utext.h File Reference

C API: Abstract Unicode Text API. More...

#include "unicode/utypes.h"

Go to the source code of this file.

Data Structures

struct  UTextChunk
 Descriptor of a chunk, or segment of text in UChar format. More...
struct  UText
 UText struct. More...

Defines

#define UTEXT_NEXT32(ut)
 inline version of utext_next32(), for performance-critical situations.
#define UTEXT_PREVIOUS32(ut)
 inline version of utext_previous32(), for performance-critical situations.
#define UTEXT_CHUNK_INIT
 Initializer for a UTextChunk.
#define UTEXT_INITIALIZER_HEAD
 Initializer for the first part of a UText struct, the part that is in common for all types of text providers.
#define UTEXT_INITIALIZER
 initializer to be used with local (stack) instances of a UText struct.

Typedefs

typedef UText UText
 C typedef for struct UText.
typedef UTextChunk UTextChunk
 C typedef for struct UTextChunk.
typedef UText *U_CALLCONV UTextClone (UText *dest, const UText *src, UBool deep, UErrorCode *status)
 Function type declaration for UText.clone().
typedef int32_t U_CALLCONV UTextNativeLength (UText *ut)
 Function type declaration for UText.nativeLength().
typedef UBool U_CALLCONV UTextAccess (UText *ut, int32_t nativeIndex, UBool forward, UTextChunk *chunk)
 Function type declaration for UText.access().
typedef int32_t U_CALLCONV UTextExtract (UText *ut, int32_t nativeStart, int32_t nativeLimit, UChar *dest, int32_t destCapacity, UErrorCode *status)
 Function type declaration for UText.extract().
typedef int32_t U_CALLCONV UTextReplace (UText *ut, int32_t nativeStart, int32_t nativeLimit, const UChar *replacementText, int32_t replacmentLength, UErrorCode *status)
 Function type declaration for UText.replace().
typedef void U_CALLCONV UTextCopy (UText *ut, int32_t nativeStart, int32_t nativeLimit, int32_t nativeDest, UBool move, UErrorCode *status)
 Function type declaration for UText.copy().
typedef int32_t U_CALLCONV UTextMapOffsetToNative (UText *ut, int32_t offset)
 Function type declaration for UText.mapOffsetToNative().
typedef int32_t U_CALLCONV UTextMapNativeIndexToUTF16 (UText *ut, int32_t nativeIndex)
 Function type declaration for UText.mapIndexToUTF16().
typedef void U_CALLCONV UTextClose (UText *ut)
 Function type declaration for UText.utextClose().

Enumerations

enum  {
  UTEXT_PROVIDER_NON_UTF16_INDEXES = 0, UTEXT_PROVIDER_LENGTH_IS_EXPENSIVE = 1, UTEXT_PROVIDER_STABLE_CHUNKS = 2, UTEXT_PROVIDER_WRITABLE = 3,
  UTEXT_PROVIDER_HAS_META_DATA = 4
}
 UText provider properties (bit field indexes). More...
enum  { UTEXT_MAGIC = 0x345ad82c }

