rfc3986.go

package oauth

import "bytes"

var hexToByte = map[byte]byte{
	0x0: 0x30,
	0x1: 0x31,
	0x2: 0x32,
	0x3: 0x33,
	0x4: 0x34,
	0x5: 0x35,
	0x6: 0x36,
	0x7: 0x37,
	0x8: 0x38,
	0x9: 0x39,
	0xA: 0x41,
	0xB: 0x42,
	0xC: 0x43,
	0xD: 0x44,
	0xE: 0x45,
	0xF: 0x46,
}

// Twitter wants RFC 3986, Go says "f you" I'm gonna use +'s
func percentEncode(s string) string {
	var buf bytes.Buffer

	for _, b := range []byte(s) {
		if !validASCII(b) {
			buf.WriteByte(0x25)
			buf.WriteByte(hexToByte[b&0xF0>>4])
			buf.WriteByte(hexToByte[b&0xF])
		} else {
			buf.WriteByte(b)
		}
	}

	return buf.String()
}

// rfc3986 returns whether or not the byte is an acceptable ASCII value to rfc3986
func validASCII(b byte) bool {
	return (b >= 0x30 && b <= 0x39) ||
		(b >= 0x41 && b <= 0x5A) ||
		(b >= 0x61 && b <= 0x7A) ||
		(b == 0x2D || b == 0x2E || b == 0x5F || b == 0x7E)
}