guava/src/com/google/common/primitives/Chars.java - platform/external/guava - Git at Google

 /*
  * 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.
  */

 package com.google.common.primitives;

 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkElementIndex;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkPositionIndexes;

 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
 import java.io.Serializable;
 import java.util.AbstractList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 import java.util.RandomAccess;
 import org.checkerframework.checker.nullness.qual.Nullable;

 /**
  * Static utility methods pertaining to {@code char} primitives, that are not already found in
  * either {@link Character} or {@link Arrays}.
  *
  * <p>All the operations in this class treat {@code char} values strictly numerically; they are
  * neither Unicode-aware nor locale-dependent.
  *
  * <p>See the Guava User Guide article on <a
  * href="https://github.com/google/guava/wiki/PrimitivesExplained">primitive utilities</a>.
  *
  * @author Kevin Bourrillion
  * @since 1.0
  */
 @GwtCompatible(emulated = true)
 public final class Chars {
   private Chars() {}

   /**
    * The number of bytes required to represent a primitive {@code char} value.
    *
    * <p><b>Java 8 users:</b> use {@link Character#BYTES} instead.
    */
   public static final int BYTES = Character.SIZE / Byte.SIZE;

   /**
    * Returns a hash code for {@code value}; equal to the result of invoking {@code ((Character)
    * value).hashCode()}.
    *
    * <p><b>Java 8 users:</b> use {@link Character#hashCode(char)} instead.
    *
    * @param value a primitive {@code char} value
    * @return a hash code for the value
    */
   public static int hashCode(char value) {
     return value;
   }

   /**
    * Returns the {@code char} value that is equal to {@code value}, if possible.
    *
    * @param value any value in the range of the {@code char} type
    * @return the {@code char} value that equals {@code value}
    * @throws IllegalArgumentException if {@code value} is greater than {@link Character#MAX_VALUE}
    *     or less than {@link Character#MIN_VALUE}
    */
   public static char checkedCast(long value) {
     char result = (char) value;
     checkArgument(result == value, "Out of range: %s", value);
     return result;
   }

   /**
    * Returns the {@code char} nearest in value to {@code value}.
    *
    * @param value any {@code long} value
    * @return the same value cast to {@code char} if it is in the range of the {@code char} type,
    *     {@link Character#MAX_VALUE} if it is too large, or {@link Character#MIN_VALUE} if it is too
    *     small
    */
   public static char saturatedCast(long value) {
     if (value > Character.MAX_VALUE) {
       return Character.MAX_VALUE;
     }
     if (value < Character.MIN_VALUE) {
       return Character.MIN_VALUE;
     }
     return (char) value;
   }

   /**
    * Compares the two specified {@code char} values. The sign of the value returned is the same as
    * that of {@code ((Character) a).compareTo(b)}.
    *
    * <p><b>Note for Java 7 and later:</b> this method should be treated as deprecated; use the
    * equivalent {@link Character#compare} method instead.
    *
    * @param a the first {@code char} to compare
    * @param b the second {@code char} to compare
    * @return a negative value if {@code a} is less than {@code b}; a positive value if {@code a} is
    *     greater than {@code b}; or zero if they are equal
    */
   public static int compare(char a, char b) {
     return a - b; // safe due to restricted range
   }

   /**
    * Returns {@code true} if {@code target} is present as an element anywhere in {@code array}.
    *
    * @param array an array of {@code char} values, possibly empty
    * @param target a primitive {@code char} value
    * @return {@code true} if {@code array[i] == target} for some value of {@code i}
    */
   public static boolean contains(char[] array, char target) {
     for (char value : array) {
       if (value == target) {
         return true;
       }
     }
     return false;
   }

   /**
    * Returns the index of the first appearance of the value {@code target} in {@code array}.
    *
    * @param array an array of {@code char} values, possibly empty
    * @param target a primitive {@code char} value
    * @return the least index {@code i} for which {@code array[i] == target}, or {@code -1} if no
    *     such index exists.
    */
   public static int indexOf(char[] array, char target) {
     return indexOf(array, target, 0, array.length);
   }

   // TODO(kevinb): consider making this public
   private static int indexOf(char[] array, char target, int start, int end) {
     for (int i = start; i < end; i++) {
       if (array[i] == target) {
         return i;
       }
     }
     return -1;
   }

