http::ext_list

A list of extensions in a comma separated HTTP field value.

Synopsis

Defined in header <boost/beast/http/rfc7230.hpp>

class ext_list

Types

Name	Description
const_iterator	A constant iterator to the list.
value_type	The type of each element in the list.

Member Functions

Name	Description
begin	Return a const iterator to the beginning of the list.
cbegin	Return a const iterator to the beginning of the list.
cend	Return a const iterator to the end of the list.
end	Return a const iterator to the end of the list.
exists	Return `true` if a token is present in the list.
ext_list [constructor]	Construct a list.
find	Find a token in the list.

Description

This container allows iteration of the extensions in an HTTP field value. The extension list is a comma separated list of token parameter list pairs.

If a parsing error is encountered while iterating the string, the behavior of the container will be as if a string containing only characters up to but excluding the first invalid character was used to construct the list.

BNF

ext-list    = *( "," OWS ) ext *( OWS "," [ OWS ext ] )
ext         = token param-list
param-list  = *( OWS ";" OWS param )
param       = token OWS [ "=" OWS ( token / quoted- string ) ]

To use this class, construct with the string to be parsed and then use begin and end, or range-for to iterate each item:

Example

for ( auto const & ext : ext_list{ "none, 7z;level=9, zip;no_context_takeover;bits=15" })
{
    std::cout << ext.first << "\n" ;
    for ( auto const & param : ext.second)
    {
        std::cout << ";" << param.first;
        if (! param.second.empty())
            std::cout << "=" << param.second;
        std::cout << "\n" ;
    }
}