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/*
*******************************************************************************
*
* Copyright (C) 2004-2008, International Business Machines
* Corporation and others. All Rights Reserved.
*
*******************************************************************************
* file name: utext.h
* encoding: US-ASCII
* tab size: 8 (not used)
* indentation:4
*
* created on: 2004oct06
* created by: Markus W. Scherer
*/
#ifndef __UTEXT_H__
#define __UTEXT_H__
/**
* \file
* \brief 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 in 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.
*
*
* <em>Iterating over text</em>
*
* Here is sample code for a forward iteration over the contents of a UText
*
* \code
* UChar32 c;
* UText *ut = whatever();
*
* for (c=utext_next32From(ut, 0); c>=0; c=utext_next32(ut)) {
* // do whatever with the codepoint c here.
* }
* \endcode
*
* And here is similar code to iterate in the reverse direction, from the end
* of the text towards the beginning.
*
* \code
* 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.
* }
* \endcode
*
* <em>Characters and Indexing</em>
*
* 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.
*
* <em>Conventions for calling UText functions</em>
*
* Most UText access functions have as their first parameter a (UText *) pointer,
* which specifies the UText to be used. Unless otherwise noted, the
* pointer must refer to a valid, open UText. Attempting to
* use a closed UText or passing a NULL pointer is a programming error and
* will produce undefined results or NULL pointer exceptions.
*
* The UText_Open family of functions can either open an existing (closed)
* UText, or heap allocate a new UText. Here is sample code for creating
* a stack-allocated UText.
*
* \code
* char *s = whatever(); // A utf-8 string
* U_ErrorCode status = U_ZERO_ERROR;
* UText ut = UTEXT_INITIALIZER;
* utext_openUTF8(ut, s, -1, &status);
* if (U_FAILURE(status)) {
* // error handling
* } else {
* // work with the UText
* }
* \endcode
*
* Any existing UText passed to an open function _must_ have been initialized,
* either by the UTEXT_INITIALIZER, or by having been originally heap-allocated
* by an open function. Passing NULL will cause the open function to
* heap-allocate and fully initialize a new UText.
*
*/
#include "unicode/utypes.h"
#ifdef XP_CPLUSPLUS
#include "unicode/rep.h"
#include "unicode/unistr.h"
#include "unicode/chariter.h"
#endif
U_CDECL_BEGIN
struct UText;
typedef struct UText UText; /**< C typedef for struct UText. @stable ICU 3.6 */
/***************************************************************************************
*
* C Functions for creating UText wrappers around various kinds of text strings.
*
****************************************************************************************/
/**
* Close function for UText instances.
* Cleans up, releases any resources being held by an open UText.
* <p>
* 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.
*
* @param ut The UText to be closed.
* @return 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.
*
* @stable ICU 3.4
*/
U_STABLE UText * U_EXPORT2
utext_close(UText *ut);
/**
* Open a read-only UText implementation for UTF-8 strings.
*
* \htmlonly
* 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.
* \endhtmlonly
*
* @param 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.
* @param s A UTF-8 string. Must not be NULL.
* @param length The length of the UTF-8 string in bytes, or -1 if the string is
* zero terminated.
* @param status Errors are returned here.
* @return A pointer to the UText. If a pre-allocated UText was provided, it
* will always be used and returned.
* @stable ICU 3.4
*/
U_STABLE UText * U_EXPORT2
utext_openUTF8(UText *ut, const char *s, int64_t length, UErrorCode *status);
/**
* Open a read-only UText for UChar * string.
*
* @param 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.
* @param s A UChar (UTF-16) string
* @param length The number of UChars in the input string, or -1 if the string is
* zero terminated.
* @param status Errors are returned here.
* @return A pointer to the UText. If a pre-allocated UText was provided, it
* will always be used and returned.
* @stable ICU 3.4
*/
U_STABLE UText * U_EXPORT2
utext_openUChars(UText *ut, const UChar *s, int64_t length, UErrorCode *status);
#ifdef XP_CPLUSPLUS
/**
* Open a writable UText for a non-const UnicodeString.
*
* @param 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 input string.
* @param s A UnicodeString.
* @param status Errors are returned here.
* @return Pointer to the UText. If a UText was supplied as input, this
* will always be used and returned.
* @stable ICU 3.4
*/
U_STABLE UText * U_EXPORT2
utext_openUnicodeString(UText *ut, U_NAMESPACE_QUALIFIER UnicodeString *s, UErrorCode *status);
/**
* Open a UText for a const UnicodeString. The resulting UText will not be writable.
