Collator class performs locale-sensitive
* String comparison. You use this class to build
* searching and sorting routines for natural language text.
*
*
* Collator is an abstract base class. Subclasses
* implement specific collation strategies. One subclass,
* RuleBasedCollator, is currently provided
* and is applicable to a wide set of languages. Other
* subclasses may be created to handle more specialized needs.
*
*
* Like other locale-sensitive classes, you can use the static
* factory method, getInstance, to obtain the appropriate
* Collator object for a given locale. You will only need
* to look at the subclasses of Collator if you need
* to understand the details of a particular collation strategy or
* if you need to modify that strategy.
*
*
* The following example shows how to compare two strings using
* the Collator for the default locale.
*
*
* // Compare two strings in the default locale
* UErrorCode success = U_ZERO_ERROR;
* Collator* myCollator = Collator::createInstance(success);
* if( myCollator->compare("abc", "ABC") < 0 ) {
* cout << "abc is less than ABC" << endl;
* }else{
* cout << "abc is greater than or equal to ABC" << endl;
* }
*
*
*
*
* You can set a Collator's strength property
* to determine the level of difference considered significant in
* comparisons. Four strengths are provided: PRIMARY,
* SECONDARY, TERTIARY, and IDENTICAL.
* The exact assignment of strengths to language features is
* locale dependant. For example, in Czech, "e" and "f" are considered
* primary differences, while "e" and "\u00EA" are secondary differences,
* "e" and "E" are tertiary differences and "e" and "e" are identical.
* The following shows how both case and accents could be ignored for
* US English.
*
*
* //Get the Collator for US English and set its strength to PRIMARY
* UErrorCode success = U_ZERO_ERROR;
* Collator* usCollator = Collator::createInstance(Locale::US, success);
* usCollator->setStrength(Collator::PRIMARY);
* if( usCollator->compare("abc", "ABC") == 0 ) {
* cout << "'abc' and 'ABC' strings are equivalent with strength PRIMARY" << endl;
* }
*
*
*
* For comparing Strings exactly once, the compare
* method provides the best performance. When sorting a list of
* Strings however, it is generally necessary to compare each
* String multiple times. In this case, CollationKeys
* provide better performance. The CollationKey class converts
* a String to a series of bits that can be compared bitwise
* against other CollationKeys. A CollationKey is
* created by a Collator object for a given String.
*
* Note: Collators with different Locale,
* CollationStrength and DecompositionMode settings will return different
* sort orders for the same set of strings. Locales have specific
* collation rules, and the way in which secondary and tertiary differences
* are taken into account, for example, will result in a different sorting order
* for same strings.
*
* * @see RuleBasedCollator * @see CollationKey * @see CollationElementIterator * @see Locale * @see Normalizer * @version 1.7 1/14/97 * @author Helena Shih */ class U_I18N_API Collator { public: /** * Base letter represents a primary difference. Set comparison * level to PRIMARY to ignore secondary and tertiary differences. * Use this to set the strength of a Collator object. * Example of primary difference, "abc" < "abd" * * Diacritical differences on the same base letter represent a secondary * difference. Set comparison level to SECONDARY to ignore tertiary * differences. Use this to set the strength of a Collator object. * Example of secondary difference, "ä" >> "a". * * Uppercase and lowercase versions of the same character represents a * tertiary difference. Set comparison level to TERTIARY to include * all comparison differences. Use this to set the strength of a Collator * object. * Example of tertiary difference, "abc" <<< "ABC". * * Two characters are considered "identical" when they have the same * unicode spellings. * For example, "ä" == "ä". * * ECollationStrength is also used to determine the strength of sort keys * generated from Collator objects. */ enum ECollationStrength { PRIMARY = 0, SECONDARY = 1, TERTIARY = 2, IDENTICAL = 3 }; /** * LESS is returned if source string is compared to be less than target * string in the compare() method. * EQUAL is returned if source string is compared to be equal to target * string in the compare() method. * GREATER is returned if source string is compared to be greater than * target string in the compare() method. * @see Collator#compare */ enum EComparisonResult { LESS = -1, EQUAL = 0, GREATER = 1 }; /** * Destructor * @stable */ virtual ~Collator(); /** * Returns true if "other" is the same as "this" * @stable */ virtual UBool operator==(const Collator& other) const; /** * Returns true if "other" is not the same as "this". * @stable */ virtual UBool operator!