438 lines
20 KiB
Java
438 lines
20 KiB
Java
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/*
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* Copyright (C) 2014 The Android Open Source Project
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* Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/*
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* (C) Copyright IBM Corp. 1999-2003 - All Rights Reserved
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*
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* The original version of this source code and documentation is
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* copyrighted and owned by IBM. These materials are provided
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* under terms of a License Agreement between IBM and Sun.
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* This technology is protected by multiple US and International
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* patents. This notice and attribution to IBM may not be removed.
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*/
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package java.text;
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/**
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* This class implements the Unicode Bidirectional Algorithm.
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* <p>
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* A Bidi object provides information on the bidirectional reordering of the text
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* used to create it. This is required, for example, to properly display Arabic
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* or Hebrew text. These languages are inherently mixed directional, as they order
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* numbers from left-to-right while ordering most other text from right-to-left.
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* <p>
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* Once created, a Bidi object can be queried to see if the text it represents is
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* all left-to-right or all right-to-left. Such objects are very lightweight and
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* this text is relatively easy to process.
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* <p>
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* If there are multiple runs of text, information about the runs can be accessed
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* by indexing to get the start, limit, and level of a run. The level represents
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* both the direction and the 'nesting level' of a directional run. Odd levels
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* are right-to-left, while even levels are left-to-right. So for example level
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* 0 represents left-to-right text, while level 1 represents right-to-left text, and
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* level 2 represents left-to-right text embedded in a right-to-left run.
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*
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* @since 1.4
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*/
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public final class Bidi {
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/** Constant indicating base direction is left-to-right. */
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public static final int DIRECTION_LEFT_TO_RIGHT = 0;
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/** Constant indicating base direction is right-to-left. */
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public static final int DIRECTION_RIGHT_TO_LEFT = 1;
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/**
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* Constant indicating that the base direction depends on the first strong
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* directional character in the text according to the Unicode
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* Bidirectional Algorithm. If no strong directional character is present,
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* the base direction is left-to-right.
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*/
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public static final int DIRECTION_DEFAULT_LEFT_TO_RIGHT = -2;
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/**
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* Constant indicating that the base direction depends on the first strong
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* directional character in the text according to the Unicode
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* Bidirectional Algorithm. If no strong directional character is present,
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* the base direction is right-to-left.
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*/
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public static final int DIRECTION_DEFAULT_RIGHT_TO_LEFT = -1;
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// Android-note: Upstream this class delegates to an internal implementation class BidiBase.
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// For Android that is replaced with android.icu.text.Bidi. BidiBase and ICU Bidi work very
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// similarly, but differ in some details like level of argument validation and how how exactly
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// runs are counted. The majority of the changes in this file exist to allow for backwards
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// compatibility with an earlier ICU4C based Bidi implementation.
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// BEGIN Android-added: translateConstToIcu(int).
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private static int translateConstToIcu(int javaInt) {
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switch (javaInt) {
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case DIRECTION_DEFAULT_LEFT_TO_RIGHT:
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return android.icu.text.Bidi.DIRECTION_DEFAULT_LEFT_TO_RIGHT;
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case DIRECTION_DEFAULT_RIGHT_TO_LEFT:
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return android.icu.text.Bidi.DIRECTION_DEFAULT_RIGHT_TO_LEFT;
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case DIRECTION_LEFT_TO_RIGHT:
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return android.icu.text.Bidi.DIRECTION_LEFT_TO_RIGHT;
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case DIRECTION_RIGHT_TO_LEFT:
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return android.icu.text.Bidi.DIRECTION_RIGHT_TO_LEFT;
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// If the parameter was unrecognized use LEFT_TO_RIGHT.
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default:
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return android.icu.text.Bidi.DIRECTION_LEFT_TO_RIGHT;
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}
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}
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// END Android-added: translateConstToIcu(int).
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// Android-changed: use ICU Bidi class instead of BidiBase.
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private final android.icu.text.Bidi bidiBase;
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/**
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* Create Bidi from the given paragraph of text and base direction.
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* @param paragraph a paragraph of text
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* @param flags a collection of flags that control the algorithm. The
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* algorithm understands the flags DIRECTION_LEFT_TO_RIGHT, DIRECTION_RIGHT_TO_LEFT,
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* DIRECTION_DEFAULT_LEFT_TO_RIGHT, and DIRECTION_DEFAULT_RIGHT_TO_LEFT.
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* Other values are reserved.
