Function parseFormatStringV2

ext/formatting_v2.go:673–717

parseFormatString formats a string according to the string.format syntax, taking the clause implementations from the provided FormatCallback and the args from the given FormatList.

(formatStr string, callback formatStringInterpolatorV2, list formatListArgs, maxPrecision int)

// parseFormatString formats a string according to the string.format syntax, taking the clause implementations
// from the provided FormatCallback and the args from the given FormatList.
func parseFormatStringV2(formatStr string, callback formatStringInterpolatorV2, list formatListArgs, maxPrecision int) (string, error) {
	i := 0
	argIndex := 0
	var builtStr strings.Builder
	for i < len(formatStr) {
		if formatStr[i] == '%' {
			if i+1 < len(formatStr) && formatStr[i+1] == '%' {
				err := builtStr.WriteByte('%')
				if err != nil {
					return "", fmt.Errorf("error writing format string: %w", err)
				}
				i += 2
				continue
			} else {
				argAny, err := list.Arg(int64(argIndex))
				if err != nil {
					return "", err
				}
				if i+1 >= len(formatStr) {
					return "", errors.New("unexpected end of string")
				}
				if int64(argIndex) >= list.Size() {
					return "", fmt.Errorf("index %d out of range", argIndex)
				}
				numRead, val, refErr := parseAndFormatClauseV2(formatStr[i:], argAny, callback, list, maxPrecision)
				if refErr != nil {
					return "", refErr
				}
				_, err = builtStr.WriteString(val)
				if err != nil {
					return "", fmt.Errorf("error writing format string: %w", err)
				}
				i += numRead
				argIndex++
			}
		} else {
			err := builtStr.WriteByte(formatStr[i])
			if err != nil {
				return "", fmt.Errorf("error writing format string: %w", err)
			}
			i++
		}
	}
	return builtStr.String(), nil
}

// parseAndFormatClause parses the format clause at the start of the given string with val, and returns
// how many characters were consumed and the substituted string form of val, or an error if one occurred.