期刊名称：International Journal of Software Engineering & Applications (IJSEA)
印刷版ISSN：0976-2221
电子版ISSN：0975-9018
出版年度：2015
卷号：6
期号：4
页码：1
出版社：Academy & Industry Research Collaboration Center (AIRCC)
摘要：This paper introduces a practical solution for dramatically enlarging the capabilities of an establishedparser, a task that presents substantial challenges. During the development of new procedures forSUDAAN®, a commercial statistical software package, we found the existing parser to be inadequate fornew situations. Like many other parsers, the one in use could be characterized as a no-repair, noguesswork,and no-backtracking look-ahead left-to-right LALR(1) parser [1, p. 300]. This paper describeshow the parser was enhanced to handle extra syntax for sophisticated mathematical and logicalexpressions. The new parser adds a noncanonical parsing technique, along with a Shunting-Yard-stylealgorithm and other techniques as a second step after the original canonical LALR [2], resulting in apowerful and efficient two-level parsing approach. Adding a second step to the successful one-step parseroffered a way to preserve existing, well-tested capabilities while adding capabilities for parsing morecomplex syntax.