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*/
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public Bidi(String paragraph, int flags) {
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if (paragraph == null) {
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throw new IllegalArgumentException("paragraph is null");
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}
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// Android-changed: use ICU Bidi class instead of BidiBase.
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bidiBase = new android.icu.text.Bidi(paragraph.toCharArray(), 0, null, 0,
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paragraph.length(), translateConstToIcu(flags));
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}
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/**
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* Create Bidi from the given paragraph of text.
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* <p>
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* The RUN_DIRECTION attribute in the text, if present, determines the base
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* direction (left-to-right or right-to-left). If not present, the base
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* direction is computes using the Unicode Bidirectional Algorithm, defaulting to left-to-right
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* if there are no strong directional characters in the text. This attribute, if
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* present, must be applied to all the text in the paragraph.
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* <p>
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* The BIDI_EMBEDDING attribute in the text, if present, represents embedding level
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* information. Negative values from -1 to -62 indicate overrides at the absolute value
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* of the level. Positive values from 1 to 62 indicate embeddings. Where values are
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* zero or not defined, the base embedding level as determined by the base direction
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* is assumed.
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* <p>
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* The NUMERIC_SHAPING attribute in the text, if present, converts European digits to
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* other decimal digits before running the bidi algorithm. This attribute, if present,
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* must be applied to all the text in the paragraph.
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*
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* @param paragraph a paragraph of text with optional character and paragraph attribute information
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*
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* @see java.awt.font.TextAttribute#BIDI_EMBEDDING
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* @see java.awt.font.TextAttribute#NUMERIC_SHAPING
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* @see java.awt.font.TextAttribute#RUN_DIRECTION
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*/
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public Bidi(AttributedCharacterIterator paragraph) {
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if (paragraph == null) {
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throw new IllegalArgumentException("paragraph is null");
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}
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// Android-changed: change from BidiBase to ICU Bidi class.
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this.bidiBase = new android.icu.text.Bidi(paragraph);
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}
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/**
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* Create Bidi from the given text, embedding, and direction information.
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* The embeddings array may be null. If present, the values represent embedding level
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* information. Negative values from -1 to -61 indicate overrides at the absolute value
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* of the level. Positive values from 1 to 61 indicate embeddings. Where values are
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* zero, the base embedding level as determined by the base direction is assumed.
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* @param text an array containing the paragraph of text to process.
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* @param textStart the index into the text array of the start of the paragraph.
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* @param embeddings an array containing embedding values for each character in the paragraph.
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* This can be null, in which case it is assumed that there is no external embedding information.
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* @param embStart the index into the embedding array of the start of the paragraph.
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* @param paragraphLength the length of the paragraph in the text and embeddings arrays.
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* @param flags a collection of flags that control the algorithm. The
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* algorithm understands the flags DIRECTION_LEFT_TO_RIGHT, DIRECTION_RIGHT_TO_LEFT,
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* DIRECTION_DEFAULT_LEFT_TO_RIGHT, and DIRECTION_DEFAULT_RIGHT_TO_LEFT.
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* Other values are reserved.
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*/
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public Bidi(char[] text, int textStart, byte[] embeddings, int embStart, int paragraphLength, int flags) {
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if (text == null) {
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throw new IllegalArgumentException("text is null");
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}
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if (paragraphLength < 0) {
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throw new IllegalArgumentException("bad length: " + paragraphLength);
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}
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if (textStart < 0 || paragraphLength > text.length - textStart) {
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throw new IllegalArgumentException("bad range: " + textStart +
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" length: " + paragraphLength +
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" for text of length: " + text.length);
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}
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if (embeddings != null && (embStart < 0 || paragraphLength > embeddings.length - embStart)) {
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throw new IllegalArgumentException("bad range: " + embStart +
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" length: " + paragraphLength +
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" for embeddings of length: " + text.length);
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}
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// Android-changed: use ICU Bidi class instead of BidiBase.
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bidiBase = new android.icu.text.Bidi(text, textStart, embeddings, embStart,
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paragraphLength, translateConstToIcu(flags));
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}
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// Android-added: private constructor based on ICU Bidi object.
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private Bidi(android.icu.text.Bidi bidiBase) {
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this.bidiBase = bidiBase;
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}
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/**
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* Create a Bidi object representing the bidi information on a line of text within
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* the paragraph represented by the current Bidi. This call is not required if the
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* entire paragraph fits on one line.
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*
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* @param lineStart the offset from the start of the paragraph to the start of the line.
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* @param lineLimit the offset from the start of the paragraph to the limit of the line.