Functions

U_DRAFT UText *U_EXPORT2 utext_close (UText *ut)
 utext_close Close function for UText instances.
U_DRAFT UText *U_EXPORT2 utext_openUTF8 (UText *ut, const char *s, int32_t length, UErrorCode *status)
 Open a read-only UText implementation for UTF-8 strings.
U_DRAFT UText *U_EXPORT2 utext_openUChars (UText *ut, const UChar *s, int32_t length, UErrorCode *status)
 Open a read-only UText for UChar * string.
U_DRAFT UText *U_EXPORT2 utext_clone (UText *dest, const UText *src, UBool deep, UErrorCode *status)
 clone a UText.
U_DRAFT int32_t U_EXPORT2 utext_nativeLength (UText *ut)
 Get the length of the text.
U_DRAFT UBool U_EXPORT2 utext_isLengthExpensive (const UText *ut)
 Return TRUE if calculating the length of the text could be expensive.
U_DRAFT UChar32 U_EXPORT2 utext_char32At (UText *ut, int32_t nativeIndex)
 Returns the code point at the requested index, or U_SENTINEL (-1) if it is out of bounds.
U_DRAFT UChar32 U_EXPORT2 utext_current32 (UText *ut)
 Get the code point at the current iteration position, or U_SENTINEL (-1) if the iteration has reached the end of the input text.
U_DRAFT UChar32 U_EXPORT2 utext_next32 (UText *ut)
 Get the code point at the current iteration position of the UText, and advance the position to the first index following the character.
U_DRAFT UChar32 U_EXPORT2 utext_previous32 (UText *ut)
 Move the iterator position to the character (code point) whose index precedes the current position, and return that character.
U_DRAFT UChar32 U_EXPORT2 utext_next32From (UText *ut, int32_t nativeIndex)
 Set the iteration index, access the text for forward iteration, and return the code point starting at or before that index.
U_DRAFT UChar32 U_EXPORT2 utext_previous32From (UText *ut, int32_t nativeIndex)
 Set the iteration index, and return the code point preceding the one specified by the initial index.
U_DRAFT int32_t U_EXPORT2 utext_getNativeIndex (UText *ut)
 Get the current iterator position, which can range from 0 to the length of the text.
U_DRAFT void U_EXPORT2 utext_setNativeIndex (UText *ut, int32_t nativeIndex)
 Set the current iteration position to the nearest code point boundary at or preceding the specified index.
U_DRAFT UBool U_EXPORT2 utext_moveIndex32 (UText *ut, int32_t delta)
 Move the iterator postion by delta code points.
U_DRAFT int32_t U_EXPORT2 utext_extract (UText *ut, int32_t nativeStart, int32_t nativeLimit, UChar *dest, int32_t destCapacity, UErrorCode *status)
 Extract text from a UText into a UChar buffer.
U_DRAFT UBool U_EXPORT2 utext_isWritable (const UText *ut)
 Return TRUE if the text can be written with utext_replace() or utext_copy().
U_DRAFT UBool U_EXPORT2 utext_hasMetaData (const UText *ut)
 Test whether there is meta data associated with the text.
U_DRAFT int32_t U_EXPORT2 utext_replace (UText *ut, int32_t nativeStart, int32_t nativeLimit, const UChar *replacementText, int32_t replacementLength, UErrorCode *status)
 Replace a range of the original text with a replacement text.
U_DRAFT void U_EXPORT2 utext_copy (UText *ut, int32_t nativeStart, int32_t nativeLimit, int32_t destIndex, UBool move, UErrorCode *status)
 Copy or move a substring from one position to another within the text, while retaining any metadata associated with the text.
U_DRAFT UText *U_EXPORT2 utext_setup (UText *ut, int32_t extraSpace, UErrorCode *status)
 Common function for use by Text Provider implementations to allocate and/or initialize a new UText struct.


Detailed Description

C API: Abstract Unicode Text API.

The Text Access API provides a means to allow text that is stored in alternative formats to work with ICU services. ICU normally operates on text that is stored UTF-16 format, in (UChar *) arrays for the C APIs or as type UnicodeString for C++ APIs.

ICU Text Access allows other formats, such as UTF-8 or non-contiguous UTF-16 strings, to be placed in a UText wrapper and then passed to ICU services.

There are three general classes of usage for UText:

Application Level Use. This is the simplest usage - applications would use one of the utext_open() functions on their input text, and pass the resulting UText to the desired ICU service.

Second is usage in ICU Services, such as break iteration, that will need to operate on input presented to them as a UText. These implementations will need to use the iteration and related UText functions to gain access to the actual text.

The third class of UText users are "text providers." These are the UText implementations for the various text storage formats. An application or system with a unique text storage format can implement a set of UText provider functions for that format, which will then allow ICU services to operate on that format.

Iterating over text

Here is sample code for a forward iteration over the contents of a UText

    UChar32  c;
    UText    *ut = whatever();

    for (c=utext_next32From(ut, 0); c>=0; c=utext_next32(ut)) {
       // do whatever with the codepoint c here.
    }

And here is similar code to iterate in the reverse direction, from the end of the text towards the beginning.

    UChar32  c;
    UText    *ut = whatever();
    int      textLength = utext_nativeLength(ut);
    for (c=utext_previous32From(ut, textLength); c>=0; c=utext_previous32(ut)) {
       // do whatever with the codepoint c here.
    }

Characters and Indexing

Indexing into text by UText functions is nearly always in terms of the native indexing of the underlying text storage. The storage format could be UTF-8 or UTF-32, for example. When coding to the UText access API, no assumptions can be made regarding the size of characters, or how far an index may move when iterating between characters.

All indices supplied to UText functions are pinned to the length of the text. An out-of-bounds index is not considered to be an error, but is adjusted to be in the range 0 <= index <= length of input text.

When an index position is returned from a UText function, it will be a native index to the underlying text. In the case of multi-unit characters, it will always refer to the first position of the character, never to the interior. This is essentially the same thing as saying that a returned index will always point to a boundary between characters.

