/*
* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code 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 General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
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 equals and 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
/**
* A <tt>CharSequence</tt> is a readable sequence of <code>char</code> values. This
* interface provides uniform, read-only access to many different kinds of
* <code>char</code> sequences.
* A <code>char</code> value represents a character in the <i>Basic
* Multilingual Plane (BMP)</i> or a surrogate. Refer to <a
* href="Character.html#unicode">Unicode Character Representation</a> for details.
*
* <p> 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 <tt>CharSequence</tt> 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 <tt>CharSequence</tt> instances as elements in a set or as keys in
* a map. </p>
*
* @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-bit chars in the sequence.
Returns: the number of chars in this sequence
/**
* Returns the length of this character sequence. The length is the number
* of 16-bit <code>char</code>s in the sequence.
*
* @return the number of <code>char</code>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.
Params: - index – the index of the
char value to be returned
Throws: - IndexOutOfBoundsException –
if the index argument is negative or not less than
length()
Returns: the specified char value
/**
* Returns the <code>char</code> value at the specified index. An index ranges from zero
* to <tt>length() - 1</tt>. The first <code>char</code> value of the sequence is at
* index zero, the next at index one, and so on, as for array
* indexing.
*
* <p>If the <code>char</code> value specified by the index is a
* <a href="{@docRoot}/java/lang/Character.html#unicode">surrogate</a>, the surrogate
* value is returned.
*
* @param index the index of the <code>char</code> value to be returned
*
* @return the specified <code>char</code> value
*
* @throws IndexOutOfBoundsException
* if the <tt>index</tt> argument is negative or not less than
* <tt>length()</tt>
*/
char charAt(int index);
Returns a 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 chars) of the
returned sequence is end - start, so if start == end
then an empty sequence is returned.
Params: - start – the start index, inclusive
- end – the end index, exclusive
Throws: - IndexOutOfBoundsException –
if start or end are negative,
if end is greater than length(),
or if start is greater than end
Returns: the specified subsequence
/**
* Returns a <code>CharSequence</code> that is a subsequence of this sequence.
* The subsequence starts with the <code>char</code> value at the specified index and
* ends with the <code>char</code> value at index <tt>end - 1</tt>. The length
* (in <code>char</code>s) of the
* returned sequence is <tt>end - start</tt>, so if <tt>start == end</tt>
* 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 <tt>start</tt> or <tt>end</tt> are negative,
* if <tt>end</tt> is greater than <tt>length()</tt>,
* or if <tt>start</tt> is greater than <tt>end</tt>
*/
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.
Returns: a string consisting of exactly this sequence of characters
/**
* 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 int zero-extending the 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.
Returns: an IntStream of char values from this sequence Since: 1.8
/**
* Returns a stream of {@code int} zero-extending the {@code char} values
* from this sequence. Any char which maps to a <a
* href="{@docRoot}/java/lang/Character.html#unicode">surrogate code
* point</a> is passed through uninterpreted.
*
* <p>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 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 int values which are then passed to the stream. If the sequence is mutated while the stream is being read, the result
is undefined.
Returns: an IntStream of Unicode code points from this sequence Since: 1.8
/**
* 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.
*
* <p>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.ORDERED,
false);
}
}