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* @return a {@code Bidi} object
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*/
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public Bidi createLineBidi(int lineStart, int lineLimit) {
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// BEGIN Android-changed: add explict argument checks and use ICU Bidi class.
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/*
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AttributedString astr = new AttributedString("");
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Bidi newBidi = new Bidi(astr.getIterator());
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return bidiBase.setLine(this, bidiBase, newBidi, newBidi.bidiBase, lineStart, lineLimit);
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*/
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if (lineStart < 0 || lineLimit < 0 || lineStart > lineLimit || lineLimit > getLength()) {
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throw new IllegalArgumentException("Invalid ranges (start=" + lineStart + ", " +
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"limit=" + lineLimit + ", length=" + getLength() + ")");
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}
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// In the special case where the start and end positions are the same, we return a new bidi
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// instance which is empty. Note that the default constructor for an empty ICU4J bidi
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// instance is not the same as passing in empty values. This way allows one to call
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// .getLength() for example and return a correct value instead of an IllegalStateException
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// being thrown, which happens in the case of using the empty constructor.
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if (lineStart == lineLimit) {
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return new Bidi(new android.icu.text.Bidi(new char[] {}, 0, new byte[] {}, 0, 0,
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translateConstToIcu(DIRECTION_LEFT_TO_RIGHT)));
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}
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return new Bidi(bidiBase.createLineBidi(lineStart, lineLimit));
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// END Android-changed: add explict argument checks and use ICU Bidi class.
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}
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/**
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* Return true if the line is not left-to-right or right-to-left. This means it either has mixed runs of left-to-right
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* and right-to-left text, or the base direction differs from the direction of the only run of text.
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*
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* @return true if the line is not left-to-right or right-to-left.
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*/
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public boolean isMixed() {
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return bidiBase.isMixed();
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}
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/**
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* Return true if the line is all left-to-right text and the base direction is left-to-right.
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*
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* @return true if the line is all left-to-right text and the base direction is left-to-right
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*/
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public boolean isLeftToRight() {
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return bidiBase.isLeftToRight();
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}
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/**
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* Return true if the line is all right-to-left text, and the base direction is right-to-left.
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* @return true if the line is all right-to-left text, and the base direction is right-to-left
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*/
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public boolean isRightToLeft() {
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return bidiBase.isRightToLeft();
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}
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/**
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* Return the length of text in the line.
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* @return the length of text in the line
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*/
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public int getLength() {
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return bidiBase.getLength();
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}
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/**
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* Return true if the base direction is left-to-right.
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* @return true if the base direction is left-to-right
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*/
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public boolean baseIsLeftToRight() {
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return bidiBase.baseIsLeftToRight();
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}
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/**
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* Return the base level (0 if left-to-right, 1 if right-to-left).
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* @return the base level
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*/
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public int getBaseLevel() {
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return bidiBase.getParaLevel();
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}
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/**
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* Return the resolved level of the character at offset. If offset is
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* {@literal <} 0 or ≥ the length of the line, return the base direction
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* level.
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*
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* @param offset the index of the character for which to return the level
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* @return the resolved level of the character at offset
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*/
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public int getLevelAt(int offset) {
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// BEGIN Android-changed: return base level on out of range offset argument.
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try {
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return bidiBase.getLevelAt(offset);
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} catch (IllegalArgumentException e) {
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return getBaseLevel();
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}
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// END Android-changed: return base level on out of range offset argument.
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}
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/**
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* Return the number of level runs.
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* @return the number of level runs
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*/
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public int getRunCount() {
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// Android-changed: ICU treats the empty string as having 0 runs, we see it as 1 empty run.
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int runCount = bidiBase.countRuns();
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return (runCount == 0 ? 1 : runCount);
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}
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/**
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* Return the level of the nth logical run in this line.
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* @param run the index of the run, between 0 and {@code getRunCount()}
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* @return the level of the run
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*/
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public int getRunLevel(int run) {
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// Android-added: Tolerate calls with run == getRunCount() for backwards compatibility.
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if (run == getRunCount()) {
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return getBaseLevel();
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}
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// Android-changed: ICU treats the empty string as having 0 runs, we see it as 1 empty run.
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return (bidiBase.countRuns() == 0 ? bidiBase.getBaseLevel() : bidiBase.getRunLevel(run));
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}
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/**
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* Return the index of the character at the start of the nth logical run in this line, as
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* an offset from the start of the line.
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* @param run the index of the run, between 0 and {@code getRunCount()}
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* @return the start of the run
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*/
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public int getRunStart(int run) {
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// Android-added: Tolerate calls with run == getRunCount() for backwards compatibility.