   /**
    * Returns the start position of the first occurrence of the specified {@code target} within
    * {@code array}, or {@code -1} if there is no such occurrence.
    *
    * <p>More formally, returns the lowest index {@code i} such that {@code Arrays.copyOfRange(array,
    * i, i + target.length)} contains exactly the same elements as {@code target}.
    *
    * @param array the array to search for the sequence {@code target}
    * @param target the array to search for as a sub-sequence of {@code array}
    */
   public static int indexOf(char[] array, char[] target) {
     checkNotNull(array, "array");
     checkNotNull(target, "target");
     if (target.length == 0) {
       return 0;
     }

     outer:
     for (int i = 0; i < array.length - target.length + 1; i++) {
       for (int j = 0; j < target.length; j++) {
         if (array[i + j] != target[j]) {
           continue outer;
         }
       }
       return i;
     }
     return -1;
   }

   /**
    * Returns the index of the last appearance of the value {@code target} in {@code array}.
    *
    * @param array an array of {@code char} values, possibly empty
    * @param target a primitive {@code char} value
    * @return the greatest index {@code i} for which {@code array[i] == target}, or {@code -1} if no
    *     such index exists.
    */
   public static int lastIndexOf(char[] array, char target) {
     return lastIndexOf(array, target, 0, array.length);
   }

   // TODO(kevinb): consider making this public
   private static int lastIndexOf(char[] array, char target, int start, int end) {
     for (int i = end - 1; i >= start; i--) {
       if (array[i] == target) {
         return i;
       }
     }
     return -1;
   }

   /**
    * Returns the least value present in {@code array}.
    *
    * @param array a <i>nonempty</i> array of {@code char} values
    * @return the value present in {@code array} that is less than or equal to every other value in
    *     the array
    * @throws IllegalArgumentException if {@code array} is empty
    */
   public static char min(char... array) {
     checkArgument(array.length > 0);
     char min = array[0];
     for (int i = 1; i < array.length; i++) {
       if (array[i] < min) {
         min = array[i];
       }
     }
     return min;
   }

   /**
    * Returns the greatest value present in {@code array}.
    *
    * @param array a <i>nonempty</i> array of {@code char} values
    * @return the value present in {@code array} that is greater than or equal to every other value
    *     in the array
    * @throws IllegalArgumentException if {@code array} is empty
    */
   public static char max(char... array) {
     checkArgument(array.length > 0);
     char max = array[0];
     for (int i = 1; i < array.length; i++) {
       if (array[i] > max) {
         max = array[i];
       }
     }
     return max;
   }

   /**
    * Returns the value nearest to {@code value} which is within the closed range {@code [min..max]}.
    *
    * <p>If {@code value} is within the range {@code [min..max]}, {@code value} is returned
    * unchanged. If {@code value} is less than {@code min}, {@code min} is returned, and if {@code
    * value} is greater than {@code max}, {@code max} is returned.
    *
    * @param value the {@code char} value to constrain
    * @param min the lower bound (inclusive) of the range to constrain {@code value} to
    * @param max the upper bound (inclusive) of the range to constrain {@code value} to
    * @throws IllegalArgumentException if {@code min > max}
    * @since 21.0
    */
   @Beta
   public static char constrainToRange(char value, char min, char max) {
     checkArgument(min <= max, "min (%s) must be less than or equal to max (%s)", min, max);
     return value < min ? min : value < max ? value : max;
   }

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

   /**
    * Returns a big-endian representation of {@code value} in a 2-element byte array; equivalent to
    * {@code ByteBuffer.allocate(2).putChar(value).array()}. For example, the input value {@code
    * '\\u5432'} would yield the byte array {@code {0x54, 0x32}}.
    *
    * <p>If you need to convert and concatenate several values (possibly even of different types),
    * use a shared {@link java.nio.ByteBuffer} instance, or use {@link
    * com.google.common.io.ByteStreams#newDataOutput()} to get a growable buffer.
    */
   @GwtIncompatible // doesn't work
   public static byte[] toByteArray(char value) {
     return new byte[] {(byte) (value >> 8), (byte) value};
   }

   /**
    * Returns the {@code char} value whose big-endian representation is stored in the first 2 bytes
    * of {@code bytes}; equivalent to {@code ByteBuffer.wrap(bytes).getChar()}. For example, the
    * input byte array {@code {0x54, 0x32}} would yield the {@code char} value {@code '\\u5432'}.
    *
    * <p>Arguably, it's preferable to use {@link java.nio.ByteBuffer}; that library exposes much more
    * flexibility at little cost in readability.
    *
    * @throws IllegalArgumentException if {@code bytes} has fewer than 2 elements
    */
   @GwtIncompatible // doesn't work
   public static char fromByteArray(byte[] bytes) {
     checkArgument(bytes.length >= BYTES, "array too small: %s < %s", bytes.length, BYTES);
     return fromBytes(bytes[0], bytes[1]);
   }