*
* @param 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 input string.
* @param s A const UnicodeString to be wrapped.
* @param status Errors are returned here.
* @return Pointer to the UText. If a UText was supplied as input, this
* will always be used and returned.
* @stable ICU 3.4
*/
U_STABLE UText * U_EXPORT2
utext_openConstUnicodeString(UText *ut, const U_NAMESPACE_QUALIFIER UnicodeString *s, UErrorCode *status);
/**
* Open a writable UText implementation for an ICU Replaceable object.
* @param ut Pointer to a UText struct. If NULL, a new UText will be created.
* If non-NULL, must refer to an already existing UText, which will then
* be reset to reference the specified replaceable text.
* @param rep A Replaceable text object.
* @param status Errors are returned here.
* @return Pointer to the UText. If a UText was supplied as input, this
* will always be used and returned.
* @see Replaceable
* @stable ICU 3.4
*/
U_STABLE UText * U_EXPORT2
utext_openReplaceable(UText *ut, U_NAMESPACE_QUALIFIER Replaceable *rep, UErrorCode *status);
/**
* Open a UText implementation over an ICU CharacterIterator.
* @param ut Pointer to a UText struct. If NULL, a new UText will be created.
* If non-NULL, must refer to an already existing UText, which will then
* be reset to reference the specified replaceable text.
* @param ci A Character Iterator.
* @param status Errors are returned here.
* @return Pointer to the UText. If a UText was supplied as input, this
* will always be used and returned.
* @see Replaceable
* @stable ICU 3.4
*/
U_STABLE UText * U_EXPORT2
utext_openCharacterIterator(UText *ut, U_NAMESPACE_QUALIFIER CharacterIterator *ic, UErrorCode *status);
#endif
/**
* Clone a UText. This is 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 affect 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.
*
* The standard UText implementations for UTF8, UChar *, UnicodeString and
* Replaceable all support deep cloning.
*
* The UText returned from a deep clone will be writable, assuming that the text
* provider is able to support writing, even if the source UText had been made
* non-writable by means of UText_freeze().
*
* 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.
*
* Shallow UText clones should be avoided if the UText functions that modify the
* text are expected to be used, either on the original or the cloned UText.
* Any such modifications can cause unpredictable behavior. Read Only
* shallow clones provide some protection against errors of this type by
* disabling text modification via the cloned UText.
*
* A shallow clone made with the readOnly parameter == FALSE will preserve the
* utext_isWritable() state of the source object. Note, however, that
* write operations must be avoided while more than one UText exists that refer
* to the same underlying text.
*
* A UText and its clone may be safely concurrently accessed by separate threads.
* This is true for read access only with shallow clones, and for both read and
* write access with deep clones.
* It is the responsibility of the Text Provider to ensure that this thread safety
* constraint is met.
*
* @param 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.
* If non-NULL, must refer to an already existing UText, which will then
* be reset to become the clone.
* @param src The UText to be cloned.
* @param deep TRUE to request a deep clone, FALSE for a shallow clone.
* @param readOnly TRUE to request that the cloned UText have read only access to the
* underlying text.
* @param 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.
* @return The newly created clone, or NULL if the clone operation failed.
* @stable ICU 3.4
*/
U_STABLE UText * U_EXPORT2
utext_clone(UText *dest, const UText *src, UBool deep, UBool readOnly, UErrorCode *status);
/**
* Compare two UText objects for equality.
* UTexts are equal if they are iterating over the same text, and
* have the same iteration position within the text.
* If either or both of the parameters are NULL, the comparison is FALSE.
*
* @param a The first of the two UTexts to compare.
* @param b The other UText to be compared.
* @return TRUE if the two UTexts are equal.
* @stable ICU 3.6
*/
U_STABLE UBool U_EXPORT2
utext_equals(const UText *a, const UText *b);
/*****************************************************************************
*
* Functions to work with the text represeted by a UText wrapper
*
*****************************************************************************/
/**
* Get the length of the text. Depending on the characteristics
* of the underlying text representation, this may be expensive.
* @see utext_isLengthExpensive()
*
*
* @param ut the text to be accessed.
* @return the length of the text, expressed in native units.
*
* @stable ICU 3.4
*/
U_STABLE int64_t U_EXPORT2
utext_nativeLength(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.