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if (run == getRunCount()) {
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return getBaseLevel();
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}
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// Android-changed: ICU treats the empty string as having 0 runs, we see it as 1 empty run.
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return (bidiBase.countRuns() == 0 ? 0 : bidiBase.getRunStart(run));
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}
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/**
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* Return the index of the character past the end of the nth logical run in this line, as
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* an offset from the start of the line. For example, this will return the length
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* of the line for the last run on the line.
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* @param run the index of the run, between 0 and {@code getRunCount()}
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* @return limit the limit of the run
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*/
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public int getRunLimit(int run) {
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// Android-added: Tolerate calls with run == getRunCount() for backwards compatibility.
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if (run == getRunCount()) {
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return getBaseLevel();
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}
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// Android-changed: ICU treats the empty string as having 0 runs, we see it as 1 empty run.
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return (bidiBase.countRuns() == 0 ? bidiBase.getLength() : bidiBase.getRunLimit(run));
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}
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/**
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* Return true if the specified text requires bidi analysis. If this returns false,
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* the text will display left-to-right. Clients can then avoid constructing a Bidi object.
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* Text in the Arabic Presentation Forms area of Unicode is presumed to already be shaped
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* and ordered for display, and so will not cause this function to return true.
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*
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* @param text the text containing the characters to test
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* @param start the start of the range of characters to test
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* @param limit the limit of the range of characters to test
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* @return true if the range of characters requires bidi analysis
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*/
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public static boolean requiresBidi(char[] text, int start, int limit) {
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// Android-added: Check arguments to throw correct exception.
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if (0 > start || start > limit || limit > text.length) {
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throw new IllegalArgumentException("Value start " + start +
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" is out of range 0 to " + limit);
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}
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return android.icu.text.Bidi.requiresBidi(text, start, limit);
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}
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|
|
||
|
/**
|
||
|
* Reorder the objects in the array into visual order based on their levels.
|
||
|
* This is a utility function to use when you have a collection of objects
|
||
|
* representing runs of text in logical order, each run containing text
|
||
|
* at a single level. The elements at {@code index} from
|
||
|
* {@code objectStart} up to {@code objectStart + count}
|
||
|
* in the objects array will be reordered into visual order assuming
|
||
|
* each run of text has the level indicated by the corresponding element
|
||
|
* in the levels array (at {@code index - objectStart + levelStart}).
|
||
|
*
|
||
|
* @param levels an array representing the bidi level of each object
|
||
|
* @param levelStart the start position in the levels array
|
||
|
* @param objects the array of objects to be reordered into visual order
|
||
|
* @param objectStart the start position in the objects array
|
||
|
* @param count the number of objects to reorder
|
||
|
*/
|
||
|
public static void reorderVisually(byte[] levels, int levelStart, Object[] objects, int objectStart, int count) {
|
||
|
// BEGIN Android-added: Check arguments to throw correct exception.
|
||
|
if (0 > levelStart || levels.length <= levelStart) {
|
||
|
throw new IllegalArgumentException("Value levelStart " +
|
||
|
levelStart + " is out of range 0 to " +
|
||
|
(levels.length-1));
|
||
|
}
|
||
|
if (0 > objectStart || objects.length <= objectStart) {
|
||
|
throw new IllegalArgumentException("Value objectStart " +
|
||
|
levelStart + " is out of range 0 to " +
|
||
|
(objects.length-1));
|
||
|
}
|
||
|
if (0 > count || objects.length < (objectStart+count)) {
|
||
|
throw new IllegalArgumentException("Value count " +
|
||
|
levelStart + " is out of range 0 to " +
|
||
|
(objects.length - objectStart));
|
||
|
}
|
||
|
// END Android-added: Check arguments to throw correct exception.
|
||
|
|
||
|
// Android-changed: use ICU Bidi class instead of BidiBase.
|
||
|
android.icu.text.Bidi.reorderVisually(levels, levelStart, objects, objectStart, count);
|
||
|
}
|
||
|
|
||
|
/**
|
||
|
* Display the bidi internal state, used in debugging.
|
||
|
*/
|
||
|
public String toString() {
|
||
|
// Android-changed: construct String representation from ICU Bidi object values.
|
||
|
return getClass().getName()
|
||
|
+ "[direction: " + bidiBase.getDirection() + " baseLevel: " + bidiBase.getBaseLevel()
|
||
|
+ " length: " + bidiBase.getLength() + " runs: " + bidiBase.getRunCount() + "]";
|
||
|
}
|
||
|
|
||
|
}
|