XML stream transformer generation through program composition and dependency analysis

AbstractXML stream transformation, which sequentially processes the input XML data on the fly, makes it possible to process large sized data within a limited amount of memory. Though being efficient in memory-use, stream transformation requires stateful programming, which is error-prone and hard to manage.This paper proposes a scheme for generating XML stream transformers. Given an attribute grammar definition of transformation over an XML tree structure, we systematically derive a stream transformer in two steps. First, an attribute grammar definition of the XML stream transformation is inferred by applying a program composition method. Second, a finite state transition machine is constructed through a dependency analysis. Due to the closure property of the program composition method, our scheme also allows modular construction of XML stream transformers.We have implemented a prototype XML stream transformer generator, called altSAX. The experimental results show that the generated transformers are efficient in memory consumption as well as in execution time

XML stream transformer generation through program composition and dependency analysis

AbstractXML stream transformation, which sequentially processes the input XML data on the fly, makes it possible to process large sized data within a limited amount of memory. Though being efficient in memory-use, stream transformation requires stateful programming, which is error-prone and hard to manage.This paper proposes a scheme for generating XML stream transformers. Given an attribute grammar definition of transformation over an XML tree structure, we systematically derive a stream transformer in two steps. First, an attribute grammar definition of the XML stream transformation is inferred by applying a program composition method. Second, a finite state transition machine is constructed through a dependency analysis. Due to the closure property of the program composition method, our scheme also allows modular construction of XML stream transformers.We have implemented a prototype XML stream transformer generator, called altSAX. The experimental results show that the generated transformers are efficient in memory consumption as well as in execution time

Shortcut fusion rules for the derivation of circular and higher-order programs

Functional programs often combine separate parts using intermediate data structures for communicating results. Programs so defined are modular, easier to understand and maintain, but suffer from inefficiencies due to the generation of those gluing data structures. To eliminate such redundant data structures, some program transformation techniques have been proposed. One such technique is shortcut fusion, and has been studied in the context of both pure and monadic functional programs. In this paper, we study several shortcut fusion extensions, so that, alternatively, circular or higher-order programs are derived. These extensions are also provided for effect-free programs and monadic ones. Our work results in a set of generic calculation rules, that are widely applicable, and whose correctness is formally established.Fundação para a Ciência e a Tecnologi

Using Circular Programs to Deforest in Accumulating Parameters

Functional languages allow a modular programming style by function composition, which however can lead to inefficient runtime behavior due to production and consumption of intermediate results. We present a new mechanizable transformation technique for removing intermediate data structures in the composition of two functions from a class of recursive functions with accumulating parameters, for which classical deforestation techniques fail. In order to avoid multiple traversals of the input data structure, the composition algorithm produces circular programs that make essential use of lazy evaluation and local recursion. The resulting programs are simplified using a post-processing phase presented in the paper