/* /////////////////////////////////////////////////////////////////////////
 * File:        unixstl/system/environment_variable.hpp
 *
 * Purpose:     Simple class that provides access to an environment variable.
 *
 * Created:     2nd November 2003
 * Updated:     10th August 2009
 *
 * Home:        http://stlsoft.org/
 *
 * Copyright (c) 2003-2009, Matthew Wilson and Synesis Software
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice, this
 *   list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * - Neither the name(s) of Matthew Wilson and Synesis Software nor the names of
 *   any contributors may be used to endorse or promote products derived from
 *   this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * ////////////////////////////////////////////////////////////////////// */


/** \file unixstl/system/environment_variable.hpp
 *
 * \brief [C++ only] Definition of the unixstl::basic_environment_variable
 *  class template
 *   (\ref group__library__system "System" Library).
 */

#ifndef UNIXSTL_INCL_UNIXSTL_SYSTEM_HPP_ENVIRONMENT_VARIABLE
#define UNIXSTL_INCL_UNIXSTL_SYSTEM_HPP_ENVIRONMENT_VARIABLE

#ifndef STLSOFT_DOCUMENTATION_SKIP_SECTION
# define UNIXSTL_VER_UNIXSTL_SYSTEM_HPP_ENVIRONMENT_VARIABLE_MAJOR      4
# define UNIXSTL_VER_UNIXSTL_SYSTEM_HPP_ENVIRONMENT_VARIABLE_MINOR      2
# define UNIXSTL_VER_UNIXSTL_SYSTEM_HPP_ENVIRONMENT_VARIABLE_REVISION   1
# define UNIXSTL_VER_UNIXSTL_SYSTEM_HPP_ENVIRONMENT_VARIABLE_EDIT       65
#endif /* !STLSOFT_DOCUMENTATION_SKIP_SECTION */

/* /////////////////////////////////////////////////////////////////////////
 * Includes
 */

#ifndef UNIXSTL_INCL_UNIXSTL_H_UNIXSTL
# include <unixstl/unixstl.h>
#endif /* !UNIXSTL_INCL_UNIXSTL_H_UNIXSTL */
#ifndef UNIXSTL_INCL_UNIXSTL_SYSTEM_HPP_SYSTEM_TRAITS
# include <unixstl/system/system_traits.hpp>       // for get_environment_variable()
#endif /* !UNIXSTL_INCL_UNIXSTL_SYSTEM_HPP_SYSTEM_TRAITS */
#ifndef STLSOFT_INCL_STLSOFT_SHIMS_ACCESS_HPP_STRING
# include <stlsoft/shims/access/string.hpp>
#endif /* !STLSOFT_INCL_STLSOFT_SHIMS_ACCESS_HPP_STRING */
#ifndef UNIXSTL_INCL_UNIXSTL_SHIMS_ACCESS_HPP_STRING
# include <unixstl/shims/access/string.hpp>
#endif /* !UNIXSTL_INCL_UNIXSTL_SHIMS_ACCESS_HPP_STRING */
#ifndef STLSOFT_INCL_STLSOFT_MEMORY_HPP_AUTO_BUFFER
# include <stlsoft/memory/auto_buffer.hpp>
#endif /* !STLSOFT_INCL_STLSOFT_MEMORY_HPP_AUTO_BUFFER */
#ifndef STLSOFT_INCL_STLSOFT_MEMORY_HPP_ALLOCATOR_SELECTOR
# include <stlsoft/memory/allocator_selector.hpp>
#endif /* !STLSOFT_INCL_STLSOFT_MEMORY_HPP_ALLOCATOR_SELECTOR */

/* /////////////////////////////////////////////////////////////////////////
 * Namespace
 */

#ifndef _UNIXSTL_NO_NAMESPACE
# if defined(_STLSOFT_NO_NAMESPACE) || \
     defined(STLSOFT_DOCUMENTATION_SKIP_SECTION)
/* There is no stlsoft namespace, so must define ::unixstl */
namespace unixstl
{
# else
/* Define stlsoft::unixstl_project */

namespace stlsoft
{

namespace unixstl_project
{

# endif /* _STLSOFT_NO_NAMESPACE */
#endif /* !_UNIXSTL_NO_NAMESPACE */

/* /////////////////////////////////////////////////////////////////////////
 * basic_environment_variable
 *
 * This class converts a relative path to an absolute one, and effectively acts
 * as a C-string of its value.
 */

/** \brief Represents an environment variable
 *
 * \ingroup group__library__system
 *
 * \param C The character type
 * \param T The traits type. Defaults to system_traits<C>. On translators that do not support default template arguments, it must be explicitly stipulated
 * \param A The allocator class. Defaults to stlsoft::allocator_selector<C>::allocator_type. On translators that do not support default template arguments, it is not part of the template parameter list.
 */
template<   ss_typename_param_k C
#ifdef STLSOFT_CF_TEMPLATE_CLASS_DEFAULT_CLASS_ARGUMENT_SUPPORT
        ,   ss_typename_param_k T = system_traits<C>
        ,   ss_typename_param_k A = ss_typename_type_def_k stlsoft_ns_qual(allocator_selector)<C>::allocator_type
#else /* ? STLSOFT_CF_TEMPLATE_CLASS_DEFAULT_CLASS_ARGUMENT_SUPPORT */
        ,   ss_typename_param_k T /* = system_traits<C> */
#endif /* STLSOFT_CF_TEMPLATE_CLASS_DEFAULT_CLASS_ARGUMENT_SUPPORT */
        >
class basic_environment_variable
{
public:
    /// The char type
    typedef C                                   char_type;
    /// The traits type
    typedef T                                   traits_type;
#ifdef STLSOFT_CF_TEMPLATE_CLASS_DEFAULT_CLASS_ARGUMENT_SUPPORT
    /// The allocator type
    typedef A                                   allocator_type;
    /// The current parameterisation of the type
    typedef basic_environment_variable<C, T, A> class_type;
#else /* ? STLSOFT_CF_TEMPLATE_CLASS_DEFAULT_CLASS_ARGUMENT_SUPPORT */
    /// The current parameterisation of the type
    typedef basic_environment_variable<C, T>    class_type;
#endif /* STLSOFT_CF_TEMPLATE_CLASS_DEFAULT_CLASS_ARGUMENT_SUPPORT */
    /// The size type
    typedef us_size_t                           size_type;
    /// The difference type
    typedef us_ptrdiff_t                        difference_type;

