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A set of utilities for classes of the java.lang and the java.util packages.
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/*
 * Copyright (C) 2008 The Guava Authors
 *
 * 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.
 *
 * Modifications:
 *
 * Copyright (C) 2011-2021 Objectos Software LTDA.
 *
 * This file is part of the ObjectosComuns project.
 *
 * ObjectosComuns is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * ObjectosComuns is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with ObjectosComuns.  If not, see .
 */
package br.com.objectos.lang;

import static br.com.objectos.lang.Lang.checkNotNull;
import static br.com.objectos.lang.Lang.isDigit;

import br.com.objectos.lang.Lang.Utf8Bytes;

/**
 * A streamlined version of Google Guava's Ints.
 *
 * Contains only the methods that are currently being used at Objectos Software.
 *
 * @author Kevin Bourrillion (original Guava version)
 */
final class Ints {

  private Ints() {}

  /**
   * Returns the values from each provided array combined into a single array.
   * For example, {@code concat(new int[] {a, b}, new int[] {}, new int[] {c}}
   * returns the array {@code {a, b, c}}.
   *
   * @param arrays
   *          zero or more {@code int} arrays
   * @return a single array containing all the values from the source arrays, in
   *         order
   */
  public static int[] concat(int[]... arrays) {
    int length = 0;
    for (int[] array : arrays) {
      length += array.length;
    }
    int[] result = new int[length];
    int pos = 0;
    for (int[] array : arrays) {
      System.arraycopy(array, 0, result, pos, array.length);
      pos += array.length;
    }
    return result;
  }

  /**
   * Returns a string containing the supplied {@code int} values separated by
   * {@code separator}. For example, {@code join("-", 1, 2, 3)} returns the
   * string {@code "1-2-3"}.
   *
   * @param separator
   *          the text that should appear between consecutive values in the
   *          resulting string (but not at the start or end)
   * @param array
   *          an array of {@code int} values, possibly empty
   * @return a string containing the supplied {@code int} values separated by
   *         {@code separator}.
   */
  public static String join(String separator, int... array) {
    checkNotNull(separator);
    if (array.length == 0) {
      return "";
    }

    // For pre-sizing a builder, just get the right order of magnitude
    StringBuilder builder = new StringBuilder(array.length * 5);
    builder.append(array[0]);
    for (int i = 1; i < array.length; i++) {
      builder.append(separator).append(array[i]);
    }
    return builder.toString();
  }

  public static int parseInt(byte utf8) {
    if (!isDigit(utf8)) {
      throw new NumberFormatException();
    }

    return utf8 - Utf8Bytes.DIGIT_0;
  }

  public static int parseInt(byte[] utf8) {
    return parseInt(utf8, 0, utf8.length);
  }

  public static int parseInt(byte[] utf8, int offset, int length) {
    byte b;

    int result;
    result = 0;

    int multiplier;
    multiplier = 1;

    for (int i = offset + length - 1; i >= offset; i--) {
      b = utf8[i];

      int digit;
      digit = parseInt(b);

      digit *= multiplier;

      result += digit;

      multiplier *= 10;
    }

    if (result < 0) {
      throw new NumberFormatException();
    }

    return result;
  }

  public static int parseInt(char c) {
    switch (c) {
      case '0':
        return 0;
      case '1':
        return 1;
      case '2':
        return 2;
      case '3':
        return 3;
      case '4':
        return 4;
      case '5':
        return 5;
      case '6':
        return 6;
      case '7':
        return 7;
      case '8':
        return 8;
      case '9':
        return 9;
      default:
        throw new NumberFormatException(c + " is not a digit");
    }
  }

}