249 lines
8.8 KiB
C++
249 lines
8.8 KiB
C++
/*
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* Copyright © {1996-1999}, International Business Machines Corporation and 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.h
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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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// 8/18/97 helena Added internal API documentation.
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// 6/26/98 erm Changed to use byte arrays and memcmp.
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//===============================================================================
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#ifndef SORTKEY_H
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#define SORTKEY_H
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#include "unicode/utypes.h"
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#include "unicode/unistr.h"
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#include "unicode/coll.h"
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/* forward declaration */
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class RuleBasedCollator;
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/**
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* Collation keys are generated by the Collator class. Use the CollationKey objects
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* instead of Collator to compare strings multiple times. A CollationKey
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* preprocesses the comparison information from the Collator object to
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* make the comparison faster. If you are not going to comparing strings
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* multiple times, then using the Collator object is generally faster,
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* since it only processes as much of the string as needed to make a
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* comparison.
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* <p> For example (with strength == tertiary)
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* <p>When comparing "Abernathy" to "Baggins-Smythworthy", Collator
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* only needs to process a couple of characters, while a comparison
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* with CollationKeys will process all of the characters. On the other hand,
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* if you are doing a sort of a number of fields, it is much faster to use
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* CollationKeys, since you will be comparing strings multiple times.
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* <p>Typical use of CollationKeys are in databases, where you store a CollationKey
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* in a hidden field, and use it for sorting or indexing.
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*
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* <p>Example of use:
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* <pre>
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* . UErrorCode success = U_ZERO_ERROR;
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* . Collator* myCollator = Collator::createInstance(success);
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* . CollationKey* keys = new CollationKey [3];
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* . myCollator->getCollationKey("Tom", keys[0], success );
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* . myCollator->getCollationKey("Dick", keys[1], success );
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* . myCollator->getCollationKey("Harry", keys[2], success );
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* .
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* . // Inside body of sort routine, compare keys this way:
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* . CollationKey tmp;
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* . if(keys[0].compareTo( keys[1] ) > 0 ) {
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* . tmp = keys[0]; keys[0] = keys[1]; keys[1] = tmp;
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* . }
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* . //...
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* </pre>
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* <p>Because Collator::compare()'s algorithm is complex, it is faster to sort
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* long lists of words by retrieving collation keys with Collator::getCollationKey().
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* You can then cache the collation keys and compare them using CollationKey::compareTo().
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* <p>
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* <strong>Note:</strong> <code>Collator</code>s with different Locale,
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* CollationStrength and DecompositionMode settings will return different
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* CollationKeys for the same set of strings. Locales have specific
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* collation rules, and the way in which secondary and tertiary differences
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* are taken into account, for example, will result in different CollationKeys
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* for same strings.
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* <p>
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* @see Collator
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* @see RuleBasedCollator
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* @version 1.3 12/18/96
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* @author Helena Shih
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*/
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class U_I18N_API CollationKey {
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public:
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/**
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* This creates an empty collation key based on the null string. An empty
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* collation key contains no sorting information. When comparing two empty
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* collation keys, the result is Collator::EQUAL. Comparing empty collation key
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* with non-empty collation key is always Collator::LESS.
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*/
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CollationKey();
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/**
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* Creates a collation key based on the collation key values.
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* @param values the collation key values
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* @param count number of collation key values, including trailing nulls.
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* @see #createBits
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*/
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CollationKey(const uint8_t* values,
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int32_t count);
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/**
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* Copy constructor.
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*/
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CollationKey(const CollationKey& other);
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/**
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* Sort key destructor.
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*/
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~CollationKey();
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/**
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* Assignment operator
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*/
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const CollationKey& operator=(const CollationKey& other);
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/**
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* Compare if two collation keys are the same.
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* @param source the collation key to compare to.
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* @return Returns true if two collation keys are equal, false otherwise.
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*/
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bool_t operator==(const CollationKey& source) const;
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/**
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* Compare if two collation keys are not the same.
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* @param source the collation key to compare to.
