 This perception changed gradually after the release of the Purdue Compiler Construction Tool Set around 1992, when it was demonstrated that many programming languages can be parsed efficiently by an LL("k") parser without triggering the worst-case behavior of the parser.Moreover, in certain cases LL parsing is feasible even with unlimited lookahead.By contrast, traditional parser generators like yacc use LALR(1) parser tables to construct a restricted LR parser with a fixed one-token lookahead.