*
* @param ut the text to be accessed.
* @return TRUE if determining the length of the text could be time consuming.
* @stable ICU 3.4
*/
U_STABLE UBool U_EXPORT2
utext_isLengthExpensive(const UText *ut);
/**
* 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 subtle difference if the index is out of bounds by being less than zero -
* utext_setNativeIndex(negative value) sets the index to zero, after which utext_current()
* will return the char at zero. utext_char32At(negative index), on the other hand, will
* return the U_SENTINEL value of -1.)
*
* @param ut the text to be accessed
* @param 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.
* @return the code point at the specified index.
* @stable ICU 3.4
*/
U_STABLE UChar32 U_EXPORT2
utext_char32At(UText *ut, int64_t nativeIndex);
/**
*
* Get the code point at the current iteration position,
* or U_SENTINEL (-1) if the iteration has reached the end of
* the input text.
*
* @param ut the text to be accessed.
* @return the Unicode code point at the current iterator position.
* @stable ICU 3.4
*/
U_STABLE UChar32 U_EXPORT2
utext_current32(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.
*
* If the position is at the end of the text (the index following
* the last character, which is also the length of the text),
* return U_SENTINEL (-1) and do not advance the index.
*
* This is a post-increment operation.
*
* An inline macro version of this function, UTEXT_NEXT32(),
* is available for performance critical use.
*
* @param ut the text to be accessed.
* @return the Unicode code point at the iteration position.
* @see UTEXT_NEXT32
* @stable ICU 3.4
*/
U_STABLE UChar32 U_EXPORT2
utext_next32(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.
*
* If the initial position is at the start of the text (index of 0)
* return U_SENTINEL (-1), and leave the position unchanged.
*
* An inline macro version of this function, UTEXT_PREVIOUS32(),
* is available for performance critical use.
*
* @param ut the text to be accessed.
* @return the previous UChar32 code point, or U_SENTINEL (-1)
* if the iteration has reached the start of the text.
* @see UTEXT_PREVIOUS32
* @stable ICU 3.4
*/
U_STABLE UChar32 U_EXPORT2
utext_previous32(UText *ut);
/**
* Set the iteration index and return the code point at 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. The results are identical to the those
* from the sequence
* \code
* utext_setIndex();
* utext_next32();
* \endcode
*
* @param ut the text to be accessed.
* @param nativeIndex Iteration index, in the native units of the text provider.
* @return Code point which starts at or before index,
* or U_SENTINEL (-1) if it is out of bounds.
* @stable ICU 3.4
*/
U_STABLE UChar32 U_EXPORT2
utext_next32From(UText *ut, int64_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.
*
* @param ut the text to be accessed.
* @param nativeIndex Iteration index in the native units of the text provider.
* @return Code point preceding the one at the initial index,
* or U_SENTINEL (-1) if it is out of bounds.
*
* @stable ICU 3.4
*/
U_STABLE UChar32 U_EXPORT2
utext_previous32From(UText *ut, int64_t nativeIndex);
/**
* 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 (possibly UTF-8 for example), and may not always be the same as
* the corresponding UChar (UTF-16) index.
* The returned position will always be aligned to a code point boundary.
*
* @param ut the text to be accessed.
* @return the current index position, in the native units of the text provider.
* @stable ICU 3.4
*/
U_STABLE int64_t U_EXPORT2
utext_getNativeIndex(const UText *ut);
/**
* 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 pinned to be within
* the range of the input text.
* <p>
* It will usually be more efficient to begin an iteration
* using the functions utext_next32From() or utext_previous32From()
* rather than setIndex().
* <p>
* 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.
*
* @param ut the text to be accessed.
* @param nativeIndex the native unit index of the new iteration position.
* @stable ICU 3.4
*/
U_STABLE void U_EXPORT2
utext_setNativeIndex(UText *ut, int64_t nativeIndex);
/**
* 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.
* <p>
* The index is moved by <code>delta</code> 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.
*
* @param ut the text to be accessed.
* @param delta the signed number of code points to move the iteration position.
* @return TRUE if the position could be moved the requested number of positions while
* staying within the range [0 - text length].
* @stable ICU 3.4
*/
U_STABLE UBool U_EXPORT2
utext_moveIndex32(UText *ut, int32_t delta);
/**
* Get the native index of the character preceeding the current position.
* If the iteration position is already at the start of the text, zero
* is returned.
* The value returned is the same as that obtained from the following sequence,
* but without the side effect of changing the iteration position.
