五

1. G中的规则r	Frist(rhs(r))	Follow(lhs(r))	PS(r)
   $S\rightarrow P$	$(,a$	$\text#$	$(,a$
   $S\rightarrow\epsilon$	$\epsilon$	None	$\text#$
   $P\rightarrow(P)P$	$($	$\text#,)$	$($
   $P\rightarrow a$	$a$	None	$a$

2. 是LL(1)文法.因为$PS(S\rightarrow P)\cap PS(S\rightarrow\epsilon)=\varnothing$,且$PS(P\rightarrow(P)P)\cap PS(P\rightarrow a)=\varnothing$.

3. 预测分析表

   	a	(	)	#
   S	$S\rightarrow P$	$S\rightarrow P$		$S\rightarrow\epsilon$
   P	$P\rightarrow a$	$P\rightarrow(P)P$

4.  
   x
   int ParseP(int P_y) {
     switch (lookahead) {
       case '(': {
         MatchToken('(');
         int P1_y = P_y;
         int P1_x = ParseP(P1_y);
         MatchToken(')');
         int P2_y = P1_x;
         int P2_x = ParseP(P2_y);
         return P1_x + P2_x;
       }
       case 'a': {
         return P_y + 1;
       }
       default:
         reportError();
     }
   }
   int ParseS() {
     switch (lookahead) {
       case '(':
       case 'a': {
         int P_y = 0;
         int P_x = ParseP(P_y);
         return P_x;
       }
       case '#': {
         return 0;
       }
       default: {
         reportError();
       }
     }
   }
   

六

1. $S\rightarrow{switch} A of \text{{L.val=A.place,L.next=S.next} L end} \\ \text{{S.code=A.code//L.code}}$

   $L\rightarrow case \text{{V.failed=newlabel}} V : \text{{S.next=L.next}}; \text{{L1.val=L.val, L1.next=L.next}}\\\text{{L.code=gen(if V.val != L.val then goto V.failed)// S.code//gen(goto L.next)//gen(V.failed :)//L.code}}$

   $L\rightarrow default \text{{S.next=L.next}} S \text{{L.code=S.code//gen(goto L.next)}}$

   $V\rightarrow d \text{{V.val=d.lexval}}$

2. $S\rightarrow while \text{{E.true=newlabel, E.false=S.next}} E do \\ \text{{S1.next=E.newlabel, S1.break=S.next}} S1\\ \text{{S.code=gen(S1.next :)//E.code//gen(E.true :)//S1.code//gen(goto S1.next)}}$

   $S\rightarrow \text{{S1.break=S.break, S1.next=newlabel}}S1\text{{S2.break=S.break, S2.next.S.next}}S2\\ \text{{S.code=S1.code//gen(S1.next : )// S2.code}}$

   $S\rightarrow break \text{{gen(goto S.break)}}$