do...while

#include <assert.h> #include "compiler.h"

int E(); void STMT(); void IF(); void BLOCK();

int tempIdx = 0, labelIdx = 0;

#define nextTemp() (tempIdx++) #define nextLabel() (labelIdx++) #define emit printf

int isNext(char *set) { //...}

int isEnd() { //...}

char *next() { //...}

char *skip(char *set) { //...}

// F = (E) | Number | Id int F() { //...}

// E = F (op E)* int E() { //...}

// ASSIGN = id '=' E; void ASSIGN() { //...}

// WHILE = while (E) STMT void WHILE() { //...}

// DO WHILE void DO(){ int DoBegin = nextLabel(); int DoEnd = nextLabel(); emit("(L%d)\n", DoBegin); skip("do"); STMT(); // block call STMTS ， } to end skip("while"); skip("("); int e = E(); emit("if not T%d goto L%d\n", e, DoEnd); skip(")"); skip(";"); // 需要過濾掉，不然一開始在main() 執行的 STMTS會觸發 ASSIGN() 裡面的 skip("=") 導致錯誤 emit("goto L%d\n", DoBegin); emit("(L%d)\n", DoEnd); }

// STMT = WHILE | BLOCK | ASSIGN void STMT() { if (isNext("do")){ DO(); } else if(isNext("while")) WHILE(); // else if (isNext("if")) // IF(); else if (isNext("{")) BLOCK(); else ASSIGN(); }

// STMTS = STMT* void STMTS() {//...}

// BLOCK = { STMTS } void BLOCK() { //...}

// PROG = STMTS void PROG() { //...}

void parse() { printf("============ parse =============\n"); tokenIdx = 0; PROG(); }