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Diffstat (limited to 'intl/icu/source/common/unicode/utf16.h')
| -rw-r--r-- | intl/icu/source/common/unicode/utf16.h | 734 |
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diff --git a/intl/icu/source/common/unicode/utf16.h b/intl/icu/source/common/unicode/utf16.h new file mode 100644 index 0000000000..3902c60e95 --- /dev/null +++ b/intl/icu/source/common/unicode/utf16.h @@ -0,0 +1,734 @@ +// © 2016 and later: Unicode, Inc. and others. +// License & terms of use: http://www.unicode.org/copyright.html +/* +******************************************************************************* +* +* Copyright (C) 1999-2012, International Business Machines +* Corporation and others. All Rights Reserved. +* +******************************************************************************* +* file name: utf16.h +* encoding: UTF-8 +* tab size: 8 (not used) +* indentation:4 +* +* created on: 1999sep09 +* created by: Markus W. Scherer +*/ + +/** + * \file + * \brief C API: 16-bit Unicode handling macros + * + * This file defines macros to deal with 16-bit Unicode (UTF-16) code units and strings. + * + * For more information see utf.h and the ICU User Guide Strings chapter + * (https://unicode-org.github.io/icu/userguide/strings). + * + * <em>Usage:</em> + * ICU coding guidelines for if() statements should be followed when using these macros. + * Compound statements (curly braces {}) must be used for if-else-while... + * bodies and all macro statements should be terminated with semicolon. + */ + +#ifndef __UTF16_H__ +#define __UTF16_H__ + +#include <stdbool.h> +#include "unicode/umachine.h" +#ifndef __UTF_H__ +# include "unicode/utf.h" +#endif + +/* single-code point definitions -------------------------------------------- */ + +/** + * Does this code unit alone encode a code point (BMP, not a surrogate)? + * @param c 16-bit code unit + * @return true or false + * @stable ICU 2.4 + */ +#define U16_IS_SINGLE(c) !U_IS_SURROGATE(c) + +/** + * Is this code unit a lead surrogate (U+d800..U+dbff)? + * @param c 16-bit code unit + * @return true or false + * @stable ICU 2.4 + */ +#define U16_IS_LEAD(c) (((c)&0xfffffc00)==0xd800) + +/** + * Is this code unit a trail surrogate (U+dc00..U+dfff)? + * @param c 16-bit code unit + * @return true or false + * @stable ICU 2.4 + */ +#define U16_IS_TRAIL(c) (((c)&0xfffffc00)==0xdc00) + +/** + * Is this code unit a surrogate (U+d800..U+dfff)? + * @param c 16-bit code unit + * @return true or false + * @stable ICU 2.4 + */ +#define U16_IS_SURROGATE(c) U_IS_SURROGATE(c) + +/** + * Assuming c is a surrogate code point (U16_IS_SURROGATE(c)), + * is it a lead surrogate? + * @param c 16-bit code unit + * @return true or false + * @stable ICU 2.4 + */ +#define U16_IS_SURROGATE_LEAD(c) (((c)&0x400)==0) + +/** + * Assuming c is a surrogate code point (U16_IS_SURROGATE(c)), + * is it a trail surrogate? + * @param c 16-bit code unit + * @return true or false + * @stable ICU 4.2 + */ +#define U16_IS_SURROGATE_TRAIL(c) (((c)&0x400)!