Nom tag that implements the /(?x) (.*?) (remainder)/ pattern.

take_until_parse_s.rs

/// Implements the /(?x) (.*?) (remainder)/ pattern:
/// looks for remainder first, then returns a tuple with the prefix and the remainder.
/// Discussion: https://www.reddit.com/r/rust/comments/4yokxd/crash_course_into_nom_kind_of_question/
macro_rules! take_until_parse_s (
  ($i: expr, $submac: ident! ($($args:tt)*)) => ({
    let input = $i as &str;
    let mut ret = IResult::Error (nom::Err::Position (nom::ErrorKind::Custom (0), input));
    for (pos, _) in $i.char_indices() {
      match $submac! (&input[pos..], $($args)*) {
        IResult::Done (i,o)    => {ret = IResult::Done (i, (&input[0..pos], o)); break},  // Found the remainder!
        IResult::Error(_)      => continue,  // Keep looking.
        IResult::Incomplete(_) => continue}}  // Keep looking.

    if !ret.is_done() {
      // Last chance. See if subparser accepts an empty string.
      if let IResult::Done (i,o) = $submac! ("", $($args)*) {
        ret = IResult::Done (i, (input, o))}}  // Empty remainder was accepted.

    ret});

  ($i: expr, $f: expr) => (take_until_parse_s! ($i, call! ($f));););

/// `$starts` is an optional `Pattern` used to optimize the `$submac` search.
/// For example, with jetscii: `take_until_find_parse_s! ("foo bar", ascii_chars! ('b'), tag_s! ("bar"))`.
macro_rules! take_until_find_parse_s (
  ($i: expr, $starts: expr, $submac: ident! ($($args:tt)*)) => ({
    let input = $i as &str;
    let mut ret = IResult::Error (nom::Err::Position (nom::ErrorKind::Custom (0), input));
    for (pos, _) in $i.match_indices ($starts) {
      match $submac! (&input[pos..], $($args)*) {
        IResult::Done (i,o)    => {ret = IResult::Done (i, (&input[0..pos], o)); break},  // Found the remainder!
        IResult::Error(_)      => continue,  // Keep looking.
        IResult::Incomplete(_) => continue}}  // Keep looking.
    ret});

  ($i: expr, $starts: expr, $f: expr) => (take_until_find_parse_s! ($i, $starts, call! ($f));););