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grammar::squelch

Squelch the value of a rule.

Synopsis

Defined in header <boost/url/grammar/tuple_rule.hpp>

template<
    class Rule>
constexpr implementation-defined
squelch(
    Rule const& r);
Description

This function returns a new rule which matches the specified rule, and converts its value type to void. This is useful for matching delimiters in a grammar, where the value for the delimiter is not needed.

Value Type
using value_type = void;
Example 1

With squelch:

system::result< std::tuple< decode_view, core::string_view > > rv = parse(
    "www.example.com:443" ,
    tuple_rule(
        pct_encoded_rule(unreserved_chars + '-' + '.' ),
        squelch( delim_rule( ':' ) ),
        token_rule( digit_chars ) ) );
Example 2

Without squelch:

system::result< std::tuple< decode_view, core::string_view, core::string_view > > rv = parse(
    "www.example.com:443" ,
    tuple_rule(
        pct_encoded_rule(unreserved_chars + '-' + '.' ),
        delim_rule( ':' ),
        token_rule( digit_chars ) ) );
Parameters

Name

Description

r

The rule to squelch

See Also

delim_rule, digit_chars, parse, tuple_rule, token_rule, decode_view, pct_encoded_rule, unreserved_chars.

Convenience header <boost/url/grammar.hpp>


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