235 lines
9.0 KiB
C
235 lines
9.0 KiB
C
/*
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******************************************************************************
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*
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* Copyright (C) 2000-2001, International Business Machines
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* Corporation and others. All Rights Reserved.
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*
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******************************************************************************
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* file name: ushape.h
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* encoding: US-ASCII
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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: 2000jun29
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* created by: Markus W. Scherer
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*/
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#ifndef __USHAPE_H__
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#define __USHAPE_H__
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#include "unicode/utypes.h"
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/**
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* \file
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* \brief C API: Arabic shaping
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*
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*/
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/**
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* Shape Arabic text on a character basis.
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*
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* <p>This function performs basic operations for "shaping" Arabic text. It is most
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* useful for use with legacy data formats and legacy display technology
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* (simple terminals). All operations are performed on Unicode characters.</p>
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*
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* <p>Text-based shaping means that some character code points in the text are
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* replaced by others depending on the context. It transforms one kind of text
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* into another. In comparison, modern displays for Arabic text select
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* appropriate, context-dependent font glyphs for each text element, which means
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* that they transform text into a glyph vector.</p>
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*
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* <p>Text transformations are necessary when modern display technology is not
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* available or when text needs to be transformed to or from legacy formats that
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* use "shaped" characters. Since the Arabic script is cursive, connecting
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* adjacent letters to each other, computers select images for each letter based
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* on the surrounding letters. This usually results in four images per Arabic
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* letter: initial, middle, final, and isolated forms. In Unicode, on the other
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* hand, letters are normally stored abstract, and a display system is expected
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* to select the necessary glyphs. (This makes searching and other text
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* processing easier because the same letter has only one code.) It is possible
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* to mimic this with text transformations because there are characters in
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* Unicode that are rendered as letters with a specific shape
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* (or cursive connectivity). They were included for interoperability with
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* legacy systems and codepages, and for unsophisticated display systems.</p>
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*
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* <p>A second kind of text transformations is supported for Arabic digits:
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* For compatibility with legacy codepages that only include European digits,
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* it is possible to replace one set of digits by another, changing the
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* character code points. These operations can be performed for either
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* Arabic-Indic Digits (U+0660...U+0669) or Eastern (Extended) Arabic-Indic
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* digits (U+06f0...U+06f9).</p>
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*
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* <p>Some replacements may result in more or fewer characters (code points).
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* By default, this means that the destination buffer may receive text with a
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* length different from the source length. Some legacy systems rely on the
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* length of the text to be constant. They expect extra spaces to be added
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* or consumed either next to the affected character or at the end of the
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* text.</p>
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*
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* <p>For details about the available operations, see the description of the
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* <code>U_SHAPE_...</code> options.</p>
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*
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* @param source The input text.
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*
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* @param sourceLength The number of UChars in <code>source</code>.
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*
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* @param dest The destination buffer that will receive the results of the
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* requested operations. It may be <code>NULL</code> only if
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* <code>destSize</code> is 0. The source and destination must not
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* overlap.
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*
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* @param destSize The size (capacity) of the destination buffer in UChars.
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* If <code>destSize</code> is 0, then no output is produced,
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* but the necessary buffer size is returned ("preflighting").
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*
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* @param options This is a 32-bit set of flags that specify the operations
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* that are performed on the input text. If no error occurs,
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* then the result will always be written to the destination
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* buffer.
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*
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* @param pErrorCode must be a valid pointer to an error code value,
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* which must not indicate a failure before the function call.
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*
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* @return The number of UChars written to the destination buffer.
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* If an error occured, then no output was written, or it may be
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* incomplete. If <code>U_BUFFER_OVERFLOW_ERROR</code> is set, then
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* the return value indicates the necessary destination buffer size.
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* @stable
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*/
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U_CAPI int32_t U_EXPORT2
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u_shapeArabic(const UChar *source, int32_t sourceLength,
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UChar *dest, int32_t destSize,
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uint32_t options,
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UErrorCode *pErrorCode);
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/**
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* Memory option: allow the result to have a different length than the source.
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* @stable
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*/
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#define U_SHAPE_LENGTH_GROW_SHRINK 0
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/**
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* Memory option: the result must have the same length as the source.
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* If more room is necessary, then try to consume spaces next to modified characters.
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* @stable
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*/
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#define U_SHAPE_LENGTH_FIXED_SPACES_NEAR 1
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/**
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* Memory option: the result must have the same length as the source.
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* If more room is necessary, then try to consume spaces at the end of the text.
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* @stable
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*/
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#define U_SHAPE_LENGTH_FIXED_SPACES_AT_END 2
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/**
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* Memory option: the result must have the same length as the source.