*
* \code
* UText *ut = whatever;
* ...
* utext_previous(ut)
* utext_getNativeIndex(ut);
* \endcode
*
* This function is most useful during forwards iteration, where it will get the
* native index of the character most recently returned from utext_next().
*
* @param ut the text to be accessed
* @return the native index of the character preceeding the current index position,
* or zero if the current position is at the start of the text.
* @stable ICU 3.6
*/
U_STABLE int64_t U_EXPORT2
utext_getPreviousNativeIndex(UText *ut);
/**
*
* 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.
* <p>
* The size (number of 16 bit UChars) of 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.
* <p>
* 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.
* <p>
* The iteration index is left at the position following the last extracted character.
*
* @param ut the UText from which to extract data.
* @param nativeStart the native index of the first character to extract.\
* If the specified index is out of range,
* it will be pinned to to be within 0 <= index <= textLength
* @param nativeLimit the native string index of the position following the last
* character to extract. If the specified index is out of range,
* it will be pinned to to be within 0 <= index <= textLength.
* nativeLimit must be >= nativeStart.
* @param dest the UChar (UTF-16) buffer into which the extracted text is placed
* @param destCapacity The size, in UChars, of the destination buffer. May be zero
* for precomputing the required size.
* @param 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.
* @return Number of UChars in the data to be extracted. Does not include a trailing NUL.
*
* @stable ICU 3.4
*/
U_STABLE int32_t U_EXPORT2
utext_extract(UText *ut,
int64_t nativeStart, int64_t nativeLimit,
UChar *dest, int32_t destCapacity,
UErrorCode *status);
/************************************************************************************
*
* #define inline versions of selected performance-critical text access functions
* Caution: do not use auto increment++ or decrement-- expressions
* as parameters to these macros.
*
* For most use, where there is no extreme performance constraint, the
* normal, non-inline functions are a better choice. The resulting code
* will be smaller, and, if the need ever arises, easier to debug.
*
* These are implemented as #defines rather than real functions
* because there is no fully portable way to do inline functions in plain C.
*
************************************************************************************/
/**
* 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.
*
* @stable ICU 3.4
*/
#define UTEXT_NEXT32(ut) \
((ut)->chunkOffset < (ut)->chunkLength && ((ut)->chunkContents)[(ut)->chunkOffset]<0xd800 ? \
((ut)->chunkContents)[((ut)->chunkOffset)++] : utext_next32(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.
*
* @stable ICU 3.4
*/
#define UTEXT_PREVIOUS32(ut) \
((ut)->chunkOffset > 0 && \
(ut)->chunkContents[(ut)->chunkOffset-1] < 0xd800 ? \
(ut)->chunkContents[--((ut)->chunkOffset)] : utext_previous32(ut))
/**
* inline version of utext_getNativeIndex(), for performance-critical situations.
*
* 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 (possibly UTF-8 for example), and may not always be the same as
* the corresponding UChar (UTF-16) index.
* The returned position will always be aligned to a code point boundary.
*
* @stable ICU 3.6
*/
#define UTEXT_GETNATIVEINDEX(ut) \
((ut)->chunkOffset <= (ut)->nativeIndexingLimit? \
(ut)->chunkNativeStart+(ut)->chunkOffset : \
(ut)->pFuncs->mapOffsetToNative(ut))
/**
* inline version of utext_setNativeIndex(), for performance-critical situations.
*
* 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 pinned to be within
* the range of the input text.
*
* @stable ICU 3.8
*/
#define UTEXT_SETNATIVEINDEX(ut, ix) \
{ int64_t __offset = (ix) - (ut)->chunkNativeStart; \
if (__offset>=0 && __offset<=(int64_t)(ut)->nativeIndexingLimit) { \
(ut)->chunkOffset=(int32_t)__offset; \
} else { \
utext_setNativeIndex((ut), (ix)); } }
/************************************************************************************
*
* Functions related to writing or modifying the text.
* These will work only with modifiable UTexts. Attempting to
* modify a read-only UText will return an error status.
*
************************************************************************************/
/**
* Return TRUE if the text can be written (modified) with utext_replace() or
* utext_copy(). For the text to be writable, the text provider must
* be of a type that supports writing and the UText must not be frozen.
*
* Attempting to modify text when utext_isWriteable() is FALSE will fail -
* the text will not be modified, and an error will be returned from the function
* that attempted the modification.
