编译原理实验参考

1、1、 完成内容1、增加单词：保留字 ELSE，FOR，STEP，UNTIL，RETURN 运算符 *=，/=，&，|，！2、修改单词：不等号# 改为 < >3、增加条件语句的ELSE子句2、 设计思路1、扩充单词 (1) 修改变量定义 1) 关键字个数增加5个const NORW = 14+5; 2) 符号表修改typedef enum NUL, IDENT, NUMBER, PLUS, MINUS, TIMES, SLASH, ODDSYM, EQL, NEQ, LSS, LEQ, GTR, GEQ, LPAREN, RPAREN, COMMA, SEMICOLON, P

2、ERIOD, BECOMES, BEGINSYM, ENDSYM, IFSYM, THENSYM, WHILESYM, WRITESYM, READSYM, DOSYM, CALLSYM, CONSTSYM, VARSYM, PROCSYM, PROGSYM, ELSESYM , FORSYM,STEPSYM,UNTILSYM,RETURNSYM,TIMESBECOMES,SLASHBECOMES, PLUSPLUS,MINUSMINUS, AND, OR, NOT SYMBOL;char *SYMOUT = "NUL", "IDENT", "

3、NUMBER", "PLUS", "MINUS", "TIMES","SLASH", "ODDSYM", "EQL", "NEQ", "LSS", "LEQ", "GTR", "GEQ","LPAREN", "RPAREN", "COMMA", "SEMICOLON", "PER

4、IOD","BECOMES", "BEGINSYM", "ENDSYM", "IFSYM", "THENSYM", "WHILESYM", "WRITESYM", "READSYM", "DOSYM", "CALLSYM","CONSTSYM", "VARSYM", "PROCSYM", "PROGSYM",

5、 "ELSESYM","FORSYM","TOSYM","DOWNTOSYM","RETURNSYM" ,"TIMESBECOMES","SLASHBECOMES", "PLUSPLUS", "MINUSMINUS", "AND", "OR", "NOT"3) 修改关键字表strcpy(KWORD 1,"BEGIN"); strcpy(K

6、WORD 2,"CALL"); strcpy(KWORD 3,"CONST"); strcpy(KWORD 4,"DO"); strcpy(KWORD 5,"ELSE");strcpy(KWORD 6,"END");strcpy(KWORD 7,"FOR");strcpy(KWORD 8,"IF"); strcpy(KWORD9,"ODD"); strcpy(KWORD10,"PROCEDURE"); strcpy(

7、KWORD11,"PROGRAM"); strcpy(KWORD12,"READ"); strcpy(KWORD13,"RETURN"); strcpy(KWORD14,"STEP"); strcpy(KWORD15,"THEN"); strcpy(KWORD16,"UNTIL"); strcpy(KWORD17,"VAR");strcpy(KWORD18,"WHILE");strcpy(KWORD19,"WRITE"

8、;); 4) 修改关键字的机内表示WSYM 1=BEGINSYM; WSYM 2=CALLSYM; WSYM 3=CONSTSYM; WSYM 4=DOSYM; WSYM 5=ELSESYM;WSYM 6=ENDSYM;WSYM 7=FORSYM;WSYM 8=IFSYM; WSYM9=ODDSYM; WSYM10=PROCSYM; WSYM11=PROGSYM; WSYM12=READSYM; WSYM13=RETURNSYM; WSYM14=STEPSYM; WSYM15=THENSYM; WSYM16=UNTILSYM; WSYM17=VARSYM;WSYM18=WHILESYM;WSY

9、M19=WRITESYM;5) 修改单字符表 SSYM'+'=PLUS; SSYM'-'=MINUS; SSYM'*'=TIMES; SSYM'/'=SLASH; SSYM'('=LPAREN; SSYM')'=RPAREN; SSYM'='=EQL; SSYM','=COMMA; SSYM'.'=PERIOD;SSYM''=SEMICOLON;SSYM'&'=AND;SSYM'|'=OR;SSY

10、M'!'=NOT;/删除SSYM'#'=NEQ; (2) 修改GetSym方法.else if (CH='<') GetCh(); if (CH='=') SYM=LEQ; GetCh(); else if(CH='>')SYM=NEQ;GetCh(); / 识别不等号< > else SYM=LSS; else if(CH='*') GetCh(); if(CH='=')SYM=TIMESBECOMES;Form1->printfs("- *

11、= -");GetCh();/ 识别 *= else SYM=TIMES; else if(CH='/') GetCh(); if(CH='=')SYM=SLASHBECOMES;Form1->printfs("- /= -");GetCh();/识别 /= else SYM=SLASH; else if(CH='+') GetCh(); if(CH='+') SYM=PLUSPLUS;Form1->printfs("- + -"); GetCh();/识别 + els

12、e SYM=PLUS; else if(CH='-') GetCh(); if(CH='-') SYM=MINUSMINUS;Form1->printfs("- - - -"); GetCh();/识别 - - else SYM=MINUS; else if(CH='&')/识别 & GetCh(); SYM=AND; Form1->printfs("- & -");GetCh(); else if(CH='|')/识别 | GetCh(); SYM=OR

13、; Form1->printfs("- | -");GetCh(); else if(CH='!')/识别 ! GetCh(); SYM=NOT; Form1->printfs("- ! -");GetCh(); (3) 修改statement方法switch(SYM)case FORSYM: Form1->printfs("-FOR-"); GetSym(); break; case STEPSYM: Form1->printfs("-STEP-"); GetSym();

14、break; case UNTILSYM: Form1->printfs("-UNTIL-"); GetSym(); break; case RETURNSYM: Form1->printfs("-RETURN-"); GetSym(); break;2、 增加else子句 (1) 语法描述图 (2) 递归下降子程序 statement()if(SYM=IFSYM)GetSym(); condition();if(SYM=THENSYM) GetSym();else Error();statement();if(SYM=ELSESYM)Get

15、Sym();statement(); (3) 举例设计的pcode代码if(a>b)then write(a);else write(b);其pcode代码如下：1) LOD 0 3 /a2) LOD 0 4 /b3) OPR 0 124) JPC 0 9)5) LOD 0 36) OPR 0 147) OPR 0 158) JMP 0 12)9) LOD 0 410) OPR 0 1411) OPR 0 1512) (4) 在递归下降子程序上加入语句动作 case IFSYM:GetSym();CONDITION(SymSetUnion(SymSetNew(THENSYM,DOSYM)

16、,FSYS),LEV,TX);if (SYM=THENSYM) GetSym();else Error(16);CX1=CX; GEN(JPC,0,0);STATEMENT(SymSetUnion(SymSetNew(ELSESYM),FSYS),LEV,TX);if(SYM=ELSESYM) GetSym(); CODECX1.A=CX; CX2=CX; GEN(JMP,0,0); STATEMENT(FSYS,LEV,TX); CODECX2.A=CX;else CODECX1.A=CX;break;3、 运行测试1、 扩充单词测试关键字用例：(TEST.PL0)PROGRAM EX01;VAR A;BEGIN FOR; UNTIL; STEP; RETURN; WRITE(A);END.运行结果截图： 测试运算符用例：（E02.PL0） PROGRAM EX02; BEGIN *=; /=; & |; !; END. 运算结果截图：2、增加ELSE子句测试ELSE子句、不等号<>用例：（E01.PL0）PROGRAM EX0