// Construction
public:
    /// Create an instance representing the given environment variable
    ss_explicit_k basic_environment_variable(char_type const* name)
        : m_buffer(1 + traits_type::get_environment_variable(name, 0, 0))
    {
        if( 0 == traits_type::get_environment_variable(name, &m_buffer[0], m_buffer.size()) &&
            0 != m_buffer.size())
        {
            m_buffer[0] = 0;
        }
    }
#ifdef STLSOFT_CF_MEMBER_TEMPLATE_CTOR_SUPPORT
    /// Create an instance representing the given environment variable
    template<ss_typename_param_k S>
    ss_explicit_k basic_environment_variable(S const& name)
        : m_buffer(1 + traits_type::get_environment_variable(stlsoft_ns_qual(c_str_ptr)(name), 0, 0))
    {
        if( 0 == traits_type::get_environment_variable(stlsoft_ns_qual(c_str_ptr)(name), &m_buffer[0], m_buffer.size()) &&
            0 != m_buffer.size())
        {
            m_buffer[0] = 0;
        }
    }
#endif /* STLSOFT_CF_MEMBER_TEMPLATE_CTOR_SUPPORT */

// Conversions
public:
    /// Implicit conversion to a non-mutable (const) pointer to the variable
    operator char_type const* () const
    {
        return m_buffer.data();
    }

// Attributes
public:
    /// Returns the length of the variable
    size_type length() const
    {
        return m_buffer.size() - 1;
    }

// Members
private:
    typedef stlsoft_ns_qual(auto_buffer_old)<   char_type
#ifdef STLSOFT_CF_TEMPLATE_CLASS_DEFAULT_CLASS_ARGUMENT_SUPPORT
                                            ,   allocator_type
#else /* ? STLSOFT_CF_TEMPLATE_CLASS_DEFAULT_CLASS_ARGUMENT_SUPPORT */
                                            ,   malloc_allocator<char_type>
#endif /* STLSOFT_CF_TEMPLATE_CLASS_DEFAULT_CLASS_ARGUMENT_SUPPORT */
                                            >       buffer_type;

    buffer_type m_buffer;

// Not to be implemented
private:
    basic_environment_variable(basic_environment_variable const&);
    basic_environment_variable& operator =(basic_environment_variable const&);
};

/* /////////////////////////////////////////////////////////////////////////
 * Typedefs for commonly encountered types
 */

/** \brief Specialisation of the basic_environment_variable template for the ANSI character type \c char
 *
 * \ingroup group__library__system
 */
typedef basic_environment_variable<us_char_a_t, system_traits<us_char_a_t> >    environment_variable_a;
/** \brief Specialisation of the basic_environment_variable template for the Unicode character type \c wchar_t
 *
 * \ingroup group__library__system
 */
typedef basic_environment_variable<us_char_w_t, system_traits<us_char_w_t> >    environment_variable_w;
/** \brief Specialisation of the basic_environment_variable template for the 'default' character type \c char
 *
 * \ingroup group__library__system
 */
typedef basic_environment_variable<char, system_traits<char> >                  environment_variable;

/* /////////////////////////////////////////////////////////////////////////
 * Helper functions
 */

#if !defined(STLSOFT_COMPILER_IS_MSVC) || \
    _MSC_VER >= 1100

/** \brief This helper function makes an environment variable without needing to
 * qualify the template parameter.
 *
 * \ingroup group__library__system
 */
template<ss_typename_param_k C>
inline basic_environment_variable<C> make_environment_variable(C const* path)
{
    return basic_environment_variable<C>(path);
}

#endif /* compiler */

////////////////////////////////////////////////////////////////////////////
// Unit-testing

#ifdef STLSOFT_UNITTEST
# include "./unittest/environment_variable_unittest_.h"
#endif /* STLSOFT_UNITTEST */

/* ////////////////////////////////////////////////////////////////////// */

#ifndef _UNIXSTL_NO_NAMESPACE
# if defined(_STLSOFT_NO_NAMESPACE) || \
     defined(STLSOFT_DOCUMENTATION_SKIP_SECTION)
} // namespace unixstl
# else
} // namespace unixstl_project
} // namespace stlsoft
# endif /* _STLSOFT_NO_NAMESPACE */
#endif /* !_UNIXSTL_NO_NAMESPACE */

/* ////////////////////////////////////////////////////////////////////// */

#endif /* UNIXSTL_INCL_UNIXSTL_SYSTEM_HPP_ENVIRONMENT_VARIABLE */

/* ///////////////////////////// end of file //////////////////////////// */