Function processScript

txscript/template.go:109–175

processScript converts the template output to actual script bytes. We scan each line, then go through each element one by one, deciding to either add a normal op code, a push data, or an integer value.

(script string)

// each line, then go through each element one by one, deciding to either add a
// normal op code, a push data, or an integer value.
func processScript(script string) ([]byte, error) {
	var builder ScriptBuilder

	// We'll a bufio scanner to take care of some of the parsing for us.
	// bufio.ScanWords will split on word boundaries, based on unicode
	// characters.
	scanner := bufio.NewScanner(strings.NewReader(script))
	scanner.Split(bufio.ScanWords)

	// Run through each word, deciding if we should add an op code, a push
	// data, or an integer value.
	for scanner.Scan() {
		token := scanner.Text()
		switch {
		// If it starts with OP_, then we'll try to parse out the op
		// code.
		case strings.HasPrefix(token, "OP_"):
			opcode, ok := OpcodeByName[token]
			if !ok {
				return nil, fmt.Errorf("unknown opcode: "+
					"%s", token)
			}

			builder.AddOp(opcode)

		// If it has an 0x prefix, then we'll try to decode it as a hex
		// string to push data.
		case strings.HasPrefix(token, "0x"):
			data, err := hex.DecodeString(
				strings.TrimPrefix(token, "0x"),
			)
			if err != nil {
				return nil, fmt.Errorf("invalid hex "+
					"data: %s", token)
			}

			builder.AddData(data)

		// Next, we'll try to parse ints for the integer op code.
		case looksLikeInt(token):
			val, err := strconv.ParseInt(token, 10, 64)
			if err != nil {
				return nil, fmt.Errorf("invalid "+
					"integer: %s", token)
			}

			builder.AddInt64(val)

		// Otherwise, we assume it's a byte string without the 0x
		// prefix.
		default:
			data, err := hex.DecodeString(token)
			if err != nil {
				return nil, fmt.Errorf("invalid token: %s",
					token)
			}

			builder.AddData(data)