[#boost-urls-grammar-delim_rule-01]
= xref:boost.adoc[boost]::xref:boost/urls.adoc[urls]::xref:boost/urls/grammar.adoc[grammar]::delim_rule
:relfileprefix: ../../../
:mrdocs:


Match a single character from a character set

== Synopsis


Declared in `<https://www.github.com/boostorg/url/blob/develop/include/boost/url/grammar/delim_rule.hpp#L155[boost/url/grammar/delim_rule.hpp]>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<xref:boost/urls/grammar/CharSet.adoc[CharSet] CS>
constexpr
/* implementation-defined */::xref:boost/urls/grammar/implementation_defined/cs_delim_rule.adoc[cs_delim_rule]<CS>
delim_rule(CS const& cs) noexcept
requires ! std::is_convertible<
        CS, char>::value;
----

== Description


This matches exactly one character which    belongs to the specified character set.    The value is a reference to the character    in the underlying buffer, expressed as a    `core::string_view`. The function xref:boost/urls/grammar/squelch.adoc[squelch]    may be used to turn this into `void` instead.    If there is no more input, the error code    xref:boost/urls/grammar/error.adoc[error::need_more] is returned.


=== Value Type

[,cpp]
----
using value_type = core::string_view;
----

=== Example

Rules are used with the function xref:boost/urls/grammar/parse-02.adoc[parse].

[,cpp]
----
system::result< core::string_view > rv = parse( "X", delim_rule( alpha_chars ) );
----


== Parameters


|===
| Name | Description

| *cs*
| The character set to use&period;


|===

== See Also


xref:boost/urls/grammar/alpha_chars.adoc[alpha&lowbar;chars],        xref:boost/urls/grammar/parse-02.adoc[parse],        xref:boost/urls/grammar/squelch.adoc[squelch]&period;






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