From f5deaec1060e2fd1b4e58c3836046434a054436f Mon Sep 17 00:00:00 2001
From: Vladimir Prus <ghost@cs.msu.su>
Date: Tue, 23 Nov 2010 07:16:28 +0000
Subject: [PATCH] Implement negative conditional requirements. For example:
 <threading>!single:<library>pthread

[SVN r66697]
---
 src/build/property.jam | 42 +++++++++++++++++++++++++++++++++++++++---
 1 file changed, 39 insertions(+), 3 deletions(-)

diff --git a/src/build/property.jam b/src/build/property.jam
index 1e5fbf2b7..a2ad5226b 100644
--- a/src/build/property.jam
+++ b/src/build/property.jam
@@ -112,12 +112,48 @@ rule evaluate-conditionals-in-context ( properties * : context * )
         # Separate condition and property.
         local s = [ MATCH (.*):(<.*) : $(p) ] ;
         # Split condition into individual properties.
-        local c = [ regex.split $(s[1]) "," ] ;
+        local condition = [ regex.split $(s[1]) "," ] ;
         # Evaluate condition.
-        if $(c) in $(context)
+        if ! [ MATCH (!).* : $(condition:G=) ]
         {
-            result += $(s[2]) ;
+            # Only positive checks
+            if $(condition) in $(context)
+            {
+                result += $(s[2]) ;
+            }
         }
+        else
+        {
+            # Have negative checks
+            local fail ;
+            while $(condition)
+            {
+                local c = $(condition[1]) ;
+                local m = [ MATCH !(.*) : $(c) ] ;
+                if $(m)
+                {
+                    local p = $(m:G=$(c:G)) ;
+                    if $(p) in $(context)
+                    {
+                        fail = true ;
+                        c = ;
+                    }                    
+                }    
+                else
+                {
+                    if ! $(c) in $(context)
+                    {
+                        fail = true ;
+                        c = ;
+                    }                    
+                }
+                condition = $(condition[2-]) ;
+            }
+            if ! $(fail)
+            {
+                result += $(s[2]) ;
+            }            
+        }                
     }
     return $(result) ;
 }