   /**
    * Returns the {@code char} value whose byte representation is the given 2 bytes, in big-endian
    * order; equivalent to {@code Chars.fromByteArray(new byte[] {b1, b2})}.
    *
    * @since 7.0
    */
   @GwtIncompatible // doesn't work
   public static char fromBytes(byte b1, byte b2) {
     return (char) ((b1 << 8) | (b2 & 0xFF));
   }

   /**
    * Returns an array containing the same values as {@code array}, but guaranteed to be of a
    * specified minimum length. If {@code array} already has a length of at least {@code minLength},
    * it is returned directly. Otherwise, a new array of size {@code minLength + padding} is
    * returned, containing the values of {@code array}, and zeroes in the remaining places.
    *
    * @param array the source array
    * @param minLength the minimum length the returned array must guarantee
    * @param padding an extra amount to "grow" the array by if growth is necessary
    * @throws IllegalArgumentException if {@code minLength} or {@code padding} is negative
    * @return an array containing the values of {@code array}, with guaranteed minimum length {@code
    *     minLength}
    */
   public static char[] ensureCapacity(char[] array, int minLength, int padding) {
     checkArgument(minLength >= 0, "Invalid minLength: %s", minLength);
     checkArgument(padding >= 0, "Invalid padding: %s", padding);
     return (array.length < minLength) ? Arrays.copyOf(array, minLength + padding) : array;
   }

   /**
    * Returns a string containing the supplied {@code char} 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 char} values, possibly empty
    */
   public static String join(String separator, char... array) {
     checkNotNull(separator);
     int len = array.length;
     if (len == 0) {
       return "";
     }

     StringBuilder builder = new StringBuilder(len + separator.length() * (len - 1));
     builder.append(array[0]);
     for (int i = 1; i < len; i++) {
       builder.append(separator).append(array[i]);
     }
     return builder.toString();
   }

   /**
    * Returns a comparator that compares two {@code char} arrays <a
    * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>; not advisable
    * for sorting user-visible strings as the ordering may not match the conventions of the user's
    * locale. That is, it compares, using {@link #compare(char, char)}), the first pair of values
    * that follow any common prefix, or when one array is a prefix of the other, treats the shorter
    * array as the lesser. For example, {@code [] < ['a'] < ['a', 'b'] < ['b']}.
    *
    * <p>The returned comparator is inconsistent with {@link Object#equals(Object)} (since arrays
    * support only identity equality), but it is consistent with {@link Arrays#equals(char[],
    * char[])}.
    *
    * @since 2.0
    */
   public static Comparator<char[]> lexicographicalComparator() {
     return LexicographicalComparator.INSTANCE;
   }

   private enum LexicographicalComparator implements Comparator<char[]> {
     INSTANCE;

     @Override
     public int compare(char[] left, char[] right) {
       int minLength = Math.min(left.length, right.length);
       for (int i = 0; i < minLength; i++) {
         int result = Chars.compare(left[i], right[i]);
         if (result != 0) {
           return result;
         }
       }
       return left.length - right.length;
     }

     @Override
     public String toString() {
       return "Chars.lexicographicalComparator()";
     }
   }

   /**
    * Copies a collection of {@code Character} instances into a new array of primitive {@code char}
    * values.
    *
    * <p>Elements are copied from the argument collection as if by {@code collection.toArray()}.
    * Calling this method is as thread-safe as calling that method.
    *
    * @param collection a collection of {@code Character} objects
    * @return an array containing the same values as {@code collection}, in the same order, converted
    *     to primitives
    * @throws NullPointerException if {@code collection} or any of its elements is null
    */
   public static char[] toArray(Collection<Character> collection) {
     if (collection instanceof CharArrayAsList) {
       return ((CharArrayAsList) collection).toCharArray();
     }

     Object[] boxedArray = collection.toArray();
     int len = boxedArray.length;
     char[] array = new char[len];
     for (int i = 0; i < len; i++) {
       // checkNotNull for GWT (do not optimize)
       array[i] = (Character) checkNotNull(boxedArray[i]);
     }
     return array;
   }

   /**
    * Sorts the elements of {@code array} in descending order.
    *
    * @since 23.1
    */
   public static void sortDescending(char[] array) {
     checkNotNull(array);
     sortDescending(array, 0, array.length);
   }

   /**
    * Sorts the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex}
    * exclusive in descending order.
    *
    * @since 23.1
    */
   public static void sortDescending(char[] array, int fromIndex, int toIndex) {
     checkNotNull(array);
     checkPositionIndexes(fromIndex, toIndex, array.length);
     Arrays.sort(array, fromIndex, toIndex);
     reverse(array, fromIndex, toIndex);
   }

   /**
    * Reverses the elements of {@code array}. This is equivalent to {@code
    * Collections.reverse(Chars.asList(array))}, but is likely to be more efficient.
    *
    * @since 23.1
    */
   public static void reverse(char[] array) {
     checkNotNull(array);
     reverse(array, 0, array.length);
   }

