Improve exception behavior; cleanup.

bitshift/query/__init__.py

@@ -209,6 +209,9 @@ class _QueryParser(object):
         def parse_binary_op(op):
             """Parse a binary operator in a nested query list."""
             index = nest.index(op)
+            if index == 0 or index == len(nest) - 1:
+                err = "Invalid query: '%s' given without argument."
+                raise QueryParseException(err % BinaryOp.OPS[op])
             left = self._parse_nest(nest[:index])
             right = self._parse_nest(nest[index + 1:])
             return BinaryOp(left, op, right)
@@ -222,6 +225,9 @@ class _QueryParser(object):
             return parse_binary_op(BinaryOp.AND)
         elif UnaryOp.NOT in nest:
             index = nest.index(UnaryOp.NOT)
+            if index == len(nest) - 1:
+                err = "Invalid query: '%s' given without argument."
+                raise QueryParseException(err % UnaryOp.OPS[op])
             right = UnaryOp(UnaryOp.NOT, self._parse_nest(nest[index + 1:]))
             if index > 0:
                 left = self._parse_nest(nest[:index])

bitshift/query/nodes.py

@@ -176,6 +176,7 @@ class BinaryOp(_Node):
     """Represents a relationship between two nodes: ``and``, ``or``."""
     AND = object()
     OR = object()
+    OPS = {AND: "AND", OR: "OR"}
 
     def __init__(self, left, op, right):
         self.left = left
@@ -183,9 +184,8 @@ class BinaryOp(_Node):
         self.right = right
 
     def __repr__(self):
-        ops = {self.AND: "AND", self.OR: "OR"}
         tmpl = "BinaryOp({0}, {1}, {2})"
-        return tmpl.format(self.left, ops[self.op], self.right)
+        return tmpl.format(self.left, self.OPS[self.op], self.right)
 
     def sortkey(self):
         return self.left.sortkey() + self.right.sortkey()
@@ -194,14 +194,14 @@ class BinaryOp(_Node):
 class UnaryOp(_Node):
     """Represents a transformation applied to one node: ``not``."""
     NOT = object()
+    OPS = {NOT: "NOT"}
 
     def __init__(self, op, node):
         self.op = op
         self.node = node
 
     def __repr__(self):
-        ops = {self.NOT: "NOT"}
-        return "UnaryOp({0}, {1})".format(ops[self.op], self.node)
+        return "UnaryOp({0}, {1})".format(self.OPS[self.op], self.node)
 
     def sortkey(self):
         return self.node.sortkey()

bitshift/query/tree.py

@@ -9,6 +9,11 @@ class Tree(object):
     def __repr__(self):
         return "Tree({0})".format(self._root)
 
+    @property
+    def root(self):
+        """The root node of the tree."""
+        return self._root
+
     def sortkey(self):
         """Return a string sort key for the query tree."""
         return self._root.sortkey()