*
* @param ut the UText to be tested.
* @return TRUE if the text is modifiable.
*
* @see utext_freeze()
* @see utext_replace()
* @see utext_copy()
* @stable ICU 3.4
*
*/
U_STABLE UBool U_EXPORT2
utext_isWritable(const UText *ut);
/**
* Test whether there is meta data associated with the text.
* @see Replaceable::hasMetaData()
*
* @param ut The UText to be tested
* @return TRUE if the underlying text includes meta data.
* @stable ICU 3.4
*/
U_STABLE UBool U_EXPORT2
utext_hasMetaData(const UText *ut);
/**
* 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.
*
* @param ut the UText representing the text to be operated on.
* @param nativeStart the native index of the start of the region to be replaced
* @param nativeLimit the native index of the character following the region to be replaced.
* @param replacementText pointer to the replacement text
* @param replacementLength length of the replacement text, or -1 if the text is NUL terminated.
* @param status receives any error status. Possible errors include
* U_NO_WRITE_PERMISSION
*
* @return The signed number of (native) storage units by which
* the length of the text expanded or contracted.
*
* @stable ICU 3.4
*/
U_STABLE int32_t U_EXPORT2
utext_replace(UText *ut,
int64_t nativeStart, int64_t nativeLimit,
const UChar *replacementText, int32_t replacementLength,
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.
*
* The iteration position is left following the newly inserted text
* at the destination position.
*
* 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.
*
* @param ut The UText representing the text to be operated on.
* @param nativeStart The native index of the start of the region to be copied or moved
* @param nativeLimit The native index of the character position following the region
* to be copied.
* @param destIndex The native destination index to which the source substring is
* copied or moved.
* @param move If TRUE, then the substring is moved, not copied/duplicated.
* @param status receives any error status. Possible errors include U_NO_WRITE_PERMISSION
*
* @stable ICU 3.4
*/
U_STABLE void U_EXPORT2
utext_copy(UText *ut,
int64_t nativeStart, int64_t nativeLimit,
int64_t destIndex,
UBool move,
UErrorCode *status);
/**
* <p>
* Freeze a UText. This prevents any modification to the underlying text itself
* by means of functions operating on this UText.
* </p>
* <p>
* Once frozen, a UText can not be unfrozen. The intent is to ensure
* that a the text underlying a frozen UText wrapper cannot be modified via that UText.
* </p>
* <p>
* Caution: freezing a UText will disable changes made via the specific
* frozen UText wrapper only; it will not have any effect on the ability to
* directly modify the text by bypassing the UText. Any such backdoor modifications
* are always an error while UText access is occuring because the underlying
* text can get out of sync with UText's buffering.
* </p>
*
* @param ut The UText to be frozen.
* @see utext_isWritable()
* @stable ICU 3.6
*/
U_STABLE void U_EXPORT2
utext_freeze(UText *ut);
/**
* UText provider properties (bit field indexes).
*
* @see UText
* @stable ICU 3.4
*/
enum {
/**
* It is potentially time consuming for the provider to determine the length of the text.
* @stable ICU 3.4
*/
UTEXT_PROVIDER_LENGTH_IS_EXPENSIVE = 1,
/**
* 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).
* @stable ICU 3.4
*/
UTEXT_PROVIDER_STABLE_CHUNKS = 2,
/**
* The provider supports modifying the text via the replace() and copy()
* functions.
* @see Replaceable
* @stable ICU 3.4
*/
UTEXT_PROVIDER_WRITABLE = 3,
/**
* There is meta data associated with the text.
* @see Replaceable::hasMetaData()
* @stable ICU 3.4
*/
UTEXT_PROVIDER_HAS_META_DATA = 4,
/**
* Text provider owns the text storage.
* Generally occurs as the result of a deep clone of the UText.
* When closing the UText, the associated text must
* also be closed/deleted/freed/ whatever is appropriate.
* @stable ICU 3.6
*/
UTEXT_PROVIDER_OWNS_TEXT = 5
};
/**
* 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.
*
* @param 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.
* @param src The UText to be cloned.
* @param deep TRUE to request a deep clone, FALSE for a shallow clone.
* @param 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.
* @return The newly created clone, or NULL if the clone operation failed.
*
* @stable ICU 3.4
*/
typedef UText * U_CALLCONV
UTextClone(UText *dest, const UText *src, UBool deep, UErrorCode *status);
/**
* Function type declaration for UText.nativeLength().
