Implement 'indirect conditional requirements', which are simular to V1's

convention that rules used in requiremenst are called to provide extra features.


[SVN r32694]

v2/build/targets.jam

@@ -79,6 +79,7 @@ import virtual-target ;
 import path ;
 import set ;
 import assert ;
+import indirect ;
 
 # Base class for all abstract targets.
 class abstract-target 
@@ -934,23 +935,47 @@ rule common-properties2 ( build-request requirements )
     local raw = [ $(build-request).raw ] ;
     raw = [ property.refine $(raw) : 
       [ feature.expand [ $(requirements).non-conditional ] ] ] ;
-    
+      
     # We've collected properties that surely must be present in common
     # properties. We now try to figure out what other properties
     # should be added in order to satisfy rules (4)-(6) from the docs.        
     
     local conditionals = [ $(requirements).conditional ] ;
-    local count = $(conditionals) and-once-more ;
+    # The 'count' variable has one element for each conditional feature
+    # and for each occurence of '<indirect-conditional>' feature.
+    # It's used as a loop counter: for each iteration of the loop
+    # before we remove one element and the property set should
+    # stabilize before we've done. It's supposed to #conditionals iterations
+    # should be enough for properties to propagate along conditions in any
+    # direction.
+    local count = $(conditionals) 
+                  [ $(requirements).get <conditional> ]                    
+                  and-once-more ;
     local prev ;
     
     local current = $(raw) ;
     
+    # It's assumed that ordinary conditional requirements can't add
+    # <indirect-conditional> properties, and that rules refered
+    # by <indirect-conditional> properties can't add new 
+    # <indirect-conditional> properties. So the list of indirect conditionals
+    # does not change.
+    local indirect = [ $(requirements).get <conditional> ] ;
+    indirect = [ MATCH @(.*) : $(indirect) ] ;  
+    
     local ok ;
     while $(count) 
     {
         # Evaluate conditionals in context of current properties
         local e = [ property.evaluate-conditionals-in-context $(conditionals) 
           : $(current) ] ;
+        
+        # Evaluate indirect conditionals.
+        for local i in $(indirect)
+        {
+            e += [ indirect.call $(i) $(current) ] ;
+        }
+                             
         if $(e) = $(prev)
         {                
             # If we got the same result, we've found final properties.

v2/test/indirect_conditional.py

@@ -0,0 +1,84 @@
+#!/usr/bin/python
+
+#  Copyright (C) Vladimir Prus 2006.
+#  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)
+
+from BoostBuild import Tester, List
+import string
+
+t = Tester()
+
+t.write("Jamroot", """ 
+exe a1 : a1.cpp : <conditional>@a1-rule ;
+
+rule a1-rule ( properties * )
+{
+    if <variant>debug in $(properties)
+    {
+	    return <define>OK ;
+    }
+}
+
+exe a2 : a2.cpp : <conditional>@$(__name__).a2-rule <variant>debug:<optimization>speed ;
+
+rule a2-rule ( properties * )
+{
+    if <optimization>speed in $(properties)
+    {
+        return <define>OK ;
+    }
+}
+
+exe a3 : a3.cpp : <conditional>@$(__name__).a3-rule-1 <conditional>@$(__name__).a3-rule-2 ;
+
+rule a3-rule-1 ( properties * )
+{
+    if <optimization>speed in $(properties)
+    {
+        return <define>OK ;
+    }
+}
+
+rule a3-rule-2 ( properties * )
+{
+    if <variant>debug in $(properties)
+    {
+        return <optimization>speed ;
+    }
+}
+
+""")
+
+t.write("a1.cpp", """ 
+#ifdef OK
+int main() {}
+#endif
+
+""")
+
+t.write("a2.cpp", """ 
+#ifdef OK
+int main() {}
+#endif
+
+""")
+
+t.write("a3.cpp", """ 
+#ifdef OK
+int main() {}
+#endif
+
+""")
+
+
+
+t.run_build_system()
+
+t.expect_addition("bin/$toolset/debug/a1.exe")
+t.expect_addition("bin/$toolset/debug/optimization-speed/a2.exe")
+t.expect_addition("bin/$toolset/debug/optimization-speed/a3.exe")
+
+t.cleanup()
+

v2/test/test_all.py

@@ -134,6 +134,7 @@ tests = [ "rebuilds",
           "project_root_rule",
           "resolution",
           "build_file",
+          "indirect_conditional",
           ]
 
 if os.name == 'posix':

v2/tools/builtin.jam

@@ -177,6 +177,9 @@ feature instruction-set :
     vr4100 vr4111 vr4120 vr4130 vr4300 vr5000 vr5400 vr5500
     #
     : propagated optional ;
+    
+    
+feature conditional : : incidental free ;    
 
 # Windows-specific features