Fast json text value encode: replace

json_encode_text.go

// EncodeToJsonAsciiText Fast json text value encode: escape " with \" and \ with \\
// Any non printable or Unicode chars will be removed.
// Please note that value is not enclosed into double quotes.
func EncodeToJsonAsciiText(plain string) string {
	plainLen := len(plain)
	newSize := plainLen
	for i := 0; i < plainLen; i++ {
		c := plain[i]
		if c < 32 || c > 127 { // skip non printable and unicode
			newSize--
		}
		if c == '\\' || c == '"' {
			newSize++
		}
	}
	if plainLen == newSize {
		return plain
	}
	encoded := make([]byte, newSize)
	encodedIdx := 0
	for i := 0; i < plainLen; i++ {
		c := plain[i]
		if c < 32 || c > 127 { // skip non printable and unicode
			continue
		}
		if c == '\\' {
			encoded[encodedIdx] = '\\'
			encodedIdx++
			encoded[encodedIdx] = '\\'
		} else if c == '"' {
			encoded[encodedIdx] = '\\'
			encodedIdx++
			encoded[encodedIdx] = '"'
		} else {
			encoded[encodedIdx] = c
		}
		encodedIdx++
	}
	return string(encoded)
}