*
* @param ut the UText to get the length of.
* @return the length, in the native units of the original text string.
* @see UText
* @stable ICU 3.4
*/
typedef int64_t U_CALLCONV
UTextNativeLength(UText *ut);
/**
* 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.
*
*
* @param ut the UText being accessed.
* @param nativeIndex Requested index of the text to be accessed.
* @param 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.
* @return 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 UText
* @stable ICU 3.4
*/
typedef UBool U_CALLCONV
UTextAccess(UText *ut, int64_t nativeIndex, UBool forward);
/**
* 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.
* <p>
* 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.
* <p>
* 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.
*
* @param ut the UText from which to extract data.
* @param nativeStart the native index of the first characer to extract.
* @param nativeLimit the native string index of the position following the last
* character to extract.
* @param dest the UChar (UTF-16) buffer into which the extracted text is placed
* @param destCapacity The size, in UChars, of the destination buffer. May be zero
* for precomputing the required size.
* @param status receives any error status.
* If U_BUFFER_OVERFLOW_ERROR: Returns number of UChars for
* preflighting.
* @return Number of UChars in the data. Does not include a trailing NUL.
*
* @stable ICU 3.4
*/
typedef int32_t U_CALLCONV
UTextExtract(UText *ut,
int64_t nativeStart, int64_t nativeLimit,
UChar *dest, int32_t destCapacity,
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.
*
* @param ut the UText representing the text to be operated on.
* @param nativeStart the index of the start of the region to be replaced
* @param nativeLimit the index of the character following the region to be replaced.
* @param replacementText pointer to the replacement text
* @param replacmentLength length of the replacement text in UChars, or -1 if the text is NUL terminated.
* @param status receives any error status. Possible errors include
* U_NO_WRITE_PERMISSION
*
* @return The signed number of (native) storage units by which
* the length of the text expanded or contracted.
*
* @stable ICU 3.4
*/
typedef int32_t U_CALLCONV
UTextReplace(UText *ut,
int64_t nativeStart, int64_t nativeLimit,
const UChar *replacementText, int32_t replacmentLength,
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.
*
* @param ut The UText representing the text to be operated on.
* @param nativeStart The index of the start of the region to be copied or moved
* @param nativeLimit The index of the character following the region to be replaced.
* @param nativeDest The destination index to which the source substring is copied or moved.
* @param move If TRUE, then the substring is moved, not copied/duplicated.
* @param status receives any error status. Possible errors include U_NO_WRITE_PERMISSION
*
* @stable ICU 3.4
*/
typedef void U_CALLCONV
UTextCopy(UText *ut,
int64_t nativeStart, int64_t nativeLimit,
int64_t nativeDest,
UBool move,
UErrorCode *status);
/**
* Function type declaration for UText.mapOffsetToNative().
* Map from the current UChar offset within the current text chunk 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.
*
* @param ut the UText.
* @return Absolute (native) index corresponding to chunkOffset in the current chunk.
* The returned native index should always be to a code point boundary.
*
* @stable ICU 3.4
*/
typedef int64_t U_CALLCONV
UTextMapOffsetToNative(const UText *ut);
/**
* Function type declaration for UText.mapIndexToUTF16().
* Map from a native index to a UChar offset within a text chunk.
* Behavior is undefined if the native index does not fall within the
* current chunk.
*
* This function is required only for text providers that do not use native UTF-16 indexes.
*
* @param ut The UText containing the text chunk.
* @param nativeIndex Absolute (native) text index, chunk->start<=index<=chunk->limit.
* @return Chunk-relative UTF-16 offset corresponding to the specified native
* index.
*
* @stable ICU 3.4
*/
typedef int32_t U_CALLCONV
UTextMapNativeIndexToUTF16(const UText *ut, int64_t nativeIndex);
/**
* 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.
*
* @param ut A UText object to be closed.
*
* @stable ICU 3.4
*/
typedef void U_CALLCONV
UTextClose(UText *ut);
/**
* (public) Function dispatch table for UText.
* Conceptually very much like a C++ Virtual Function Table.
* This struct defines the organization of the table.
* Each text provider implementation must provide an
* actual table that is initialized with the appropriate functions
* for the type of text being handled.
* @stable ICU 3.6
*/
struct UTextFuncs {
/**
* (public) Function table size, sizeof(UTextFuncs)
* Intended for use should the table grow to accomodate added
* functions in the future, to allow tests for older format
* function tables that do not contain the extensions.