When a native index is supplied to a UText function, all indices that refer to any part of a multi-unit character representation are considered to be equivalent. In the case of multi-unit characters, an incoming index will be logically normalized to refer to the start of the character.

It is possible to test whether a native index is on a code point boundary by doing a utext_setNativeIndex() followed by a utext_getNativeIndex(). If the index is returned unchanged, it was on a code point boundary. If an adjusted index is returned, the original index referred to the interior of a character.

Definition in file utext.h.


Define Documentation

#define UTEXT_CHUNK_INIT
 

Value:

{                               \
                  NULL,                /* contents      */ \
                  0,                   /* offset        */ \
                  0,                   /* length        */ \
                  0,                   /* start         */ \
                  0,                   /* limit         */ \
                  FALSE,               /* nonUTF16idx   */ \
                  FALSE, FALSE, FALSE, /* padding1,2,3  */ \
                  0, 0,                /* padInt1, 2    */ \
                  sizeof(UTextChunk)                       \
}
Initializer for a UTextChunk.

Internal:
Do not use. This API is for interal use only.

Definition at line 1233 of file utext.h.

#define UTEXT_INITIALIZER
 

Value:

{                                \
                  UTEXT_INITIALIZER_HEAD,                  \
                  NULL,                 /* clone ()     */ \
                  NULL,                 /* length ()    */ \
                  NULL,                 /* access ()    */ \
                  NULL,                 /* extract ()   */ \
                  NULL,                 /* replace ()   */ \
                  NULL,                 /* copy ()      */ \
                  NULL, NULL,           /* map * 2 ()   */ \
                  NULL                  /* close ()     */ \
}
initializer to be used with local (stack) instances of a UText struct.

UText structs must be initialized before passing them to one of the utext_open functions.

Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

Definition at line 1274 of file utext.h.

#define UTEXT_INITIALIZER_HEAD
 

Value:

NULL,                 /* context       */ \
                  NULL, NULL, NULL,     /* p, q, r       */ \
                  NULL,                 /* pExtra        */ \
                  0,                    /* extraSize     */ \
                  0,                    /* flags         */ \
                  UTEXT_MAGIC,          /* magic         */ \
                  sizeof(UText),        /* sizeOfStruct  */ \
                  0, 0, 0,              /* a, b, c       */ \
                  0,                    /* providerProps */ \
                  UTEXT_CHUNK_INIT
Initializer for the first part of a UText struct, the part that is in common for all types of text providers.

Internal:
Do not use. This API is for interal use only.

Definition at line 1253 of file utext.h.

#define UTEXT_NEXT32 ut   ) 
 

Value:

((ut)->chunk.offset < (ut)->chunk.length && ((ut)->chunk.contents)[(ut)->chunk.offset]<0xd800 ? \
    ((ut)->chunk.contents)[((ut)->chunk.offset)++] : utext_next32(ut))
inline version of utext_next32(), for performance-critical situations.

Get the code point at the current iteration position of the UText, and advance the position to the first index following the character. This is a post-increment operation. Returns U_SENTINEL (-1) if the position is at the end of the text.

Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

Definition at line 570 of file utext.h.

#define UTEXT_PREVIOUS32 ut   ) 
 

Value:

((ut)->chunk.offset > 0 && \
     (ut)->chunk.contents[(ut)->chunk.offset-1] < 0xd800 ? \
          (ut)->chunk.contents[--((ut)->chunk.offset)]  :  utext_previous32(ut))
inline version of utext_previous32(), for performance-critical situations.

Move the iterator position to the character (code point) whose index precedes the current position, and return that character. This is a pre-decrement operation. Returns U_SENTINEL (-1) if the position is at the start of the text.

Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

Definition at line 584 of file utext.h.


Typedef Documentation

typedef struct UText UText
 

C typedef for struct UText.

Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

Definition at line 120 of file utext.h.

typedef UBool U_CALLCONV UTextAccess(UText *ut, int32_t nativeIndex, UBool forward, UTextChunk *chunk)
 

Function type declaration for UText.access().

Get the description of the text chunk containing the text at a requested native index. The UText's iteration position will be left at the requested index. If the index is out of bounds, the iteration position will be left at the start or end of the string, as appropriate.

Chunks must begin and end on code point boundaries. A single code point comprised of multiple storage units must never span a chunk boundary.

