golang digit 代码
文件路径：/src/unicode/digit.go
/ Copyright 2009 The Go Authors. All rights reserved.
/ Use of this source code is governed by a BSD-style
/ license that can be found in the LICENSE file.
package unicode
/ IsDigit reports whether the rune is a decimal digit.
func IsDigit(r rune) bool {
if r <= MaxLatin1 {
return '0' <= r && r <= '9'
}
return isExcludingLatin(Digit, r)
}