The subroutines in YACC
, which are rules for correctness determination of solving fraction, are used to analyze learning status of students while solving fraction questions.
In addition to the parsing algorithms, we have implemented attribute evaluation and two styles of error recovery--the method of Yacc
[Johnson 1975], which depends on user annotations to the input grammar, and Rohrich's automatic backtrack-free mechanism [Rohrich 1980].
7432 An implementation of an LALR parser generator.
Two of the most popular are LEX , a scanner generator that accepts regular expressions and produces a table-driven recognizer, and Yacc
, an LALR(1) parser generator.