/*

 *******************************************************************************

 *

 *   Copyright (C) 1999-2005, International Business Machines

 *   Corporation and others.  All Rights Reserved.

 *

 *******************************************************************************

 *   file name:  utf16.h

 *   encoding:   US-ASCII

 *   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.

  * utf16.h is included by utf.h after unicode/umachine.h

  * and some common definitions.

  *

  * For more information see utf.h and the ICU User Guide Strings chapter

  * (http://icu.sourceforge.net/userguide/strings.html).

  *

  * <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__

 /* utf.h must be included first. */

 #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)

 /**

  * 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) { \

     (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)); \

         } \

     } \

 }

 /**

  * 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.

  * If the offset points to a single, unpaired surrogate, then that itself

  * will be returned as the code point.

  * 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, 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) { \

     (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)-1>=(start) && U16_IS_LEAD(__c2=(s)[(i)-1])) { \

                 (c)=U16_GET_SUPPLEMENTARY(__c2, (c)); \

             } \

         } \

     } \

 }

 /* 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) { \

     (c)=(s)[(i)++]; \

     if(U16_IS_LEAD(c)) { \

         (c)=U16_GET_SUPPLEMENTARY((c), (s)[(i)++]); \

     } \

 }

 /**

  * 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 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 that itself

  * will be returned as the code point.

  *

  * @param s const UChar * string

  * @param i string offset, 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) { \

     (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); \

         } \

     } \

 }

 /**

  * 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) { \

     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); \

     } \

 }

 /**

  * 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, i<length

  * @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) { \

     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; \

     } \

 }

 /**

  * 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) { \

     if(U16_IS_LEAD((s)[(i)++])) { \

         ++(i); \

     } \

 }

 /**

  * 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.

  *

  * @param s const UChar * string

  * @param i string offset, i<length

  * @param length string length

  * @see U16_FWD_1_UNSAFE

  * @stable ICU 2.4

  */

 #define U16_FWD_1(s, i, length) { \

     if(U16_IS_LEAD((s)[(i)++]) && (i)<(length) && U16_IS_TRAIL((s)[i])) { \

         ++(i); \

     } \

 }

 /**

  * 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) { \

     int32_t __N=(n); \

     while(__N>0) { \

         U16_FWD_1_UNSAFE(s, i); \

         --__N; \

     } \

 }

 /**

  * 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.

  *

  * @param s const UChar * string

  * @param i string offset, i<length

  * @param length 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) { \

     int32_t __N=(n); \

     while(__N>0 && (i)<(length)) { \

         U16_FWD_1(s, i, length); \

         --__N; \

     } \

 }

 /**

  * 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) { \

     if(U16_IS_TRAIL((s)[i])) { \

         --(i); \

     } \

 }

 /**

  * 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, start<=i

  * @see U16_SET_CP_START_UNSAFE

  * @stable ICU 2.4

  */

 #define U16_SET_CP_START(s, start, i) { \

     if(U16_IS_TRAIL((s)[i]) && (i)>(start) && U16_IS_LEAD((s)[(i)-1])) { \

         --(i); \

     } \

 }

 /* 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) { \

     (c)=(s)[--(i)]; \

     if(U16_IS_TRAIL(c)) { \

         (c)=U16_GET_SUPPLEMENTARY((s)[--(i)], (c)); \

     } \

 }

 /**

  * 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 that itself

  * will be returned as the code point.

  *

  * @param s const UChar * string

  * @param start starting string offset (usually 0)

  * @param i string offset, start<=i

  * @param c output UChar32 variable

  * @see U16_PREV_UNSAFE

  * @stable ICU 2.4

  */

 #define U16_PREV(s, start, i, c) { \

     (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)); \

         } \

     } \

 }

 /**

  * 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) { \

     if(U16_IS_TRAIL((s)[--(i)])) { \

         --(i); \

     } \

 }

 /**

  * 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, start<=i

  * @see U16_BACK_1_UNSAFE

  * @stable ICU 2.4

  */

 #define U16_BACK_1(s, start, i) { \

     if(U16_IS_TRAIL((s)[--(i)]) && (i)>(start) && U16_IS_LEAD((s)[(i)-1])) { \

         --(i); \

     } \

 }

 /**

  * 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) { \

     int32_t __N=(n); \

     while(__N>0) { \

         U16_BACK_1_UNSAFE(s, i); \

         --__N; \

     } \

 }

 /**

  * 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, i<length

  * @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) { \

     int32_t __N=(n); \

     while(__N>0 && (i)>(start)) { \

         U16_BACK_1(s, start, i); \

         --__N; \

     } \

 }

 /**

  * 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) { \

     if(U16_IS_LEAD((s)[(i)-1])) { \

         ++(i); \

     } \

 }

 /**

  * 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.

  *

  * @param s const UChar * string

  * @param start starting string offset (usually 0)

  * @param i string offset, start<=i<=length

  * @param length string length

  * @see U16_SET_CP_LIMIT_UNSAFE

  * @stable ICU 2.4

  */

 #define U16_SET_CP_LIMIT(s, start, i, length) { \

     if((start)<(i) && (i)<(length) && U16_IS_LEAD((s)[(i)-1]) && U16_IS_TRAIL((s)[i])) { \

         ++(i); \

     } \

 }

 #endif