Collator
class performs locale-sensitive String
comparison.
More...
#include <coll.h>
Class diagram for Collator:
Public Members | |||
![]() | ![]() | enum | ECollationStrength { PRIMARY, SECONDARY, TERTIARY, IDENTICAL } |
![]() | ![]() | Base letter represents a primary difference. More... | |
![]() | ![]() | enum | EComparisonResult { LESS, EQUAL, GREATER } |
![]() | ![]() | LESS is returned if source string is compared to be less than target string in the compare() method. More... | |
![]() | ![]() | virtual | ~Collator () |
![]() | ![]() | Destructor. More... | |
![]() | ![]() | virtual bool_t | operator== (const Collator& other) const |
![]() | ![]() | Returns true if "other" is the same as "this". More... | |
![]() | ![]() | virtual bool_t | operator!= (const Collator& other) const |
![]() | ![]() | Returns true if "other" is not the same as "this". More... | |
![]() | ![]() | virtual Collator* | clone (void) const = 0 |
![]() | ![]() | Makes a shallow copy of the current object. More... | |
![]() | ![]() | virtual EComparisonResult | compare ( const UnicodeString& source, const UnicodeString& target) const = 0 |
![]() | ![]() | The comparison function compares the character data stored in two different strings. More... | |
![]() | ![]() | virtual EComparisonResult | compare ( const UnicodeString& source, const UnicodeString& target, int32_t length) const = 0 |
![]() | ![]() | Does the same thing as compare but limits the comparison to a specified length
Example of use:. More... | |
![]() | ![]() | virtual EComparisonResult | compare ( const UChar* source, int32_t sourceLength, const UChar* target, int32_t targetLength) const = 0 |
![]() | ![]() | The comparison function compares the character data stored in two different string arrays. More... | |
![]() | ![]() | 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(). More... | |
![]() | ![]() | virtual CollationKey& | getCollationKey (const UChar *source, int32_t sourceLength, CollationKey& key, UErrorCode& status) const = 0 |
![]() | ![]() | Transforms the string into a series of characters that can be compared with CollationKey::compareTo(). More... | |
![]() | ![]() | virtual int32_t | hashCode (void) const = 0 |
![]() | ![]() | Generates the hash code for the collation object. More... | |
![]() | ![]() | bool_t | greater ( const UnicodeString& source, const UnicodeString& target) const |
![]() | ![]() | Convenience method for comparing two strings based on the collation rules. More... | |
![]() | ![]() | bool_t | greaterOrEqual ( const UnicodeString& source, const UnicodeString& target) const |
![]() | ![]() | Convenience method for comparing two strings based on the collation rules. More... | |
![]() | ![]() | bool_t | equals ( const UnicodeString& source, const UnicodeString& target) const |
![]() | ![]() | Convenience method for comparing two strings based on the collation rules. More... | |
![]() | ![]() | Normalizer::EMode | getDecomposition (void) const |
![]() | ![]() | Get the decomposition mode of the collator object. More... | |
![]() | ![]() | void | setDecomposition (Normalizer::EMode mode) |
![]() | ![]() | Set the decomposition mode of the collator object. More... | |
![]() | ![]() | ECollationStrength | getStrength (void) const |
![]() | ![]() | Determines the minimum strength that will be use in comparison or transformation. More... | |
![]() | ![]() | void | setStrength ( ECollationStrength newStrength) |
![]() | ![]() | Sets the minimum strength to be used in comparison or transformation. More... | |
![]() | ![]() | virtual UClassID | getDynamicClassID (void) const = 0 |
![]() | ![]() | Returns a unique class ID POLYMORPHICALLY. More... | |
Static Public Members | |||
![]() | ![]() | Collator* | createInstance ( UErrorCode& err) |
![]() | ![]() | Creates the collator object for the current default locale. More... | |
![]() | ![]() | Collator* | createInstance ( const Locale& loc, UErrorCode& err) |
![]() | ![]() | Gets the table-based collation object for the desired locale. More... | |
![]() | ![]() | UnicodeString& | getDisplayName ( const Locale& objectLocale, const Locale& displayLocale, UnicodeString& name) |
![]() | ![]() | Get name of the object for the desired Locale, in the desired langauge. More... | |
![]() | ![]() | UnicodeString& | getDisplayName ( const Locale& objectLocale, UnicodeString& name) |
![]() | ![]() | Get name of the object for the desired Locale, in the langauge of the default locale. More... | |
![]() | ![]() | const Locale* | getAvailableLocales (int32_t& count) |
![]() | ![]() | Get the set of Locales for which Collations are installed. More... | |
Protected Members | |||
![]() | ![]() | Collator () | |
![]() | ![]() | Constructors. | |
![]() | ![]() | Collator (ECollationStrength collationStrength, Normalizer::EMode decompositionMode) | |
![]() | ![]() | Collator (const Collator& other) | |
![]() | ![]() | const Collator& | operator= (const Collator& other) |
![]() | ![]() | Assignment operator. |
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 String
s exactly once, the compare
method provides the best performance. When sorting a list of String
s however, it is generally necessary to compare each String
multiple times. In this case, CollationKey
s provide better performance. The CollationKey
class converts a String
to a series of bits that can be compared bitwise against other CollationKey
s. A CollationKey
is created by a Collator
object for a given String
.
