Refactor env.Append() and env.Prepend().

1 files changed, 92 insertions, 36 deletions

diff --git a/src/engine/SCons/Environment.py b/src/engine/SCons/Environment.py
index dc52ee1..1d61ae8 100644
--- a/src/engine/SCons/Environment.py
+++ b/src/engine/SCons/Environment.py
@@ -454,26 +454,53 @@ class Base:
         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]):
-                if kw[key]:
-                    self._dict[key] = self._dict[key] + [ kw[key] ]
-                #self._dict[key] = map(None, self._dict[key] + [ kw[key] ])
-            elif SCons.Util.is_List(kw[key]) and not \
-                 SCons.Util.is_List(self._dict[key]):
-                if self._dict[key]:
-                    self._dict[key] = [ self._dict[key] ] + kw[key]
-                else:
-                    self._dict[key] = kw[key]
-                #self._dict[key] = map(None, self._dict[key] + [ kw[key] ])
-            elif SCons.Util.is_Dict(self._dict[key]) and \
-                 SCons.Util.is_Dict(kw[key]):
-                self._dict[key].update(kw[key])
+        for key, val in kw.items():
+            try:
+                orig = self._dict[key]
+            except KeyError:
+                # No existing variable in the environment, so just set
+                # it to the new value.
+                self._dict[key] = val
+                continue
+
+            try:
+                # Most straightforward:  just try to add them together.
+                # This will work in most cases, when the original and
+                # new values are of compatible types.
+                self._dict[key] = orig + val
+                continue
+            except TypeError:
+                pass
+
+            try:
+                # Try to update a dictionary value with another.
+                # If orig isn't a dictionary, it won't have an
+                # update() method; if val isn't a dictionary, it
+                # won't have a keys() method.  Either way, it's
+                # an AttributeError.
+                orig.update(val)
+                continue
+            except AttributeError:
+                pass
+
+            try:
+                # Check if the original is a list.
+                add_to_orig = orig.append
+            except AttributeError:
+                pass
             else:
-                self._dict[key] = self._dict[key] + kw[key]
+                # The original is a list, so append the new value to it
+                # (if there's a value to append).
+                if val:
+                    add_to_orig(val)
+                continue
+
+            # The original isn't a list, but the new value is (by process
+            # of elimination), so insert the original in the new value
+            # (if there's one to insert) and replace the variable with it.
+            if orig:
+                val.insert(0, orig)
+            self._dict[key] = val
 
     def AppendENVPath(self, name, newpath, envname = 'ENV', sep = os.pathsep):
         """Append path elements to the path 'name' in the 'ENV'
@@ -662,24 +689,53 @@ class Base:
         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]):
-                if 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]):
-                if self._dict[key]:
-                    self._dict[key] = kw[key] + [ self._dict[key] ]
-                else:
-                    self._dict[key] = kw[key]
-            elif SCons.Util.is_Dict(self._dict[key]) and \
-                 SCons.Util.is_Dict(kw[key]):
-                self._dict[key].update(kw[key])
+        for key, val in kw.items():
+            try:
+                orig = self._dict[key]
+            except KeyError:
+                # No existing variable in the environment, so just set
+                # it to the new value.
+                self._dict[key] = val
+                continue
+
+            try:
+                # Most straightforward:  just try to add them together.
+                # This will work in most cases, when the original and
+                # new values are of compatible types.
+                self._dict[key] = val + orig
+                continue
+            except TypeError:
+                pass
+
+            try:
+                # Try to update a dictionary value with another.
+                # If orig isn't a dictionary, it won't have an
+                # update() method; if val isn't a dictionary, it
+                # won't have a keys() method.  Either way, it's
+                # an AttributeError.
+                orig.update(val)
+                continue
+            except AttributeError:
+                pass
+
+            try:
+                # Check if the added value is a list.
+                add_to_val = val.append
+            except AttributeError:
+                pass
             else:
-                self._dict[key] = kw[key] + self._dict[key]
+                # The added value is a list, so append the original to it
+                # (if there's a value to append).
+                if orig:
+                    add_to_val(orig)
+                self._dict[key] = val
+                continue
+
+            # The added value isn't a list, but the original is (by
+            # process of elimination), so insert the the new value in
+            # the original (if there's one to insert).
+            if val:
+                orig.insert(0, val)
 
     def PrependENVPath(self, name, newpath, envname = 'ENV', sep = os.pathsep):
         """Prepend path elements to the path 'name' in the 'ENV'