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* If more room is necessary, then try to consume spaces at the beginning of the text.
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* @stable
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*/
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#define U_SHAPE_LENGTH_FIXED_SPACES_AT_BEGINNING 3
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/** Bit mask for memory options. @stable */
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#define U_SHAPE_LENGTH_MASK 3
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/** Direction indicator: the source is in logical (keyboard) order. @stable */
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#define U_SHAPE_TEXT_DIRECTION_LOGICAL 0
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/**
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* Direction indicator:
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* the source is in visual LTR order,
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* the leftmost displayed character stored first.
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* @stable
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*/
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#define U_SHAPE_TEXT_DIRECTION_VISUAL_LTR 4
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/** Bit mask for direction indicators. @stable */
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#define U_SHAPE_TEXT_DIRECTION_MASK 4
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/** Letter shaping option: do not perform letter shaping. @stable */
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#define U_SHAPE_LETTERS_NOOP 0
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/** Letter shaping option: replace abstract letter characters by "shaped" ones. @stable */
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#define U_SHAPE_LETTERS_SHAPE 8
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/** Letter shaping option: replace "shaped" letter characters by abstract ones. @stable */
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#define U_SHAPE_LETTERS_UNSHAPE 0x10
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/**
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* Letter shaping option: replace abstract letter characters by "shaped" ones.
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* The only difference with U_SHAPE_LETTERS_SHAPE is that Tashkeel letters
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* are always "shaped" into the isolated form instead of the medial form
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* (selecting code points from the Arabic Presentation Forms-B block).
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* @draft ICU 2.0
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*/
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#define U_SHAPE_LETTERS_SHAPE_TASHKEEL_ISOLATED 0x18
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/** Bit mask for letter shaping options. @stable */
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#define U_SHAPE_LETTERS_MASK 0x18
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/** Digit shaping option: do not perform digit shaping. @stable */
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#define U_SHAPE_DIGITS_NOOP 0
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/**
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* Digit shaping option:
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* Replace European digits (U+0030...) by Arabic-Indic digits.
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* @stable
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*/
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#define U_SHAPE_DIGITS_EN2AN 0x20
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/**
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* Digit shaping option:
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* Replace Arabic-Indic digits by European digits (U+0030...).
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* @stable
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*/
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#define U_SHAPE_DIGITS_AN2EN 0x40
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/**
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* Digit shaping option:
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* Replace European digits (U+0030...) by Arabic-Indic digits if the most recent
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* strongly directional character is an Arabic letter
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* (<code>u_charDirection()</code> result <code>U_RIGHT_TO_LEFT_ARABIC</code> [AL]).<br>
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* The direction of "preceding" depends on the direction indicator option.
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* For the first characters, the preceding strongly directional character
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* (initial state) is assumed to be not an Arabic letter
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* (it is <code>U_LEFT_TO_RIGHT</code> [L] or <code>U_RIGHT_TO_LEFT</code> [R]).
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* @stable
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*/
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#define U_SHAPE_DIGITS_ALEN2AN_INIT_LR 0x60
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/**
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* Digit shaping option:
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* Replace European digits (U+0030...) by Arabic-Indic digits if the most recent
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* strongly directional character is an Arabic letter
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* (<code>u_charDirection()</code> result <code>U_RIGHT_TO_LEFT_ARABIC</code> [AL]).<br>
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* The direction of "preceding" depends on the direction indicator option.
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* For the first characters, the preceding strongly directional character
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* (initial state) is assumed to be an Arabic letter.
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* @stable
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*/
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#define U_SHAPE_DIGITS_ALEN2AN_INIT_AL 0x80
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/** Not a valid option value. May be replaced by a new option. */
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#define U_SHAPE_DIGITS_RESERVED 0xa0
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/** Bit mask for digit shaping options. @stable */
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#define U_SHAPE_DIGITS_MASK 0xe0
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/** Digit type option: Use Arabic-Indic digits (U+0660...U+0669). @stable */
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#define U_SHAPE_DIGIT_TYPE_AN 0
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/** Digit type option: Use Eastern (Extended) Arabic-Indic digits (U+06f0...U+06f9). @stable */
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#define U_SHAPE_DIGIT_TYPE_AN_EXTENDED 0x100
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/** Not a valid option value. May be replaced by a new option. */
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#define U_SHAPE_DIGIT_TYPE_RESERVED 0x200
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/** Bit mask for digit type options. @stable */
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#define U_SHAPE_DIGIT_TYPE_MASK 0x3f00
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#endif
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