#10542: Add 4 macros to work with surrogates: Py_UNICODE_IS_SURROGATE, Py_UNICODE_IS_HIGH_SURROGATE, Py_UNICODE_IS_LOW_SURROGATE, Py_UNICODE_JOIN_SURROGATES.

Doc/c-api/unicode.rst

@@ -195,6 +195,27 @@ These APIs can be used for fast direct character conversions:
    possible.  This macro does not raise exceptions.
 
 
+These APIs can be used to work with surrogates:
+
+.. c:macro:: Py_UNICODE_IS_SURROGATE(ch)
+
+   Check if *ch* is a surrogate (``0xD800 <= ch <= 0xDFFF``).
+
+.. c:macro:: Py_UNICODE_IS_HIGH_SURROGATE(ch)
+
+   Check if *ch* is an high surrogate (``0xD800 <= ch <= 0xDBFF``).
+
+.. c:macro:: Py_UNICODE_IS_LOW_SURROGATE(ch)
+
+   Check if *ch* is a low surrogate (``0xDC00 <= ch <= 0xDFFF``).
+
+.. c:macro:: Py_UNICODE_JOIN_SURROGATES(high, low)
+
+   Join two surrogate characters and return a single Py_UCS4 value.
+   *high* and *low* are respectively the leading and trailing surrogates in a
+   surrogate pair.
+
+
 Plain Py_UNICODE
 """"""""""""""""
 

Include/unicodeobject.h

@@ -362,6 +362,15 @@ typedef PY_UNICODE_TYPE Py_UNICODE;
     for (i_ = 0; i_ < (length); i_++) t_[i_] = v_;\
     } while (0)
 
+/* macros to work with surrogates */
+#define Py_UNICODE_IS_SURROGATE(ch) (0xD800 <= ch && ch <= 0xDFFF)
+#define Py_UNICODE_IS_HIGH_SURROGATE(ch) (0xD800 <= ch && ch <= 0xDBFF)
+#define Py_UNICODE_IS_LOW_SURROGATE(ch) (0xDC00 <= ch && ch <= 0xDFFF)
+/* Join two surrogate characters and return a single Py_UCS4 value. */
+#define Py_UNICODE_JOIN_SURROGATES(high, low)  \
+    (((((Py_UCS4)(high) & 0x03FF) << 10) |      \
+      ((Py_UCS4)(low) & 0x03FF)) + 0x10000)
+
 /* Check if substring matches at given offset.  The offset must be
    valid, and the substring must not be empty. */
 

Misc/NEWS

@@ -1395,6 +1395,10 @@ Tests
 C-API
 -----
 
+- Issue #10542: Add 4 macros to work with surrogates: Py_UNICODE_IS_SURROGATE,
+  Py_UNICODE_IS_HIGH_SURROGATE, Py_UNICODE_IS_LOW_SURROGATE,
+  Py_UNICODE_JOIN_SURROGATES.
+
 - Issue #12724: Add Py_RETURN_NOTIMPLEMENTED macro for returning NotImplemented.
 
 - PY_PATCHLEVEL_REVISION has been removed, since it's meaningless with