=(const Collator& other) const; /** * Makes a shallow copy of the current object. * @stable */ virtual Collator* clone(void) const = 0; /** * Creates the collator object for the current default locale. * The default locale is determined by Locale::getDefault. * @return the collation object of the default locale.(for example, en_US) * @see Locale#getDefault * The UErrorCode& err parameter is used to return status information to the user. * To check whether the construction succeeded or not, you should check * the value of U_SUCCESS(err). If you wish more detailed information, you * can check for informational error results which still indicate success. * U_USING_FALLBACK_ERROR indicates that a fall back locale was used. For * example, 'de_CH' was requested, but nothing was found there, so 'de' was * used. U_USING_DEFAULT_ERROR indicates that the default locale data was * used; neither the requested locale nor any of its fall back locales * could be found. * The caller owns the returned object and is responsible for deleting it. * @stable */ static Collator* createInstance( UErrorCode& err); /** * Gets the table-based collation object for the desired locale. The * resource of the desired locale will be loaded by ResourceLoader. * Locale::ENGLISH is the base collation table and all other languages are * built on top of it with additional language-specific modifications. * @param desiredLocale the desired locale to create the collation table * with. * @return the created table-based collation object based on the desired * locale. * @see Locale * @see ResourceLoader * The UErrorCode& err parameter is used to return status information to the user. * To check whether the construction succeeded or not, you should check * the value of U_SUCCESS(err). If you wish more detailed information, you * can check for informational error results which still indicate success. * U_USING_FALLBACK_ERROR indicates that a fall back locale was used. For * example, 'de_CH' was requested, but nothing was found there, so 'de' was * used. U_USING_DEFAULT_ERROR indicates that the default locale data was * used; neither the requested locale nor any of its fall back locales * could be found. * The caller owns the returned object and is responsible for deleting it. * @stable */ static Collator* createInstance( const Locale& loc, UErrorCode& err); // comparison /** * The comparison function compares the character data stored in two * different strings. Returns information about whether a string * is less than, greater than or equal to another string. *
Example of use: *
* . UErrorCode status = U_ZERO_ERROR;
* . Collator *myCollation = Collator::createInstance(Locale::US, status);
* . if (U_FAILURE(status)) return;
* . myCollation->setStrength(Collator::PRIMARY);
* . // result would be Collator::EQUAL ("abc" == "ABC")
* . // (no primary difference between "abc" and "ABC")
* . Collator::EComparisonResult result = myCollation->compare("abc", "ABC");
* . myCollation->setStrength(Collator::TERTIARY);
* . // result would be Collator::LESS (abc" <<< "ABC")
* . // (with tertiary difference between "abc" and "ABC")
* . Collator::EComparisonResult result = myCollation->compare("abc", "ABC");
*
* @param source the source string to be compared with.
* @param target the string that is to be compared with the source string.
* @return Returns a byte value. GREATER if source is greater
* than target; EQUAL if source is equal to target; LESS if source is less
* than target
* @stable
**/
virtual EComparisonResult compare( const UnicodeString& source,
const UnicodeString& target) const = 0;
/**
* Does the same thing as compare but limits the comparison to a specified length
* Example of use: *
* . UErrorCode status = U_ZERO_ERROR;
* . Collator *myCollation = Collator::createInstance(Locale::US, status);
* . if (U_FAILURE(status)) return;
* . myCollation->setStrength(Collator::PRIMARY);
* . // result would be Collator::EQUAL ("abc" == "ABC")
* . // (no primary difference between "abc" and "ABC")
* . Collator::EComparisonResult result = myCollation->compare("abc", "ABC",3);
* . myCollation->setStrength(Collator::TERTIARY);
* . // result would be Collator::LESS (abc" <<< "ABC")
* . // (with tertiary difference between "abc" and "ABC")
* . Collator::EComparisonResult result = myCollation->compare("abc", "ABC",3);
*
* @param source the source string to be compared with.
* @param target the string that is to be compared with the source string.
* @param length the length the comparison is limitted to
* @return Returns a byte value. GREATER if source (up to the specified length) is greater
* than target; EQUAL if source (up to specified length) is equal to target; LESS if source
* (up to the specified length) is less than target.
* @draft
**/
virtual EComparisonResult compare( const UnicodeString& source,
const UnicodeString& target,
int32_t length) const = 0;
/**
* The comparison function compares the character data stored in two
* different string arrays. Returns information about whether a string
* array is less than, greater than or equal to another string array.
