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

A set of characters

== Synopsis

Declared in `<https://www.github.com/boostorg/url/blob/develop/include/boost/url/grammar/lut_chars.hpp#L64[boost/url/grammar/lut_chars.hpp]>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
class lut_chars;
----

== Member Functions

[cols=2]
|===
| Name
| Description
| xref:boost/urls/grammar/lut_chars/2constructor-029.adoc[`lut_chars`]         [.small]#[constructor]#
| Constructors
| xref:boost/urls/grammar/lut_chars/operator_call-09.adoc[`operator()`] 
| Return true if ch is in the character set.
| xref:boost/urls/grammar/lut_chars/operator_bitnot.adoc[`operator~`] 
| Return a new character set which is the complement of another character set.
|===

== Friends

[cols=2]
|===
| Name
| Description
| `xref:boost/urls/grammar/operator_minus.adoc[operator‐]`
| Return a new character set by subtracting
| `xref:boost/urls/grammar/operator_plus.adoc[operator+]`
| Return the union of two character sets.
|===

== Description

The characters defined by instances of this set are provided upon construction. The `constexpr` implementation allows these to become compile‐time constants.

== Example
Character sets are used with rules and the functions xref:boost/urls/grammar/find_if.adoc[`find_if`] and xref:boost/urls/grammar/find_if_not.adoc[`find_if_not`].

[,cpp]
----
constexpr lut_chars vowel_chars = "AEIOU" "aeiou";

system::result< core::string_view > rv = parse( "Aiea", token_rule( vowel_chars ) );
----
== See Also

xref:boost/urls/grammar/find_if.adoc[`find&lowbar;if`], xref:boost/urls/grammar/find_if_not.adoc[`find&lowbar;if&lowbar;not`], xref:boost/urls/grammar/parse-09.adoc[`parse`], xref:boost/urls/grammar/token_rule.adoc[`token&lowbar;rule`]&period;


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