   /**
    * Reverses the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex}
    * exclusive. This is equivalent to {@code
    * Collections.reverse(Chars.asList(array).subList(fromIndex, toIndex))}, but is likely to be more
    * efficient.
    *
    * @throws IndexOutOfBoundsException if {@code fromIndex < 0}, {@code toIndex > array.length}, or
    *     {@code toIndex > fromIndex}
    * @since 23.1
    */
   public static void reverse(char[] array, int fromIndex, int toIndex) {
     checkNotNull(array);
     checkPositionIndexes(fromIndex, toIndex, array.length);
     for (int i = fromIndex, j = toIndex - 1; i < j; i++, j--) {
       char tmp = array[i];
       array[i] = array[j];
       array[j] = tmp;
     }
   }

   /**
    * Returns a fixed-size list backed by the specified array, similar to {@link
    * Arrays#asList(Object[])}. The list supports {@link List#set(int, Object)}, but any attempt to
    * set a value to {@code null} will result in a {@link NullPointerException}.
    *
    * <p>The returned list maintains the values, but not the identities, of {@code Character} objects
    * written to or read from it. For example, whether {@code list.get(0) == list.get(0)} is true for
    * the returned list is unspecified.
    *
    * @param backingArray the array to back the list
    * @return a list view of the array
    */
   public static List<Character> asList(char... backingArray) {
     if (backingArray.length == 0) {
       return Collections.emptyList();
     }
     return new CharArrayAsList(backingArray);
   }

   @GwtCompatible
   private static class CharArrayAsList extends AbstractList<Character>
       implements RandomAccess, Serializable {
     final char[] array;
     final int start;
     final int end;

     CharArrayAsList(char[] array) {
       this(array, 0, array.length);
     }

     CharArrayAsList(char[] array, int start, int end) {
       this.array = array;
       this.start = start;
       this.end = end;
     }

     @Override
     public int size() {
       return end - start;
     }

     @Override
     public boolean isEmpty() {
       return false;
     }

     @Override
     public Character get(int index) {
       checkElementIndex(index, size());
       return array[start + index];
     }

     @Override
     public boolean contains(Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Character)
           && Chars.indexOf(array, (Character) target, start, end) != -1;
     }

     @Override
     public int indexOf(Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Character) {
         int i = Chars.indexOf(array, (Character) target, start, end);
         if (i >= 0) {
           return i - start;
         }
       }
       return -1;
     }

     @Override
     public int lastIndexOf(Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Character) {
         int i = Chars.lastIndexOf(array, (Character) target, start, end);
         if (i >= 0) {
           return i - start;
         }
       }
       return -1;
     }

     @Override
     public Character set(int index, Character element) {
       checkElementIndex(index, size());
       char oldValue = array[start + index];
       // checkNotNull for GWT (do not optimize)
       array[start + index] = checkNotNull(element);
       return oldValue;
     }

     @Override
     public List<Character> subList(int fromIndex, int toIndex) {
       int size = size();
       checkPositionIndexes(fromIndex, toIndex, size);
       if (fromIndex == toIndex) {
         return Collections.emptyList();
       }
       return new CharArrayAsList(array, start + fromIndex, start + toIndex);
     }

     @Override
     public boolean equals(@Nullable Object object) {
       if (object == this) {
         return true;
       }
       if (object instanceof CharArrayAsList) {
         CharArrayAsList that = (CharArrayAsList) object;
         int size = size();
         if (that.size() != size) {
           return false;
         }
         for (int i = 0; i < size; i++) {
           if (array[start + i] != that.array[that.start + i]) {
             return false;
           }
         }
         return true;
       }
       return super.equals(object);
     }

     @Override
     public int hashCode() {
       int result = 1;
       for (int i = start; i < end; i++) {
         result = 31 * result + Chars.hashCode(array[i]);
       }
       return result;
     }

     @Override
     public String toString() {
       StringBuilder builder = new StringBuilder(size() * 3);
       builder.append('[').append(array[start]);
       for (int i = start + 1; i < end; i++) {
         builder.append(", ").append(array[i]);
       }
       return builder.append(']').toString();
     }

     char[] toCharArray() {
       return Arrays.copyOfRange(array, start, end);
     }

     private static final long serialVersionUID = 0;
   }
 }
	/*
	* 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.
	*/

	package com.google.common.primitives;

	import static com.google.common.base.Preconditions.checkArgument;
	import static com.google.common.base.Preconditions.checkElementIndex;
	import static com.google.common.base.Preconditions.checkNotNull;
	import static com.google.common.base.Preconditions.checkPositionIndexes;

	import com.google.common.annotations.Beta;
	import com.google.common.annotations.GwtCompatible;
	import com.google.common.annotations.GwtIncompatible;
	import java.io.Serializable;
	import java.util.AbstractList;
	import java.util.Arrays;
	import java.util.Collection;
	import java.util.Collections;
	import java.util.Comparator;
	import java.util.List;
	import java.util.RandomAccess;
	import org.checkerframework.checker.nullness.qual.Nullable;