Parameters:
ut the UText being accessed.
nativeIndex Requested index of the text to be accessed.
forward If TRUE, then the returned chunk must contain text starting from the index, so that start<=index<limit. If FALSE, then the returned chunk must contain text before the index, so that start<index<=limit.
Returns:
True if the requested index could be accessed. The chunk will contain the requested text. False value if a chunk cannot be accessed (the requested index is out of bounds).
See also:
UText
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

Definition at line 871 of file utext.h.

typedef struct UTextChunk UTextChunk
 

C typedef for struct UTextChunk.

Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

Definition at line 123 of file utext.h.

typedef UText* U_CALLCONV UTextClone(UText *dest, const UText *src, UBool deep, UErrorCode *status)
 

Function type declaration for UText.clone().

clone a UText. Much like opening a UText where the source text is itself another UText.

A deep clone will copy both the UText data structures and the underlying text. The original and cloned UText will operate completely independently; modifications made to the text in one will not effect the other. Text providers are not required to support deep clones. The user of clone() must check the status return and be prepared to handle failures.

A shallow clone replicates only the UText data structures; it does not make a copy of the underlying text. Shallow clones can be used as an efficient way to have multiple iterators active in a single text string that is not being modified.

A shallow clone operation must not fail except for truly exceptional conditions such as memory allocation failures.

A UText and its clone may be safely concurrently accessed by separate threads. This is true for both shallow and deep clones. It is the responsibility of the Text Provider to ensure that this thread safety constraint is met.

Parameters:
dest A UText struct to be filled in with the result of the clone operation, or NULL if the clone function should heap-allocate a new UText struct.
src The UText to be cloned.
deep TRUE to request a deep clone, FALSE for a shallow clone.
status Errors are returned here. For deep clones, U_UNSUPPORTED_ERROR should be returned if the text provider is unable to clone the original text.
Returns:
The newly created clone, or NULL if the clone operation failed.
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

Definition at line 831 of file utext.h.

typedef void U_CALLCONV UTextClose(UText *ut)
 

Function type declaration for UText.utextClose().

A Text Provider close function is only required for provider types that make allocations in their open function (or other functions) that must be cleaned when the UText is closed.

The allocation of the UText struct itself and any "extra" storage associated with the UText is handled by the common UText implementation and does not require provider specific cleanup in a close function.

Most UText provider implementations do not need to implement this function.

Parameters:
ut A UText object to be closed.
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

Definition at line 1032 of file utext.h.

typedef void U_CALLCONV UTextCopy(UText *ut, int32_t nativeStart, int32_t nativeLimit, int32_t nativeDest, UBool move, UErrorCode *status)
 

Function type declaration for UText.copy().

Copy or move a substring from one position to another within the text, while retaining any metadata associated with the text. This function is used to duplicate or reorder substrings. The destination index must not overlap the source range.

The text to be copied or moved is inserted at destIndex; it does not replace or overwrite any existing text.

This function need only be implemented for UText types that support writing.

When using this function, there should be only a single UText opened onto the underlying native text string. The function is responsible for updating the text chunk within the UText to reflect the updated iteration position, taking into account any changes to the underlying string's structure caused by the replace operation.

Parameters:
ut The UText representing the text to be operated on.
nativeStart The index of the start of the region to be copied or moved
nativeLimit The index of the character following the region to be replaced.
nativeDest The destination index to which the source substring is copied or moved.
move If TRUE, then the substring is moved, not copied/duplicated.
status receives any error status. Possible errors include U_NO_WRITE_PERMISSION
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

Definition at line 970 of file utext.h.

typedef int32_t U_CALLCONV UTextExtract(UText *ut, int32_t nativeStart, int32_t nativeLimit, UChar *dest, int32_t destCapacity, UErrorCode *status)
 

Function type declaration for UText.extract().

Extract text from a UText into a UChar buffer. The range of text to be extracted is specified in the native indices of the UText provider. These may not necessarily be UTF-16 indices.

The size (number of 16 bit UChars) in the data to be extracted is returned. The full amount is returned, even when the specified buffer size is smaller.

The extracted string will (if you are a user) / must (if you are a text provider) be NUL-terminated if there is sufficient space in the destination buffer.

Parameters:
ut the UText from which to extract data.
nativeStart the native index of the first characer to extract.
nativeLimit the native string index of the position following the last character to extract.
dest the UChar (UTF-16) buffer into which the extracted text is placed
destCapacity The size, in UChars, of the destination buffer. May be zero for precomputing the required size.
status receives any error status. If U_BUFFER_OVERFLOW_ERROR: Returns number of UChars for preflighting.
Returns:
Number of UChars in the data. Does not include a trailing NUL.
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

Definition at line 901 of file utext.h.

typedef int32_t U_CALLCONV UTextMapNativeIndexToUTF16(UText *ut, int32_t nativeIndex)
 

Function type declaration for UText.mapIndexToUTF16().