=0) + +/** + * Helper constant for U16_GET_SUPPLEMENTARY. + * @internal + */ +#define U16_SURROGATE_OFFSET ((0xd800<<10UL)+0xdc00-0x10000) + +/** + * Get a supplementary code point value (U+10000..U+10ffff) + * from its lead and trail surrogates. + * The result is undefined if the input values are not + * lead and trail surrogates. + * + * @param lead lead surrogate (U+d800..U+dbff) + * @param trail trail surrogate (U+dc00..U+dfff) + * @return supplementary code point (U+10000..U+10ffff) + * @stable ICU 2.4 + */ +#define U16_GET_SUPPLEMENTARY(lead, trail) \ + (((UChar32)(lead)<<10UL)+(UChar32)(trail)-U16_SURROGATE_OFFSET) + + +/** + * Get the lead surrogate (0xd800..0xdbff) for a + * supplementary code point (0x10000..0x10ffff). + * @param supplementary 32-bit code point (U+10000..U+10ffff) + * @return lead surrogate (U+d800..U+dbff) for supplementary + * @stable ICU 2.4 + */ +#define U16_LEAD(supplementary) (UChar)(((supplementary)>>10)+0xd7c0) + +/** + * Get the trail surrogate (0xdc00..0xdfff) for a + * supplementary code point (0x10000..0x10ffff). + * @param supplementary 32-bit code point (U+10000..U+10ffff) + * @return trail surrogate (U+dc00..U+dfff) for supplementary + * @stable ICU 2.4 + */ +#define U16_TRAIL(supplementary) (UChar)(((supplementary)&0x3ff)|0xdc00) + +/** + * How many 16-bit code units are used to encode this Unicode code point? (1 or 2) + * The result is not defined if c is not a Unicode code point (U+0000..U+10ffff). + * @param c 32-bit code point + * @return 1 or 2 + * @stable ICU 2.4 + */ +#define U16_LENGTH(c) ((uint32_t)(c)<=0xffff ? 1 : 2) + +/** + * The maximum number of 16-bit code units per Unicode code point (U+0000..U+10ffff). + * @return 2 + * @stable ICU 2.4 + */ +#define U16_MAX_LENGTH 2 + +/** + * Get a code point from a string at a random-access offset, + * without changing the offset. + * "Unsafe" macro, assumes well-formed UTF-16. + * + * The offset may point to either the lead or trail surrogate unit + * for a supplementary code point, in which case the macro will read + * the adjacent matching surrogate as well. + * The result is undefined if the offset points to a single, unpaired surrogate. + * Iteration through a string is more efficient with U16_NEXT_UNSAFE or U16_NEXT. + * + * @param s const UChar * string + * @param i string offset + * @param c output UChar32 variable + * @see U16_GET + * @stable ICU 2.4 + */ +#define U16_GET_UNSAFE(s, i, c) UPRV_BLOCK_MACRO_BEGIN { \ + (c)=(s)[i]; \ + if(U16_IS_SURROGATE(c)) { \ + if(U16_IS_SURROGATE_LEAD(c)) { \ + (c)=U16_GET_SUPPLEMENTARY((c), (s)[(i)+1]); \ + } else { \ + (c)=U16_GET_SUPPLEMENTARY((s)[(i)-1], (c)); \ + } \ + } \ +} UPRV_BLOCK_MACRO_END + +/** + * Get a code point from a string at a random-access offset, + * without changing the offset. + * "Safe" macro, handles unpaired surrogates and checks for string boundaries. + * + * The offset may point to either the lead or trail surrogate unit + * for a supplementary code point, in which case the macro will read + * the adjacent matching surrogate as well. + * + * The length can be negative for a NUL-terminated string. + * + * If the offset points to a single, unpaired surrogate, then + * c is set to that unpaired surrogate. + * Iteration through a string is more efficient with U16_NEXT_UNSAFE or U16_NEXT. + * + * @param s const UChar * string + * @param start starting string offset (usually 0) + * @param i string offset, must be start<=i<length + * @param length string length + * @param c output UChar32 variable + * @see U16_GET_UNSAFE + * @stable ICU 2.4 + */ +#define U16_GET(s, start, i, length, c) UPRV_BLOCK_MACRO_BEGIN { \ + (c)=(s)[i]; \ + if(U16_IS_SURROGATE(c)) { \ + uint16_t __c2; \ + if(U16_IS_SURROGATE_LEAD(c)) { \ + if((i)+1!