optimized char check for low surrogate (#1109)

Author: antonin-janec

jsoniter-scala-core/js/src/main/scala/com/github/plokhotnyuk/jsoniter_scala/core/JsonReader.scala

@@ -3541,7 +3541,7 @@ final class JsonReader private[jsoniter_scala](
                 if (buf(pos + 6) != '\\') illegalEscapeSequenceError(pos + 6)
                 if (buf(pos + 7) != 'u') illegalEscapeSequenceError(pos + 7)
                 val ch2 = readEscapedUnicode(pos + 8, buf)
-                if (ch1 >= 0xDC00 || ch2 < 0xDC00 || ch2 > 0xDFFF) decodeError("illegal surrogate character pair", pos + 11)
+                if (ch1 >= 0xDC00 || (ch2 & 0xFC00) != 0xDC00) decodeError("illegal surrogate character pair", pos + 11)
                 charBuf(i + 1) = ch2
                 parseEncodedString(i + 2, lim, charBuf, pos + 12)
               } else parseEncodedString(i, lim, charBuf, loadMoreOrError(pos))

jsoniter-scala-core/js/src/main/scala/com/github/plokhotnyuk/jsoniter_scala/core/JsonWriter.scala

@@ -1480,7 +1480,7 @@ final class JsonWriter private[jsoniter_scala](
       } else { // 110110uuuuccccbb 110111bbbbaaaaaa (UTF-16 chars) -> 11110ddd 10ddcccc 10bbbbbb 10aaaaaa (UTF-8 bytes), where ddddd = uuuu + 1
         if (ch1 >= 0xDC00 || from + 1 >= to) illegalSurrogateError()
         val ch2 = s.charAt(from + 1)
-        if (ch2 < 0xDC00 || ch2 > 0xDFFF) illegalSurrogateError()
+        if ((ch2 & 0xFC00) != 0xDC00) illegalSurrogateError()
         val cp = (ch1 << 10) + (ch2 - 56613888) // -56613888 == 0x10000 - (0xD800 << 10) - 0xDC00
         buf(pos) = (cp >> 18 | 0xF0).toByte
         buf(pos + 1) = (cp >> 12 & 0x3F | 0x80).toByte
@@ -1511,7 +1511,7 @@ final class JsonWriter private[jsoniter_scala](
       } else {
         if (ch1 >= 0xDC00 || from + 1 >= to) illegalSurrogateError()
         val ch2 = s.charAt(from + 1).toInt
-        if (ch2 < 0xDC00 || ch2 > 0xDFFF) illegalSurrogateError()
+        if ((ch2 & 0xFC00) != 0xDC00) illegalSurrogateError()
         writeEscapedString(s, from + 2, to, writeEscapedUnicode(ch2, writeEscapedUnicode(ch1, pos, buf), buf), posLim, escapedChars)
       }
     }

jsoniter-scala-core/jvm/src/main/scala/com/github/plokhotnyuk/jsoniter_scala/core/JsonReader.scala

@@ -4035,7 +4035,7 @@ final class JsonReader private[jsoniter_scala](
                 if (buf(pos + 6) != '\\') illegalEscapeSequenceError(pos + 6)
                 if (buf(pos + 7) != 'u') illegalEscapeSequenceError(pos + 7)
                 val ch2 = readEscapedUnicode(pos + 8, buf)
-                if (ch1 >= 0xDC00 || ch2 < 0xDC00 || ch2 > 0xDFFF) decodeError("illegal surrogate character pair", pos + 11)
+                if (ch1 >= 0xDC00 || (ch2 & 0xFC00) != 0xDC00) decodeError("illegal surrogate character pair", pos + 11)
                 charBuf(i + 1) = ch2
                 parseEncodedString(i + 2, lim, charBuf, pos + 12)
               } else parseEncodedString(i, lim, charBuf, loadMoreOrError(pos))

jsoniter-scala-core/jvm/src/main/scala/com/github/plokhotnyuk/jsoniter_scala/core/JsonWriter.scala