Map from a native index to a UChar offset within a text chunk

This function is required only for text providers that do not use native UTF-16 indexes.

Parameters:
ut The UText containing the text chunk.
nativeIndex Absolute (native) text index, chunk->start<=index<=chunk->limit.
Returns:
Chunk-relative UTF-16 offset corresponding to the specified native index.
TODO: specify behavior with out-of-bounds index? Shouldn't ever occur.
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

Definition at line 1011 of file utext.h.

typedef int32_t U_CALLCONV UTextMapOffsetToNative(UText *ut, int32_t offset)
 

Function type declaration for UText.mapOffsetToNative().

Map from a UChar offset within the current text chunk within the UText to the corresponding native index in the original source text.

This is required only for text providers that do not use native UTF-16 indexes.

TODO: specify behavior with out-of-bounds offset? Shouldn't ever occur.

Parameters:
ut the UText.
offset UTF-16 offset within text chunk 0<=offset<=chunk->length.
Returns:
Absolute (native) index corresponding to the specified chunk offset. The returned native index should always be to a code point boundary.
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

Definition at line 994 of file utext.h.

typedef int32_t U_CALLCONV UTextNativeLength(UText *ut)
 

Function type declaration for UText.nativeLength().

Parameters:
ut the UText to get the length of.
Returns:
the length, in the native units of the original text string.
See also:
UText
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

Definition at line 843 of file utext.h.

typedef int32_t U_CALLCONV UTextReplace(UText *ut, int32_t nativeStart, int32_t nativeLimit, const UChar *replacementText, int32_t replacmentLength, UErrorCode *status)
 

Function type declaration for UText.replace().

Replace a range of the original text with a replacement text.

Leaves the current iteration position at the position following the newly inserted replacement text.

This function need only be implemented on UText types that support writing.

When using this function, there should be only a single UText opened onto the underlying native text string. The function is responsible for updating the text chunk within the UText to reflect the updated iteration position, taking into account any changes to the underlying string's structure caused by the replace operation.

Parameters:
ut the UText representing the text to be operated on.
nativeStart the index of the start of the region to be replaced
nativeLimit the index of the character following the region to be replaced.
replacementText pointer to the replacement text
replacmentLength length of the replacement text in UChars, or -1 if the text is NUL terminated.
status receives any error status. Possible errors include U_NO_WRITE_PERMISSION
Returns:
The signed number of (native) storage units by which the length of the text expanded or contracted.
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

Definition at line 936 of file utext.h.


Enumeration Type Documentation

anonymous enum
 

UText provider properties (bit field indexes).

See also:
UText
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4
Enumerator:
UTEXT_PROVIDER_NON_UTF16_INDEXES  The provider works with non-UTF-16 ("native") text indexes.

For example, byte indexes into UTF-8 text or UTF-32 indexes into UTF-32 text.

Draft:
This API may be changed in the future versions and was introduced in ICU 3.4
UTEXT_PROVIDER_LENGTH_IS_EXPENSIVE  It is potentially time consuming for the provider to determine the length of the text.

Draft:
This API may be changed in the future versions and was introduced in ICU 3.4
UTEXT_PROVIDER_STABLE_CHUNKS  Text chunks remain valid and usable until the text object is modified or deleted, not just until the next time the access() function is called (which is the default).

Draft:
This API may be changed in the future versions and was introduced in ICU 3.4
UTEXT_PROVIDER_WRITABLE  The provider supports modifying the text via the replace() and copy() functions.

See also:
Replaceable
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4
UTEXT_PROVIDER_HAS_META_DATA  There is meta data associated with the text.

See also:
Replaceable::hasMetaData()
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

Definition at line 759 of file utext.h.

anonymous enum
 

Internal:
Do not use. This API is for interal use only.

Definition at line 1224 of file utext.h.


Function Documentation

U_DRAFT UChar32 U_EXPORT2 utext_char32At UText ut,
int32_t  nativeIndex
 

Returns the code point at the requested index, or U_SENTINEL (-1) if it is out of bounds.

If the specified index points to the interior of a multi-unit character - one of the trail bytes of a UTF-8 sequence, for example - the complete code point will be returned.

The iteration position will be set to the start of the returned code point.

