327 lines
13 KiB
C++
327 lines
13 KiB
C++
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/*
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******************************************************************************
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*
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* © 2016 and later: Unicode, Inc. and others.
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* License & terms of use: http://www.unicode.org/copyright.html
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*
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******************************************************************************
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* file name: ubiditransform.h
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* encoding: UTF-8
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* tab size: 8 (not used)
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* indentation:4
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*
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* created on: 2016jul24
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* created by: Lina Kemmel
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*
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*/
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#ifndef UBIDITRANSFORM_H
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#define UBIDITRANSFORM_H
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#include "unicode/utypes.h"
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#include "unicode/ubidi.h"
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#include "unicode/uchar.h"
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#if U_SHOW_CPLUSPLUS_API
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#include "unicode/localpointer.h"
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#endif // U_SHOW_CPLUSPLUS_API
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/**
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* \file
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* \brief Bidi Transformations
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*/
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/**
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* `UBiDiOrder` indicates the order of text.
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*
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* This bidi transformation engine supports all possible combinations (4 in
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* total) of input and output text order:
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*
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* - <logical input, visual output>: unless the output direction is RTL, this
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* corresponds to a normal operation of the Bidi algorithm as described in the
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* Unicode Technical Report and implemented by `UBiDi` when the
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* reordering mode is set to `UBIDI_REORDER_DEFAULT`. Visual RTL
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* mode is not supported by `UBiDi` and is accomplished through
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* reversing a visual LTR string,
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*
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* - <visual input, logical output>: unless the input direction is RTL, this
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* corresponds to an "inverse bidi algorithm" in `UBiDi` with the
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* reordering mode set to `UBIDI_REORDER_INVERSE_LIKE_DIRECT`.
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* Visual RTL mode is not not supported by `UBiDi` and is
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* accomplished through reversing a visual LTR string,
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*
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* - <logical input, logical output>: if the input and output base directions
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* mismatch, this corresponds to the `UBiDi` implementation with the
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* reordering mode set to `UBIDI_REORDER_RUNS_ONLY`; and if the
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* input and output base directions are identical, the transformation engine
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* will only handle character mirroring and Arabic shaping operations without
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* reordering,
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*
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* - <visual input, visual output>: this reordering mode is not supported by
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* the `UBiDi` engine; it implies character mirroring, Arabic
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* shaping, and - if the input/output base directions mismatch - string
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* reverse operations.
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* @see ubidi_setInverse
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* @see ubidi_setReorderingMode
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* @see UBIDI_REORDER_DEFAULT
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* @see UBIDI_REORDER_INVERSE_LIKE_DIRECT
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* @see UBIDI_REORDER_RUNS_ONLY
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* @stable ICU 58
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*/
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typedef enum {
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/** 0: Constant indicating a logical order.
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* This is the default for input text.
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* @stable ICU 58
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*/
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UBIDI_LOGICAL = 0,
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/** 1: Constant indicating a visual order.
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* This is a default for output text.
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* @stable ICU 58
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*/
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UBIDI_VISUAL
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} UBiDiOrder;
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/**
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* <code>UBiDiMirroring</code> indicates whether or not characters with the
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* "mirrored" property in RTL runs should be replaced with their mirror-image
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* counterparts.
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* @see UBIDI_DO_MIRRORING
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* @see ubidi_setReorderingOptions
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* @see ubidi_writeReordered
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* @see ubidi_writeReverse
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* @stable ICU 58
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*/
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typedef enum {
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/** 0: Constant indicating that character mirroring should not be
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* performed.
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* This is the default.
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* @stable ICU 58
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*/
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UBIDI_MIRRORING_OFF = 0,
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/** 1: Constant indicating that character mirroring should be performed.
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* This corresponds to calling <code>ubidi_writeReordered</code> or
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* <code>ubidi_writeReverse</code> with the
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* <code>UBIDI_DO_MIRRORING</code> option bit set.
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* @stable ICU 58
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*/
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UBIDI_MIRRORING_ON
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} UBiDiMirroring;
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/**
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* Forward declaration of the <code>UBiDiTransform</code> structure that stores
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* information used by the layout transformation engine.
