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* published by the Free Software Foundation. Oracle designates this
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*
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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package java.lang;
import java.util.NoSuchElementException;
import java.util.PrimitiveIterator;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.function.IntConsumer;
import java.util.stream.IntStream;
import java.util.stream.StreamSupport;
/**
* A CharSequence is a readable sequence of char
values. This
* interface provides uniform, read-only access to many different kinds of
* char
sequences.
* A char
value represents a character in the Basic
* Multilingual Plane (BMP) or a surrogate. Refer to Unicode Character Representation for details.
*
*
This interface does not refine the general contracts of the {@link * java.lang.Object#equals(java.lang.Object) equals} and {@link * java.lang.Object#hashCode() hashCode} methods. The result of comparing two * objects that implement CharSequence is therefore, in general, * undefined. Each object may be implemented by a different class, and there * is no guarantee that each class will be capable of testing its instances * for equality with those of the other. It is therefore inappropriate to use * arbitrary CharSequence instances as elements in a set or as keys in * a map.
* * @author Mike McCloskey * @since 1.4 * @spec JSR-51 */ public interface CharSequence { /** * Returns the length of this character sequence. The length is the number * of 16-bitchar
s in the sequence.
*
* @return the number of char
s in this sequence
*/
int length();
/**
* Returns the char
value at the specified index. An index ranges from zero
* to length() - 1. The first char
value of the sequence is at
* index zero, the next at index one, and so on, as for array
* indexing.
*
* If the char
value specified by the index is a
* surrogate, the surrogate
* value is returned.
*
* @param index the index of the char
value to be returned
*
* @return the specified char
value
*
* @throws IndexOutOfBoundsException
* if the index argument is negative or not less than
* length()
*/
char charAt(int index);
/**
* Returns a new CharSequence
that is a subsequence of this sequence.
* The subsequence starts with the char
value at the specified index and
* ends with the char
value at index end - 1. The length
* (in char
s) of the
* returned sequence is end - start, so if start == end
* then an empty sequence is returned.
*
* @param start the start index, inclusive
* @param end the end index, exclusive
*
* @return the specified subsequence
*
* @throws IndexOutOfBoundsException
* if start or end are negative,
* if end is greater than length(),
* or if start is greater than end
*/
CharSequence subSequence(int start, int end);
/**
* Returns a string containing the characters in this sequence in the same
* order as this sequence. The length of the string will be the length of
* this sequence.
*
* @return a string consisting of exactly this sequence of characters
*/
public String toString();
/**
* Returns a stream of {@code int} zero-extending the {@code char} values
* from this sequence. Any char which maps to a surrogate code
* point is passed through uninterpreted.
*
*
If the sequence is mutated while the stream is being read, the * result is undefined. * * @return an IntStream of char values from this sequence * @since 1.8 */ public default IntStream chars() { class CharIterator implements PrimitiveIterator.OfInt { int cur = 0; public boolean hasNext() { return cur < length(); } public int nextInt() { if (hasNext()) { return charAt(cur++); } else { throw new NoSuchElementException(); } } @Override public void forEachRemaining(IntConsumer block) { for (; cur < length(); cur++) { block.accept(charAt(cur)); } } } return StreamSupport.intStream(() -> Spliterators.spliterator( new CharIterator(), length(), Spliterator.ORDERED), Spliterator.SUBSIZED | Spliterator.SIZED | Spliterator.ORDERED, false); } /** * Returns a stream of code point values from this sequence. Any surrogate * pairs encountered in the sequence are combined as if by {@linkplain * Character#toCodePoint Character.toCodePoint} and the result is passed * to the stream. Any other code units, including ordinary BMP characters, * unpaired surrogates, and undefined code units, are zero-extended to * {@code int} values which are then passed to the stream. * *
If the sequence is mutated while the stream is being read, the result * is undefined. * * @return an IntStream of Unicode code points from this sequence * @since 1.8 */ public default IntStream codePoints() { class CodePointIterator implements PrimitiveIterator.OfInt { int cur = 0; @Override public void forEachRemaining(IntConsumer block) { final int length = length(); int i = cur; try { while (i < length) { char c1 = charAt(i++); if (!Character.isHighSurrogate(c1) || i >= length) { block.accept(c1); } else { char c2 = charAt(i); if (Character.isLowSurrogate(c2)) { i++; block.accept(Character.toCodePoint(c1, c2)); } else { block.accept(c1); } } } } finally { cur = i; } } public boolean hasNext() { return cur < length(); } public int nextInt() { final int length = length(); if (cur >= length) { throw new NoSuchElementException(); } char c1 = charAt(cur++); if (Character.isHighSurrogate(c1) && cur < length) { char c2 = charAt(cur); if (Character.isLowSurrogate(c2)) { cur++; return Character.toCodePoint(c1, c2); } } return c1; } } return StreamSupport.intStream(() -> Spliterators.spliteratorUnknownSize( new CodePointIterator(), Spliterator.ORDERED), Spliterator.SUBSIZED | Spliterator.SIZED | Spliterator.ORDERED, false); } }