Add a Prepend() method to Environments. (Chad Austin)

2 files changed, 46 insertions, 0 deletions

diff --git a/src/engine/SCons/Environment.py b/src/engine/SCons/Environment.py
index 4a86ae6..47ab58b 100644
--- a/src/engine/SCons/Environment.py
+++ b/src/engine/SCons/Environment.py
@@ -269,6 +269,24 @@ class Environment:
                 self._dict[key] = self._dict[key] + kw[key]
         self.__updateBuildersAndScanners()
 
+    def Prepend(self, **kw):
+        """Prepend values to existing construction variables
+        in an Environment.
+        """
+        kw = our_deepcopy(kw)
+        for key in kw.keys():
+            if not self._dict.has_key(key):
+                self._dict[key] = kw[key]
+            elif SCons.Util.is_List(self._dict[key]) and not \
+                 SCons.Util.is_List(kw[key]):
+                self._dict[key] = [ kw[key] ] + self._dict[key]
+            elif SCons.Util.is_List(kw[key]) and not \
+                 SCons.Util.is_List(self._dict[key]):
+                self._dict[key] = kw[key] + [ self._dict[key] ]
+            else:
+                self._dict[key] = kw[key] + self._dict[key]
+        self.__updateBuildersAndScanners()
+
     def	Depends(self, target, dependency):
 	"""Explicity specify that 'target's depend on 'dependency'."""
         tlist = SCons.Node.arg2nodes(target, self.fs.File)
diff --git a/src/engine/SCons/EnvironmentTests.py b/src/engine/SCons/EnvironmentTests.py
index eefb605..8154990 100644
--- a/src/engine/SCons/EnvironmentTests.py
+++ b/src/engine/SCons/EnvironmentTests.py
@@ -345,6 +345,34 @@ class EnvironmentTestCase(unittest.TestCase):
         except:
             raise
 
+    def test_Prepend(self):
+        """Test prepending to construction variables in an Environment
+        """
+        import UserList
+        UL = UserList.UserList
+        env1 = Environment(AAA = 'a', BBB = 'b', CCC = 'c', DDD = 'd',
+                           EEE = ['e'], FFF = ['f'], GGG = ['g'], HHH = ['h'],
+                           III = UL(['i']), JJJ = UL(['j']),
+                           KKK = UL(['k']), LLL = UL(['l']))
+        env1.Prepend(BBB = 'B', CCC = ['C'], DDD = UL(['D']),
+                    FFF = 'F', GGG = ['G'], HHH = UL(['H']),
+                    JJJ = 'J', KKK = ['K'], LLL = UL(['L']))
+        env2 = Environment(AAA = 'a', BBB = 'Bb',
+                           CCC = ['C', 'c'], DDD = UL(['D', 'd']),
+                           EEE = ['e'], FFF = ['F', 'f'],
+                           GGG = ['G', 'g'], HHH = UL(['H', 'h']),
+                           III = UL(['i']), JJJ = UL(['J', 'j']),
+                           KKK = UL(['K', 'k']), LLL = UL(['L', 'l']))
+        assert env1 == env2, diff_env(env1, env2)
+
+        env3 = Environment(X = {'x' : 7})
+        try:
+            env3.Prepend(X = {'x' : 8})
+        except TypeError:
+            pass
+        except:
+            raise
+
     def test_Depends(self):
 	"""Test the explicit Depends method."""
 	env = Environment()