RWUCollationKey Class Reference

Stores preprocessed comparison information for a Unicode string to speed repeated string comparisons. More...

#include <rw/i18n/RWUCollationKey.h>

Public Member Functions
	RWUCollationKey (const RWUCollationKey &original)
	RWUCollationKey (void)
	~RWUCollationKey (void)
RWUString	getString (void) const
unsigned	hash () const
bool	isValid (void) const
RWUCollationKey &	operator= (const RWUCollationKey &rhs)

Friends
std::strong_ordering	operator<=> (const RWUCollationKey &lhs, const RWUCollationKey &rhs)
bool	operator== (const RWUCollationKey &lhs, const RWUCollationKey &rhs)
class	RWUCollator

Detailed Description

RWUCollationKey stores preprocessed comparison information for a Unicode string, and can be used to speed repeated string comparisons. For example, you might choose to use collation keys when sorting a set of strings.

To create a valid RWUCollationKey, call RWUCollator::getCollationKey(). Generating a key is a non-trivial operation, since it involves determining the collation elements and weights for an entire string. Comparing two RWUCollationKey objects, however, is fast.

Note

Collation keys can only meaningfully be compared if they are created by the same collator, or by collators with the same attributes.

Example

#include <rw/i18n/RWUCollationKey.h>
#include <rw/i18n/RWUCollator.h>
#include <rw/i18n/RWUConversionContext.h>
#include <rw/tvsrtvec.h>
#include <iostream>
 
using std::cout;
using std::endl;
 
int main() {
  // Indicate that source and target strings are
  // encoded as UTF-8.
  RWUConversionContext context("UTF-8");
 
  // Create an array of country names.
  RWUString array[] = {"United States", "Netherlands", "United Kingdom",
                       "Germany",       "France",      "Italy",
                       "Japan",         "Australia",   ""};
  size_t max_array_length = 20;
 
  // Create a collator based on the "en" locale.
  RWUCollator collator("en");
 
  // Create an empty vector.  An RWTValSortedVector<T>
  // will automatically keep its contents in sorted
  // order.
  RWTValSortedVector<RWUCollationKey, std::less<RWUCollationKey> >
      vector(max_array_length);
  // Populate the vector with RWUCollationKey objects.
  // Note that the vector will use
  // RWUCollationKey::operator<() and operator==().
  size_t i;
  for (i = 0; array[i].isNull() == false; ++i) {
    vector.insert(collator.getCollationKey(array[i]));
  }  // for
 
  // Print the sorted vector.  Obtain RWUString objects
  // from the stored RWUCollationKey objects, implicitly
  // convert them to UTF-8, and print the UTF-8.
  cout << "Rogue Wave has offices in the following "
          "countries:"
       << endl;
  for (i = 0; i < vector.entries(); ++i) {
    cout << "  " << vector[i].getString() << endl;
  }
 
  return 0;
}

Program output:

Rogue Wave has offices in the following countries:
  Australia
  France
  Germany
  Italy
  Japan
  Netherlands
  United Kingdom
  United States

See also

RWUCollator

Constructor & Destructor Documentation

RWUCollationKey() [1/2]

RWUCollationKey::RWUCollationKey ( void )

inline

Default constructor. Creates an invalid key.

Invalid keys are equal to each other, and not equal to any other key. They are less than all other keys. Calling getString() on an invalid key results in an RWUException.

This constructor exists only as a convenience–for example, when creating an array of RWUCollationKey objects. To create a valid, usable RWUCollationKey, call RWUCollator::getCollationKey().

RWUCollationKey() [2/2]

RWUCollationKey::RWUCollationKey

(

const RWUCollationKey &

original

)

Copy constructor. Makes self a deep copy of original.

~RWUCollationKey()

RWUCollationKey::~RWUCollationKey ( void )

inline

Destructor.

Member Function Documentation

getString()

RWUString RWUCollationKey::getString

(

void

)

const

Returns the string whose collation value self holds. Throws RWUException if self is an invalid key.

hash()

unsigned RWUCollationKey::hash ( ) const

inline

Returns a hash value for self.

isValid()

bool RWUCollationKey::isValid ( void ) const

inline

Returns true if self is a valid key. Otherwise, returns false.

operator=()

RWUCollationKey & RWUCollationKey::operator=

(

const RWUCollationKey &

rhs

)

Assignment operator. Makes self a deep copy of rhs.

Friends And Related Symbol Documentation

operator<=>

std::strong_ordering operator<=> ( const RWUCollationKey & lhs, const RWUCollationKey & rhs )

friend

Performs a comparison of the collation keys represented by lhs to rhs.

Note

collation keys can only meaningfully be compared if they are created by the same collator, or by collators with the same attributes.

If a compiler does not support rewritten expressions (i.e. before C++20), comparison operators are explicitly implemented to provide equivalent behavior.

operator==

bool operator== ( const RWUCollationKey & lhs, const RWUCollationKey & rhs )

friend

Returns true if lhs compares equal to rhs. Otherwise, returns false.

Note

collation keys can only meaningfully be compared if they are created by the same collator, or by collators with the same attributes.

If a compiler does not support rewritten expressions (i.e. before C++20), equality operators are explicitly implemented to provide equivalent behavior.