	/**
	* Static utility methods pertaining to {@code char} primitives, that are not already found in
	* either {@link Character} or {@link Arrays}.
	*
	* <p>All the operations in this class treat {@code char} values strictly numerically; they are
	* neither Unicode-aware nor locale-dependent.
	*
	* <p>See the Guava User Guide article on <a
	* href="https://github.com/google/guava/wiki/PrimitivesExplained">primitive utilities</a>.
	*
	* @author Kevin Bourrillion
	* @since 1.0
	*/
	@GwtCompatible(emulated = true)
	public final class Chars {
	private Chars() {}

	/**
	* The number of bytes required to represent a primitive {@code char} value.
	*
	* <p><b>Java 8 users:</b> use {@link Character#BYTES} instead.
	*/
	public static final int BYTES = Character.SIZE / Byte.SIZE;

	/**
	* Returns a hash code for {@code value}; equal to the result of invoking {@code ((Character)
	* value).hashCode()}.
	*
	* <p><b>Java 8 users:</b> use {@link Character#hashCode(char)} instead.
	*
	* @param value a primitive {@code char} value
	* @return a hash code for the value
	*/
	public static int hashCode(char value) {
	return value;
	}

	/**
	* Returns the {@code char} value that is equal to {@code value}, if possible.
	*
	* @param value any value in the range of the {@code char} type
	* @return the {@code char} value that equals {@code value}
	* @throws IllegalArgumentException if {@code value} is greater than {@link Character#MAX_VALUE}
	* or less than {@link Character#MIN_VALUE}
	*/
	public static char checkedCast(long value) {
	char result = (char) value;
	checkArgument(result == value, "Out of range: %s", value);
	return result;
	}

	/**
	* Returns the {@code char} nearest in value to {@code value}.
	*
	* @param value any {@code long} value
	* @return the same value cast to {@code char} if it is in the range of the {@code char} type,
	* {@link Character#MAX_VALUE} if it is too large, or {@link Character#MIN_VALUE} if it is too
	* small
	*/
	public static char saturatedCast(long value) {
	if (value > Character.MAX_VALUE) {
	return Character.MAX_VALUE;
	}
	if (value < Character.MIN_VALUE) {
	return Character.MIN_VALUE;
	}
	return (char) value;
	}

	/**
	* Compares the two specified {@code char} values. The sign of the value returned is the same as
	* that of {@code ((Character) a).compareTo(b)}.
	*
	* <p><b>Note for Java 7 and later:</b> this method should be treated as deprecated; use the
	* equivalent {@link Character#compare} method instead.
	*
	* @param a the first {@code char} to compare
	* @param b the second {@code char} to compare
	* @return a negative value if {@code a} is less than {@code b}; a positive value if {@code a} is
	* greater than {@code b}; or zero if they are equal
	*/
	public static int compare(char a, char b) {
	return a - b; // safe due to restricted range
	}

	/**
	* Returns {@code true} if {@code target} is present as an element anywhere in {@code array}.
	*
	* @param array an array of {@code char} values, possibly empty
	* @param target a primitive {@code char} value
	* @return {@code true} if {@code array[i] == target} for some value of {@code i}
	*/
	public static boolean contains(char[] array, char target) {
	for (char value : array) {
	if (value == target) {
	return true;
	}
	}
	return false;
	}

	/**
	* Returns the index of the first appearance of the value {@code target} in {@code array}.
	*
	* @param array an array of {@code char} values, possibly empty
	* @param target a primitive {@code char} value
	* @return the least index {@code i} for which {@code array[i] == target}, or {@code -1} if no
	* such index exists.
	*/
	public static int indexOf(char[] array, char target) {
	return indexOf(array, target, 0, array.length);
	}

	// TODO(kevinb): consider making this public
	private static int indexOf(char[] array, char target, int start, int end) {
	for (int i = start; i < end; i++) {
	if (array[i] == target) {
	return i;
	}
	}
	return -1;
	}

