PROCEDURE S BEGIN CASE lookahead OF if BEGIN match(if) (B truelist, B. falselist): =B backpatch(B truelist, ip IF lookahead= then THEN BEGIN match( then S1nextlist=S END ELSE ERRORPROCEDURE S; BEGIN CASE lookahead OF ´if´ : BEGIN match(´if´); (B.truelist, B.falselist):=B; backpatch(B.truelist, ip); IF lookahead=´then´ THEN BEGIN match(´then´); S1.nextlist:=S END ELSE ERROR;