Generalized pattern matcher generated null test.

1 files changed, 10 insertions, 0 deletions

diff --git a/src/compiler/scala/tools/nsc/ast/TreeDSL.scala b/src/compiler/scala/tools/nsc/ast/TreeDSL.scala
index 253994744b..6d1914f88b 100644
--- a/src/compiler/scala/tools/nsc/ast/TreeDSL.scala
+++ b/src/compiler/scala/tools/nsc/ast/TreeDSL.scala
@@ -23,6 +23,15 @@ trait TreeDSL {
     // clarity aliases
     type TreeFunction1 = Tree => Tree
     type TreeFunction2 = (Tree, Tree) => Tree
+    type BooleanTreeFunction2 = (Tree, Tree) => Boolean
+
+    // Add a null check to a Tree => Tree function
+    // (this assumes your result Tree is representing a Boolean expression)
+    def nullSafe[T](f: TreeFunction1): TreeFunction1 =
+      tree => (tree OBJ_!= NULL) AND f(tree)
+
+    // XXX these two are in scala.PartialFunction now, just have to
+    // settle on the final names.
 
     // Create a conditional based on a partial function - for values not defined
     // on the partial, it is false.
@@ -102,6 +111,7 @@ trait TreeDSL {
       def APPLY(params: Tree*)      = Apply(target, params.toList)
       def APPLY(params: List[Tree]) = Apply(target, params)
       def MATCH(cases: CaseDef*)    = Match(target, cases.toList)
+
       def DOT(member: Name)         = SelectStart(Select(target, member))
       def DOT(sym: Symbol)          = SelectStart(Select(target, sym))