| /* |
| * Copyright (c) 2000, 2020, 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.Objects; |
| 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 {@code CharSequence} is a readable sequence of {@code char} values. This |
| * interface provides uniform, read-only access to many different kinds of |
| * {@code char} sequences. |
| * A {@code char} 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 testing two objects |
| * that implement {@code CharSequence} for equality 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 {@code CharSequence} instances as elements in a set or as keys in |
| * a map. </p> |
| * |
| * @author Mike McCloskey |
| * @since 1.4 |
| */ |
| |
| public interface CharSequence { |
| |
| /** |
| * Returns the length of this character sequence. The length is the number |
| * of 16-bit {@code char}s in the sequence. |
| * |
| * @return the number of {@code char}s in this sequence |
| */ |
| int length(); |
| |
| /** |
| * Returns the {@code char} value at the specified index. An index ranges from zero |
| * to {@code length() - 1}. The first {@code char} 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} value specified by the index is a |
| * <a href="{@docRoot}/java.base/java/lang/Character.html#unicode">surrogate</a>, the surrogate |
| * value is returned. |
| * |
| * @param index the index of the {@code char} value to be returned |
| * |
| * @return the specified {@code char} value |
| * |
| * @throws IndexOutOfBoundsException |
| * if the {@code index} argument is negative or not less than |
| * {@code length()} |
| */ |
| char charAt(int index); |
| |
| /** |
| * Returns {@code true} if this character sequence is empty. |
| * |
| * @implSpec |
| * The default implementation returns the result of calling {@code length() == 0}. |
| * |
| * @return {@code true} if {@link #length()} is {@code 0}, otherwise |
| * {@code false} |
| * |
| * @since 15 |
| */ |
| default boolean isEmpty() { |
| return this.length() == 0; |
| } |
| |
| /** |
| * Returns a {@code CharSequence} that is a subsequence of this sequence. |
| * The subsequence starts with the {@code char} value at the specified index and |
| * ends with the {@code char} value at index {@code end - 1}. The length |
| * (in {@code char}s) of the |
| * returned sequence is {@code end - start}, so if {@code 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 {@code start} or {@code end} are negative, |
| * if {@code end} is greater than {@code length()}, |
| * or if {@code start} is greater than {@code 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 <a |
| * href="{@docRoot}/java.base/java/lang/Character.html#unicode">surrogate code |
| * point</a> is passed through uninterpreted. |
| * |
| * <p>The stream binds to this sequence when the terminal stream operation |
| * commences (specifically, for mutable sequences the spliterator for the |
| * stream is <a href="../util/Spliterator.html#binding"><em>late-binding</em></a>). |
| * If the sequence is modified during that operation then 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. |
| * |
| * <p>The stream binds to this sequence when the terminal stream operation |
| * commences (specifically, for mutable sequences the spliterator for the |
| * stream is <a href="../util/Spliterator.html#binding"><em>late-binding</em></a>). |
| * If the sequence is modified during that operation then 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); |
| } |
| |
| /** |
| * Compares two {@code CharSequence} instances lexicographically. Returns a |
| * negative value, zero, or a positive value if the first sequence is lexicographically |
| * less than, equal to, or greater than the second, respectively. |
| * |
| * <p> |
| * The lexicographical ordering of {@code CharSequence} is defined as follows. |
| * Consider a {@code CharSequence} <i>cs</i> of length <i>len</i> to be a |
| * sequence of char values, <i>cs[0]</i> to <i>cs[len-1]</i>. Suppose <i>k</i> |
| * is the lowest index at which the corresponding char values from each sequence |
| * differ. The lexicographic ordering of the sequences is determined by a numeric |
| * comparison of the char values <i>cs1[k]</i> with <i>cs2[k]</i>. If there is |
| * no such index <i>k</i>, the shorter sequence is considered lexicographically |
| * less than the other. If the sequences have the same length, the sequences are |
| * considered lexicographically equal. |
| * |
| * |
| * @param cs1 the first {@code CharSequence} |
| * @param cs2 the second {@code CharSequence} |
| * |
| * @return the value {@code 0} if the two {@code CharSequence} are equal; |
| * a negative integer if the first {@code CharSequence} |
| * is lexicographically less than the second; or a |
| * positive integer if the first {@code CharSequence} is |
| * lexicographically greater than the second. |
| * |
| * @since 11 |
| */ |
| @SuppressWarnings("unchecked") |
| public static int compare(CharSequence cs1, CharSequence cs2) { |
| if (Objects.requireNonNull(cs1) == Objects.requireNonNull(cs2)) { |
| return 0; |
| } |
| |
| if (cs1.getClass() == cs2.getClass() && cs1 instanceof Comparable) { |
| return ((Comparable<Object>) cs1).compareTo(cs2); |
| } |
| |
| for (int i = 0, len = Math.min(cs1.length(), cs2.length()); i < len; i++) { |
| char a = cs1.charAt(i); |
| char b = cs2.charAt(i); |
| if (a != b) { |
| return a - b; |
| } |
| } |
| |
| return cs1.length() - cs2.length(); |
| } |
| |
| } |
