Port cast

[SVN r64434]

v2/tools/cast.py

@@ -0,0 +1,69 @@
+# Status: ported
+# Base revision: 64432.
+# Copyright 2005-2010 Vladimir Prus.
+# Distributed under the Boost Software License, Version 1.0. (See
+# accompanying file LICENSE_1_0.txt or copy at
+# http://www.boost.org/LICENSE_1_0.txt)
+
+# Defines main target 'cast', used to change type for target. For example, in Qt
+# library one wants two kinds of CPP files -- those that just compiled and those
+# that are passed via the MOC tool.
+#
+# This is done with:
+#
+#    exe main : main.cpp [ cast _ moccable-cpp : widget.cpp ] ;
+#
+# Boost.Build will assing target type CPP to both main.cpp and widget.cpp. Then,
+# the cast rule will change target type of widget.cpp to MOCCABLE-CPP, and Qt
+# support will run the MOC tool as part of the build process.
+#
+# At the moment, the 'cast' rule only works for non-derived (source) targets.
+#
+# TODO: The following comment is unclear or incorrect. Clean it up.
+# > Another solution would be to add a separate main target 'moc-them' that
+# > would moc all the passed sources, no matter what their type is, but I prefer
+# > cast, as defining a new target type + generator for that type is somewhat
+# > simpler than defining a main target rule.
+
+import b2.build.targets as targets
+import b2.build.virtual_target as virtual_target
+
+from b2.manager import get_manager
+from b2.util import bjam_signature
+
+class CastTargetClass(targets.TypedTarget):
+
+    def construct(name, source_targets, ps):
+        result = []
+        for s in source_targets:
+            if not isinstance(s, virtual_targets.FileTarget):
+                get_manager().errors()("Source to the 'cast' metatager is not a file")
+
+            if s.action():
+                get_manager().errors()("Only non-derived targets allowed as sources for 'cast'.")
+
+
+            r = s.clone_with_different_type(self.type())
+            result.append(get_manager().virtual_targets().register(r))
+
+        return result
+    
+
+@bjam_signature((["name", "type"], ["sources", "*"], ["requirements", "*"],
+                 ["default_build", "*"], ["usage_requirements", "*"]))
+def cast(name, type, sources, requirements, default_build, usage_requirements):
+   
+    from b2.manager import get_manager
+    t = get_manager().targets()
+    
+    project = get_manager().projects().current()
+        
+    return t.main_target_alternative(
+        CastTargetClass(name, project, type,
+                        t.main_target_sources(sources, name),
+                        t.main_target_requirements(requirements, project),
+                        t.main_target_default_build(default_build, project),
+                        t.main_target_usage_requirements(usage_requirements, project)))
+
+
+get_manager().projects().add_rule("cast", cast)