=(length) && U16_IS_TRAIL(__c2=(s)[(i)+1])) { \ + (c)=U16_GET_SUPPLEMENTARY((c), __c2); \ + } \ + } else { \ + if((i)>(start) && U16_IS_LEAD(__c2=(s)[(i)-1])) { \ + (c)=U16_GET_SUPPLEMENTARY(__c2, (c)); \ + } \ + } \ + } \ +} UPRV_BLOCK_MACRO_END + +/** + * Get a code point from a string at a random-access offset, + * without changing the offset. + * "Safe" macro, handles unpaired surrogates and checks for string boundaries. + * + * The offset may point to either the lead or trail surrogate unit + * for a supplementary code point, in which case the macro will read + * the adjacent matching surrogate as well. + * + * The length can be negative for a NUL-terminated string. + * + * If the offset points to a single, unpaired surrogate, then + * c is set to U+FFFD. + * Iteration through a string is more efficient with U16_NEXT_UNSAFE or U16_NEXT_OR_FFFD. + * + * @param s const UChar * string + * @param start starting string offset (usually 0) + * @param i string offset, must be start<=i<length + * @param length string length + * @param c output UChar32 variable + * @see U16_GET_UNSAFE + * @stable ICU 60 + */ +#define U16_GET_OR_FFFD(s, start, i, length, c) UPRV_BLOCK_MACRO_BEGIN { \ + (c)=(s)[i]; \ + if(U16_IS_SURROGATE(c)) { \ + uint16_t __c2; \ + if(U16_IS_SURROGATE_LEAD(c)) { \ + if((i)+1!=(length) && U16_IS_TRAIL(__c2=(s)[(i)+1])) { \ + (c)=U16_GET_SUPPLEMENTARY((c), __c2); \ + } else { \ + (c)=0xfffd; \ + } \ + } else { \ + if((i)>(start) && U16_IS_LEAD(__c2=(s)[(i)-1])) { \ + (c)=U16_GET_SUPPLEMENTARY(__c2, (c)); \ + } else { \ + (c)=0xfffd; \ + } \ + } \ + } \ +} UPRV_BLOCK_MACRO_END + +/* definitions with forward iteration --------------------------------------- */ + +/** + * Get a code point from a string at a code point boundary offset, + * and advance the offset to the next code point boundary. + * (Post-incrementing forward iteration.) + * "Unsafe" macro, assumes well-formed UTF-16. + * + * The offset may point to the lead surrogate unit + * for a supplementary code point, in which case the macro will read + * the following trail surrogate as well. + * If the offset points to a trail surrogate, then that itself + * will be returned as the code point. + * The result is undefined if the offset points to a single, unpaired lead surrogate. + * + * @param s const UChar * string + * @param i string offset + * @param c output UChar32 variable + * @see U16_NEXT + * @stable ICU 2.4 + */ +#define U16_NEXT_UNSAFE(s, i, c) UPRV_BLOCK_MACRO_BEGIN { \ + (c)=(s)[(i)++]; \ + if(U16_IS_LEAD(c)) { \ + (c)=U16_GET_SUPPLEMENTARY((c), (s)[(i)++]); \ + } \ +} UPRV_BLOCK_MACRO_END + +/** + * Get a code point from a string at a code point boundary offset, + * and advance the offset to the next code point boundary. + * (Post-incrementing forward iteration.) + * "Safe" macro, handles unpaired surrogates and checks for string boundaries. + * + * The length can be negative for a NUL-terminated string. + * + * The offset may point to the lead surrogate unit + * for a supplementary code point, in which case the macro will read + * the following trail surrogate as well. + * If the offset points to a trail surrogate or + * to a single, unpaired lead surrogate, then c is set to that unpaired surrogate. + * + * @param s const UChar * string + * @param i string offset, must be i<length + * @param length string length + * @param c output UChar32 variable + * @see U16_NEXT_UNSAFE + * @stable ICU 2.4 + */ +#define U16_NEXT(s, i, length, c) UPRV_BLOCK_MACRO_BEGIN { \ + (c)=(s)[(i)++]; \ + if(U16_IS_LEAD(c)) { \ + uint16_t __c2; \ + if((i)!