* Example of use: *
* . UErrorCode status = U_ZERO_ERROR;
* . Collator *myCollation = Collator::createInstance(Locale::US, status);
* . if (U_FAILURE(status)) return;
* . myCollation->setStrength(Collator::PRIMARY);
* . // result would be Collator::EQUAL ("abc" == "ABC")
* . // (no primary difference between "abc" and "ABC")
* . Collator::EComparisonResult result = myCollation->compare(L"abc", 3, L"ABC", 3);
* . myCollation->setStrength(Collator::TERTIARY);
* . // result would be Collator::LESS (abc" <<< "ABC")
* . // (with tertiary difference between "abc" and "ABC")
* . Collator::EComparisonResult result = myCollation->compare(L"abc", 3, L"ABC", 3);
*
* @param source the source string array to be compared with.
* @param sourceLength the length of the source string array. If this value
* is equal to -1, the string array is null-terminated.
* @param target the string that is to be compared with the source string.
* @param targetLength the length of the target string array. If this value
* is equal to -1, the string array is null-terminated.
* @return Returns a byte value. GREATER if source is greater
* than target; EQUAL if source is equal to target; LESS if source is less
* than target
* @stable
**/
virtual EComparisonResult compare( const UChar* source,
int32_t sourceLength,
const UChar* target,
int32_t targetLength) const = 0;
/** Transforms the string into a series of characters that can be compared
* with CollationKey::compareTo. It is not possible to restore the original
* string from the chars in the sort key. The generated sort key handles
* only a limited number of ignorable characters.
* Use CollationKey::equals or CollationKey::compare to compare the * generated sort keys. *
Example of use: *
* . UErrorCode status = U_ZERO_ERROR;
* . Collator *myCollation = Collator::createInstance(Locale::US, status);
* . if (U_FAILURE(status)) return;
* . myCollation->setStrength(Collator::PRIMARY);
* . UErrorCode key1Status, key2Status;
* . CollationKey CollationKey1
* . CollationKey1 = myCollation->getCollationKey("abc", CollationKey1, key1Status);
* . CollationKey CollationKey2
* . CollationKey2 = myCollation->getCollationKey("ABC", CollationKey2, key2Status);
* . if (U_FAILURE(key1Status) || U_FAILURE(key2Status)) { delete myCollation; return; }
* . // Use CollationKey::compare() to compare the sort keys
* . // result would be 0 (CollationKey1 == CollationKey2)
* . int result = CollationKey1.compare(CollationKey2);
* . myCollation->setStrength(Collator::TERTIARY);
* . CollationKey1 = myCollation->getCollationKey("abc", CollationKey1, key1Status);
* . CollationKey2 = myCollation->getCollationKey("ABC", CollationKey2, key2Status);
* . if (U_FAILURE(key1Status) || U_FAILURE(key2Status)) { delete myCollation; return; }
* . // Use CollationKey::compareTo to compare the collation keys
* . // result would be -1 (CollationKey1 < CollationKey2)
* . result = CollationKey1.compareTo(CollationKey2);
* . delete myCollation;
*
* If the source string is null, a null collation key will be returned. * @param source the source string to be transformed into a sort key. * @param key the collation key to be filled in * @return the collation key of the string based on the collation rules. * @see CollationKey#compare * @draft */ virtual CollationKey& getCollationKey(const UnicodeString& source, CollationKey& key, UErrorCode& status) const = 0; /** Transforms the string into a series of characters that can be compared * with CollationKey::compareTo. It is not possible to restore the original * string from the chars in the sort key. The generated sort key handles * only a limited number of ignorable characters. *
Use CollationKey::equals or CollationKey::compare to compare the * generated sort keys. *
If the source string is null, a null collation key will be returned. * @param source the source string to be transformed into a sort key. * @param sourceLength length of the collation key * @param key the collation key to be filled in * @return the collation key of the string based on the collation rules. * @see CollationKey#compare * @draft */ virtual CollationKey& getCollationKey(const UChar *source, int32_t sourceLength, CollationKey& key, UErrorCode& status) const = 0; /** * Generates the hash code for the collation object * @stable */ virtual int32_t hashCode(void) const = 0; /** * Convenience method for comparing two strings based on * the collation rules. * @param source the source string to be compared with. * @param target the target string to be compared with. * @return true if the first string is greater than the second one, * according to the collation rules. false, otherwise. * @see Collator#compare * @stable */ UBool greater( const UnicodeString& source, const UnicodeString& target) const; /** * Convenience method for comparing two strings based on the collation * rules. * @param source the source string to be compared with. * @param target the target string to be compared with. * @return true if the first string is greater than or equal to the * second one, according