Note: Collator
s 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.
enum Collator::ECollationStrength |
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 Collator::EComparisonResult |
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.
virtual Collator::~Collator () [virtual]
|
Destructor.
bool_t Collator::operator== (const Collator & other) const [inline, virtual]
|
bool_t Collator::operator!= (const Collator & other) const [inline, virtual]
|
virtual Collator * Collator::clone (void) const [pure virtual]
|
virtual EComparisonResult Collator::compare (const UnicodeString & source, const UnicodeString & target) const [pure virtual]
|
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");
source | the source string to be compared with. |
target | the string that is to be compared with the source string. |
Reimplemented in RuleBasedCollator.
virtual EComparisonResult Collator::compare (const UnicodeString & source, const UnicodeString & target, int32_t length) const [pure virtual]
|
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);
source | the source string to be compared with. |
target | the string that is to be compared with the source string. |
length | the length the comparison is limitted to |
Reimplemented in RuleBasedCollator.
virtual EComparisonResult Collator::compare (const UChar * source, int32_t sourceLength, const UChar * target, int32_t targetLength) const [pure virtual]
|
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);
source | the source string array to be compared with. |
sourceLength | the length of the source string array. If this value is equal to -1, the string array is null-terminated. |
target | the string that is to be compared with the source string. |
targetLength | the length of the target string array. If this value is equal to -1, the string array is null-terminated. |
Reimplemented in RuleBasedCollator.
virtual CollationKey & Collator::getCollationKey (const UnicodeString & source, CollationKey & key, UErrorCode & status) const [pure virtual]
|
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.
source | the source string to be transformed into a sort key. |
key | the collation key to be filled in |
Reimplemented in RuleBasedCollator.
virtual CollationKey & Collator::getCollationKey (const UChar * source, int32_t sourceLength, CollationKey & key, UErrorCode & status) const [pure virtual]
|
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.
source | the source string to be transformed into a sort key. |
sourceLength | length of the collation key |
key | the collation key to be filled in |
Reimplemented in RuleBasedCollator.
virtual int32_t Collator::hashCode (void) const [pure virtual]
|
bool_t Collator::greater (const UnicodeString & source, const UnicodeString & target) const |
Convenience method for comparing two strings based on the collation rules.
source | the source string to be compared with. |
target | the target string to be compared with. |
bool_t Collator::greaterOrEqual (const UnicodeString & source, const UnicodeString & target) const |
Convenience method for comparing two strings based on the collation rules.
source | the source string to be compared with. |
target | the target string to be compared with. |
bool_t Collator::equals (const UnicodeString & source, const UnicodeString & target) const |
Convenience method for comparing two strings based on the collation rules.
source | the source string to be compared with. |
target | the target string to be compared with. |
Normalizer::EMode Collator::getDecomposition (void) const [inline]
|
Get the decomposition mode of the collator object.
void Collator::setDecomposition (Normalizer::EMode mode) |
Set the decomposition mode of the collator object.
success is equal to U_ILLEGAL_ARGUMENT_ERROR if error occurs.
the | new decomposition mode |
Collator::ECollationStrength Collator::getStrength (void) const [inline]
|
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.
void Collator::setStrength (ECollationStrength newStrength) |
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");
newStrength | the new comparison level. |
virtual UClassID Collator::getDynamicClassID (void) const [pure virtual]
|
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;
Reimplemented in RuleBasedCollator.
Collator * Collator::createInstance (UErrorCode & err) [static]
|
Creates the collator object for the current default locale.
The default locale is determined by Locale::getDefault().
Collator * Collator::createInstance (const Locale & loc, UErrorCode & err) [static]
|
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.
desiredLocale | the desired locale to create the collation table with. |
UnicodeString & Collator::getDisplayName (const Locale & objectLocale, const Locale & displayLocale, UnicodeString & name) [static]
|
Get name of the object for the desired Locale, in the desired langauge.
objectLocale | must be from getAvailableLocales |
displayLocale | specifies the desired locale for output |
name | the fill-in parameter of the return value |
UnicodeString & Collator::getDisplayName (const Locale & objectLocale, UnicodeString & name) [static]
|
Get name of the object for the desired Locale, in the langauge of the default locale.
objectLocale | must be from getAvailableLocales |
name | the fill-in parameter of the return value |
const Locale * Collator::getAvailableLocales (int32_t & count) [static]
|
Get the set of Locales for which Collations are installed.
count | the output parameter of number of elements in the locale list |
Collator::Collator () [protected]
|
Constructors.
Collator::Collator (ECollationStrength collationStrength, Normalizer::EMode decompositionMode) [protected]
|
Collator::Collator (const Collator & other) [protected]
|
const Collator & Collator::operator= (const Collator & other) [protected]
|
Assignment operator.