ICU-66108.tar.gz

[apple/icu.git] / icuSources / common / unicode / utf16.h

diff --git a/icuSources/common/unicode/utf16.h b/icuSources/common/unicode/utf16.h
index 5079c1146b3d347230cd698a0e1396897e4845ad..f3bdb82374aa1563990086c46eab637ba8a3245a 100644 (file)
--- a/icuSources/common/unicode/utf16.h
+++ b/icuSources/common/unicode/utf16.h
@@ -1,12 +1,14 @@
+// © 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html

 /*
 *******************************************************************************
 *
 /*
 *******************************************************************************
 *

-*   Copyright (C) 1999-2010, International Business Machines
+*   Copyright (C) 1999-2012, International Business Machines

 *   Corporation and others.  All Rights Reserved.
 *
 *******************************************************************************
 *   file name:  utf16.h
 *   Corporation and others.  All Rights Reserved.
 *
 *******************************************************************************
 *   file name:  utf16.h

-*   encoding:   US-ASCII
+*   encoding:   UTF-8

 *   tab size:   8 (not used)
 *   indentation:4
 *
 *   tab size:   8 (not used)
 *   indentation:4
 *


@@ -19,11 +21,9 @@
  * \brief C API: 16-bit Unicode handling macros
  * 
  * This file defines macros to deal with 16-bit Unicode (UTF-16) code units and strings.
  * \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
  *
  * For more information see utf.h and the ICU User Guide Strings chapter

- * (http://icu-project.org/userguide/strings.html).
+ * (http://userguide.icu-project.org/strings).

  *
  * <em>Usage:</em>
  * ICU coding guidelines for if() statements should be followed when using these macros.
  *
  * <em>Usage:</em>
  * ICU coding guidelines for if() statements should be followed when using these macros.


@@ -34,7 +34,7 @@
 #ifndef __UTF16_H__
 #define __UTF16_H__
 
 #ifndef __UTF16_H__
 #define __UTF16_H__
 

-/* utf.h must be included first. */
+#include "unicode/umachine.h"

 #ifndef __UTF_H__
 #   include "unicode/utf.h"
 #endif
 #ifndef __UTF_H__
 #   include "unicode/utf.h"
 #endif


@@ -163,7 +163,7 @@
  * @see U16_GET
  * @stable ICU 2.4
  */
  * @see U16_GET
  * @stable ICU 2.4
  */

-#define U16_GET_UNSAFE(s, i, c) { \
+#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)=(s)[i]; \
     if(U16_IS_SURROGATE(c)) { \
         if(U16_IS_SURROGATE_LEAD(c)) { \


@@ -172,7 +172,7 @@
             (c)=U16_GET_SUPPLEMENTARY((s)[(i)-1], (c)); \
         } \
     } \
             (c)=U16_GET_SUPPLEMENTARY((s)[(i)-1], (c)); \
         } \
     } \

-}
+} UPRV_BLOCK_MACRO_END

 
 /**
  * Get a code point from a string at a random-access offset,
 
 /**
  * Get a code point from a string at a random-access offset,


@@ -182,8 +182,11 @@
  * 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 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.
+ *
+ * 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
  * Iteration through a string is more efficient with U16_NEXT_UNSAFE or U16_NEXT.
  *
  * @param s const UChar * string


@@ -194,21 +197,64 @@
  * @see U16_GET_UNSAFE
  * @stable ICU 2.4
  */
  * @see U16_GET_UNSAFE
  * @stable ICU 2.4
  */

-#define U16_GET(s, start, i, length, c) { \
+#define U16_GET(s, start, i, length, c) UPRV_BLOCK_MACRO_BEGIN { \
+    (c)=(s)[i]; \
+    if(U16_IS_SURROGATE(c)) { \
+        uint16_t __c2 = 0; \
+        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)) { \
     (c)=(s)[i]; \
     if(U16_IS_SURROGATE(c)) { \

-        uint16_t __c2; \
+        uint16_t __c2 = 0; \

         if(U16_IS_SURROGATE_LEAD(c)) { \
         if(U16_IS_SURROGATE_LEAD(c)) { \

-            if((i)+1<(length) && U16_IS_TRAIL(__c2=(s)[(i)+1])) { \
+            if((i)+1!=(length) && U16_IS_TRAIL(__c2=(s)[(i)+1])) { \

                 (c)=U16_GET_SUPPLEMENTARY((c), __c2); \
                 (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 { \
             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 --------------------------------------- */
 
 
 /* definitions with forward iteration --------------------------------------- */
 


@@ -231,12 +277,12 @@
  * @see U16_NEXT
  * @stable ICU 2.4
  */
  * @see U16_NEXT
  * @stable ICU 2.4
  */

-#define U16_NEXT_UNSAFE(s, i, c) { \
+#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)++]); \
     } \
     (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,
 
 /**
  * Get a code point from a string at a code point boundary offset,


@@ -244,12 +290,13 @@
  * (Post-incrementing forward iteration.)
  * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
  *
  * (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
  * 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.
+ * 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 s const UChar * string
  * @param i string offset, must be i<length


