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// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
*******************************************************************************
*
* Copyright (C) 2004-2012, International Business Machines
* Corporation and others. All Rights Reserved.
*
*******************************************************************************
* file name: utext.h
* encoding: UTF-8
* tab size: 8 (not used)
* indentation:4
*
* created on: 2004oct06
* created by: Markus W. Scherer
*/
#ifndef __UTEXT_H__
#define __UTEXT_H__
/**
* @addtogroup ICU4C
* @{
* \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"
#include "unicode/uchar.h"
#if U_SHOW_CPLUSPLUS_API
#include "unicode/localpointer.h"
#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. \xrefitem stable "Stable" "Stable List" 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.
*
* \xrefitem stable "Stable" "Stable List" ICU 3.4
*/
U_CAPI UText * U_EXPORT2
utext_close(UText *ut) __INTRODUCED_IN(31);
/**
* 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.
* \xrefitem stable "Stable" "Stable List" ICU 3.4
*/
U_CAPI UText * U_EXPORT2
utext_openUTF8(UText *ut, const char *s, int64_t length, UErrorCode *status) __INTRODUCED_IN(31);
/**
* 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.
* \xrefitem stable "Stable" "Stable List" ICU 3.4
*/
U_CAPI UText * U_EXPORT2
utext_openUChars(UText *ut, const UChar *s, int64_t length, UErrorCode *status) __INTRODUCED_IN(31);
#if U_SHOW_CPLUSPLUS_API
#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.
* \xrefitem stable "Stable" "Stable List" ICU 3.4
*/
U_CAPI UText * U_EXPORT2
utext_clone(UText *dest, const UText *src, UBool deep, UBool readOnly, UErrorCode *status) __INTRODUCED_IN(31);
/**
* 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.
* \xrefitem stable "Stable" "Stable List" ICU 3.6
*/
U_CAPI UBool U_EXPORT2
utext_equals(const UText *a, const UText *b) __INTRODUCED_IN(31);
/*****************************************************************************
*
* Functions to work with the text represented 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.
*
* \xrefitem stable "Stable" "Stable List" ICU 3.4
*/
U_CAPI int64_t U_EXPORT2
utext_nativeLength(UText *ut) __INTRODUCED_IN(31);
/**
* 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 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.
* \xrefitem stable "Stable" "Stable List" ICU 3.4
*/
U_CAPI UChar32 U_EXPORT2
utext_char32At(UText *ut, int64_t nativeIndex) __INTRODUCED_IN(31);
/**
*
* 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.
* \xrefitem stable "Stable" "Stable List" ICU 3.4
*/
U_CAPI UChar32 U_EXPORT2
utext_current32(UText *ut) __INTRODUCED_IN(31);
/**
* 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
* \xrefitem stable "Stable" "Stable List" ICU 3.4
*/
U_CAPI UChar32 U_EXPORT2
utext_next32(UText *ut) __INTRODUCED_IN(31);
/**
* 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
* \xrefitem stable "Stable" "Stable List" ICU 3.4
*/
U_CAPI UChar32 U_EXPORT2
utext_previous32(UText *ut) __INTRODUCED_IN(31);
/**
* 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.
* \xrefitem stable "Stable" "Stable List" ICU 3.4
*/
U_CAPI UChar32 U_EXPORT2
utext_next32From(UText *ut, int64_t nativeIndex) __INTRODUCED_IN(31);
/**
* 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.
*
* \xrefitem stable "Stable" "Stable List" ICU 3.4
*/
U_CAPI UChar32 U_EXPORT2
utext_previous32From(UText *ut, int64_t nativeIndex) __INTRODUCED_IN(31);
/**
* 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.
* \xrefitem stable "Stable" "Stable List" ICU 3.4
*/
U_CAPI int64_t U_EXPORT2
utext_getNativeIndex(const UText *ut) __INTRODUCED_IN(31);
/**
* 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.
* \xrefitem stable "Stable" "Stable List" ICU 3.4
*/
U_CAPI void U_EXPORT2
utext_setNativeIndex(UText *ut, int64_t nativeIndex) __INTRODUCED_IN(31);
/**
* Move the iterator position 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].
* \xrefitem stable "Stable" "Stable List" ICU 3.4
*/
U_CAPI UBool U_EXPORT2
utext_moveIndex32(UText *ut, int32_t delta) __INTRODUCED_IN(31);
/**
* Get the native index of the character preceding 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 preceding the current index position,
* or zero if the current position is at the start of the text.
* \xrefitem stable "Stable" "Stable List" ICU 3.6
*/
U_CAPI 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 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 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.
*
* \xrefitem stable "Stable" "Stable List" ICU 3.4
*/
U_CAPI int32_t U_EXPORT2
utext_extract(UText *ut,
int64_t nativeStart, int64_t nativeLimit,
UChar *dest, int32_t destCapacity,
UErrorCode *status) __INTRODUCED_IN(31);
U_CDECL_END
#if U_SHOW_CPLUSPLUS_API
U_NAMESPACE_BEGIN
/**
* \class LocalUTextPointer
* "Smart pointer" class, closes a UText via utext_close().
* For most methods see the LocalPointerBase base class.
*
* @see LocalPointerBase
* @see LocalPointer
* \xrefitem stable "Stable" "Stable List" ICU 4.4
*/
U_DEFINE_LOCAL_OPEN_POINTER(LocalUTextPointer, UText, utext_close);
U_NAMESPACE_END
#endif
#endif
/** @} */ // addtogroup
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