368 lines
8.2 KiB
C++
368 lines
8.2 KiB
C++
/*
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*******************************************************************************
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* Copyright (C) 1996-1999, International Business Machines Corporation and *
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* others. All Rights Reserved. *
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*******************************************************************************
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*/
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//===============================================================================
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//
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// File sortkey.cpp
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//
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//
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//
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// Created by: Helena Shih
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//
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// Modification History:
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//
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// Date Name Description
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//
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// 6/20/97 helena Java class name change.
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// 6/23/97 helena Added comments to make code more readable.
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// 6/26/98 erm Canged to use byte arrays instead of UnicodeString
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// 7/31/98 erm hashCode: minimum inc should be 2 not 1,
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// Cleaned up operator=
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// 07/12/99 helena HPUX 11 CC port.
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//===============================================================================
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#ifndef _SORTKEY
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#include "unicode/sortkey.h"
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#endif
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#ifndef _CMEMORY
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#include "cmemory.h"
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#endif
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// A hash code of kInvalidHashCode indicates that the has code needs
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// to be computed. A hash code of kEmptyHashCode is used for empty keys
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// and for any key whose computed hash code is kInvalidHashCode.
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const int32_t CollationKey::kInvalidHashCode = 0;
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const int32_t CollationKey::kEmptyHashCode = 1;
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CollationKey::CollationKey()
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: fBogus(FALSE), fCount(0), fCapacity(0),
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fHashCode(kEmptyHashCode), fBytes(NULL)
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{
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}
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// Create a collation key from a bit array.
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CollationKey::CollationKey(const uint8_t* newValues, int32_t count)
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: fBogus(FALSE), fCount(count), fCapacity(count),
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fHashCode(kInvalidHashCode)
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{
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fBytes = new uint8_t[count];
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if (fBytes == NULL)
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{
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setToBogus();
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return;
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}
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uprv_memcpy(fBytes, newValues, fCount);
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}
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CollationKey::CollationKey(const UnicodeString& value)
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{
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copyUnicodeString(value);
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}
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CollationKey::CollationKey(const CollationKey& other)
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: fBogus(FALSE), fCount(other.fCount), fCapacity(other.fCapacity),
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fHashCode(other.fHashCode), fBytes(NULL)
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{
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if (other.fBogus)
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{
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setToBogus();
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return;
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}
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fBytes = new uint8_t[fCapacity];
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if (fBytes == NULL)
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{
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setToBogus();
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return;
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}
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uprv_memcpy(fBytes, other.fBytes, other.fCount);
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if(fCapacity>fCount) {
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uprv_memset(fBytes+fCount, 0, fCapacity-fCount);
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}
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}
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CollationKey::~CollationKey()
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{
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delete[] fBytes;
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}
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// set the key to an empty state
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CollationKey&
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CollationKey::reset()
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{
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fCount = 0;
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fBogus = FALSE;
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fHashCode = kEmptyHashCode;
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return *this;
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}
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// set the key to a "bogus" or invalid state
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CollationKey&
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CollationKey::setToBogus()
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{
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delete[] fBytes;
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fBytes = NULL;
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fCapacity = 0;
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fCount = 0;
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fHashCode = kInvalidHashCode;
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return *this;
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}
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UBool
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CollationKey::operator==(const CollationKey& source) const
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{
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return (this->fCount == source.fCount &&
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(this->fBytes == source.fBytes ||
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uprv_memcmp(this->fBytes, source.fBytes, this->fCount) == 0));
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}
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const CollationKey&
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CollationKey::operator=(const CollationKey& other)
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{
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if (this != &other)
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{
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if (other.isBogus())
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{
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return setToBogus();
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}
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if (other.fBytes != NULL)
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{
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ensureCapacity(other.fCount);
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if (isBogus())
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{
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return *this;
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}
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fHashCode = other.fHashCode;
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uprv_memcpy(fBytes, other.fBytes, fCount);
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}
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else
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{
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reset();
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}
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}
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return *this;
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}
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// Bitwise comparison for the collation keys.
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// NOTE: this is somewhat messy 'cause we can't count
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// on memcmp returning the exact values which match
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// Collator::EComparisonResult
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Collator::EComparisonResult
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CollationKey::compareTo(const CollationKey& target) const
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{
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int count = (this->fCount < target.fCount) ? this->fCount : target.fCount;
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if (count == 0)
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{
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// If count is 0, at least one of the keys is empty.
