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*
*
* Copyright 1990-2007 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
*
* This program is free software; you can redistribute it and/or
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* 2 only, as published by the Free Software Foundation.
*
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License version 2 for more details (a copy is
* included at /legal/license.txt).
*
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
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*/
package com.sun.j2me.global;
/**
* This interface is used to get collation elements from one or more unicode
* code points.
*/
public abstract class CollationElementTable {
/**
* A value which is used to terminate the code point sequence when
* traversing possible contractions.
*
* @see #getChildBookmark
*/
public static final int TERMINAL_CODE_POINT = 0xffffffff;
/**
* A value which represents an invalid bookmark. It can be returned by the
* {@link #getChildBookmark} method when trying to get the bookmark for
* a non-existing contraction.
*/
public static final int INVALID_BOOKMARK_VALUE = 0xffffffff;
/** A mask to decode the L1 weight value of an encoded collation element. */
protected static final int L1_MASK = 0x0000ffff;
/** A mask to decode the L2 weight value of an encoded collation element. */
protected static final int L2_MASK = 0x01ff0000;
/** A mask to decode the L3 weight value of an encoded collation element. */
protected static final int L3_MASK = 0x1e000000;
/** A flag indicating a code point with a variable weight. */
protected static final int VW_FLAG = 0x20000000;
/** A flag indicating a single encoded collation element. */
protected static final int SINGLE_CE_FLAG = 0x40000000;
/** A flag indicating a bookmark. */
protected static final int BOOKMARK_FLAG = 0x80000000;
/**
* A shift value to decode the L2 weight value of an encoded collation
* element.
*/
protected static final int L2_SHIFT = 16;
/**
* A shift value to decode the L3 weight value of an encoded collation
* element.
*/
protected static final int L3_SHIFT = 25;
/**
* Returns the L1 weight value of an encoded collation element.
*
* @param ecol the encoded collation element
* @return the L1 weight value
*/
public static final int getL1(int ecol) {
return ecol & L1_MASK;
}
/**
* Returns the L2 weight value of an encoded collation element.
*
* @param ecol the encoded collation element
* @return the L2 weight value
*/
public static final int getL2(int ecol) {
return (ecol & L2_MASK) >>> L2_SHIFT;
}
/**
* Returns the L3 weight value of an encoded collation element.
*
* @param ecol the encoded collation element
* @return the L3 weight value
*/
public static final int getL3(int ecol) {
return (ecol & L3_MASK) >>> L3_SHIFT;
}
/**
* Test if the given collation element has a variable weight.
*
* @param ecol the encoded collation element
* @return <code>true</code> if the collation element has a variable weight
*/
public static final boolean isVariableElement(int ecol) {
return (ecol & VW_FLAG) != 0;
}
/**
* Test if the given value is a bookmark.
*
* @param cbc the value
* @return <code>true</code> if the value is a bookmark
* @see #getCollationElements
*/
public static final boolean isBookmark(int cbc) {
return (cbc & BOOKMARK_FLAG) != 0;
}
/**
* Test if the given value is a single encoded collation element.
*
* @param cbc the value
* @return <code>true</code> if the value is a single encoded collation
* element
* @see #getCollationElements
*/
public static final boolean isSingleCollationEl(int cbc) {
return (cbc & SINGLE_CE_FLAG) != 0;
}
/**
* Returns the collation element/elements for the given code point/points.
* Each returned collation element is encoded in a single integer value,
* which can be further decoded by the static methods of this class.
* <p>
* There are three types of possible return value and two types of the
* input values.
* </p><p>
* If the parameters are an integer buffer, an offset to this buffer and
* a single code point, the method can return:
* </p><p>
* <ol>
* <li>
* A single encoded collation element value, when the code point
* decomposes into one collation element and it isn't a starting
* code point of any contraction. In this case nothing is written
* into the buffer.
* </li>
* <li>
* The number of encoded collation elements, when the code point
* decomposes into more than one collation elements and it isn't
* a starting code point of any contraction. The encoded collation
* elements are written to the buffer on the given offset.
* </li>
* <li>
* A bookmark value, when the given code point is a starting code
* point of a contraction. Nothing is written into the buffer.
* </li>
* </ol>
* </p><p>
* If the parameters are an integer buffer, an offset to this buffer and
* a bookmark, the method can return:
* </p><p>
* <ol>
* <li>
* A single encoded collation element value, when the code point
* sequence behind the bookmark decomposes into one collation
* element. Nothing is written into the buffer.
* </li>
* <li>
* The number of encoded collation elements, when the code point
* sequence behind the bookmark decomposes into more than one
* collation elements. The encoded collation elements are written
* to the buffer on the given offset.
* </li>
* <li>
* A zero value, when the given bookmark is invalid or it doesn't
* target the complete (terminated) code point sequence.
* </li>
* </ol>
* </p>
*
* @param buffer the array for the decomposition
* @param offset the offset from the beginning of the array, where to place
* the collation elements
* @param cp a code point or a bookmark
* @return a single encoded collation element or the number of returned
* collation elements or a bookmark or
* <code>INVALID_BOOKMARK_VALUE</code>
* @see #isBookmark
* @see #isSingleCollationEl
* @see #getChildBookmark
*/
public abstract int getCollationElements(int[] buffer, int offset, int cp);
/**
* This method can be used to traverse the contractions. The traversing
* starts when the {@link #getCollationElements} method returns a bookmark
* instead of collation elements. The returned bookmark, which represents
* a code point sequence consisting only of one code point, can be further
* tested if it's extensible by various other code points.
* <p>
* If a partial match is found, the method returns another bookmark which
* represents the new sequence. The new bookmark can be further "refined"
* as well. To get the collation elements for the sequence, the sequence
* has to be terminated by the
* <code>getChildBookmark(bookmark, TERMINAL_CODE_POINT)</code> call.
* If the call returns a valid bookmark, it is guaranteed, that the
* <code>getCollationElements</code> method will return the collation
* elements for this final bookmark.
* </p><p>
* If no match can be found for the given bookmark and the code point
* value, the method returns <code>INVALID_BOOKMARK_VALUE</code>.
* </p>
*
* @param bookmark the bookmark
* @param cp a code point value or <code>TERMINAL_CODE_POINT</code>
* @return the new bookmark for the new code point sequence if a match is
* found or <code>INVALID_BOOKMARK_VALUE</code> if no match can be
* found in the table
* @see #getCollationElements
*/
public abstract int getChildBookmark(int bookmark, int cp);
/**
* Returns the length of the longest possible contraction in the table.
*
* @return the longest contraction
*/
public abstract int getMaxContractionLength();
}
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