*
* Fields are placed for optimal alignment on
* 32/64/128-bit-pointer machines, by normally grouping together
* 4 32-bit fields,
* 4 pointers,
* 2 64-bit fields
* in sequence.
* @stable ICU 3.6
*/
int32_t tableSize;
/**
* (private) Alignment padding.
* Do not use, reserved for use by the UText framework only.
* @internal
*/
int32_t reserved1, /** @internal */ reserved2, /** @internal */ reserved3;
/**
* (public) Function pointer for UTextClone
*
* @see UTextClone
* @stable ICU 3.6
*/
UTextClone *clone;
/**
* (public) function pointer for UTextLength
* May be expensive to compute!
*
* @see UTextLength
* @stable ICU 3.6
*/
UTextNativeLength *nativeLength;
/**
* (public) Function pointer for UTextAccess.
*
* @see UTextAccess
* @stable ICU 3.6
*/
UTextAccess *access;
/**
* (public) Function pointer for UTextExtract.
*
* @see UTextExtract
* @stable ICU 3.6
*/
UTextExtract *extract;
/**
* (public) Function pointer for UTextReplace.
*
* @see UTextReplace
* @stable ICU 3.6
*/
UTextReplace *replace;
/**
* (public) Function pointer for UTextCopy.
*
* @see UTextCopy
* @stable ICU 3.6
*/
UTextCopy *copy;
/**
* (public) Function pointer for UTextMapOffsetToNative.
*
* @see UTextMapOffsetToNative
* @stable ICU 3.6
*/
UTextMapOffsetToNative *mapOffsetToNative;
/**
* (public) Function pointer for UTextMapNativeIndexToUTF16.
*
* @see UTextMapNativeIndexToUTF16
* @stable ICU 3.6
*/
UTextMapNativeIndexToUTF16 *mapNativeIndexToUTF16;
/**
* (public) Function pointer for UTextClose.
*
* @see UTextClose
* @stable ICU 3.6
*/
UTextClose *close;
/**
* (private) Spare function pointer
* @internal
*/
UTextClose *spare1;
/**
* (private) Spare function pointer
* @internal
*/
UTextClose *spare2;
/**
* (private) Spare function pointer
* @internal
*/
UTextClose *spare3;
};
/**
* Function dispatch table for UText
* @see UTextFuncs
*/
typedef struct UTextFuncs UTextFuncs;
/**
* UText struct. Provides the interface between the generic UText access code
* and the UText provider code that works on specific kinds of
* text (UTF-8, noncontiguous UTF-16, whatever.)
*
* Applications that are using predefined types of text providers
* to pass text data to ICU services will have no need to view the
* internals of the UText structs that they open.
*
* @stable ICU 3.6
*/
struct UText {
/**
* (private) Magic. Used to help detect when UText functions are handed
* invalid or unitialized UText structs.
* utext_openXYZ() functions take an initialized,
* but not necessarily open, UText struct as an
* optional fill-in parameter. This magic field
* is used to check for that initialization.
* Text provider close functions must NOT clear
* the magic field because that would prevent
* reuse of the UText struct.
* @internal
*/
uint32_t magic;
/**
* (private) Flags for managing the allocation and freeing of
* memory associated with this UText.
* @internal
*/
int32_t flags;
/**
* Text provider properties. This set of flags is maintainted by the
* text provider implementation.
* @stable ICU 3.4
*/
int32_t providerProperties;
/**
* (public) sizeOfStruct=sizeof(UText)
* Allows possible backward compatible extension.
*
* @stable ICU 3.4
*/
int32_t sizeOfStruct;
/* ------ 16 byte alignment boundary ----------- */
/**
* (protected) Native index of the first character position following
* the current chunk.
* @stable ICU 3.6
*/
int64_t chunkNativeLimit;
/**
* (protected) Size in bytes of the extra space (pExtra).
* @stable ICU 3.4
*/
int32_t extraSize;
/**
* (protected) The highest chunk offset where native indexing and
* chunk (UTF-16) indexing correspond. For UTF-16 sources, value
* will be equal to chunkLength.
*
* @stable ICU 3.6
*/
int32_t nativeIndexingLimit;
/* ---- 16 byte alignment boundary------ */
/**
* (protected) Native index of the first character in the text chunk.
* @stable ICU 3.6
*/
int64_t chunkNativeStart;
/**
* (protected) Current iteration position within the text chunk (UTF-16 buffer).
