
    }

    if (str.indexOf('\n') != -1) {
      str = str.replace("\n", "\\n");
    }

    if (str.indexOf('\r') != -1) {
      str = str.replace("\r", "\\r");
    }

    if (str.indexOf('\t') != -1) {
      str = str.replace("\t", "\\t");
    }

    // Don't re-quote already quoted strings.
    if (str.length() > 1 && str.startsWith("\"") && str.endsWith("\"")) {
      return str;
    } else {
      return "\"" + str + "\"";
    }
  }

  private static boolean needsDisambiguating(IExceptionStackFrame frame1,
      IExceptionStackFrame frame2) {
    if (frame1.getShortName().equals(frame2.getShortName())) {
      // These will need disambiguating if the long names are different.

      return !frame1.getLongName().equals(frame2.getLongName());
    }

    return false;
  }

  private DebuggerUtils() {

  }

}