This function is roughly equivalent to the the sequence utext_setNativeIndex(index); utext_current32(); (There is a difference if the index is out of bounds by being less than zero)

Parameters:
ut the text to be accessed
nativeIndex the native index of the character to be accessed. If the index points to other than the first unit of a multi-unit character, it will be adjusted to the start of the character.
Returns:
the code point at the specified index.
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

U_DRAFT UText* U_EXPORT2 utext_clone UText dest,
const UText src,
UBool  deep,
UErrorCode status
 

clone a UText.

Much like opening a UText where the source text is itself another UText.

A deep clone will copy both the UText data structures and the underlying text. The original and cloned UText will operate completely independently; modifications made to the text in one will not effect the other. Text providers are not required to support deep clones. The user of clone() must check the status return and be prepared to handle failures.

A shallow clone replicates only the UText data structures; it does not make a copy of the underlying text. Shallow clones can be used as an efficient way to have multiple iterators active in a single text string that is not being modified.

A shallow clone operation will not fail, barring truly exceptional conditions such as memory allocation failures.

A UText and its clone may be safely concurrently accessed by separate threads. This is true for both shallow and deep clones. It is the responsibility of the Text Provider to ensure that this thread safety constraint is met.

Parameters:
dest A UText struct to be filled in with the result of the clone operation, or NULL if the clone function should heap-allocate a new UText struct.
src The UText to be cloned.
deep TRUE to request a deep clone, FALSE for a shallow clone.
status Errors are returned here. For deep clones, U_UNSUPPORTED_ERROR will be returned if the text provider is unable to clone the original text.
Returns:
The newly created clone, or NULL if the clone operation failed.
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

U_DRAFT UText* U_EXPORT2 utext_close UText ut  ) 
 

utext_close Close function for UText instances.

Cleans up, releases any resources being held by an open UText.

If the UText was originally allocated by one of the utext_open functions, the storage associated with the utext will also be freed. If the UText storage originated with the application, as it would with a local or static instance, the storage will not be deleted.

An open UText can be reset to refer to new string by using one of the utext_open() functions without first closing the UText.

Parameters:
ut The UText to be closed.
Returns:
NULL if the UText struct was deleted by the close. If the UText struct was originally provided by the caller to the open function, it is returned by this function, and may be safely used again in a subsequent utext_open.
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

U_DRAFT void U_EXPORT2 utext_copy UText ut,
int32_t  nativeStart,
int32_t  nativeLimit,
int32_t  destIndex,
UBool  move,
UErrorCode status
 

Copy or move a substring from one position to another within the text, while retaining any metadata associated with the text.

This function is used to duplicate or reorder substrings. The destination index must not overlap the source range.

The text to be copied or moved is inserted at destIndex; it does not replace or overwrite any existing text.

This function is only available on UText types that support writing, that is, ones where utext_isWritable() returns TRUE.

When using this function, there should be only a single UText opened onto the underlying native text string. Behavior after a copy operation on a UText is undefined in any other additional UTexts that refer to the modified string.

Parameters:
ut The UText representing the text to be operated on.
nativeStart The native index of the start of the region to be copied or moved
nativeLimit The native index of the character position following the region to be copied.
destIndex The native destination index to which the source substring is copied or moved.
move If TRUE, then the substring is moved, not copied/duplicated.
status receives any error status. Possible errors include U_NO_WRITE_PERMISSION
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

U_DRAFT UChar32 U_EXPORT2 utext_current32 UText ut  ) 
 

Get the code point at the current iteration position, or U_SENTINEL (-1) if the iteration has reached the end of the input text.

Parameters:
ut the text to be accessed.
Returns:
the Unicode code point at the current iterator position.
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

U_DRAFT int32_t U_EXPORT2 utext_extract UText ut,
int32_t  nativeStart,
int32_t  nativeLimit,
UChar *  dest,
int32_t  destCapacity,
UErrorCode status
 

Extract text from a UText into a UChar buffer.

The range of text to be extracted is specified in the native indices of the UText provider. These may not necessarily be UTF-16 indices.

The size (number of 16 bit UChars) in the data to be extracted is returned. The full number of UChars is returned, even when the extracted text is truncated because the specified buffer size is too small.

The extracted string will (if you are a user) / must (if you are a text provider) be NUL-terminated if there is sufficient space in the destination buffer. This terminating NUL is not included in the returned length.

