编译原理实验报告-- PL-0编译程序的修改.docx

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1、实验报告课程名称编译原理颗目名称PL/O编译程序的修改学生学院计算机学院有11/耕级一12级软件4班一、基本内容(成绩范围：“中”、“及格”或“不及格”)对PL/O作以下修改扩充：(1)增力口单词：保留字 ELSE, FOR, STEP, UNTIL, DO,RETURN 运算符 *=, /=, &, , !(2)修改单词：不等号#改为v(3)增加条件语句的ELSE子句，要求：写出相关文法，语法图，语义 规则。二、设计思路1.扩充单词1）修改变量定义a）先修改保留字的个数COnSt NORW = 19;b）修改枚举变量SYMBOL的个数为43typedef enum NUL, IDENT, N

2、UMBER, PLUS, MINUS, TIMES,Timesequal, slashequal,SLASH, ODDSYM, EQL, NEQ, LSS, LEQ, GTR, GEQ, LPAREN, RPAREN, COMMA, SEMICOLON, PERIOD, BECOMES, BEGINSYM, ENDSYM, IFSYM, THENSYM, WHILESYM, WRITESYM, READSYM, DOSYM, CALLSYM, CONSTSYM, VARSYM, PROCSYM, PROGSYM, ELSESYM, FORSYM, STEPSYM, UNTILSYM, RETU

3、RNSYM9 AND, OR,NOT SYMBOL;c）修改SYMOUT数组的个数为43char *SYMOUT = NUL, IDENT, nNUMBERn, nPLUSn, nMlNus V TIMESn9nTIMESEQUALn9 nSLASHEQUALn9 SLASH, nODDSYMn9 EQLn, nNEQn, LSSn, ,LEQn, nGTRn, GEQ, hLPARENh, nRPARENn, COMMA, nSEMICOLONn, PERIOD, nBECOMESn, hBEGINSYMh, nENDSYMn, IFSYM, hTHENSYMh, nWHILESYMn, n

4、WRITESYMn, nREADSYMn, DOSYM, nCALLSYMn, nCONSTSYMn, VARSYM, nPROCSYMn, nPROGSYMn, nELSESYMnnFORSYMn9 nSTEPSYMn9 nUNTILSYMn, nRETURNSYMn,AND, OR, NOT)；d)增加关键字和保留字strcpy(KWORD 1,nBEGIN); strcpy(KWORD 2,CALLn);strcpy(KWORD 3,nCONST);strcpy(KWORD 4,DO);StrCPy(KWORD 5 JELSE);StrCPy(KWORD6 JEND)；StrCPy(KW

5、ORD7 JFoR);strcpy(KWORD 8,IF);StrCPy(KWORD9, ODD)；strcpy(KWORD10,PROCEDURE);strcpy(KWORD 11, PROGRAM);strcpy (KWORD 12, nREADn);StrCPy(KWORD13,RETURN);StrCPy(KWoRD14,STEP);strcpy(KWORD15,THEN);StrCPy(KWoRD16 JUNTlL);strcpy (KWORD 17,n VARn);strcpy (KWORD 18, WHILE);strcpy(KWORD19,WRITE);WSYM 1=BEGIN

6、SYM; WSYM 2=CALLSYM;WSYM 3=CONSTSYM; WSYM 4=DOSYM;WSYM 5=ELSESYM; WSYM6=ENDSYM;WSYM7=FORSYM;WSYM8=IFSYM;WSYM9=ODDSYM;WSYM10=PROCSYM;WSYM11=PROGSYM;WSYM12=READSYM;WSYM13=RETURNSYM; WSYM14=STEPSYM;WSYM15=THENSYM;WSYM16=UNTILSYM;WSYM17=VARSYM;WSYM18=WHILESYM;ws YM 19 =writesym ；e.在STATEMENT方法 中添加case E

7、LSESYM:FOrmlprintfs(读取至! ELSE);break;case FORSYM:FOrmIprintfs(读取至(j FORn);break;case STEPSYM:FonnLprintfs(读取到 STEP);break;case UNTILSYM:FOrmIprintfs(读取到 UNTILn); break;case RETURNSYM:FormLprintfs(读取至! RETURN);break;case TIMESEQUAL:FOrmlprintfs(读取到 *=”)； break;case SLASHEQUAL:Formlprintfs(读取到/=);brea

8、k;case AND:FormIprintfs(读取到&”)； break;case OR:FOrml printfs(读取至! );break;case NOT:FormLprintfs(，读取至! NOT);break;2)修改GetSym()方法void GetSym() int i,J,K； ALFA A;while (CH=,A, & CH=,Z,) *ID OR RESERVED WORD*/ K=O;do if(K=A & CH=,O, & CH=9);AK=,0,;strcpy(ID,A); i=zl; J=NORW;do K=(i+J) / 2;if (strcmp(ID,K

9、WORDK)=0) i=K+l;while(i J) SYM=WSYMK;If(SYM=ELSESYM) Forml-printfs(ELSE);if(SYM=FORSYM) Forml-printfs(FOR);If(SYM=STEPSYM) Forml-printfs(STEP);If(SYM=UNTILSYM) Forml-printfs(UNTIL);If(SYM=RETURNSYM) Forml-printfs(RETURN);)else SYM=IDENT;)elseif(CH=,0, & CH=,0, & CHNMAX)Error(30);)elseif (CH=T) GetCh

10、();if (CH=,=f) SYM=BECOMES; GetCh(); else SYM=NUL;)else * THE FOLLOWING TWO CHECK WERE ADDEDBECAUSE ASCII DOES NOT HAVE A SINGLE CHARACTERFOR = */if (CH=,) SYM=NEQ; GetCh(); else SYM=LSS;elseif (CH=,) GetCh();if (CH=,=, SYM=GEQ; GetCh(); else SYM=GTR;)elseif(CH=W)GetCh();添加运算符*二if (CH=,) SYM=TIMESEQ

11、UAL; GetCh(); else SYM=TIMES;)elseif(CH=7,)GetCh();添加运算符/二if(CH=,=, SYM= SLASHEQUAL, GetCh();) else SYM=SLASH;)elseif(CH=,) SYM= AND, GetCh(); 添加运算符&elseif(CH=,)GetCh();if(CH=T) SYM= OR, GetCh(); 添加运算符 else SYM=NUL;)elseif(CH=,!,) SYM= NOT, GetCh(); 添加运算符!else SYM=SSYMCH; GetCh(); /*GetSym()*/2 .修改单

12、词：不等号#改为a.在文件中的设置单字符符号的部分，将SSym铲=NEQ删除。b.在GetSym()方法中elseif (CH=T) GetCh();if (CH=,=t) SYM=BECOMES; GetCh(); else SYM=NUL;)else * THE FOLLOWING TWO CHECK WERE ADDEDBECAUSE ASCII DOES NOT HAVE A SINGLE CHARACTER FOR =if (CH=,) SYM=NEQ; GetCh(); else SYM=LSS;)elseif (CH=A) GetCh();if (CH=) SYM=GEQ; Ge

13、tCh(); else SYM=GTR;)3 .增加条件语句的ELSE子句1)语法图2)修改 STATEMENT ()方法case IFSYM:GetSymQ;CONDITION(SymSetUnion(SymSetNew(THENSYM,DOSYM),FSYS),LEV,TX);if (Sym=THENSYM) GetSym();else Error(16);CXl=CX; GEN(JPC9O9O);STATEMENT(SymSetUnion(SymSetNew(ELSESYM), FSYS), LEV9 TX); if(SYM != ELSESYM)CODECX1.A=CX;elseGetSym();CX2 = CX;GEN(JMP, 0