Boost C++ Libraries

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Get a C-style String from a String Type
extract_c_string

extract_c_string returns a pointer to an array of elements of a const character type. It is invoked through a static method call. This customization point is responsible for handling it's own garbage collecting; the lifetime of the returned C-string must be no shorter than the lifetime of the string instance passed to the call method.

Module Headers
#include <boost/spirit/home/support/string_traits.hpp>

Also, see Include Structure.

[Note] Note

This header file does not need to be included directly by any user program as it is normally included by other Spirit header files relying on its content.

Namespace

Name

boost::spirit::traits

Synopsis
template <typename String>
struct extract_c_string
{
    typedef <unspecified> char_type;

    static char_type const* call (String const&);
};
Template parameters

Parameter

Description

Default

String

A string type.

none

Notation

T

An arbitrary type.

Char

A character type.

Traits

A character traits type.

Allocator

A standard allocator type.

str

A string instance.

Expression Semantics

Expression

Semantics

extract_c_string<T>::char_type

The return type of call.

extract_c_string<T>::call(str)

Extract a c-string of type char_type from str.

Predefined Specializations

Type

Semantics

T

call takes a parameter of type T const*, and returns it without modification. An overload of call takes a parameter of type T* and casts it to T const*, returning the result. char_type is char_type_of<T>::type.

T const

call takes a parameter str of type T const and returns extract_c_string<T>::call(str). char_type is char_type_of<T>::type.

T&

call takes a parameter str of type T& and returns extract_c_string<T>::call(str). char_type is char_type_of<T>::type.

T const&

call takes a parameter str of type T const& and returns extract_c_string<T>::call(str). char_type is char_type_of<T>::type.

std::basic_string<Char, Traits, Allocator>

call takes a parameter str and returns str.c_str(). char_type is Char.

When to implement

This customization point needs to be implemented whenever traits::is_string is implemented.

Related Attribute Customization Points

If this customization point is implemented, the following other customization points need to be implemented as well.

Name

When to implement

traits::is_char

For string types whose underlying character type is not char or wchar_t, is_char must be implemented.

traits::is_string

Whenever extract_c_string is implemented.

traits::char_type_of

Whenever extract_c_string is implemented.


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