* This is the index to the character that will be returned by utext_next32().
* @stable ICU 3.6
*/
int32_t chunkOffset;
/**
* (protected) Length the text chunk (UTF-16 buffer), in UChars.
* @stable ICU 3.6
*/
int32_t chunkLength;
/* ---- 16 byte alignment boundary-- */
/**
* (protected) pointer to a chunk of text in UTF-16 format.
* May refer either to original storage of the source of the text, or
* if conversion was required, to a buffer owned by the UText.
* @stable ICU 3.6
*/
const UChar *chunkContents;
/**
* (public) Pointer to Dispatch table for accessing functions for this UText.
* @stable ICU 3.6
*/
const UTextFuncs *pFuncs;
/**
* (protected) Pointer to additional space requested by the
* text provider during the utext_open operation.
* @stable ICU 3.4
*/
void *pExtra;
/**
* (protected) Pointer to string or text-containin object or similar.
* This is the source of the text that this UText is wrapping, in a format
* that is known to the text provider functions.
* @stable ICU 3.4
*/
const void *context;
/* --- 16 byte alignment boundary--- */
/**
* (protected) Pointer fields available for use by the text provider.
* Not used by UText common code.
* @stable ICU 3.6
*/
const void *p;
/**
* (protected) Pointer fields available for use by the text provider.
* Not used by UText common code.
* @stable ICU 3.6
*/
const void *q;
/**
* (protected) Pointer fields available for use by the text provider.
* Not used by UText common code.
* @stable ICU 3.6
*/
const void *r;
/**
* Private field reserved for future use by the UText framework
* itself. This is not to be touched by the text providers.
* @internal ICU 3.4
*/
void *privP;
/* --- 16 byte alignment boundary--- */
/**
* (protected) Integer field reserved for use by the text provider.
* Not used by the UText framework, or by the client (user) of the UText.
* @stable ICU 3.4
*/
int64_t a;
/**
* (protected) Integer field reserved for use by the text provider.
* Not used by the UText framework, or by the client (user) of the UText.
* @stable ICU 3.4
*/
int32_t b;
/**
* (protected) Integer field reserved for use by the text provider.
* Not used by the UText framework, or by the client (user) of the UText.
* @stable ICU 3.4
*/
int32_t c;
/* ---- 16 byte alignment boundary---- */
/**
* Private field reserved for future use by the UText framework
* itself. This is not to be touched by the text providers.
* @internal ICU 3.4
*/
int64_t privA;
/**
* Private field reserved for future use by the UText framework
* itself. This is not to be touched by the text providers.
* @internal ICU 3.4
*/
int32_t privB;
/**
* Private field reserved for future use by the UText framework
* itself. This is not to be touched by the text providers.
* @internal ICU 3.4
*/
int32_t privC;
};
/**
* 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.
*
* @param ut pointer to a UText struct to be re-used, or null if a new UText
* should be allocated.
* @param extraSpace The amount of additional space to be allocated as part
* of this UText, for use by types of providers that require
* additional storage.
* @param status Errors are returned here.
* @return pointer to the UText, allocated if necessary, with extra space set up if requested.
* @stable ICU 3.4
*/
U_STABLE UText * U_EXPORT2
utext_setup(UText *ut, int32_t extraSpace, UErrorCode *status);
/**
* @internal
* Value used to help identify correctly initialized UText structs.
* Note: must be publicly visible so that UTEXT_INITIALIZER can access it.
*/
enum {
UTEXT_MAGIC = 0x345ad82c
};
/**
* 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.
*
* @stable ICU 3.6
*/
#define UTEXT_INITIALIZER { \
UTEXT_MAGIC, /* magic */ \
0, /* flags */ \
0, /* providerProps */ \
sizeof(UText), /* sizeOfStruct */ \
0, /* chunkNativeLimit */ \
0, /* extraSize */ \
0, /* nativeIndexingLimit */ \
0, /* chunkNativeStart */ \
0, /* chunkOffset */ \
0, /* chunkLength */ \
NULL, /* chunkContents */ \
NULL, /* pFuncs */ \
NULL, /* pExtra */ \
NULL, /* context */ \
NULL, NULL, NULL, /* p, q, r */ \
NULL, /* privP */ \
0, 0, 0, /* a, b, c */ \
0, 0, 0 /* privA,B,C, */ \
}
U_CDECL_END
#endif