Collator
class performs locale-sensitive string comparison.
More...
#include <coll.h>
Inheritance diagram for Collator:
Public Types | |
enum | ECollationStrength { PRIMARY = 0, SECONDARY = 1, TERTIARY = 2, IDENTICAL = 3 } |
Base letter represents a primary difference. More... | |
enum | EComparisonResult { LESS = -1, EQUAL = 0, GREATER = 1 } |
LESS is returned if source string is compared to be less than target string in the compare() method. More... | |
Public Methods | |
virtual | ~Collator () |
Destructor. More... | |
virtual UBool | operator== (const Collator& other) const |
Returns true if "other" is the same as "this". More... | |
virtual UBool | 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: . 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);. 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... | |
UBool | greater ( const UnicodeString& source, const UnicodeString& target) const |
Convenience method for comparing two strings based on the collation rules. More... | |
UBool | greaterOrEqual ( const UnicodeString& source, const UnicodeString& target) const |
Convenience method for comparing two strings based on the collation rules. More... | |
UBool | 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... | |
void | getVersion (UVersionInfo info) const |
Gets the version information for a Collator. More... | |
virtual UClassID | getDynamicClassID (void) const = 0 |
Returns a unique class ID POLYMORPHICALLY. More... | |
virtual void | setAttribute (UColAttribute attr, UColAttributeValue value, UErrorCode &status) = 0 |
Universal attribute setter. More... | |
virtual UColAttributeValue | getAttribute (UColAttribute attr, UErrorCode &status) = 0 |
Universal attribute getter. More... | |
virtual Collator* | safeClone (void) = 0 |
Thread safe cloning operation. More... | |
virtual EComparisonResult | compare (ForwardCharacterIterator &source, ForwardCharacterIterator &target) = 0 |
String compare that uses user supplied character iteration. More... | |
virtual int32_t | getSortKey (const UnicodeString& source, uint8_t *result, int32_t resultLength) const = 0 |
Get the sort key as an array of bytes from an UnicodeString. More... | |
virtual int32_t | getSortKey (const UChar *source, int32_t sourceLength, uint8_t *result, int32_t resultLength) const = 0 |
Get the sort key as an array of bytes from an UChar buffer. More... | |
Static Public Methods | |
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 Methods | |
Collator () | |
Constructors. | |
Collator (ECollationStrength collationStrength, Normalizer::EMode decompositionMode) | |
Collator (const Collator& other) | |
const Collator& | operator= (const Collator& other) |
Assignment operator. | |
Private Attributes | |
ECollationStrength | strength |
Normalizer::EMode | decmp |
Static Private Attributes | |
const UVersionInfo | fVersion |
Collator
class performs locale-sensitive string comparison.
You use this class to build searching and sorting routines for natural language text. Important: The ICU collation implementation is being reworked. This means that collation results and especially sort keys will change from ICU 1.6 to 1.7 and again to 1.8. For details, see the collation design document.
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, sort keys provide better performance. The getSortKey
methods convert a string to a series of bytes that can be compared bitwise against other sort keys using strcmp()
. Sort keys are written as zero-terminated byte strings. They consist of several substrings, one for each collation strength level, that are delimited by 0x01 bytes. If the string code points are appended for UCOL_IDENTICAL, then they are processed for correct code point order comparison and may contain 0x01 bytes but not zero bytes.
An older set of APIs returns a CollationKey
object that wraps the sort key bytes instead of returning the bytes themselves. Its use is deprecated, but it is still available for compatibility with Java.
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.
Definition at line 158 of file coll.h.
|
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. |
|
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.
|
|
Destructor.
|
|
Constructors.
|
|
|
|
|
|
Makes a shallow copy of the current object.
Reimplemented in RuleBasedCollator. |
|
String compare that uses user supplied character iteration. The idea is to prevent users from having to convert the whole string into UChar's before comparing since sometimes strings differ on first couple of characters.
Reimplemented in RuleBasedCollator. |
|
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);
Reimplemented in RuleBasedCollator. |
|
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);.
Reimplemented in RuleBasedCollator. |
|
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");
Reimplemented in RuleBasedCollator. |
|
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.
|
|
Creates the collator object for the current default locale. The default locale is determined by Locale::getDefault.
|
|
Convenience method for comparing two strings based on the collation rules.
|
|
Universal attribute getter.
Reimplemented in RuleBasedCollator. |
|
Get the set of Locales for which Collations are installed.
|
|
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.
Reimplemented in RuleBasedCollator. |
|
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.
Reimplemented in RuleBasedCollator. |
|
Get the decomposition mode of the collator object.
|
|
Get name of the object for the desired Locale, in the langauge of the default locale.
|
|
Get name of the object for the desired Locale, in the desired langauge.
|
|
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. |
|
Get the sort key as an array of bytes from an UChar buffer. Sort key byte arrays are zero-terminated and can be compared using strcmp().
Reimplemented in RuleBasedCollator. |
|
Get the sort key as an array of bytes from an UnicodeString. Sort key byte arrays are zero-terminated and can be compared using strcmp().
Reimplemented in RuleBasedCollator. |
|
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.
|
|
Gets the version information for a Collator.
|
|
Convenience method for comparing two strings based on the collation rules.
|
|
Convenience method for comparing two strings based on the collation rules.
|
|
Generates the hash code for the collation object.
Reimplemented in RuleBasedCollator. |
|
Returns true if "other" is not the same as "this".
Reimplemented in RuleBasedCollator. |
|
Assignment operator.
|
|
Returns true if "other" is the same as "this".
Reimplemented in RuleBasedCollator. |
|
Thread safe cloning operation.
Reimplemented in RuleBasedCollator. |
|
Universal attribute setter.
Reimplemented in RuleBasedCollator. |
|
Set the decomposition mode of the collator object. success is equal to U_ILLEGAL_ARGUMENT_ERROR if error occurs.
|
|
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");
|
|
|
|
|
|
|