(3)构造优先关系表的算法 FOR每条产生式PX1X2XnDO FOR i: =1 TO n-1 DO BEGIN IFX和X均为终结符 THEN X=X+1; IFi<=n-2且X和X2均为终结符但X∈ EVN THEN X-Xi+2 IFX∈VnX+1∈VN then Va∈ FIRSTVT(X1)≤a; FXEVN ∈VT THEN VaELASTVT(Xi a>Xi+ END(3)构造优先关系表的算法 FOR 每条产生式P→X1X2…Xn DO FOR i:=1 TO n-1 DO BEGIN IF Xi和Xi+1均为终结符 THEN Xi= Xi+1; IF i<=n-2 且 Xi和Xi+2均为终结符 但 XiVN THEN Xi=Xi+2; IF XiVT , Xi+1VN THEN aFIRSTVT(Xi+1) Xi<a; IF XiVN, Xi+1VT THEN aLASTVT(Xi ) a>Xi+1 END;