Tree::addBranch

- Now returns a pointer to the new node, for convenience.  Throws on error.

src/parser/Tree.cpp

@@ -76,10 +76,14 @@ Tree* Tree::operator[] (const int branch)
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-void Tree::addBranch (Tree* branch)
+Tree* Tree::addBranch (Tree* branch)
 {
+  if (! branch)
+    throw "Failed to allocate memory for parse tree.";
+
   branch->_trunk = this;
   _branches.push_back (branch);
+  return branch;
 }
 
 ////////////////////////////////////////////////////////////////////////////////

src/parser/Tree.h

@@ -42,7 +42,7 @@ public:
   Tree& operator= (const Tree&);
   Tree* operator[] (const int);
 
-  void addBranch (Tree*);
+  Tree* addBranch (Tree*);
   void removeBranch (Tree*);
   void replaceBranch (Tree*, Tree*);
   int branches ();