# Copyright 2017 Rene Rivera
# Distributed under the Boost Software License, Version 1.0.
# (See accompanying file LICENSE.txt or copy at
# https://www.bfgroup.xyz/b2/LICENSE.txt)

import feature ;
import modules ;
import os ;

.os-names =
    none
    aix android appletv bsd cygwin darwin freebsd haiku hpux iphone linux
    netbsd openbsd osf qnx qnxnto sgi solaris unix unixware windows vms vxworks
    freertos

    # Not actually an OS -- used for targeting bare metal where object
    # format is ELF.  This catches both -elf and -eabi gcc targets as well
    # as other compilers targeting ELF. It is not clear how often we need
    # the 'elf' key as opposed to other bare metal targets, but let us
    # stick with gcc naming.
    elf
    ;

# Feature used to determine which OS we're on. New <target-os> and <host-os>
# features should be used instead.
local os = [ modules.peek : OS ] ;
feature.feature os : $(os) : propagated link-incompatible ;

# Translates from bjam current OS to the os tags used in host-os and
# target-os, i.e. returns the running host-os.
#
local rule default-host-os ( )
{
    local host-os ;
    if [ os.name ] in $(.os-names:U)
    {
        host-os = [ os.name ] ;
    }
    else
    {
        switch [ os.name ]
        {
            case NT           : host-os = windows ;
            case AS400        : host-os = unix    ;
            case MINGW        : host-os = windows ;
            case BSDI         : host-os = bsd     ;
            case COHERENT     : host-os = unix    ;
            case DRAGONFLYBSD : host-os = bsd     ;
            case IRIX         : host-os = sgi     ;
            case HAIKU        : host-os = haiku   ;
            case MACOSX       : host-os = darwin  ;
            case KFREEBSD     : host-os = freebsd ;
            case LINUX        : host-os = linux   ;
            case VMS          : host-os = vms     ;
            case SUNOS        :
                ECHO
                    "SunOS is not a supported operating system."
                    "We believe last version of SunOS was released in 1992, "
                    "so if you get this message, something is very wrong with "
                    "configuration logic. Please report this as a bug. " ;
                EXIT ;
            case *            : host-os = unix    ;
        }
    }
    return $(host-os:L) ;
}


# The two OS features define a known set of abstract OS names. The host-os is
# the OS under which bjam is running. Even though this should really be a fixed
# property we need to list all the values to prevent unknown value errors. Both
# set the default value to the current OS to account for the default use case of
# building on the target OS.
feature.feature host-os : $(.os-names) ;
feature.set-default host-os : [ default-host-os ] ;

#| tag::doc[]

[[b2.builtin.features.target-os]]`target-os`::
*Allowed values:* `aix`, `android`, `appletv`, `bsd`, `cygwin`, `darwin`,
`freebsd`, `haiku`, `hpux`, `iphone`, `linux`, `netbsd`, `openbsd`, `osf`,
`qnx`, `qnxnto`, `sgi`, `solaris`, `unix`, `unixware`, `windows`, `vms`,
`vxworks`, `freertos`.
+
Specifies the operating system for which the code is to be generated. The
compiler you used should be the compiler for that operating system. This option
causes B2 to use naming conventions suitable for that operating
system, and adjust build process accordingly. For example, with gcc, it
controls if import libraries are produced for shared libraries or not.
+
See the section <<Cross-compilation>> for details of cross-compilation.

|# # end::doc[]

feature.feature target-os : $(.os-names) : propagated link-incompatible ;
feature.set-default target-os : [ default-host-os ] ;
