算符优先语法分析中句型分界符的处理

Dealing with Syntactic Bracket in Operand_ First Syntax Analysis

算符优先语法分析过程中要处理句型分界符与文法终结符之间的优先关系 ,但这类优先关系不能由现有的构造算符优先表的算法直接得到。文中提出了一种方案 ,通过拓广算符优先文法 ,使句型分界符成为拓广文法的一个终结符 ,再对拓广文法施行构造算符优先表算法 ,可同时得到原文法终结符与句型分界符之间的算符优先关系。

A priority of handling syntactic bracket and grammar character is needed in operand__first syntax analysis. But the priorities can not be calculated by usual algorithm of building operand__priority table. In this paper, an operand__first grammar is modified by adding the syntactic bracket into its character set,and then,a new grammar named expansionary grammar is obtained. The needed priorities can be drawn directly by executing the same algorithm on expansionary grammar.