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// An empty key is always LESS than a non-empty one
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// and EQUAL to another empty
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if (this->fCount < target.fCount)
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{
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return Collator::LESS;
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}
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if (this->fCount > target.fCount)
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{
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return Collator::GREATER;
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}
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return Collator::EQUAL;
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}
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int result = uprv_memcmp(this->fBytes, target.fBytes, count);
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if (result < 0)
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{
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return Collator::LESS;
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}
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if (result > 0)
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{
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return Collator::GREATER;
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}
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return Collator::EQUAL;
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}
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CollationKey&
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CollationKey::ensureCapacity(int32_t newSize)
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{
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if (fCapacity < newSize)
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{
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delete[] fBytes;
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fBytes = new uint8_t[newSize];
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if (fBytes == NULL)
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{
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return setToBogus();
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}
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uprv_memset(fBytes, 0, fCapacity);
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fCapacity = newSize;
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}
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fBogus = FALSE;
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fCount = newSize;
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fHashCode = kInvalidHashCode;
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return *this;
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}
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int32_t
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CollationKey::storeUnicodeString(int32_t cursor, const UnicodeString &value)
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{
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UTextOffset input = 0;
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int32_t charCount = value.length();
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while (input < charCount)
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{
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cursor = storeBytes(cursor, value[input++]);
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}
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return storeBytes(cursor, 0);
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}
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CollationKey&
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CollationKey::copyUnicodeString(const UnicodeString &value)
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{
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int32_t charCount = value.length();
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// We allocate enough space for two null bytes at the end.
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ensureCapacity((charCount * 2) + 2);
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if (isBogus())
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{
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return *this;
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}
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storeUnicodeString(0, value);
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return *this;
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}
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void
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CollationKey::reverseBytes(UTextOffset from, UTextOffset to)
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{
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uint8_t *left = &fBytes[from];
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uint8_t *right = &fBytes[to - 2];
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while (left < right)
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{
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uint8_t swap[2];
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swap[0] = right[0];
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swap[1] = right[1];
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right[0] = left[0];
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right[1] = left[1];
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left[0] = swap[0];
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left[1] = swap[1];
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left += 2;
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right -= 2;
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}
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}
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// Create a copy of the byte array.
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uint8_t*
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CollationKey::toByteArray(int32_t& count) const
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{
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uint8_t *result = new uint8_t[fCount];
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if (result == NULL)
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{
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count = 0;
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}
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else
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{
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count = fCount;
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uprv_memcpy(result, fBytes, fCount);
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}
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return result;
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}
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uint16_t*
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CollationKey::copyValues(int32_t &size) const
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{
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uint16_t *result;
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uint8_t *input = fBytes;
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UTextOffset output = 0;
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size = fCount / 2;
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result = new uint16_t[size];
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if (result == NULL)
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{
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size = 0;
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}
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else
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{
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while (output < size)
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{
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result[output] = (uint16_t)((input[0] << 8) | input[1]);
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output += 1;
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input += 2;
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}
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}
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return result;
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}
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int32_t
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CollationKey::hashCode() const
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{
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// (Cribbed from UnicodeString)
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// We cache the hashCode; when it becomes invalid, due to any change to the
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// string, we note this by setting it to kInvalidHashCode. [LIU]
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// Note: This method is semantically const, but physically non-const.
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if (fHashCode == kInvalidHashCode)
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{
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// We compute the hash by iterating sparsely over 64 (at most) characters
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// spaced evenly through the string. For each character, we multiply the
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// previous hash value by a prime number and add the new character in,
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// in the manner of a additive linear congruential random number generator,
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// thus producing a pseudorandom deterministic value which should be well
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// distributed over the output range. [LIU]
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const uint8_t *p = fBytes, *limit = fBytes + fCount;
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int32_t inc = (fCount >= 256) ? fCount/128 : 2; // inc = max(fSize/64, 1);
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int32_t hash = 0;
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while (p < limit)
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{
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hash = ( hash * 37 ) + ((p[0] << 8) + p[1]);
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p += inc;
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}
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// If we happened to get kInvalidHashCode, replace it with kEmptyHashCode
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if (hash == kInvalidHashCode)
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{
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hash = kEmptyHashCode;
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}
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((CollationKey *)this)->fHashCode = hash; // cast away const
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}
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return fHashCode;
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}
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