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CollationElementIterator Class Reference

The CollationElementIterator class is used as an iterator to walk through each character of an international string. More...

#include <coleitr.h>


Public Methods

 CollationElementIterator (const CollationElementIterator &other)
 Copy constructor. More...

 ~CollationElementIterator ()
 Destructor @stable.

UBool operator== (const CollationElementIterator &other) const
 Returns true if "other" is the same as "this" @stable.

UBool operator!= (const CollationElementIterator &other) const
 Returns true if "other" is not the same as "this". More...

void reset (void)
 Resets the cursor to the beginning of the string. More...

int32_t next (UErrorCode &status)
 Gets the ordering priority of the next character in the string. More...

int32_t previous (UErrorCode &status)
 Get the ordering priority of the previous collation element in the string. More...

int32_t getMaxExpansion (int32_t order) const
 Return the maximum length of any expansion sequences that end with the specified comparison order. More...

int32_t strengthOrder (int32_t order) const
 Gets the comparison order in the desired strength. More...

void setText (const UnicodeString &str, UErrorCode &status)
 Sets the source string. More...

void setText (CharacterIterator &str, UErrorCode &status)
 Sets the source string. More...

UTextOffset getOffset (void) const
 Gets the offset of the currently processed character in the source string. More...

void setOffset (UTextOffset newOffset, UErrorCode &status)
 Sets the offset of the currently processed character in the source string. More...


Static Public Methods

int32_t primaryOrder (int32_t order)
 Gets the primary order of a collation order. More...

int32_t secondaryOrder (int32_t order)
 Gets the secondary order of a collation order. More...

int32_t tertiaryOrder (int32_t order)
 Gets the tertiary order of a collation order. More...

UBool isIgnorable (int32_t order)
 Checks if a comparison order is ignorable. More...


Static Public Attributes

int32_t const NULLORDER
 NULLORDER indicates that an error has occured while processing.


Protected Methods

 CollationElementIterator (const UnicodeString &sourceText, const RuleBasedCollator *order, UErrorCode &status)
 CollationElementIterator constructor. More...

 CollationElementIterator (const CharacterIterator &sourceText, const RuleBasedCollator *order, UErrorCode &status)
 CollationElementIterator constructor. More...

const CollationElementIterator & operator= (const CollationElementIterator &other)
 Assignment operator.


Friends

class RuleBasedCollator


Detailed Description

The CollationElementIterator class is used as an iterator to walk through each character of an international string.

Use the iterator to return the ordering priority of the positioned character. The ordering priority of a character, which we refer to as a key, defines how a character is collated in the given collation object. For example, consider the following in Spanish:

 
        "ca" -> the first key is key('c') and second key is key('a').
        "cha" -> the first key is key('ch') and second key is key('a').
And in German,
 
        "ęb"-> the first key is key('a'), the second key is key('e'), and
        the third key is key('b').
The key of a character, is an integer composed of primary order(short), secondary order(char), and tertiary order(char). Java strictly defines the size and signedness of its primitive data types. Therefore, the static functions primaryOrder(), secondaryOrder(), and tertiaryOrder() return int32_t to ensure the correctness of the key value.

Example of the iterator usage: (without error checking)

 
   void CollationElementIterator_Example()
   {
       UnicodeString str = "This is a test";
       UErrorCode success = U_ZERO_ERROR;
       RuleBasedCollator* rbc =
           (RuleBasedCollator*) RuleBasedCollator::createInstance(success);
       CollationElementIterator* c =
           rbc->createCollationElementIterator( str );
       int32_t order = c->next(success);
       c->reset();
       order = c->previous(success);
       delete c;
       delete rbc;
   }

CollationElementIterator::next returns the collation order of the next character based on the comparison level of the collator. CollationElementIterator::previous returns the collation order of the previous character based on the comparison level of the collator. The Collation Element Iterator moves only in one direction between calls to CollationElementIterator::reset. That is, CollationElementIterator::next() and CollationElementIterator::previous can not be inter-used. Whenever CollationElementIterator::previous is to be called after CollationElementIterator::next() or vice versa, CollationElementIterator::reset has to be called first to reset the status, shifting pointers to either the end or the start of the string. Hence at the next call of CollationElementIterator::previous or CollationElementIterator::next(), the first or last collation order will be returned. If a change of direction is done without a CollationElementIterator::reset(), the result is undefined. The result of a forward iterate (CollationElementIterator::next) and reversed result of the backward iterate (CollationElementIterator::previous) on the same string are equivalent, if collation orders with the value UCOL_IGNORABLE are ignored. Character based on the comparison level of the collator. A collation order consists of primary order, secondary order and tertiary order. The data type of the collation order is t_int32.

