fixed an issue where escaping didn't work properly for \uXXXX unicode sequences.

Author: jacobwilliams

src/json_string_utilities.F90

@@ -335,7 +335,23 @@ subroutine escape_string(str_in, str_out)
             if (ipos+3>len(str_out)) str_out = str_out // repeat(space, chunk_size)
 
             select case(c)
-            case(quotation_mark,backslash,slash)
+            case(backslash)
+
+                !test for unicode sequence: '\uXXXX'
+                ![don't add an extra '\' for those]
+                if (i+5<=len(str_in)) then
+                    if (str_in(i+1:i+1)==CK_'u' .and. &
+                        valid_json_hex(str_in(i+2:i+5))) then
+                        str_out(ipos:ipos) = c
+                        ipos = ipos + 1
+                        cycle
+                    end if
+                end if
+
+                str_out(ipos:ipos+1) = backslash//c
+                ipos = ipos + 2
+
+            case(quotation_mark,slash)
                 str_out(ipos:ipos+1) = backslash//c
                 ipos = ipos + 2
             case(bspace)