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* @stable ICU 58
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*/
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typedef struct UBiDiTransform UBiDiTransform;
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/**
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* Performs transformation of text from the bidi layout defined by the input
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* ordering scheme to the bidi layout defined by the output ordering scheme,
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* and applies character mirroring and Arabic shaping operations.<p>
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* In terms of <code>UBiDi</code>, such a transformation implies:
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* <ul>
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* <li>calling <code>ubidi_setReorderingMode</code> as needed (when the
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* reordering mode is other than normal),</li>
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* <li>calling <code>ubidi_setInverse</code> as needed (when text should be
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* transformed from a visual to a logical form),</li>
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* <li>resolving embedding levels of each character in the input text by
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* calling <code>ubidi_setPara</code>,</li>
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* <li>reordering the characters based on the computed embedding levels, also
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* performing character mirroring as needed, and streaming the result to the
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* output, by calling <code>ubidi_writeReordered</code>,</li>
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* <li>performing Arabic digit and letter shaping on the output text by calling
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* <code>u_shapeArabic</code>.</li>
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* </ul>
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* An "ordering scheme" encompasses the base direction and the order of text,
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* and these characteristics must be defined by the caller for both input and
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* output explicitly .<p>
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* There are 36 possible combinations of <input, output> ordering schemes,
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* which are partially supported by <code>UBiDi</code> already. Examples of the
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* currently supported combinations:
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* <ul>
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* <li><Logical LTR, Visual LTR>: this is equivalent to calling
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* <code>ubidi_setPara</code> with <code>paraLevel == UBIDI_LTR</code>,</li>
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* <li><Logical RTL, Visual LTR>: this is equivalent to calling
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* <code>ubidi_setPara</code> with <code>paraLevel == UBIDI_RTL</code>,</li>
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* <li><Logical Default ("Auto") LTR, Visual LTR>: this is equivalent to
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* calling <code>ubidi_setPara</code> with
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* <code>paraLevel == UBIDI_DEFAULT_LTR</code>,</li>
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* <li><Logical Default ("Auto") RTL, Visual LTR>: this is equivalent to
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* calling <code>ubidi_setPara</code> with
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* <code>paraLevel == UBIDI_DEFAULT_RTL</code>,</li>
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* <li><Visual LTR, Logical LTR>: this is equivalent to
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* calling <code>ubidi_setInverse(UBiDi*, true)</code> and then
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* <code>ubidi_setPara</code> with <code>paraLevel == UBIDI_LTR</code>,</li>
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* <li><Visual LTR, Logical RTL>: this is equivalent to
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* calling <code>ubidi_setInverse(UBiDi*, true)</code> and then
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* <code>ubidi_setPara</code> with <code>paraLevel == UBIDI_RTL</code>.</li>
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* </ul>
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* All combinations that involve the Visual RTL scheme are unsupported by
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* <code>UBiDi</code>, for instance:
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* <ul>
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* <li><Logical LTR, Visual RTL>,</li>
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* <li><Visual RTL, Logical RTL>.</li>
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* </ul>
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* <p>Example of usage of the transformation engine:<br>
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* <pre>
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* \code
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* UChar text1[] = {'a', 'b', 'c', 0x0625, '1', 0};
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* UChar text2[] = {'a', 'b', 'c', 0x0625, '1', 0};
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* UErrorCode errorCode = U_ZERO_ERROR;
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* // Run a transformation.
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* ubiditransform_transform(pBidiTransform,
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* text1, -1, text2, -1,
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* UBIDI_LTR, UBIDI_VISUAL,
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* UBIDI_RTL, UBIDI_LOGICAL,
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* UBIDI_MIRRORING_OFF,
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* U_SHAPE_DIGITS_AN2EN | U_SHAPE_DIGIT_TYPE_AN_EXTENDED,
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* &errorCode);
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* // Do something with text2.
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* text2[4] = '2';
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* // Run a reverse transformation.
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* ubiditransform_transform(pBidiTransform,
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* text2, -1, text1, -1,
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* UBIDI_RTL, UBIDI_LOGICAL,
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* UBIDI_LTR, UBIDI_VISUAL,
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* UBIDI_MIRRORING_OFF,
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* U_SHAPE_DIGITS_EN2AN | U_SHAPE_DIGIT_TYPE_AN_EXTENDED,
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* &errorCode);
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*\endcode
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* </pre>
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* </p>
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*
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* @param pBiDiTransform A pointer to a <code>UBiDiTransform</code> object
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* allocated with <code>ubiditransform_open()</code> or
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* <code>NULL</code>.<p>
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* This object serves for one-time setup to amortize initialization
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* overheads. Use of this object is not thread-safe. All other threads
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* should allocate a new <code>UBiDiTransform</code> object by calling
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* <code>ubiditransform_open()</code> before using it. Alternatively,
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* a caller can set this parameter to <code>NULL</code>, in which case
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* the object will be allocated by the engine on the fly.</p>
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* @param src A pointer to the text that the Bidi layout transformations will
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* be performed on.
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* <p><strong>Note:</strong> the text must be (at least)
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* <code>srcLength</code> long.</p>
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* @param srcLength The length of the text, in number of UChars. If
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* <code>length == -1</code> then the text must be zero-terminated.
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* @param dest A pointer to where the processed text is to be copied.
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* @param destSize The size of the <code>dest</code> buffer, in number of
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* UChars. If the <code>U_SHAPE_LETTERS_UNSHAPE</code> option is set,
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* then the destination length could be as large as
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* <code>srcLength * 2</code>. Otherwise, the destination length will
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* not exceed <code>srcLength</code>. If the caller reserves the last
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* position for zero-termination, it should be excluded from
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* <code>destSize</code>.
