utf8: use lookup table to validate ASCII (#654)

2021-11-04 16:05:36 -04:00
parent 3dbca20bc9
commit 6617e7e73d
2 changed files with 57 additions and 1 deletions
@@ -140,8 +140,45 @@ func utf8ValidNext(p []byte) int {
 	return size
 }

+var invalidAsciiTable = [256]bool{
+	0x00: true,
+	0x01: true,
+	0x02: true,
+	0x03: true,
+	0x04: true,
+	0x05: true,
+	0x06: true,
+	0x07: true,
+	0x08: true,
+	// 0x09 TAB
+	// 0x0A LF
+	0x0B: true,
+	0x0C: true,
+	// 0x0D CR
+	0x0E: true,
+	0x0F: true,
+	0x10: true,
+	0x11: true,
+	0x12: true,
+	0x13: true,
+	0x14: true,
+	0x15: true,
+	0x16: true,
+	0x17: true,
+	0x18: true,
+	0x19: true,
+	0x1A: true,
+	0x1B: true,
+	0x1C: true,
+	0x1D: true,
+	0x1E: true,
+	0x1F: true,
+	// 0x20 - 0x7E Printable ASCII characters
+	0x7F: true,
+}
+
 func invalidAscii(b byte) bool {
-	return b <= 0x08 || (b > 0x0A && b < 0x0D) || (b > 0x0D && b <= 0x1F) || b == 0x7F
+	return invalidAsciiTable[b]
 }

 // acceptRange gives the range of valid values for the second byte in a UTF-8