@@ -258,16 +305,50 @@
  * @see U16_NEXT_UNSAFE
  * @stable ICU 2.4
  */
  * @see U16_NEXT_UNSAFE
  * @stable ICU 2.4
  */

-#define U16_NEXT(s, i, length, c) { \
+#define U16_NEXT(s, i, length, c) UPRV_BLOCK_MACRO_BEGIN { \

     (c)=(s)[(i)++]; \
     if(U16_IS_LEAD(c)) { \
     (c)=(s)[(i)++]; \
     if(U16_IS_LEAD(c)) { \

-        uint16_t __c2; \
-        if((i)<(length) && U16_IS_TRAIL(__c2=(s)[(i)])) { \
+        uint16_t __c2 = 0; \
+        if((i)!=(length) && U16_IS_TRAIL(__c2=(s)[(i)])) { \

             ++(i); \
             (c)=U16_GET_SUPPLEMENTARY((c), __c2); \
         } \
     } \
             ++(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 = 0; \
+        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.
 
 /**
  * Append a code point to a string, overwriting 1 or 2 code units.


@@ -282,14 +363,14 @@
  * @see U16_APPEND
  * @stable ICU 2.4
  */
  * @see U16_APPEND
  * @stable ICU 2.4
  */

-#define U16_APPEND_UNSAFE(s, i, c) { \
+#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); \
     } \
     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.
 
 /**
  * Append a code point to a string, overwriting 1 or 2 code units.


@@ -308,7 +389,7 @@
  * @see U16_APPEND_UNSAFE
  * @stable ICU 2.4
  */
  * @see U16_APPEND_UNSAFE
  * @stable ICU 2.4
  */

-#define U16_APPEND(s, i, capacity, c, isError) { \
+#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)) { \
     if((uint32_t)(c)<=0xffff) { \
         (s)[(i)++]=(uint16_t)(c); \
     } else if((uint32_t)(c)<=0x10ffff && (i)+1<(capacity)) { \


@@ -317,7 +398,7 @@
     } else /* c>0x10ffff or not enough space */ { \
         (isError)=TRUE; \
     } \
     } 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.
 
 /**
  * Advance the string offset from one code point boundary to the next.


@@ -329,28 +410,30 @@
  * @see U16_FWD_1
  * @stable ICU 2.4
  */
  * @see U16_FWD_1
  * @stable ICU 2.4
  */

-#define U16_FWD_1_UNSAFE(s, i) { \
+#define U16_FWD_1_UNSAFE(s, i) UPRV_BLOCK_MACRO_BEGIN { \

     if(U16_IS_LEAD((s)[(i)++])) { \
         ++(i); \
     } \
     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.
  *
 
 /**
  * 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
  */
  * @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) { \
-    if(U16_IS_LEAD((s)[(i)++]) && (i)<(length) && U16_IS_TRAIL((s)[i])) { \
+#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); \
     } \
         ++(i); \
     } \

-}
+} UPRV_BLOCK_MACRO_END

 
 /**
  * Advance the string offset from one code point boundary to the n-th next one,
 
 /**
  * Advance the string offset from one code point boundary to the n-th next one,


@@ -364,13 +447,13 @@
  * @see U16_FWD_N
  * @stable ICU 2.4
  */
  * @see U16_FWD_N
  * @stable ICU 2.4
  */

-#define U16_FWD_N_UNSAFE(s, i, n) { \
+#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; \
     } \
     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,
 
 /**
  * Advance the string offset from one code point boundary to the n-th next one,


@@ -378,20 +461,22 @@
  * (Post-incrementing iteration.)
  * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
  *
  * (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 s const UChar * string

- * @param i string offset, must be i<length
- * @param length string length
+ * @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
  */
  * @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) { \
+#define U16_FWD_N(s, i, length, n) UPRV_BLOCK_MACRO_BEGIN { \

     int32_t __N=(n); \
     int32_t __N=(n); \

-    while(__N>0 && (i)<(length)) { \
+    while(__N>0 && ((i)<(length) || ((length)<0 && (s)[i]!=0))) { \

         U16_FWD_1(s, i, length); \
         --__N; \
     } \
         U16_FWD_1(s, i, length); \
         --__N; \
     } \

-}
+} UPRV_BLOCK_MACRO_END

 
 /**
  * Adjust a random-access offset to a code point boundary
 
 /**
  * Adjust a random-access offset to a code point boundary


@@ -406,11 +491,11 @@
  * @see U16_SET_CP_START
  * @stable ICU 2.4
  */
  * @see U16_SET_CP_START
  * @stable ICU 2.4
  */

-#define U16_SET_CP_START_UNSAFE(s, i) { \
+#define U16_SET_CP_START_UNSAFE(s, i) UPRV_BLOCK_MACRO_BEGIN { \