@@ -1339,7 +1339,7 @@ final class JsonWriter private[jsoniter_scala](
       } else { // 110110uuuuccccbb 110111bbbbaaaaaa (UTF-16 chars) -> 11110ddd 10ddcccc 10bbbbbb 10aaaaaa (UTF-8 bytes), where ddddd = uuuu + 1
         if (ch1 >= 0xDC00 || from + 1 >= to) illegalSurrogateError()
         val ch2 = s.charAt(from + 1)
-        if (ch2 < 0xDC00 || ch2 > 0xDFFF) illegalSurrogateError()
+        if ((ch2 & 0xFC00) != 0xDC00) illegalSurrogateError()
         val cp = (ch1 << 10) + (ch2 - 56613888) // -56613888 == 0x10000 - (0xD800 << 10) - 0xDC00
         ByteArrayAccess.setInt(buf, pos, cp >> 18 | (cp >> 4 & 0x3F00) | (cp << 10 & 0x3F0000) | (cp << 24 & 0x3F000000) | 0x808080F0)
         writeEncodedString(s, from + 2, to, pos + 4, posLim, escapedChars)
@@ -1366,7 +1366,7 @@ final class JsonWriter private[jsoniter_scala](
       } else {
         if (ch1 >= 0xDC00 || from + 1 >= to) illegalSurrogateError()
         val ch2 = s.charAt(from + 1).toInt
-        if (ch2 < 0xDC00 || ch2 > 0xDFFF) illegalSurrogateError()
+        if ((ch2 & 0xFC00) != 0xDC00) illegalSurrogateError()
         writeEscapedString(s, from + 2, to, writeEscapedUnicode(ch2, writeEscapedUnicode(ch1, pos, buf), buf), posLim, escapedChars)
       }
     }

jsoniter-scala-core/native/src/main/scala/com/github/plokhotnyuk/jsoniter_scala/core/JsonReader.scala

@@ -4032,7 +4032,7 @@ final class JsonReader private[jsoniter_scala](
                 if (buf(pos + 6) != '\\') illegalEscapeSequenceError(pos + 6)
                 if (buf(pos + 7) != 'u') illegalEscapeSequenceError(pos + 7)
                 val ch2 = readEscapedUnicode(pos + 8, buf)
-                if (ch1 >= 0xDC00 || ch2 < 0xDC00 || ch2 > 0xDFFF) decodeError("illegal surrogate character pair", pos + 11)
+                if (ch1 >= 0xDC00 || (ch2 & 0xFC00) != 0xDC00) decodeError("illegal surrogate character pair", pos + 11)
                 charBuf(i + 1) = ch2
                 parseEncodedString(i + 2, lim, charBuf, pos + 12)
               } else parseEncodedString(i, lim, charBuf, loadMoreOrError(pos))

jsoniter-scala-core/native/src/main/scala/com/github/plokhotnyuk/jsoniter_scala/core/JsonWriter.scala

@@ -1339,7 +1339,7 @@ final class JsonWriter private[jsoniter_scala](
       } else { // 110110uuuuccccbb 110111bbbbaaaaaa (UTF-16 chars) -> 11110ddd 10ddcccc 10bbbbbb 10aaaaaa (UTF-8 bytes), where ddddd = uuuu + 1
         if (ch1 >= 0xDC00 || from + 1 >= to) illegalSurrogateError()
         val ch2 = s.charAt(from + 1)
-        if (ch2 < 0xDC00 || ch2 > 0xDFFF) illegalSurrogateError()
+        if ((ch2 & 0xFC00) != 0xDC00) illegalSurrogateError()
         val cp = (ch1 << 10) + (ch2 - 56613888) // -56613888 == 0x10000 - (0xD800 << 10) - 0xDC00
         ByteArrayAccess.setInt(buf, pos, cp >> 18 | (cp >> 4 & 0x3F00) | (cp << 10 & 0x3F0000) | (cp << 24 & 0x3F000000) | 0x808080F0)
         writeEncodedString(s, from + 2, to, pos + 4, posLim, escapedChars)
@@ -1366,7 +1366,7 @@ final class JsonWriter private[jsoniter_scala](
       } else {
         if (ch1 >= 0xDC00 || from + 1 >= to) illegalSurrogateError()
         val ch2 = s.charAt(from + 1).toInt
-        if (ch2 < 0xDC00 || ch2 > 0xDFFF) illegalSurrogateError()
+        if ((ch2 & 0xFC00) != 0xDC00) illegalSurrogateError()
         writeEscapedString(s, from + 2, to, writeEscapedUnicode(ch2, writeEscapedUnicode(ch1, pos, buf), buf), posLim, escapedChars)
       }
     }