to the collation rules. false, otherwise. * @see Collator#compare * @stable */ UBool greaterOrEqual( const UnicodeString& source, const UnicodeString& target) const; /** * Convenience method for comparing two strings based on the collation * rules. * @param source the source string to be compared with. * @param target the target string to be compared with. * @return true if the strings are equal according to the collation * rules. false, otherwise. * @see Collator#compare * @stable */ UBool equals( const UnicodeString& source, const UnicodeString& target) const; // getter/setter /** * Get the decomposition mode of the collator object. * @return the decomposition mode * @see Collator#setDecomposition * @stable */ Normalizer::EMode getDecomposition(void) const; /** * Set the decomposition mode of the collator object. success is equal * to U_ILLEGAL_ARGUMENT_ERROR if error occurs. * @param the new decomposition mode * @see Collator#getDecomposition * @stable */ void setDecomposition(Normalizer::EMode mode); /** * Determines the minimum strength that will be use in comparison or * transformation. *
E.g. with strength == SECONDARY, the tertiary difference is ignored *
E.g. with strength == PRIMARY, the secondary and tertiary difference * are ignored. * @return the current comparison level. * @see Collator#setStrength * @stable */ ECollationStrength getStrength(void) const; /** * Sets the minimum strength to be used in comparison or transformation. *
Example of use: *
* . UErrorCode status = U_ZERO_ERROR;
* . Collator *myCollation = Collator::createInstance(Locale::US, status);
* . if (U_FAILURE(status)) return;
* . myCollation->setStrength(Collator::PRIMARY);
* . // result will be "abc" == "ABC"
* . // tertiary differences will be ignored
* . Collator::ComparisonResult result = myCollation->compare("abc", "ABC");
*
* @see Collator#getStrength
* @param newStrength the new comparison level.
* @stable
*/
void setStrength( ECollationStrength newStrength);
/**
* Get name of the object for the desired Locale, in the desired langauge
* @param objectLocale must be from getAvailableLocales
* @param displayLocale specifies the desired locale for output
* @param name the fill-in parameter of the return value
* @return display-able name of the object for the object locale in the
* desired language
* @stable
*/
static UnicodeString& getDisplayName( const Locale& objectLocale,
const Locale& displayLocale,
UnicodeString& name) ;
/**
* Get name of the object for the desired Locale, in the langauge of the
* default locale.
* @param objectLocale must be from getAvailableLocales
* @param name the fill-in parameter of the return value
* @return name of the object for the desired locale in the default
* language
* @stable
*/
static UnicodeString& getDisplayName( const Locale& objectLocale,
UnicodeString& name) ;
/**
* Get the set of Locales for which Collations are installed
* @param count the output parameter of number of elements in the locale list
* @return the list of available locales which collations are installed
* @stable
*/
static const Locale* getAvailableLocales(int32_t& count);
/**
* Gets the version information for a Collator.
* @param info the version # information, the result will be filled in
* @stable
*/
void getVersion(UVersionInfo info) const;
/**
* Returns a unique class ID POLYMORPHICALLY. Pure virtual method.
* This method is to implement a simple version of RTTI, since not all
* C++ compilers support genuine RTTI. Polymorphic operator==() and
* clone() methods call this method.
*
* Concrete subclasses of Format must implement getDynamicClassID()
* and also a static method and data member:
*
* static UClassID getStaticClassID() { return (UClassID)&fgClassID; }
* static char fgClassID;
*
* @return The class ID for this object. All objects of a
* given class have the same class ID. Objects of
* other classes have different class IDs.
* @stable
*/
virtual UClassID getDynamicClassID(void) const = 0;
protected:
/**
* Constructors
*/
Collator();
Collator(ECollationStrength collationStrength,
Normalizer::EMode decompositionMode);
Collator(const Collator& other);
/**
* Assignment operator
*/
const Collator& operator=(const Collator& other);
//--------------------------------------------------------------------------
private:
ECollationStrength strength;
Normalizer::EMode decmp;
static const UVersionInfo fVersion;
};
inline UBool
Collator::operator==(const Collator& other) const
{
UBool result;
if (this == &other) result = TRUE;
else result = ((strength == other.strength) && (decmp == other.decmp));
return result;
}
inline UBool
Collator::operator!=(const Collator& other) const
{
UBool result;
result = !(*this == other);
return result;
}
inline Collator::ECollationStrength
Collator::getStrength() const
{
return strength;
}
inline Normalizer::EMode
Collator::getDecomposition() const
{
return decmp;
}
inline void
Collator::getVersion(UVersionInfo versionInfo) const
{
if(versionInfo!=NULL) {
uprv_memcpy(versionInfo, fVersion, U_MAX_VERSION_LENGTH);
}
}
#endif