	/**
	* Returns the start position of the first occurrence of the specified {@code target} within
	* {@code array}, or {@code -1} if there is no such occurrence.
	*
	* <p>More formally, returns the lowest index {@code i} such that {@code Arrays.copyOfRange(array,
	* i, i + target.length)} contains exactly the same elements as {@code target}.
	*
	* @param array the array to search for the sequence {@code target}
	* @param target the array to search for as a sub-sequence of {@code array}
	*/
	public static int indexOf(char[] array, char[] target) {
	checkNotNull(array, "array");
	checkNotNull(target, "target");
	if (target.length == 0) {
	return 0;
	}

	outer:
	for (int i = 0; i < array.length - target.length + 1; i++) {
	for (int j = 0; j < target.length; j++) {
	if (array[i + j] != target[j]) {
	continue outer;
	}
	}
	return i;
	}
	return -1;
	}

	/**
	* Returns the index of the last appearance of the value {@code target} in {@code array}.
	*
	* @param array an array of {@code char} values, possibly empty
	* @param target a primitive {@code char} value
	* @return the greatest index {@code i} for which {@code array[i] == target}, or {@code -1} if no
	* such index exists.
	*/
	public static int lastIndexOf(char[] array, char target) {
	return lastIndexOf(array, target, 0, array.length);
	}

	// TODO(kevinb): consider making this public
	private static int lastIndexOf(char[] array, char target, int start, int end) {
	for (int i = end - 1; i >= start; i--) {
	if (array[i] == target) {
	return i;
	}
	}
	return -1;
	}

	/**
	* Returns the least value present in {@code array}.
	*
	* @param array a <i>nonempty</i> array of {@code char} values
	* @return the value present in {@code array} that is less than or equal to every other value in
	* the array
	* @throws IllegalArgumentException if {@code array} is empty
	*/
	public static char min(char... array) {
	checkArgument(array.length > 0);
	char min = array[0];
	for (int i = 1; i < array.length; i++) {
	if (array[i] < min) {
	min = array[i];
	}
	}
	return min;
	}

	/**
	* Returns the greatest value present in {@code array}.
	*
	* @param array a <i>nonempty</i> array of {@code char} values
	* @return the value present in {@code array} that is greater than or equal to every other value
	* in the array
	* @throws IllegalArgumentException if {@code array} is empty
	*/
	public static char max(char... array) {
	checkArgument(array.length > 0);
	char max = array[0];
	for (int i = 1; i < array.length; i++) {
	if (array[i] > max) {
	max = array[i];
	}
	}
	return max;
	}

	/**
	* Returns the value nearest to {@code value} which is within the closed range {@code [min..max]}.
	*
	* <p>If {@code value} is within the range {@code [min..max]}, {@code value} is returned
	* unchanged. If {@code value} is less than {@code min}, {@code min} is returned, and if {@code
	* value} is greater than {@code max}, {@code max} is returned.
	*
	* @param value the {@code char} value to constrain
	* @param min the lower bound (inclusive) of the range to constrain {@code value} to
	* @param max the upper bound (inclusive) of the range to constrain {@code value} to
	* @throws IllegalArgumentException if {@code min > max}
	* @since 21.0
	*/
	@Beta
	public static char constrainToRange(char value, char min, char max) {
	checkArgument(min <= max, "min (%s) must be less than or equal to max (%s)", min, max);
	return value < min ? min : value < max ? value : max;
	}

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

	/**
	* Returns a big-endian representation of {@code value} in a 2-element byte array; equivalent to
	* {@code ByteBuffer.allocate(2).putChar(value).array()}. For example, the input value {@code
	* '\\u5432'} would yield the byte array {@code {0x54, 0x32}}.
	*
	* <p>If you need to convert and concatenate several values (possibly even of different types),
	* use a shared {@link java.nio.ByteBuffer} instance, or use {@link
	* com.google.common.io.ByteStreams#newDataOutput()} to get a growable buffer.
	*/
	@GwtIncompatible // doesn't work
	public static byte[] toByteArray(char value) {
	return new byte[] {(byte) (value >> 8), (byte) value};
	}

	/**
	* Returns the {@code char} value whose big-endian representation is stored in the first 2 bytes
	* of {@code bytes}; equivalent to {@code ByteBuffer.wrap(bytes).getChar()}. For example, the
	* input byte array {@code {0x54, 0x32}} would yield the {@code char} value {@code '\\u5432'}.
	*
	* <p>Arguably, it's preferable to use {@link java.nio.ByteBuffer}; that library exposes much more
	* flexibility at little cost in readability.
	*
	* @throws IllegalArgumentException if {@code bytes} has fewer than 2 elements
	*/
	@GwtIncompatible // doesn't work
	public static char fromByteArray(byte[] bytes) {
	checkArgument(bytes.length >= BYTES, "array too small: %s < %s", bytes.length, BYTES);
	return fromBytes(bytes[0], bytes[1]);
	}

