Function `escaped`

fn escaped<Input, Error, Normal, NormalOutput, Escape, EscapeOutput, Output>(normal: Normal, control_char: char, escape: Escape) -> impl Parser<Input, Output, Error>
where
    Input: StreamIsPartial + Stream + Compare<char>,
    Normal: Parser<Input, NormalOutput, Error>,
    Escape: Parser<Input, EscapeOutput, Error>,
    Output: Accumulate<NormalOutput> + Accumulate<EscapeOutput>,
    Error: ParserError<Input>

Parse escaped characters, unescaping them

Arguments:

normal: unescapeable characters
- Must not include control
control_char: e.g. \ for strings in most languages
escape: parse and transform the escaped character

Parsing ends when:

alt(normal, control._char) [Backtracks][crate::error::ErrMode::Backtrack]
normal doesn't advance the input stream
(complete) input stream is exhausted

Warning: If the normal parser passed to escaped_transform accepts empty inputs (like alpha0 or digit0), escaped_transform will return an error, to prevent going into an infinite loop.

Example

# #[cfg(feature = "std")] {
# use winnow::prelude::*;
# use std::str::from_utf8;
use winnow::token::literal;
use winnow::ascii::escaped_transform;
use winnow::ascii::alpha1;
use winnow::combinator::alt;

fn parser<'s>(input: &mut &'s str) -> ModalResult<String> {
  escaped_transform(
    alpha1,
    '\\',
    alt((
      "\\".value("\\"),
      "\"".value("\""),
      "n".value("\n"),
    ))
  ).parse_next(input)
}

assert_eq!(parser.parse_peek("ab\\\"cd"), Ok(("", String::from("ab\"cd"))));
assert_eq!(parser.parse_peek("ab\\ncd"), Ok(("", String::from("ab\ncd"))));
# }

# #[cfg(feature = "std")] {
# use winnow::prelude::*;
# use winnow::{error::ErrMode, error::Needed};
# use std::str::from_utf8;
# use winnow::Partial;
use winnow::token::literal;
use winnow::ascii::escaped_transform;
use winnow::ascii::alpha1;
use winnow::combinator::alt;

fn parser<'s>(input: &mut Partial<&'s str>) -> ModalResult<String> {
  escaped_transform(
    alpha1,
    '\\',
    alt((
      "\\".value("\\"),
      "\"".value("\""),
      "n".value("\n"),
    ))
  ).parse_next(input)
}

assert_eq!(parser.parse_peek(Partial::new("ab\\\"cd\"")), Ok((Partial::new("\""), String::from("ab\"cd"))));
# }