=(length) && U16_IS_TRAIL(__c2=(s)[(i)])) { \ + ++(i); \ + (c)=U16_GET_SUPPLEMENTARY((c), __c2); \ + } \ + } \ +} UPRV_BLOCK_MACRO_END + +/** + * Get a code point from a string at a code point boundary offset, + * and advance the offset to the next code point boundary. + * (Post-incrementing forward iteration.) + * "Safe" macro, handles unpaired surrogates and checks for string boundaries. + * + * The length can be negative for a NUL-terminated string. + * + * The offset may point to the lead surrogate unit + * for a supplementary code point, in which case the macro will read + * the following trail surrogate as well. + * If the offset points to a trail surrogate or + * to a single, unpaired lead surrogate, then c is set to U+FFFD. + * + * @param s const UChar * string + * @param i string offset, must be i<length + * @param length string length + * @param c output UChar32 variable + * @see U16_NEXT_UNSAFE + * @stable ICU 60 + */ +#define U16_NEXT_OR_FFFD(s, i, length, c) UPRV_BLOCK_MACRO_BEGIN { \ + (c)=(s)[(i)++]; \ + if(U16_IS_SURROGATE(c)) { \ + uint16_t __c2; \ + if(U16_IS_SURROGATE_LEAD(c) && (i)!=(length) && U16_IS_TRAIL(__c2=(s)[(i)])) { \ + ++(i); \ + (c)=U16_GET_SUPPLEMENTARY((c), __c2); \ + } else { \ + (c)=0xfffd; \ + } \ + } \ +} UPRV_BLOCK_MACRO_END + +/** + * Append a code point to a string, overwriting 1 or 2 code units. + * The offset points to the current end of the string contents + * and is advanced (post-increment). + * "Unsafe" macro, assumes a valid code point and sufficient space in the string. + * Otherwise, the result is undefined. + * + * @param s const UChar * string buffer + * @param i string offset + * @param c code point to append + * @see U16_APPEND + * @stable ICU 2.4 + */ +#define U16_APPEND_UNSAFE(s, i, c) UPRV_BLOCK_MACRO_BEGIN { \ + if((uint32_t)(c)<=0xffff) { \ + (s)[(i)++]=(uint16_t)(c); \ + } else { \ + (s)[(i)++]=(uint16_t)(((c)>>10)+0xd7c0); \ + (s)[(i)++]=(uint16_t)(((c)&0x3ff)|0xdc00); \ + } \ +} UPRV_BLOCK_MACRO_END + +/** + * Append a code point to a string, overwriting 1 or 2 code units. + * The offset points to the current end of the string contents + * and is advanced (post-increment). + * "Safe" macro, checks for a valid code point. + * If a surrogate pair is written, checks for sufficient space in the string. + * If the code point is not valid or a trail surrogate does not fit, + * then isError is set to true. + * + * @param s const UChar * string buffer + * @param i string offset, must be i<capacity + * @param capacity size of the string buffer + * @param c code point to append + * @param isError output UBool set to true if an error occurs, otherwise not modified + * @see U16_APPEND_UNSAFE + * @stable ICU 2.4 + */ +#define U16_APPEND(s, i, capacity, c, isError) UPRV_BLOCK_MACRO_BEGIN { \ + if((uint32_t)(c)<=0xffff) { \ + (s)[(i)++]=(uint16_t)(c); \ + } else if((uint32_t)(c)<=0x10ffff && (i)+1<(capacity)) { \ + (s)[(i)++]=(uint16_t)(((c)>>10)+0xd7c0); \ + (s)[(i)++]=(uint16_t)(((c)&0x3ff)|0xdc00); \ + } else /* c>0x10ffff or not enough space */ { \ + (isError)=true; \ + } \ +} UPRV_BLOCK_MACRO_END + +/** + * Advance the string offset from one code point boundary to the next. + * (Post-incrementing iteration.) + * "Unsafe" macro, assumes well-formed UTF-16. + * + * @param s const UChar * string + * @param i string offset + * @see U16_FWD_1 + * @stable ICU 2.4 + */ +#define U16_FWD_1_UNSAFE(s, i) UPRV_BLOCK_MACRO_BEGIN { \ + if(U16_IS_LEAD((s)[(i)++])) { \ + ++(i); \ + } \ +} UPRV_BLOCK_MACRO_END + +/** + * Advance the string offset from one code point boundary to the next. + * (Post-incrementing iteration.) + * "Safe" macro, handles unpaired surrogates and checks for string boundaries. + * + * The length can be negative for a NUL-terminated string. + * + * @param s const UChar * string + * @param i string offset, must be i<length + * @param length string length + * @see U16_FWD_1_UNSAFE + * @stable ICU 2.4 + */ +#define U16_FWD_1(s, i, length) UPRV_BLOCK_MACRO_BEGIN { \ + if(U16_IS_LEAD((s)[(i)++]) && (i)!=(length) && U16_IS_TRAIL((s)[i])) { \ + ++(i); \ + } \ +} UPRV_BLOCK_MACRO_END + +/** + * Advance the string offset from one code point boundary to the n-th next one, + * i.e., move forward by n code points. + * (Post-incrementing iteration.) + * "Unsafe" macro, assumes well-formed UTF-16. + * + * @param s const UChar * string + * @param i string offset + * @param n number of code points to skip + * @see U16_FWD_N + * @stable ICU 2.4 + */ +#define U16_FWD_N_UNSAFE(s, i, n) UPRV_BLOCK_MACRO_BEGIN { \ + int32_t __N=(n); \ + while(__N>0) { \ + U16_FWD_1_UNSAFE(s, i); \ + --__N; \ + } \ +} UPRV_BLOCK_MACRO_END + +/** + * Advance the string offset from one code point boundary to the n-th next one, + * i.e., move forward by n code points. + * (Post-incrementing iteration.) + * "Safe" macro, handles unpaired surrogates and checks for string boundaries. + * + * The length can be negative for a NUL-terminated string. + * + * @param s const UChar * string + * @param i int32_t string offset, must be i<length + * @param length int32_t string length + * @param n number of code points to skip + * @see U16_FWD_N_UNSAFE + * @stable ICU 2.4 + */ +#define U16_FWD_N(s, i, length, n) UPRV_BLOCK_MACRO_BEGIN { \ + int32_t __N=(n); \ + while(__N>0 && ((i)<(length) || ((length)<0 && (s)[i]!=0))) { \ + U16_FWD_1(s, i, length); \ + --__N; \ + } \ +} UPRV_BLOCK_MACRO_END + +/** + * Adjust a random-access offset to a code point boundary + * at the start of a code point. + * If the offset points to the trail surrogate of a surrogate pair, + * then the offset is decremented. + * Otherwise, it is not modified. + * "Unsafe" macro, assumes well-formed UTF-16. + * + * @param s const UChar * string + * @param i string offset + * @see U16_SET_CP_START + * @stable ICU 2.4 + */ +#define U16_SET_CP_START_UNSAFE(s, i) UPRV_BLOCK_MACRO_BEGIN { \ + if(U16_IS_TRAIL((s)[i])) { \ + --(i); \ + } \ +} UPRV_BLOCK_MACRO_END + +/** + * Adjust a random-access offset to a code point boundary + * at the start of a code point. + * If the offset points to the trail surrogate of a surrogate pair, + * then the offset is decremented. + * Otherwise, it is not modified. + * "Safe" macro, handles unpaired surrogates and checks for string boundaries. + * + * @param s const UChar * string + * @param start starting string offset (usually 0) + * @param i string offset, must be start<=i + * @see U16_SET_CP_START_UNSAFE + * @stable ICU 2.4 + */ +#define U16_SET_CP_START(s, start, i) UPRV_BLOCK_MACRO_BEGIN { \ + if(U16_IS_TRAIL((s)[i]) && (i)>(start) && U16_IS_LEAD((s)[(i)-1])) { \ + --(i); \ + } \ +} UPRV_BLOCK_MACRO_END + +/* definitions with backward iteration -------------------------------------- */ + +/** + * Move the string offset from one code point boundary to the previous one + * and get the code point between them. + * (Pre-decrementing backward iteration.) + * "Unsafe" macro, assumes