Note, CollationElementIterator should not be subclassed.

See also:
Collator , RuleBasedCollator
Version:
1.8 Jan 16 2001


Constructor & Destructor Documentation

CollationElementIterator::CollationElementIterator const CollationElementIterator &    other
 

Copy constructor.

@stable

CollationElementIterator::CollationElementIterator const UnicodeString   sourceText,
const RuleBasedCollator   order,
UErrorCode   status
[protected]
 

CollationElementIterator constructor.

This takes the source string and the collation object. The cursor will walk thru the source string based on the predefined collation rules. If the source string is empty, NULLORDER will be returned on the calls to next().

Parameters:
sourceText  the source string.
startOffset  the beginning offset of the string where the cursor starts the iterating.
endOffset  the ending offset of the string where the cursor stops the iterating.
order  the collation object.

CollationElementIterator::CollationElementIterator const CharacterIterator   sourceText,
const RuleBasedCollator   order,
UErrorCode   status
[protected]
 

CollationElementIterator constructor.

This takes the source string and the collation object. The cursor will walk thru the source string based on the predefined collation rules. If the source string is empty, NULLORDER will be returned on the calls to next().

Parameters:
sourceText  the source string.
startOffset  the beginning offset of the string where the cursor starts the iterating.
endOffset  the ending offset of the string where the cursor stops the iterating.
order  the collation object.


Member Function Documentation

int32_t CollationElementIterator::getMaxExpansion int32_t    order const [inline]
 

Return the maximum length of any expansion sequences that end with the specified comparison order.

Parameters:
order  a collation order returned by previous or next.
Returns:
maximum size of the expansion sequences ending with the collation element or 1 if collation element does not occur at the end of any expansion sequence @stable

UTextOffset CollationElementIterator::getOffset void    const
 

Gets the offset of the currently processed character in the source string.

Returns:
the offset of the character. @stable

UBool CollationElementIterator::isIgnorable int32_t    order [inline, static]
 

Checks if a comparison order is ignorable.

Parameters:
order  the collation order.
Returns:
TRUE if a character is ignorable, FALSE otherwise. @stable

int32_t CollationElementIterator::next UErrorCode   status
 

Gets the ordering priority of the next character in the string.

Parameters:
status  the error code status.
Returns:
the next character's ordering. otherwise returns NULLORDER if an error has occured or if the end of string has been reached @stable

UBool CollationElementIterator::operator!= const CollationElementIterator &    other const
 

Returns true if "other" is not the same as "this".

@stable

int32_t CollationElementIterator::previous UErrorCode   status
 

Get the ordering priority of the previous collation element in the string.

Parameters:
status  the error code status.
Returns:
the previous element's ordering. otherwise returns NULLORDER if an error has occured or if the start of string has been reached @stable

int32_t CollationElementIterator::primaryOrder int32_t    order [inline, static]
 

Gets the primary order of a collation order.

Parameters:
order  the collation order
Returns:
the primary order of a collation order. @stable

void CollationElementIterator::reset void   
 

Resets the cursor to the beginning of the string.

@stable

int32_t CollationElementIterator::secondaryOrder int32_t    order [inline, static]
 

Gets the secondary order of a collation order.

Parameters:
order  the collation order
Returns:
the secondary order of a collation order. @stable

void CollationElementIterator::setOffset UTextOffset    newOffset,
UErrorCode   status
 

Sets the offset of the currently processed character in the source string.

Parameters:
newOffset  the new offset.
status  the error code status.
Returns:
the offset of the character. @stable

void CollationElementIterator::setText CharacterIterator   str,
UErrorCode   status
 

Sets the source string.

Parameters:
str  the source character iterator.
status  the error code status. @stable

void CollationElementIterator::setText const UnicodeString   str,
UErrorCode   status
 

Sets the source string.

Parameters:
str  the source string.
status  the error code status. @stable

int32_t CollationElementIterator::strengthOrder int32_t    order const
 

Gets the comparison order in the desired strength.

Ignore the other differences.

Parameters:
order  The order value @stable

int32_t CollationElementIterator::tertiaryOrder int32_t    order [inline, static]
 

Gets the tertiary order of a collation order.

Parameters:
order  the collation order
Returns:
the tertiary order of a collation order. @stable


The documentation for this class was generated from the following file:
Generated on Tue Mar 5 13:05:53 2002 for ICU 2.0 by doxygen1.2.14 written by Dimitri van Heesch, © 1997-2002