Abstract: A method may include deriving by a computing device, from an initial representation that describes a node set of an XML document, a derived representation of the node set, the initial representation including an ordered sequence of set manipulations of the XML document, the derived representation including: a first set of nodes such that all nodes in the node set are included in or descendants of a node in the first set of nodes, a second set of nodes such that no nodes in the node set are included in or descendants of a node in the second set of nodes, and a set of node tests that characterize the node set, to be applied to those nodes within the first set of nodes but outside the second set of nodes. The method may further include evaluating the derived representation to compute the node set.

Abstract: A method may include deriving by a computing device, from an initial representation that describes a node set of an XML document, a derived representation of the node set, the initial representation including an ordered sequence of set manipulations of the XML document, the derived representation including: a first set of nodes such that all nodes in the node set are included in or descendants of a node in the first set of nodes, a second set of nodes such that no nodes in the node set are included in or descendants of a node in the second set of nodes, and a set of node tests that characterize the node set, to be applied to those nodes within the first set of nodes but outside the second set of nodes. The method may further include evaluating the derived representation to compute the node set.

Abstract: A method for representing, manipulating and enumerating a node set in an XML document can create and manipulate a node set in time that is typically constant or, at worst, logarithmic in the size of the underlying document, and can enumerate a node set in time that is substantially linear in the size of the node set. The method comprises steps of deriving a high-level representation of a node set. This step need not include an enumeration of the nodes of the set. The method may then manipulate the high-level representation of a node set in order to effect transformations on the node set. The high-level representation can then be analyzed in order to determine how to most efficiently process the nodes of the node set. The node set can then be efficiently enumerated, in document order, by taking advantage of the results of the previous analysis step.