	/**
	* Returns the {@code char} value whose byte representation is the given 2 bytes, in big-endian
	* order; equivalent to {@code Chars.fromByteArray(new byte[] {b1, b2})}.
	*
	* @since 7.0
	*/
	@GwtIncompatible // doesn't work
	public static char fromBytes(byte b1, byte b2) {
	return (char) ((b1 << 8) \| (b2 & 0xFF));
	}

	/**
	* Returns an array containing the same values as {@code array}, but guaranteed to be of a
	* specified minimum length. If {@code array} already has a length of at least {@code minLength},
	* it is returned directly. Otherwise, a new array of size {@code minLength + padding} is
	* returned, containing the values of {@code array}, and zeroes in the remaining places.
	*
	* @param array the source array
	* @param minLength the minimum length the returned array must guarantee
	* @param padding an extra amount to "grow" the array by if growth is necessary
	* @throws IllegalArgumentException if {@code minLength} or {@code padding} is negative
	* @return an array containing the values of {@code array}, with guaranteed minimum length {@code
	* minLength}
	*/
	public static char[] ensureCapacity(char[] array, int minLength, int padding) {
	checkArgument(minLength >= 0, "Invalid minLength: %s", minLength);
	checkArgument(padding >= 0, "Invalid padding: %s", padding);
	return (array.length < minLength) ? Arrays.copyOf(array, minLength + padding) : array;
	}

	/**
	* Returns a string containing the supplied {@code char} 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 char} values, possibly empty
	*/
	public static String join(String separator, char... array) {
	checkNotNull(separator);
	int len = array.length;
	if (len == 0) {
	return "";
	}

	StringBuilder builder = new StringBuilder(len + separator.length() * (len - 1));
	builder.append(array[0]);
	for (int i = 1; i < len; i++) {
	builder.append(separator).append(array[i]);
	}
	return builder.toString();
	}

	/**
	* Returns a comparator that compares two {@code char} arrays <a
	* href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>; not advisable
	* for sorting user-visible strings as the ordering may not match the conventions of the user's
	* locale. That is, it compares, using {@link #compare(char, char)}), the first pair of values
	* that follow any common prefix, or when one array is a prefix of the other, treats the shorter
	* array as the lesser. For example, {@code [] < ['a'] < ['a', 'b'] < ['b']}.
	*
	* <p>The returned comparator is inconsistent with {@link Object#equals(Object)} (since arrays
	* support only identity equality), but it is consistent with {@link Arrays#equals(char[],
	* char[])}.
	*
	* @since 2.0
	*/
	public static Comparator<char[]> lexicographicalComparator() {
	return LexicographicalComparator.INSTANCE;
	}

	private enum LexicographicalComparator implements Comparator<char[]> {
	INSTANCE;

	@Override
	public int compare(char[] left, char[] right) {
	int minLength = Math.min(left.length, right.length);
	for (int i = 0; i < minLength; i++) {
	int result = Chars.compare(left[i], right[i]);
	if (result != 0) {
	return result;
	}
	}
	return left.length - right.length;
	}

	@Override
	public String toString() {
	return "Chars.lexicographicalComparator()";
	}
	}

	/**
	* Copies a collection of {@code Character} instances into a new array of primitive {@code char}
	* values.
	*
	* <p>Elements are copied from the argument collection as if by {@code collection.toArray()}.
	* Calling this method is as thread-safe as calling that method.
	*
	* @param collection a collection of {@code Character} objects
	* @return an array containing the same values as {@code collection}, in the same order, converted
	* to primitives
	* @throws NullPointerException if {@code collection} or any of its elements is null
	*/
	public static char[] toArray(Collection<Character> collection) {
	if (collection instanceof CharArrayAsList) {
	return ((CharArrayAsList) collection).toCharArray();
	}

	Object[] boxedArray = collection.toArray();
	int len = boxedArray.length;
	char[] array = new char[len];
	for (int i = 0; i < len; i++) {
	// checkNotNull for GWT (do not optimize)
	array[i] = (Character) checkNotNull(boxedArray[i]);
	}
	return array;
	}

	/**
	* Sorts the elements of {@code array} in descending order.
	*
	* @since 23.1
	*/
	public static void sortDescending(char[] array) {
	checkNotNull(array);
	sortDescending(array, 0, array.length);
	}

	/**
	* Sorts the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex}
	* exclusive in descending order.
	*
	* @since 23.1
	*/
	public static void sortDescending(char[] array, int fromIndex, int toIndex) {
	checkNotNull(array);
	checkPositionIndexes(fromIndex, toIndex, array.length);
	Arrays.sort(array, fromIndex, toIndex);
	reverse(array, fromIndex, toIndex);
	}