Parameters:
ut the UText from which to extract data.
nativeStart the native index of the first character to extract.
nativeLimit the native string index of the position following the last character to extract. If the specified limit is greater than the length of the text, the limit will be trimmed back to the text length.
dest the UChar (UTF-16) buffer into which the extracted text is placed
destCapacity The size, in UChars, of the destination buffer. May be zero for precomputing the required size.
status receives any error status. U_BUFFER_OVERFLOW_ERROR: the extracted text was truncated because the buffer was too small. Returns number of UChars for preflighting.
Returns:
Number of UChars in the data to be extracted. Does not include a trailing NUL.
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

U_DRAFT int32_t U_EXPORT2 utext_getNativeIndex UText ut  ) 
 

Get the current iterator position, which can range from 0 to the length of the text.

The position is a native index into the input text, in whatever format it may have, and may not always correspond to a UChar (UTF-16) index into the text. The returned position will always be aligned to a code point boundary

Parameters:
ut the text to be accessed.
Returns:
the current index position, in the native units of the text provider.
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

U_DRAFT UBool U_EXPORT2 utext_hasMetaData const UText ut  ) 
 

Test whether there is meta data associated with the text.

See also:
Replaceable::hasMetaData()
Parameters:
ut The UText to be tested
Returns:
TRUE if the underlying text includes meta data.
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

U_DRAFT UBool U_EXPORT2 utext_isLengthExpensive const UText ut  ) 
 

Return TRUE if calculating the length of the text could be expensive.

Finding the length of NUL terminated strings is considered to be expensive.

Note that the value of this function may change as the result of other operations on a UText. Once the length of a string has been discovered, it will no longer be expensive to report it.

Parameters:
ut the text to be accessed.
Returns:
TRUE if determining the length of the text could be time consuming.
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

U_DRAFT UBool U_EXPORT2 utext_isWritable const UText ut  ) 
 

Return TRUE if the text can be written with utext_replace() or utext_copy().

For the text to be writable, the text provider must be of a type that supports writing.

Parameters:
ut the UText to be tested.
Returns:
TRUE if the text is modifiable.
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

U_DRAFT UBool U_EXPORT2 utext_moveIndex32 UText ut,
int32_t  delta
 

Move the iterator postion by delta code points.

The number of code points is a signed number; a negative delta will move the iterator backwards, towards the start of the text.

The index is moved by delta code points forward or backward, but no further backward than to 0 and no further forward than to utext_nativeLength(). The resulting index value will be in between 0 and length, inclusive.

Because the index is kept in the native units of the text provider, the actual numeric amount by which the index moves depends on the underlying text storage representation of the text provider.

Parameters:
ut the text to be accessed.
delta the signed number of code points to move the iteration position.
Returns:
TRUE if the position could be moved the requested number of positions while staying within the range [0 - text length].
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

U_DRAFT int32_t U_EXPORT2 utext_nativeLength UText ut  ) 
 

Get the length of the text.

Depending on the characteristics of the underlying text representation, this may be expensive.

See also:
utext_isLengthExpensive()
Parameters:
ut the text to be accessed.
Returns:
the length of the text, expressed in native units.
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

U_DRAFT UChar32 U_EXPORT2 utext_next32 UText ut  ) 
 

Get the code point at the current iteration position of the UText, and advance the position to the first index following the character.

Returns U_SENTINEL (-1) if the position is at the end of the text. This is a post-increment operation

An inline macro version of this function, UTEXT_NEXT32(), is available for performance critical use.

Parameters:
ut the text to be accessed.
Returns:
the Unicode code point at the iteration position.
See also:
UTEXT_NEXT32
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

U_DRAFT UChar32 U_EXPORT2 utext_next32From UText ut,
int32_t  nativeIndex
 

Set the iteration index, access the text for forward iteration, and return the code point starting at or before that index.

Leave the iteration index at the start of the following code point.

This function is the most efficient and convenient way to begin a forward iteration.

Parameters:
ut the text to be accessed.
nativeIndex Iteration index, in the native units of the text provider.
Returns:
Code point which starts at or before index, or U_SENTINEL (-1) if it is out of bounds.
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

U_DRAFT UText* U_EXPORT2 utext_openUChars UText ut,
const UChar *  s,
int32_t  length,
UErrorCode status
 

Open a read-only UText for UChar * string.

Parameters:
ut Pointer to a UText struct. If NULL, a new UText will be created. If non-NULL, must refer to an initialized UText struct, which will then be reset to reference the specified UChar string.
s A UChar (UTF-16) string
length The number of UChars in the input string, or -1 if the string is zero terminated.
status Errors are returned here.
Returns:
A pointer to the UText. If a pre-allocated UText was provided, it will always be used and returned.
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

U_DRAFT UText* U_EXPORT2 utext_openUTF8 UText ut,
const char *  s,
int32_t  length,
UErrorCode status
 

Open a read-only UText implementation for UTF-8 strings.

