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/*
 * Copyright 2000-2016 JetBrains s.r.o.
 *
 * 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.jetbrains.java.decompiler.util;

import java.io.*;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;

public class InterpreterUtil {
  public static final boolean IS_WINDOWS = System.getProperty("os.name", "").startsWith("Windows");

  public static final int[] EMPTY_INT_ARRAY = new int[0];

  private static final int BUFFER_SIZE = 16 * 1024;

  public static void copyFile(File source, File target) throws IOException {
    try (FileInputStream in = new FileInputStream(source); FileOutputStream out = new FileOutputStream(target)) {
      copyStream(in, out);
    }
  }

  public static void copyStream(InputStream in, OutputStream out) throws IOException {
    byte[] buffer = new byte[BUFFER_SIZE];
    int len;
    while ((len = in.read(buffer)) >= 0) {
      out.write(buffer, 0, len);
    }
  }

  public static byte[] getBytes(ZipFile archive, ZipEntry entry) throws IOException {
    try (InputStream stream = archive.getInputStream(entry)) {
      return readBytes(stream, (int)entry.getSize());
    }
  }

  public static byte[] getBytes(File file) throws IOException {
    try (FileInputStream stream = new FileInputStream(file)) {
      return readBytes(stream, (int)file.length());
    }
  }

  public static byte[] readBytes(InputStream stream, int length) throws IOException {
    byte[] bytes = new byte[length];

    int n = 0, off = 0;
    while (n < length) {
      int count = stream.read(bytes, off + n, length - n);
      if (count < 0) {
        throw new IOException("premature end of stream");
      }
      n += count;
    }

    return bytes;
  }

  public static void discardBytes(InputStream stream, int length) throws IOException {
    if (stream.skip(length) != length) {
      throw new IOException("premature end of stream");
    }
  }

  public static boolean equalSets(Collection c1, Collection c2) {
    if (c1 == null) {
      return c2 == null;
    }
    else if (c2 == null) {
      return false;
    }

    if (c1.size() != c2.size()) {
      return false;
    }

    HashSet