From 84162fb87c4fa7a129de6dd306aa223d0ef8b142 Mon Sep 17 00:00:00 2001
From: Rene Rivera <grafikrobot@gmail.com>
Date: Tue, 15 Aug 2006 18:46:13 +0000
Subject: [PATCH] Add host-os and target-os features.

[SVN r34889]
---
 src/tools/builtin.jam | 51 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/src/tools/builtin.jam b/src/tools/builtin.jam
index 4e1bba72e..74e81e5d7 100644
--- a/src/tools/builtin.jam
+++ b/src/tools/builtin.jam
@@ -25,9 +25,60 @@ import project ;
 
 # This feature is used to determine which OS we're on.
 # In future, this may become <target-os> and <host-os>
+# The future is now...
 local os = [ modules.peek : OS ] ;
 feature os : $(os) : propagated link-incompatible ;
 
+# Translates from bjam current OS to the os tags used
+# in host-os and target-os. I.e. it returns the
+# running host-os.
+local rule default-host-os ( )
+{
+    local host-os ;
+    local os-list = [ feature.values host-os ] ;
+    if [ os.name ] in $(os-list: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 MACOSX : host-os = darwin ;
+            case KFREEBSD : host-os = freebsd ;
+            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 unkown 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 host-os
+    :   amiga aix bsd cygwin darwin dos emx freebsd hpux
+        linux netbsd openbsd osf qnx qnxnto sgi solaris sun sunos
+        svr4 sysv ultrix unixware vms windows
+    :   optional ;
+        feature.set-default host-os : [ default-host-os ] ;
+feature target-os
+    :   amiga aix bsd cygwin darwin dos emx freebsd hpux
+        linux netbsd openbsd osf qnx qnxnto sgi solaris sun sunos
+        svr4 sysv ultrix unixware vms windows
+    :   propagated link-incompatible ;
+        feature.set-default target-os : [ default-host-os ] ;
+
+
 feature toolset : : implicit propagated symmetric ;
 
 feature stdlib : native : propagated composite ;