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package jdk.internal.icu.impl;
import java.io.IOException;
import java.nio.ByteBuffer;
Author: aheninger
A read-only Trie2, holding 16 bit data values.
A Trie2 is a highly optimized data structure for mapping from Unicode
code points (values ranging from 0 to 0x10ffff) to a 16 or 32 bit value.
See class Trie2 for descriptions of the API for accessing the contents of a trie.
The fundamental data access methods are declared final in this class, with
the intent that applications might gain a little extra performance, when compared
with calling the same methods via the abstract UTrie2 base class.
/**
* @author aheninger
*
* A read-only Trie2, holding 16 bit data values.
*
* A Trie2 is a highly optimized data structure for mapping from Unicode
* code points (values ranging from 0 to 0x10ffff) to a 16 or 32 bit value.
*
* See class Trie2 for descriptions of the API for accessing the contents of a trie.
*
* The fundamental data access methods are declared final in this class, with
* the intent that applications might gain a little extra performance, when compared
* with calling the same methods via the abstract UTrie2 base class.
*/
public final class Trie2_16 extends Trie2 {
Internal constructor, not for general use.
/**
* Internal constructor, not for general use.
*/
Trie2_16() {
}
Create a Trie2 from its serialized form. Inverse of utrie2_serialize().
The serialized format is identical between ICU4C and ICU4J, so this function
will work with serialized Trie2s from either.
The serialized Trie2 in the bytes may be in either little or big endian byte order.
This allows using serialized Tries from ICU4C without needing to consider the
byte order of the system that created them.
Params: - bytes – a byte buffer to the serialized form of a UTrie2.
Throws: - IllegalArgumentException – if the buffer does not contain a serialized Trie2.
- IOException – if a read error occurs in the buffer.
- ClassCastException – if the bytes contain a serialized Trie2_32
Returns: An unserialized Trie2_16, ready for use.
/**
* Create a Trie2 from its serialized form. Inverse of utrie2_serialize().
* The serialized format is identical between ICU4C and ICU4J, so this function
* will work with serialized Trie2s from either.
*
* The serialized Trie2 in the bytes may be in either little or big endian byte order.
* This allows using serialized Tries from ICU4C without needing to consider the
* byte order of the system that created them.
*
* @param bytes a byte buffer to the serialized form of a UTrie2.
* @return An unserialized Trie2_16, ready for use.
* @throws IllegalArgumentException if the buffer does not contain a serialized Trie2.
* @throws IOException if a read error occurs in the buffer.
* @throws ClassCastException if the bytes contain a serialized Trie2_32
*/
public static Trie2_16 createFromSerialized(ByteBuffer bytes) throws IOException {
return (Trie2_16) Trie2.createFromSerialized(bytes);
}
Get the value for a code point as stored in the Trie2.
Params: - codePoint – the code point
Returns: the value
/**
* Get the value for a code point as stored in the Trie2.
*
* @param codePoint the code point
* @return the value
*/
@Override
public final int get(int codePoint) {
int value;
int ix;
if (codePoint >= 0) {
if (codePoint < 0x0d800 || (codePoint > 0x0dbff && codePoint <= 0x0ffff)) {
// Ordinary BMP code point, excluding leading surrogates.
// BMP uses a single level lookup. BMP index starts at offset 0 in the Trie2 index.
// 16 bit data is stored in the index array itself.
ix = index[codePoint >> UTRIE2_SHIFT_2];
ix = (ix << UTRIE2_INDEX_SHIFT) + (codePoint & UTRIE2_DATA_MASK);
value = index[ix];
return value;
}
if (codePoint <= 0xffff) {
// Lead Surrogate Code Point. A Separate index section is stored for
// lead surrogate code units and code points.
// The main index has the code unit data.
// For this function, we need the code point data.
// Note: this expression could be refactored for slightly improved efficiency, but
// surrogate code points will be so rare in practice that it's not worth it.
ix = index[UTRIE2_LSCP_INDEX_2_OFFSET + ((codePoint - 0xd800) >> UTRIE2_SHIFT_2)];
ix = (ix << UTRIE2_INDEX_SHIFT) + (codePoint & UTRIE2_DATA_MASK);
value = index[ix];
return value;
}
if (codePoint < highStart) {
// Supplemental code point, use two-level lookup.
ix = (UTRIE2_INDEX_1_OFFSET - UTRIE2_OMITTED_BMP_INDEX_1_LENGTH) + (codePoint >> UTRIE2_SHIFT_1);
ix = index[ix];
ix += (codePoint >> UTRIE2_SHIFT_2) & UTRIE2_INDEX_2_MASK;
ix = index[ix];
ix = (ix << UTRIE2_INDEX_SHIFT) + (codePoint & UTRIE2_DATA_MASK);
value = index[ix];
return value;
}
if (codePoint <= 0x10ffff) {
value = index[highValueIndex];
return value;
}
}
// Fall through. The code point is outside of the legal range of 0..0x10ffff.
return errorValue;
}
Get a Trie2 value for a UTF-16 code unit.
This function returns the same value as get() if the input
character is outside of the lead surrogate range
There are two values stored in a Trie2 for inputs in the lead
surrogate range. This function returns the alternate value,
while Trie2.get() returns the main value.
Params: - codeUnit – a 16 bit code unit or lead surrogate value.
Returns: the value
/**
* Get a Trie2 value for a UTF-16 code unit.
*
* This function returns the same value as get() if the input
* character is outside of the lead surrogate range
*
* There are two values stored in a Trie2 for inputs in the lead
* surrogate range. This function returns the alternate value,
* while Trie2.get() returns the main value.
*
* @param codeUnit a 16 bit code unit or lead surrogate value.
* @return the value
*/
@Override
public int getFromU16SingleLead(char codeUnit) {
int value;
int ix;
// Because the input is a 16 bit char, we can skip the tests for it being in
// the BMP range. It is.
ix = index[codeUnit >> UTRIE2_SHIFT_2];
ix = (ix << UTRIE2_INDEX_SHIFT) + (codeUnit & UTRIE2_DATA_MASK);
value = index[ix];
return value;
}
Returns: the number of bytes of the serialized trie
/**
* @return the number of bytes of the serialized trie
*/
public int getSerializedLength() {
return 16+(header.indexLength+dataLength)*2;
}
}