well-formed UTF-16. + * + * The input offset may be the same as the string length. + * If the offset is behind a trail surrogate unit + * for a supplementary code point, then the macro will read + * the preceding lead surrogate as well. + * If the offset is behind a lead surrogate, then that itself + * will be returned as the code point. + * The result is undefined if the offset is behind a single, unpaired trail surrogate. + * + * @param s const UChar * string + * @param i string offset + * @param c output UChar32 variable + * @see U16_PREV + * @stable ICU 2.4 + */ +#define U16_PREV_UNSAFE(s, i, c) UPRV_BLOCK_MACRO_BEGIN { \ + (c)=(s)[--(i)]; \ + if(U16_IS_TRAIL(c)) { \ + (c)=U16_GET_SUPPLEMENTARY((s)[--(i)], (c)); \ + } \ +} UPRV_BLOCK_MACRO_END + +/** + * Move the string offset from one code point boundary to the previous one + * and get the code point between them. + * (Pre-decrementing backward iteration.) + * "Safe" macro, handles unpaired surrogates and checks for string boundaries. + * + * The input offset may be the same as the string length. + * If the offset is behind a trail surrogate unit + * for a supplementary code point, then the macro will read + * the preceding lead surrogate as well. + * If the offset is behind a lead surrogate or behind a single, unpaired + * trail surrogate, then c is set to that unpaired surrogate. + * + * @param s const UChar * string + * @param start starting string offset (usually 0) + * @param i string offset, must be start<i + * @param c output UChar32 variable + * @see U16_PREV_UNSAFE + * @stable ICU 2.4 + */ +#define U16_PREV(s, start, i, c) UPRV_BLOCK_MACRO_BEGIN { \ + (c)=(s)[--(i)]; \ + if(U16_IS_TRAIL(c)) { \ + uint16_t __c2; \ + if((i)>(start) && U16_IS_LEAD(__c2=(s)[(i)-1])) { \ + --(i); \ + (c)=U16_GET_SUPPLEMENTARY(__c2, (c)); \ + } \ + } \ +} UPRV_BLOCK_MACRO_END + +/** + * Move the string offset from one code point boundary to the previous one + * and get the code point between them. + * (Pre-decrementing backward iteration.) + * "Safe" macro, handles unpaired surrogates and checks for string boundaries. + * + * The input offset may be the same as the string length. + * If the offset is behind a trail surrogate unit + * for a supplementary code point, then the macro will read + * the preceding lead surrogate as well. + * If the offset is behind a lead surrogate or behind a single, unpaired + * trail surrogate, then c is set to U+FFFD. + * + * @param s const UChar * string + * @param start starting string offset (usually 0) + * @param i string offset, must be start<i + * @param c output UChar32 variable + * @see U16_PREV_UNSAFE + * @stable ICU 60 + */ +#define U16_PREV_OR_FFFD(s, start, i, c) UPRV_BLOCK_MACRO_BEGIN { \ + (c)=(s)[--(i)]; \ + if(U16_IS_SURROGATE(c)) { \ + uint16_t __c2; \ + if(U16_IS_SURROGATE_TRAIL(c) && (i)>(start) && U16_IS_LEAD(__c2=(s)[(i)-1])) { \ + --(i); \ + (c)=U16_GET_SUPPLEMENTARY(__c2, (c)); \ + } else { \ + (c)=0xfffd; \ + } \ + } \ +} UPRV_BLOCK_MACRO_END + +/** + * Move the string offset from one code point boundary to the previous one. + * (Pre-decrementing backward iteration.) + * The input offset may be the same as the string length. + * "Unsafe" macro, assumes well-formed UTF-16. + * + * @param s const UChar * string + * @param i string offset + * @see U16_BACK_1 + * @stable ICU 2.4 + */ +#define U16_BACK_1_UNSAFE(s, i) UPRV_BLOCK_MACRO_BEGIN { \ + if(U16_IS_TRAIL((s)[--(i)])) { \ + --(i); \ + } \ +} UPRV_BLOCK_MACRO_END + +/** + * Move the string offset from one code point boundary to the previous one. + * (Pre-decrementing backward iteration.) + * The input offset may be the same as the string length. + * "Safe" macro, handles unpaired surrogates and checks for string boundaries. + * + * @param s const UChar * string + * @param start starting string offset (usually 0) + * @param i string offset, must be start<i + * @see U16_BACK_1_UNSAFE + * @stable ICU 2.4 + */ +#define U16_BACK_1(s, start, i) UPRV_BLOCK_MACRO_BEGIN { \ + if(U16_IS_TRAIL((s)[--(i)]) && (i)>(start) && U16_IS_LEAD((s)[(i)-1])) { \ + --(i); \ + } \ +} UPRV_BLOCK_MACRO_END + +/** + * Move the string offset from one code point boundary to the n-th one before it, + * i.e., move backward by n code points. + * (Pre-decrementing backward iteration.) + * The input offset may be the same as the string length. + * "Unsafe" macro, assumes well-formed UTF-16. + * + * @param s const UChar * string + * @param i string offset + * @param n number of code points to skip + * @see U16_BACK_N + * @stable ICU 2.4 + */ +#define U16_BACK_N_UNSAFE(s, i, n) UPRV_BLOCK_MACRO_BEGIN { \ + int32_t __N=(n); \ + while(__N>0) { \ + U16_BACK_1_UNSAFE(s, i); \ + --__N; \ + } \ +} UPRV_BLOCK_MACRO_END + +/** + * Move the string offset from one code point boundary to the n-th one before it, + * i.e., move backward by n code points. + * (Pre-decrementing backward iteration.) + * The input offset may be the same as the string length. + * "Safe" macro, handles unpaired surrogates and checks for string boundaries. + * + * @param s const UChar * string + * @param start start of string + * @param i string offset, must be start<i + * @param n number of code points to skip + * @see U16_BACK_N_UNSAFE + * @stable ICU 2.4 + */ +#define U16_BACK_N(s, start, i, n) UPRV_BLOCK_MACRO_BEGIN { \ + int32_t __N=(n); \ + while(__N>0 && (i)>(start)) { \ + U16_BACK_1(s, start, i); \ + --__N; \ + } \ +} UPRV_BLOCK_MACRO_END + +/** + * Adjust a random-access offset to a code point boundary after a code point. + * If the offset is behind the lead surrogate of a surrogate pair, + * then the offset is incremented. + * Otherwise, it is not modified. + * The input offset may be the same as the string length. + * "Unsafe" macro, assumes well-formed UTF-16. + * + * @param s const UChar * string + * @param i string offset + * @see U16_SET_CP_LIMIT + * @stable ICU 2.4 + */ +#define U16_SET_CP_LIMIT_UNSAFE(s, i) UPRV_BLOCK_MACRO_BEGIN { \ + if(U16_IS_LEAD((s)[(i)-1])) { \ + ++(i); \ + } \ +} UPRV_BLOCK_MACRO_END + +/** + * Adjust a random-access offset to a code point boundary after a code point. + * If the offset is behind the lead surrogate of a surrogate pair, + * then the offset is incremented. + * Otherwise, it is not modified. + * The input offset may be the same as the string length. + * "Safe" macro, handles unpaired surrogates and checks for string boundaries. + * + * The length can be negative for a NUL-terminated string. + * + * @param s const UChar * string + * @param start int32_t starting string offset (usually 0) + * @param i int32_t string offset, start<=i<=length + * @param length int32_t string length + * @see U16_SET_CP_LIMIT_UNSAFE + * @stable ICU 2.4 + */ +#define U16_SET_CP_LIMIT(s, start, i, length) UPRV_BLOCK_MACRO_BEGIN { \ + if((start)<(i) && ((i)<(length) || (length)<0) && U16_IS_LEAD((s)[(i)-1]) && U16_IS_TRAIL((s)[i])) { \ + ++(i); \ + } \ +} UPRV_BLOCK_MACRO_END + +#endif |