7. A computer program product for processing parse tree data, the computer program product comprising: a non-transitory computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor to cause the processor to perform a method comprising: receiving a parse tree data structure, wherein the parse tree data structure is representative of a document object model (DOM) tree data structure; concomitant to receiving the parse tree data structure, receiving an assignment of index values for the DOM nodes consisting of distinct index values for each existing DOM node; receiving a request to manipulate the parse tree data structure, wherein the request comprises an insert DOM node request for a new DOM node; concomitant to receiving the request to manipulate the parse tree data structure, receiving an indication of a parse tree insert location for the new DOM node to be inserted; responsive to receiving the indication of the parse tree insert location: assigning a distinguishable index value to the new DOM node to be inserted; and inserting the new DOM node at the indicated parse tree insert location; receiving a document order comparison request to determine an earlier of a first given DOM node and a second given DOM node; responsive to receiving the document order comparison request, determining whether the document order comparison request can be satisfied by a comparison of the index values of the first given DOM node and the second given DOM node; responsive to determining that the document order comparison request can be satisfied by a comparison of the index values of the first given DOM node and the second given DOM node, selecting as the earlier DOM node one of the first given DOM node and the second DOM node based on the comparison of the index values of the first given DOM node and the second given DOM node; responsive to a determination that the document order comparison request cannot be satisfied by the comparison of the index values of the first given DOM node and the second given DOM node, selecting as the earlier DOM node one of the first given DOM node and the second DOM node using a secondary comparison method; performing a re-index operation on the assignment of index values for the DOM nodes to assign distinct index values for each existing DOM node; subsequent to receiving the parse tree data structure, storing an initially empty projection containing no associations of DOM nodes to binary tree nodes; responsive to receiving, by the processor, a delete DOM node request, deleting from the binary tree structure a corresponding binary tree node associated with the DOM node for which deletion was requested only when the DOM node has an associated binary tree node; responsive to receiving, by the processor, an insert DOM node request for a new DOM node, the processor identifies the binary tree insertion point location for the corresponding binary tree node associated with the new DOM node by: obtaining a pre-order traversal predecessor DOM node, denoted P, of the new DOM node; responsive to a determination P has an associated binary tree node, identifying a binary tree successor insertion location of the binary tree node associated with P; and responsive to a determination P does not have an associated binary tree node, determining the binary tree insertion point location using a specialized binary tree search using a value of the index of P; and subsequent to performing a re-index operation on the assignment of index values for the DOM nodes to assign distinct index values for each existing DOM node, returning the projection and the binary tree data structure to an empty state.
7. A computer program product for processing parse tree data, the computer program product comprising: a non-transitory computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor to cause the processor to perform a method comprising: receiving a parse tree data structure, wherein the parse tree data structure is representative of a document object model (DOM) tree data structure; concomitant to receiving the parse tree data structure, receiving an assignment of index values for the DOM nodes consisting of distinct index values for each existing DOM node; receiving a request to manipulate the parse tree data structure, wherein the request comprises an insert DOM node request for a new DOM node; concomitant to receiving the request to manipulate the parse tree data structure, receiving an indication of a parse tree insert location for the new DOM node to be inserted; responsive to receiving the indication of the parse tree insert location: assigning a distinguishable index value to the new DOM node to be inserted; and inserting the new DOM node at the indicated parse tree insert location; receiving a document order comparison request to determine an earlier of a first given DOM node and a second given DOM node; responsive to receiving the document order comparison request, determining whether the document order comparison request can be satisfied by a comparison of the index values of the first given DOM node and the second given DOM node; responsive to determining that the document order comparison request can be satisfied by a comparison of the index values of the first given DOM node and the second given DOM node, selecting as the earlier DOM node one of the first given DOM node and the second DOM node based on the comparison of the index values of the first given DOM node and the second given DOM node; responsive to a determination that the document order comparison request cannot be satisfied by the comparison of the index values of the first given DOM node and the second given DOM node, selecting as the earlier DOM node one of the first given DOM node and the second DOM node using a secondary comparison method; performing a re-index operation on the assignment of index values for the DOM nodes to assign distinct index values for each existing DOM node; subsequent to receiving the parse tree data structure, storing an initially empty projection containing no associations of DOM nodes to binary tree nodes; responsive to receiving, by the processor, a delete DOM node request, deleting from the binary tree structure a corresponding binary tree node associated with the DOM node for which deletion was requested only when the DOM node has an associated binary tree node; responsive to receiving, by the processor, an insert DOM node request for a new DOM node, the processor identifies the binary tree insertion point location for the corresponding binary tree node associated with the new DOM node by: obtaining a pre-order traversal predecessor DOM node, denoted P, of the new DOM node; responsive to a determination P has an associated binary tree node, identifying a binary tree successor insertion location of the binary tree node associated with P; and responsive to a determination P does not have an associated binary tree node, determining the binary tree insertion point location using a specialized binary tree search using a value of the index of P; and subsequent to performing a re-index operation on the assignment of index values for the DOM nodes to assign distinct index values for each existing DOM node, returning the projection and the binary tree data structure to an empty state. 8. The computer program product of claim 7 , wherein: the distinct index values for each existing DOM node are non-negative integers; the distinguishable index value assigned to the new DOM node to be inserted is a constant negative integer; the processor determines whether the document order comparison request can be satisfied by a comparison of the index values of the first given DOM node and the second given DOM node by determining that the index values of the first given DOM node and the second given DOM node are both non-negative; and responsive to a determination that the document order comparison request can be satisfied by a comparison of the index values of the first given DOM node and the second given DOM node, the program instructions are further executable by the processor for selecting as the earlier DOM node one of the first given DOM node and the second DOM node by selecting the given DOM node with the lesser assigned distinct index value.