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* @return Returns TRUE if two collation keys are different, FALSE otherwise.
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*/
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bool_t operator!=(const CollationKey& source) const;
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/**
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* Test to see if the key is in an invalid state. The key will be in an
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* invalid state if it couldn't allocate memory for some operation.
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* @return Returns TRUE if the key is in an invalid, FALSE otherwise.
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*/
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bool_t isBogus(void) const;
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/**
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* Returns a pointer to the collation key values. The storage is owned
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* by the collation key and the pointer will become invalid if the key
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* is deleted.
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* @param count the output parameter of number of collation key values,
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* including any trailing nulls.
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*/
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const uint8_t* getByteArray(int32_t& count) const;
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/**
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* Extracts the collation key values into a new array. The caller owns
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* this storage and should free it.
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* @param count the output parameter of number of collation key values,
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* including any trailing nulls.
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*/
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uint8_t* toByteArray(int32_t& count) const;
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/**
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* Convenience method which does a string(bit-wise) comparison of the
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* two collation keys.
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* @param sourceKey source collation key
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* @param targetKey target collation key
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* @return Returns Collator::LESS if sourceKey < targetKey,
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* Collator::GREATER if sourceKey > targetKey and Collator::EQUAL
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* otherwise.
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*/
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Collator::EComparisonResult compareTo(const CollationKey& target) const;
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/**
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* Creates an integer that is unique to the collation key. NOTE: this
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* is not the same as String.hashCode.
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* <p>Example of use:
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* <pre>
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* . UErrorCode status = U_ZERO_ERROR;
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* . Collator *myCollation = Collator::createInstance(Locale::US, status);
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* . if (U_FAILURE(status)) return;
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* . CollationKey key1, key2;
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* . UErrorCode status1 = U_ZERO_ERROR, status2 = U_ZERO_ERROR;
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* . myCollation->getCollationKey("abc", key1, status1);
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* . if (U_FAILURE(status1)) { delete myCollation; return; }
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* . myCollation->getCollationKey("ABC", key2, status2);
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* . if (U_FAILURE(status2)) { delete myCollation; return; }
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* . // key1.hashCode() != key2.hashCode()
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* </pre>
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* @return the hash value based on the string's collation order.
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* @see UnicodeString#hashCode
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*/
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int32_t hashCode(void) const;
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private:
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/**
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* Returns an array of the collation key values as 16-bit integers.
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* The caller owns the storage and must delete it.
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* @param size output parameter of the number of collation key values
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* @return a pointer to an array of 16-bit collation key values.
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*/
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uint16_t* copyValues(int32_t &size) const;
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/*
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* Creates a collation key with a string.
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*/
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CollationKey(const UnicodeString& value);
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int32_t storeBytes(int32_t cursor, uint32_t byteValue);
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int32_t storeUnicodeString(int32_t cursor, const UnicodeString &value);
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void reverseBytes(int32_t from, int32_t to);
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CollationKey& ensureCapacity(int32_t newSize);
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CollationKey& copyUnicodeString(const UnicodeString &value);
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CollationKey& setToBogus(void);
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CollationKey& reset(void);
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friend class RuleBasedCollator;
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static const int32_t kInvalidHashCode;
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static const int32_t kEmptyHashCode;
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bool_t fBogus;
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int32_t fCount;
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int32_t fCapacity;
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int32_t fHashCode;
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uint8_t* fBytes;
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};
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inline bool_t
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CollationKey::operator!=(const CollationKey& other) const
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{
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return !(*this == other);
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}
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inline bool_t
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CollationKey::isBogus() const
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{
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return fBogus;
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}
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inline const uint8_t*
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CollationKey::getByteArray(int32_t &count) const
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{
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count = fCount;
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return fBytes;
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}
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inline UTextOffset
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CollationKey::storeBytes(UTextOffset cursor, uint32_t byteValue)
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{
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fBytes[cursor++] = (uint8_t) (byteValue >> 8);
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fBytes[cursor++] = (uint8_t) byteValue;
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return cursor;
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}
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#endif
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