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

-}
+} UPRV_BLOCK_MACRO_END

 
 /**
  * Adjust a random-access offset to a code point boundary
 
 /**
  * Adjust a random-access offset to a code point boundary


@@ -426,11 +511,11 @@
  * @see U16_SET_CP_START_UNSAFE
  * @stable ICU 2.4
  */
  * @see U16_SET_CP_START_UNSAFE
  * @stable ICU 2.4
  */

-#define U16_SET_CP_START(s, start, i) { \
+#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); \
     } \
     if(U16_IS_TRAIL((s)[i]) && (i)>(start) && U16_IS_LEAD((s)[(i)-1])) { \
         --(i); \
     } \

-}
+} UPRV_BLOCK_MACRO_END

 
 /* definitions with backward iteration -------------------------------------- */
 
 
 /* definitions with backward iteration -------------------------------------- */
 


@@ -454,12 +539,12 @@
  * @see U16_PREV
  * @stable ICU 2.4
  */
  * @see U16_PREV
  * @stable ICU 2.4
  */

-#define U16_PREV_UNSAFE(s, i, c) { \
+#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)); \
     } \
     (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
 
 /**
  * Move the string offset from one code point boundary to the previous one


@@ -472,8 +557,7 @@
  * 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
  * 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.
+ * trail surrogate, then c is set to that unpaired surrogate.

  *
  * @param s const UChar * string
  * @param start starting string offset (usually 0)
  *
  * @param s const UChar * string
  * @param start starting string offset (usually 0)


@@ -482,16 +566,49 @@
  * @see U16_PREV_UNSAFE
  * @stable ICU 2.4
  */
  * @see U16_PREV_UNSAFE
  * @stable ICU 2.4
  */

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

     (c)=(s)[--(i)]; \
     if(U16_IS_TRAIL(c)) { \
     (c)=(s)[--(i)]; \
     if(U16_IS_TRAIL(c)) { \

-        uint16_t __c2; \
+        uint16_t __c2 = 0; \

         if((i)>(start) && U16_IS_LEAD(__c2=(s)[(i)-1])) { \
             --(i); \
             (c)=U16_GET_SUPPLEMENTARY(__c2, (c)); \
         } \
     } \
         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 = 0; \
+        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.
 
 /**
  * Move the string offset from one code point boundary to the previous one.


@@ -504,11 +621,11 @@
  * @see U16_BACK_1
  * @stable ICU 2.4
  */
  * @see U16_BACK_1
  * @stable ICU 2.4
  */

-#define U16_BACK_1_UNSAFE(s, i) { \
+#define U16_BACK_1_UNSAFE(s, i) UPRV_BLOCK_MACRO_BEGIN { \

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

-}
+} UPRV_BLOCK_MACRO_END

 
 /**
  * Move the string offset from one code point boundary to the previous one.
 
 /**
  * Move the string offset from one code point boundary to the previous one.


@@ -522,11 +639,11 @@
  * @see U16_BACK_1_UNSAFE
  * @stable ICU 2.4
  */
  * @see U16_BACK_1_UNSAFE
  * @stable ICU 2.4
  */

-#define U16_BACK_1(s, start, i) { \
+#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); \
     } \
     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,
 
 /**
  * Move the string offset from one code point boundary to the n-th one before it,


@@ -541,13 +658,13 @@
  * @see U16_BACK_N
  * @stable ICU 2.4
  */
  * @see U16_BACK_N
  * @stable ICU 2.4
  */

-#define U16_BACK_N_UNSAFE(s, i, n) { \
+#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; \
     } \
     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,
 
 /**
  * Move the string offset from one code point boundary to the n-th one before it,


@@ -563,13 +680,13 @@
  * @see U16_BACK_N_UNSAFE
  * @stable ICU 2.4
  */
  * @see U16_BACK_N_UNSAFE
  * @stable ICU 2.4
  */

-#define U16_BACK_N(s, start, i, n) { \
+#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; \
     } \
     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.
 
 /**
  * Adjust a random-access offset to a code point boundary after a code point.


@@ -584,11 +701,11 @@
  * @see U16_SET_CP_LIMIT
  * @stable ICU 2.4
  */
  * @see U16_SET_CP_LIMIT
  * @stable ICU 2.4
  */

-#define U16_SET_CP_LIMIT_UNSAFE(s, i) { \
+#define U16_SET_CP_LIMIT_UNSAFE(s, i) UPRV_BLOCK_MACRO_BEGIN { \

     if(U16_IS_LEAD((s)[(i)-1])) { \
         ++(i); \
     } \
     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.
 
 /**
  * Adjust a random-access offset to a code point boundary after a code point.


@@ -598,17 +715,19 @@
  * The input offset may be the same as the string length.
  * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
  *
  * 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 s const UChar * string

- * @param start starting string offset (usually 0)
- * @param i string offset, start<=i<=length
- * @param length string length
+ * @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
  */
  * @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])) { \
+#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); \
     } \
         ++(i); \
     } \

-}
+} UPRV_BLOCK_MACRO_END

 
 #endif
 
 #endif