Any invalid UTF-8 in the input will be handled in this way: a sequence of bytes that has the form of a truncated, but otherwise valid, UTF-8 sequence will be replaced by a single unicode replacement character, \uFFFD. Any other illegal bytes will each be replaced by a \uFFFD.

Parameters:
ut Pointer to a UText struct. If NULL, a new UText will be created. If non-NULL, must refer to an initialized UText struct, which will then be reset to reference the specified UTF-8 string.
s A UTF-8 string
length The length of the UTF-8 string in bytes, or -1 if the string is zero terminated.
status Errors are returned here.
Returns:
A pointer to the UText. If a pre-allocated UText was provided, it will always be used and returned.
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

U_DRAFT UChar32 U_EXPORT2 utext_previous32 UText ut  ) 
 

Move the iterator position to the character (code point) whose index precedes the current position, and return that character.

This is a pre-decrement operation. Returns U_SENTINEL (-1) if the position is at the start of the text. This is a pre-decrement operation.

An inline macro version of this function, UTEXT_PREVIOUS32(), is available for performance critical use.

Parameters:
ut the text to be accessed.
Returns:
the previous UChar32 code point, or U_SENTINEL (-1) if the iteration has reached the start of the text.
See also:
UTEXT_PREVIOUS32
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

U_DRAFT UChar32 U_EXPORT2 utext_previous32From UText ut,
int32_t  nativeIndex
 

Set the iteration index, and return the code point preceding the one specified by the initial index.

Leave the iteration position at the start of the returned code point.

This function is the most efficient and convenient way to begin a backwards iteration.

Parameters:
ut the text to be accessed.
nativeIndex Iteration index in the native units of the text provider.
Returns:
Code point preceding the one at the initial index, or U_SENTINEL (-1) if it is out of bounds.
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

U_DRAFT int32_t U_EXPORT2 utext_replace UText ut,
int32_t  nativeStart,
int32_t  nativeLimit,
const UChar *  replacementText,
int32_t  replacementLength,
UErrorCode status
 

Replace a range of the original text with a replacement text.

Leaves the current iteration position at the position following the newly inserted replacement text.

This function is only available on UText types that support writing, that is, ones where utext_isWritable() returns TRUE.

When using this function, there should be only a single UText opened onto the underlying native text string. Behavior after a replace operation on a UText is undefined for any other additional UTexts that refer to the modified string.

Parameters:
ut the UText representing the text to be operated on.
nativeStart the native index of the start of the region to be replaced
nativeLimit the native index of the character following the region to be replaced.
replacementText pointer to the replacement text
replacementLength length of the replacement text, or -1 if the text is NUL terminated.
status receives any error status. Possible errors include U_NO_WRITE_PERMISSION
Returns:
The signed number of (native) storage units by which the length of the text expanded or contracted.
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

U_DRAFT void U_EXPORT2 utext_setNativeIndex UText ut,
int32_t  nativeIndex
 

Set the current iteration position to the nearest code point boundary at or preceding the specified index.

The index is in the native units of the original input text. If the index is out of range, it will be trimmed to be within the range of the input text.

It will usually be more efficient to begin an iteration using the functions utext_next32From() or utext_previous32From() rather than setIndex().

Moving the index position to an adjacent character is best done with utext_next32(), utext_previous32() or utext_moveIndex32(). Attempting to do direct arithmetic on the index position is complicated by the fact that the size (in native units) of a character depends on the underlying representation of the character (UTF-8, UTF-16, UTF-32, arbitrary codepage), and is not easily knowable.

Parameters:
ut the text to be accessed.
nativeIndex the native unit index of the new iteration position.
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4

U_DRAFT UText* U_EXPORT2 utext_setup UText ut,
int32_t  extraSpace,
UErrorCode status
 

Common function for use by Text Provider implementations to allocate and/or initialize a new UText struct.

To be called in the implementation of utext_open() functions. If the supplied UText parameter is null, a new UText struct will be allocated on the heap. If the supplied UText is already open, the provider's close function will be called so that the struct can be reused by the open that is in progress.

Parameters:
ut pointer to a UText struct to be re-used, or null if a new UText should be allocated.
extraSpace The amount of additional space to be allocated as part of this UText, for use by types of providers that require additional storage.
status Errors are returned here.
Returns:
pointer to the UText, allocated if necessary, with extra space set up if requested.
Draft:
This API may be changed in the future versions and was introduced in ICU 3.4


Generated on Tue Sep 13 11:03:26 2005 for ICU 3.4 by  doxygen 1.4.4