Help people discover how to do take_while, et al, with parsers instead of predicates

[epage]

Prerequisites

Here are a few things you should provide to help me understand the issue:

• Rust version : 1.55.0
• nom version : 7.0.0
• nom compilation features used: default

Test case

It was unclear how to do take_while with a parser, rather than a predicate, so I wrote my own take_many, used like

        take_many0(alt((
            // CAUTION: If adding an ignorable literal, if it doesn't start with `is_xid_continue`,
            // - Update `is_ignore_char` to make sure `sep1` doesn't eat it all up
            // - Make sure you always consume it
            terminated(uuid_literal, sep1),
            terminated(hash_literal, sep1),
            terminated(hex_literal, sep1),
            terminated(dec_literal, sep1),
            terminated(ordinal_literal, sep1),
            terminated(base64_literal, sep1),
            terminated(email_literal, sep1),
            terminated(url_literal, sep1),
            terminated(c_escape, sep1),
            terminated(printf, sep1),
            sep1,
        )))(input)

Turns out, there are built-in ways of doing this with recognize and many0_count.

[epage]

One thought on this:

• Have take_while* says "if you need to use a predicate, see recognize and add an example to recognize for this
• Have many* link to ``many0_count` for a non-allocating consuming (since the name doesn't stand out for that intention)
• Have many*_count link to recognize as well.

[epage]

Lack of #1393 makes this a bit annoying to deal with.