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* <p><code>destSize == -1</code> is allowed and makes sense when
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* <code>dest</code> was holds some meaningful value, e.g. that of
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* <code>src</code>. In this case <code>dest</code> must be
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* zero-terminated.</p>
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* @param inParaLevel A base embedding level of the input as defined in
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* <code>ubidi_setPara</code> documentation for the
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* <code>paraLevel</code> parameter.
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* @param inOrder An order of the input, which can be one of the
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* <code>UBiDiOrder</code> values.
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* @param outParaLevel A base embedding level of the output as defined in
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* <code>ubidi_setPara</code> documentation for the
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* <code>paraLevel</code> parameter.
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* @param outOrder An order of the output, which can be one of the
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* <code>UBiDiOrder</code> values.
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* @param doMirroring Indicates whether or not to perform character mirroring,
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* and can accept one of the <code>UBiDiMirroring</code> values.
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* @param shapingOptions Arabic digit and letter shaping options defined in the
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* ushape.h documentation.
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* <p><strong>Note:</strong> Direction indicator options are computed by
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* the transformation engine based on the effective ordering schemes, so
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* user-defined direction indicators will be ignored.</p>
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* @param pErrorCode A pointer to an error code value.
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*
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* @return The destination length, i.e. the number of UChars written to
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* <code>dest</code>. If the transformation fails, the return value
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* will be 0 (and the error code will be written to
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* <code>pErrorCode</code>).
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*
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* @see UBiDiLevel
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* @see UBiDiOrder
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* @see UBiDiMirroring
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* @see ubidi_setPara
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* @see u_shapeArabic
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* @stable ICU 58
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*/
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U_CAPI uint32_t U_EXPORT2
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ubiditransform_transform(UBiDiTransform *pBiDiTransform,
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const UChar *src, int32_t srcLength,
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UChar *dest, int32_t destSize,
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UBiDiLevel inParaLevel, UBiDiOrder inOrder,
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UBiDiLevel outParaLevel, UBiDiOrder outOrder,
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UBiDiMirroring doMirroring, uint32_t shapingOptions,
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UErrorCode *pErrorCode);
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/**
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* Allocates a <code>UBiDiTransform</code> object. This object can be reused,
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* e.g. with different ordering schemes, mirroring or shaping options.<p>
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* <strong>Note:</strong>The object can only be reused in the same thread.
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* All other threads should allocate a new <code>UBiDiTransform</code> object
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* before using it.<p>
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* Example of usage:<p>
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* <pre>
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* \code
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* UErrorCode errorCode = U_ZERO_ERROR;
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* // Open a new UBiDiTransform.
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* UBiDiTransform* transform = ubiditransform_open(&errorCode);
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* // Run a transformation.
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* ubiditransform_transform(transform,
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* text1, -1, text2, -1,
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* UBIDI_RTL, UBIDI_LOGICAL,
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* UBIDI_LTR, UBIDI_VISUAL,
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* UBIDI_MIRRORING_ON,
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* U_SHAPE_DIGITS_EN2AN,
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* &errorCode);
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* // Do something with the output text and invoke another transformation using
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* // that text as input.
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* ubiditransform_transform(transform,
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* text2, -1, text3, -1,
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* UBIDI_LTR, UBIDI_VISUAL,
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* UBIDI_RTL, UBIDI_VISUAL,
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* UBIDI_MIRRORING_ON,
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* 0, &errorCode);
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*\endcode
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* </pre>
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* <p>
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* The <code>UBiDiTransform</code> object must be deallocated by calling
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* <code>ubiditransform_close()</code>.
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*
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* @return An empty <code>UBiDiTransform</code> object.
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* @stable ICU 58
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*/
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U_CAPI UBiDiTransform* U_EXPORT2
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ubiditransform_open(UErrorCode *pErrorCode);
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/**
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* Deallocates the given <code>UBiDiTransform</code> object.
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* @stable ICU 58
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*/
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U_CAPI void U_EXPORT2
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ubiditransform_close(UBiDiTransform *pBidiTransform);
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#if U_SHOW_CPLUSPLUS_API
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U_NAMESPACE_BEGIN
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/**
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* \class LocalUBiDiTransformPointer
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* "Smart pointer" class, closes a UBiDiTransform via ubiditransform_close().
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* For most methods see the LocalPointerBase base class.
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*
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* @see LocalPointerBase
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* @see LocalPointer
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* @stable ICU 58
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*/
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U_DEFINE_LOCAL_OPEN_POINTER(LocalUBiDiTransformPointer, UBiDiTransform, ubiditransform_close);
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U_NAMESPACE_END
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#endif
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#endif
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