add static QChar::is(High|Low)Surrogate methods

to avoid recoding of character

this also adds QChar::requiresSurrogates() static member
supposed to save from common mistake like `ucs4 > 0x10000`

Merge-request: 606
Reviewed-by: Thiago Macieira <thiago.macieira@nokia.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/src/corelib/tools/qchar.h b/src/corelib/tools/qchar.h
index 1432c7f..205f911 100644
--- a/src/corelib/tools/qchar.h
+++ b/src/corelib/tools/qchar.h
@@ -285,6 +285,15 @@ public:
     inline void setCell(uchar cell);
     inline void setRow(uchar row);
 
+    static inline bool isHighSurrogate(uint ucs4) {
+        return ((ucs4 & 0xfffffc00) == 0xd800);
+    }
+    static inline bool isLowSurrogate(uint ucs4) {
+        return ((ucs4 & 0xfffffc00) == 0xdc00);
+    }
+    static inline bool requiresSurrogates(uint ucs4) {
+        return (ucs4 >= 0x10000);
+    }
     static inline uint surrogateToUcs4(ushort high, ushort low) {
         return (uint(high)<<10) + low - 0x35fdc00;
     }