	/**
	* Reverses the elements of {@code array}. This is equivalent to {@code
	* Collections.reverse(Chars.asList(array))}, but is likely to be more efficient.
	*
	* @since 23.1
	*/
	public static void reverse(char[] array) {
	checkNotNull(array);
	reverse(array, 0, array.length);
	}

	/**
	* Reverses the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex}
	* exclusive. This is equivalent to {@code
	* Collections.reverse(Chars.asList(array).subList(fromIndex, toIndex))}, but is likely to be more
	* efficient.
	*
	* @throws IndexOutOfBoundsException if {@code fromIndex < 0}, {@code toIndex > array.length}, or
	* {@code toIndex > fromIndex}
	* @since 23.1
	*/
	public static void reverse(char[] array, int fromIndex, int toIndex) {
	checkNotNull(array);
	checkPositionIndexes(fromIndex, toIndex, array.length);
	for (int i = fromIndex, j = toIndex - 1; i < j; i++, j--) {
	char tmp = array[i];
	array[i] = array[j];
	array[j] = tmp;
	}
	}

	/**
	* Returns a fixed-size list backed by the specified array, similar to {@link
	* Arrays#asList(Object[])}. The list supports {@link List#set(int, Object)}, but any attempt to
	* set a value to {@code null} will result in a {@link NullPointerException}.
	*
	* <p>The returned list maintains the values, but not the identities, of {@code Character} objects
	* written to or read from it. For example, whether {@code list.get(0) == list.get(0)} is true for
	* the returned list is unspecified.
	*
	* @param backingArray the array to back the list
	* @return a list view of the array
	*/
	public static List<Character> asList(char... backingArray) {
	if (backingArray.length == 0) {
	return Collections.emptyList();
	}
	return new CharArrayAsList(backingArray);
	}

	@GwtCompatible
	private static class CharArrayAsList extends AbstractList<Character>
	implements RandomAccess, Serializable {
	final char[] array;
	final int start;
	final int end;

	CharArrayAsList(char[] array) {
	this(array, 0, array.length);
	}

	CharArrayAsList(char[] array, int start, int end) {
	this.array = array;
	this.start = start;
	this.end = end;
	}

	@Override
	public int size() {
	return end - start;
	}

	@Override
	public boolean isEmpty() {
	return false;
	}

	@Override
	public Character get(int index) {
	checkElementIndex(index, size());
	return array[start + index];
	}

	@Override
	public boolean contains(Object target) {
	// Overridden to prevent a ton of boxing
	return (target instanceof Character)
	&& Chars.indexOf(array, (Character) target, start, end) != -1;
	}

	@Override
	public int indexOf(Object target) {
	// Overridden to prevent a ton of boxing
	if (target instanceof Character) {
	int i = Chars.indexOf(array, (Character) target, start, end);
	if (i >= 0) {
	return i - start;
	}
	}
	return -1;
	}

	@Override
	public int lastIndexOf(Object target) {
	// Overridden to prevent a ton of boxing
	if (target instanceof Character) {
	int i = Chars.lastIndexOf(array, (Character) target, start, end);
	if (i >= 0) {
	return i - start;
	}
	}
	return -1;
	}

	@Override
	public Character set(int index, Character element) {
	checkElementIndex(index, size());
	char oldValue = array[start + index];
	// checkNotNull for GWT (do not optimize)
	array[start + index] = checkNotNull(element);
	return oldValue;
	}

	@Override
	public List<Character> subList(int fromIndex, int toIndex) {
	int size = size();
	checkPositionIndexes(fromIndex, toIndex, size);
	if (fromIndex == toIndex) {
	return Collections.emptyList();
	}
	return new CharArrayAsList(array, start + fromIndex, start + toIndex);
	}

	@Override
	public boolean equals(@Nullable Object object) {
	if (object == this) {
	return true;
	}
	if (object instanceof CharArrayAsList) {
	CharArrayAsList that = (CharArrayAsList) object;
	int size = size();
	if (that.size() != size) {
	return false;
	}
	for (int i = 0; i < size; i++) {
	if (array[start + i] != that.array[that.start + i]) {
	return false;
	}
	}
	return true;
	}
	return super.equals(object);
	}

	@Override
	public int hashCode() {
	int result = 1;
	for (int i = start; i < end; i++) {
	result = 31 * result + Chars.hashCode(array[i]);
	}
	return result;
	}

	@Override
	public String toString() {
	StringBuilder builder = new StringBuilder(size() * 3);
	builder.append('[').append(array[start]);
	for (int i = start + 1; i < end; i++) {
	builder.append(", ").append(array[i]);
	}
	return builder.append(']').toString();
	}

	char[] toCharArray() {
	return Arrays.copyOfRange(array, start, end);
	}

	private static final long serialVersionUID = 0;
	}
	}