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Title Lexical Analyser for languages like C,PASCAL etc. (Mini Project)
Author Jatin Rajpal
Author Email jatin911 [at]
Description A simulated lexical analyser for HLL like C,PASCAL etc. I have given a sample text file from which the source code reads the dummy
program n analyses it. The program can be extended by adding more.
Category C++ » Complier Development
Hits 36927
Code Select and Copy the Code
/* LEX.cpp */ /*PROGRAM TO IMPLEMENT LEXICAL ANALYSER ON C AS A LANGUAUGE */ # include <iostream.h> # include <conio.h> # include <fstream.h> # include <ctype.h> //header files # include <dos.h> # include <stdlib.h> # include <stdio.h> # include <string.h> # define MAX 50 # define ERROR 0 # define ID 1 # define KEY 2 # define DELIM 3 # define OP 4 //constant declarations # define DATA_TYPE 0 # define OPER 2 # define KWORD 4 # define RTYPE 5 # define NUM 6 int bcount=0; char *msg[]={"error!!","id","key","delim","oprtr","num"},token[MAX][MAX],lex[MA X][MAX],attr[MAX][MAX]; char *msg2[]={"data type","identifier","operator","special character","keyword","return type","number"}; char buff[MAX],spl[]={' ',',',';',' ','(',')','{','}'}; char *data[]={"int","char","float","long","unsigned","void"}; char oper[]={'+','-','*','/','%','=','|','^','<','>','<=','>=','<>'}; char keys[4][10]={{"begin"},{"end"},{"start"},{"int"}},row[2],col[2]; /********************FUNCTIONS************************/ void display(int symcount); //display function for symbol table int flush_buff(char buff[MAX]) { for(int i=0;buff[i]!='<8;i++) //function for checkin spl.char if(x==spl[i]) return 1; return 0; } int chkoper(char x) { for(int i=0;i<13;i++) //function for checkin spl.char if(x==oper[i]) return 1; return 0; } int chkkey(char *x) { for(int i=0;i<4;i++) //function for checkin keywords { if(!strcmp(x,keys[i])) return 1; if(!strcmp(x,data[i])) return 2; } if(!buff[0]) return -1; return 0; } int rw=0,cl=1; //variables for row coloumn position int attr_assign(int symcount,int rw,int cl) { itoa(rw,row,10); itoa(cl-1,col,10); strcat(attr[symcount]," ("); //function for assigning the (row,coloumn) // position in atrribute coloumn strcat(attr[symcount],row); strcat(attr[symcount],","); strcat(attr[symcount],col); strcat(attr[symcount++],")"); return symcount; } void main() { clrscr(); cout<<" press enter to start compiler action on the specified input file--->"; if(getch()) clrscr(); char ch,temp; int match=0,symcount=0; fstream f;"code.txt",ios::out|ios::in|ios::binary); //source code file opened x: while(ch!=EOF) { cl++; f.get(ch); if(isalpha(ch)) buff[bcount]=ch; while(isdigit(ch)) //checking for invalid identifiers { buff[bcount++]=ch; f.get(ch); if(isalpha(buff[0])) continue; //this continue is for allowing // identifiers like a11a if(isalpha(ch)) { buff[bcount++]=ch; strcpy(lex[symcount],buff); strcpy(token[symcount],msg[ERROR]); //making an ERROR entry strcpy(attr[symcount],msg[ERROR]); //in the symbol table symcount=attr_assign(symcount,rw,cl); bcount=flush_buff(buff); goto x; } } if(isalpha(ch)) //after identifier validity go ahead { if((isalpha(ch))||(isdigit(ch))) buff[bcount++]=ch; } //end of alpha check if((chkspl(ch))||(chkoper(ch))) //checkin ch for spl. characters or delimiters { temp=ch; if(temp==' '||temp==' ') { rw++; //if theres a line change,increment row no. cl=1; //coloumn no. reset to 1 } match=chkkey(buff); //checking buffer for keyword validity if(match==1) { /*assigning keyword entry*/ strcpy(lex[symcount],buff); strcpy(token[symcount],msg[KEY]); strcpy(attr[symcount],msg2[KWORD]); symcount=attr_assign(symcount,rw,cl); /*flushing the buffer*/ bcount=flush_buff(buff); } if(match==2) { strcpy(lex[symcount],buff); /*assigning keyword data entry*/ strcpy(token[symcount],msg[KEY]); strcpy(attr[symcount],msg2[DATA_TYPE]); symcount=attr_assign(symcount,rw,cl); bcount=flush_buff(buff); } if(!match) { strcpy(lex[symcount],buff); if(isdigit(buff[0])) /*assigning identifier or number entry*/ { strcpy(token[symcount],msg[5]); strcpy(attr[symcount],msg2[NUM]); } else { strcpy(token[symcount],msg[ID]); strcpy(attr[symcount],msg2[ID]); } symcount=attr_assign(symcount,rw,cl); bcount=flush_buff(buff); } if(temp!=' ') //not assignin any token to white space { if(chkspl(temp)) { if(temp==' ') temp='n'; //make n cuz it cant print if(temp=='(') strcpy(attr[symcount-2],msg2[RTYPE]); //if function is encountered lex[symcount][0]=temp; //go back and assign "return type" strcpy(token[symcount],msg[DELIM]); //to keyword strcpy(attr[symcount],msg2[DELIM]); symcount=attr_assign(symcount,rw,cl); } else { lex[symcount][0]=temp; strcpy(token[symcount],msg[OP]); //assignin operator entry strcpy(attr[symcount],msg2[OPER]); symcount=attr_assign(symcount,rw,cl); } bcount=flush_buff(buff); } }// end of spl char fn } display(symcount); //display the final symbol table f.close(); getch(); } void display(int symcount) { int j=0; strcpy(lex[symcount],NULL); //assign the last symbol table entry NULL //to avoid invalid or garbled entry cout<<" SYMBOL TABLE "; cout<<" LEXEMES"<<" "<<"TOKENS"<<" "<<"ATTRIBUTES "; cout<<"---------"<<" -------"<<" ----------"; cout<<" "; while(j<=(symcount-1)) { for(int p=0;lex[j][p]!=0;p++) cout<<lex[j][p]; cout<<" "; for(int q=0;token[j][q]!=0;q++) cout<<token[j][q]; cout<<" "; for(int r=0;attr[j][r]!=0;r++) cout<<attr[j][r]; cout<<" "; delay(100); j++; } cout<<" *note:the 'n' here is to represent SLASH n since it cant be printed"; } /// sample text file from which the code reads//// // code.txt START USING 4,15 ST 1,ONE L 2,TWO ONE DC F'1' TWO EQU 2 ENDS". 000552 02 LINE IS 54. 000553 03 COLUMN 6 PIC X(40) VALUE "MINIMUM ACCOUNT ( ); scanf("%c",&ch2); choice2=toupper(ch2); for(i=1;i<=p_two;i++) { if(player2_card[i

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