ICU 74.2: i18n/unicode/ucoleitr.h File Reference

ICU 74.2 74.2

Macros | Typedefs | Functions
ucoleitr.h File Reference

C API: UCollationElements. More...

`#include "unicode/utypes.h"`
`#include "unicode/ucol.h"`

Go to the source code of this file.

## Macros
#define | UCOL_NULLORDER ((int32_t)0xFFFFFFFF)
| This indicates an error has occurred during processing or if no more CEs is to be returned.

## Typedefs
typedef struct UCollationElements | UCollationElements
| The UCollationElements struct.

## Functions
U_CAPI UCollationElements * | ucol_openElements (const UCollator *coll, const UChar *text, int32_t textLength, UErrorCode *status)
| Open the collation elements for a string.
U_CAPI int32_t | ucol_keyHashCode (const uint8_t *key, int32_t length)
| get a hash code for a key... Not very useful!
U_CAPI void | ucol_closeElements (UCollationElements *elems)
| Close a UCollationElements.
U_CAPI void | ucol_reset (UCollationElements *elems)
| Reset the collation elements to their initial state.
U_CAPI int32_t | ucol_next (UCollationElements *elems, UErrorCode *status)
| Get the ordering priority of the next collation element in the text.
U_CAPI int32_t | ucol_previous (UCollationElements *elems, UErrorCode *status)
| Get the ordering priority of the previous collation element in the text.
U_CAPI int32_t | ucol_getMaxExpansion (const UCollationElements *elems, int32_t order)
| Get the maximum length of any expansion sequences that end with the specified comparison order.
U_CAPI void | ucol_setText (UCollationElements *elems, const UChar *text, int32_t textLength, UErrorCode *status)
| Set the text containing the collation elements.
U_CAPI int32_t | ucol_getOffset (const UCollationElements *elems)
| Get the offset of the current source character.
U_CAPI void | ucol_setOffset (UCollationElements *elems, int32_t offset, UErrorCode *status)
| Set the offset of the current source character.
U_CAPI int32_t | ucol_primaryOrder (int32_t order)
| Get the primary order of a collation order.
U_CAPI int32_t | ucol_secondaryOrder (int32_t order)
| Get the secondary order of a collation order.
U_CAPI int32_t | ucol_tertiaryOrder (int32_t order)
| Get the tertiary order of a collation order.

## Detailed Description

C API: UCollationElements.

The UCollationElements API 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 Slovak and in traditional Spanish collation:

    .       "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 phonebook collation,

    .       "<ae ligature>b"-> the first key is key('a'), the second key is key('e'), and
    .       the third key is key('b').

Example of the iterator usage: (without error checking)

    .  void CollationElementIterator_Example()
    .  {
    .      UChar *s;
    .      t_int32 order, primaryOrder;
    .      UCollationElements *c;
    .      UCollatorOld *coll;
    .      UErrorCode success = U_ZERO_ERROR;
    .      str=(UChar*)malloc(sizeof(UChar) * (strlen("This is a test")+1) );
    .      u_uastrcpy(str, "This is a test");
    .      coll = ucol_open(NULL, &success);
    .      c = ucol_openElements(coll, str, u_strlen(str), &status);
    .      order = ucol_next(c, &success);
    .      ucol_reset(c);
    .      order = ucol_prev(c, &success);
    .      free(str);
    .      ucol_close(coll);
    .      ucol_closeElements(c);
    .  }

<p<blockquote>‍

ucol_next() returns the collation order of the next. ucol_prev() returns the collation order of the previous character. The Collation Element Iterator moves only in one direction between calls to ucol_reset. That is, ucol_next() and ucol_prev can not be inter-used. Whenever ucol_prev is to be called after ucol_next() or vice versa, ucol_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 ucol_prev or ucol_next, the first or last collation order will be returned. If a change of direction is done without a ucol_reset, the result is undefined. The result of a forward iterate (ucol_next) and reversed result of the
backward iterate (ucol_prev) on the same string are equivalent, if collation orders with the value 0 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 int32_t.

See also
  UCollator

Definition in file ucoleitr.h.

## Macro Definition Documentation

## ◆ UCOL_NULLORDER

#define UCOL_NULLORDER ((int32_t)0xFFFFFFFF)

This indicates an error has occurred during processing or if no more CEs is to be returned.

Stable:
  ICU 2.0

Definition at line 30 of file ucoleitr.h.

## Typedef Documentation

## ◆ UCollationElements

typedef struct UCollationElements UCollationElements

The UCollationElements struct.

For usage in C programs.

Stable:
  ICU 2.0

Definition at line 39 of file ucoleitr.h.

## Function Documentation

## ◆ ucol_closeElements()

U_CAPI void ucol_closeElements | ( | UCollationElements * | elems | ) |

Close a UCollationElements.

Once closed, a UCollationElements may no longer be used.

Parameters

  elems | The UCollationElements to close.

Stable:
  ICU 2.0

## ◆ ucol_getMaxExpansion()

U_CAPI int32_t ucol_getMaxExpansion | ( | const UCollationElements * | elems,
|  | int32_t | order
| ) |  |

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

This is useful for .... ?

Parameters

  elems | The UCollationElements containing the text.
  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:
  ICU 2.0

## ◆ ucol_getOffset()

U_CAPI int32_t ucol_getOffset | ( | const UCollationElements * | elems | ) |

Get the offset of the current source character.

This is an offset into the text of the character containing the current collation elements.

Parameters

  elems | The UCollationElements to query.

Returns
  The offset of the current source character.

See also
  ucol_setOffset

Stable:
  ICU 2.0

## ◆ ucol_keyHashCode()

U_CAPI int32_t ucol_keyHashCode | ( | const uint8_t * | key,
|  | int32_t | length
| ) |  |

get a hash code for a key... Not very useful!

Parameters

  key | the given key.
  length | the size of the key array.

Returns
  the hash code.

Stable:
  ICU 2.0

## ◆ ucol_next()

U_CAPI int32_t ucol_next | ( | UCollationElements * | elems,
|  | UErrorCode * | status
| ) |  |

Get the ordering priority of the next collation element in the text.

A single character may contain more than one collation element.

Parameters

  elems | The UCollationElements containing the text.
  status | A pointer to a UErrorCode to receive any errors.

Returns
  The next collation elements ordering, otherwise returns UCOL_NULLORDER if an error has occurred or if the end of string has been reached

Stable:
  ICU 2.0

## ◆ ucol_openElements()

U_CAPI UCollationElements * ucol_openElements | ( | const UCollator * | coll,
|  | const UChar * | text,
|  | int32_t | textLength,
|  | UErrorCode * | status
| ) |  |

Open the collation elements for a string.

The UCollationElements retains a pointer to the supplied text. The caller must not modify or delete the text while the UCollationElements object is used to iterate over this text.

Parameters

  coll | The collator containing the desired collation rules.
  text | The text to iterate over.
  textLength | The number of characters in text, or -1 if null-terminated
  status | A pointer to a UErrorCode to receive any errors.

Returns
  a struct containing collation element information

Stable:
  ICU 2.0

## ◆ ucol_previous()

U_CAPI int32_t ucol_previous | ( | UCollationElements * | elems,
|  | UErrorCode * | status
| ) |  |

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

A single character may contain more than one collation element. Note that internally a stack is used to store buffered collation elements.

Parameters

  elems | The UCollationElements containing the text.
  status | A pointer to a UErrorCode to receive any errors. Notably a U_BUFFER_OVERFLOW_ERROR is returned if the internal stack buffer has been exhausted.

Returns
  The previous collation elements ordering, otherwise returns UCOL_NULLORDER if an error has occurred or if the start of string has been reached.

Stable:
  ICU 2.0

## ◆ ucol_primaryOrder()

U_CAPI int32_t ucol_primaryOrder | ( | int32_t | order | ) |

Get the primary order of a collation order.

Parameters

  order | the collation order

Returns
  the primary order of a collation order.

Stable:
  ICU 2.6

## ◆ ucol_reset()

U_CAPI void ucol_reset | ( | UCollationElements * | elems | ) |

Reset the collation elements to their initial state.

This will move the 'cursor' to the beginning of the text. Property settings for collation will be reset to the current status.

Parameters

  elems | The UCollationElements to reset.

See also
  ucol_next
  ucol_previous

Stable:
  ICU 2.0

## ◆ ucol_secondaryOrder()

U_CAPI int32_t ucol_secondaryOrder | ( | int32_t | order | ) |

Get the secondary order of a collation order.

Parameters

  order | the collation order

Returns
  the secondary order of a collation order.

Stable:
  ICU 2.6

## ◆ ucol_setOffset()

U_CAPI void ucol_setOffset | ( | UCollationElements * | elems,
|  | int32_t | offset,
|  | UErrorCode * | status
| ) |  |

Set the offset of the current source character.

This is an offset into the text of the character to be processed. Property settings for collation will remain the same. In order to reset the iterator to the current collation property settings, the API reset() has to be called.

Parameters

  elems | The UCollationElements to set.
  offset | The desired character offset.
  status | A pointer to a UErrorCode to receive any errors.

See also
  ucol_getOffset

Stable:
  ICU 2.0

## ◆ ucol_setText()

U_CAPI void ucol_setText | ( | UCollationElements * | elems,
|  | const UChar * | text,
|  | int32_t | textLength,
|  | UErrorCode * | status
| ) |  |

Set the text containing the collation elements.

Property settings for collation will remain the same. In order to reset the iterator to the current collation property settings, the API reset() has to be called.

The UCollationElements retains a pointer to the supplied text. The caller must not modify or delete the text while the UCollationElements object is used to iterate over this text.

Parameters

  elems | The UCollationElements to set.
  text | The source text containing the collation elements.
  textLength | The length of text, or -1 if null-terminated.
  status | A pointer to a UErrorCode to receive any errors.

See also
  ucol_getText

Stable:
  ICU 2.0

## ◆ ucol_tertiaryOrder()

U_CAPI int32_t ucol_tertiaryOrder | ( | int32_t | order | ) |

Get the tertiary order of a collation order.

Parameters

  order | the collation order

Returns
  the tertiary order of a collation order.

Stable:
  ICU 2.6