lexer.c

/*
    Batch No: 47
    Gyanendra Mishra 2013A7PS126P
    Prabhjyot Singh Sodhi 2013A7PS151P
    Filename:lexer.c
*/

// File lexer.c  : This file contains following functions

#include "lexerDef.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "lexer.h"
/* getStream function
 * FILE *getStream(FILE *fp, buffer B, buffersize k)
 * This function takes the  input from the file pointed to by 'fp'. This file is the source code written in the
 * given language. The function uses efficient technique to bring the fixed sized piece (of size k)  of source
 * code into the buffer B  for processing so as to avoid intensive I/O operations mixed with CPU intensive
 * tasks. The function also maintains the file pointer after every access so that it can get more data into
 * the memory on demand.
 */
FILE *getStream(FILE *fp, buffer b, buffersize k)
{	int count;
	if (!feof(fp))
        count = fread(b, 1, k, fp);
    //hack
    b[k - (k - count)] = 0;
    return fp;
}

/* getNextToken function
 * tokenInfo  getNextToken(FILE *fp)
 * This function reads the input character stream and uses efficient mechanism to recognize lexemes.
 * The function tokenizes the lexeme appropriately and returns all relevant information it collects in this
 * phase (lexical analysis phase) encapsulated as  tokenInfo. The function also displays lexical errors
 * appropriately. The input parameters are made flexible and students can select appropriate input parameters.
 * The function also takes care of ignoring the white spaces and comments.
 */
/*
	Updates line number as '\n' is encountered.
	On finding a token it returns the token.
	The global variable offset and state is continuously updated.
	Errors are printed as they come.
*/
tokenInfo getNextToken(FILE *fp, buffer b, buffersize k)
{
	state = 1;
	buffer lexeme = (buffer) malloc(k*sizeof(buffer));
	memset(lexeme, 0, 100);
	int i = 0;
	tokenInfo token;
	token.name = (buffer) malloc(k*sizeof(buffer));
	int error = 0;

	while(1){
		if (offset == k || strlen(b)==0 || b[offset] == '\0'){
			if(feof(fp)){
				// printf("\nScanning Complete!\n");
				token.id = 55;
				token.name = "$";
				token.lineNo = lineNo;
				return token;
			}
			memset(b, 0, sizeof(b));
			fp = getStream(fp, b, k);
			offset = 0;
		}
		switch(state){
			//starting state
			case 1:
				switch(b[offset])
				{
					case '\t':
						state=1;
						offset++;
						break;
					case ' ':
						state=1;
						offset++;
						break;
					case '\r':
						state = 1;
						offset++;
						break;
					case '\n':
						state=1;
						lineNo++;
						offset++;
						break;
					case '%':
						state=2;
						offset++;
						break;
					case '<':
						state=3;
						lexeme[i++] = b[offset++];
						break;
					case 'a':
					case 'e':
					case 'f':
					case 'g':
					case 'h':
					case 'i':
					case 'j':
					case 'k':
					case 'l':
					case 'm':
					case 'n':
					case 'o':
					case 'p':
					case 'q':
					case 'r':
					case 's':
					case 't':
					case 'u':
					case 'v':
					case 'w':
					case 'x':
					case 'y':
					case 'z':
						state = 8;
						lexeme[i++]=b[offset++];
						break;
					case 'b':
					case 'c':
					case 'd':
						state = 9;
						lexeme[i++]=b[offset++];
						break;
					case '0':
					case '1':
					case '2':
					case '3':
					case '4':
					case '5':
					case '6':
					case '7':
					case '8':
					case '9':
						state = 13;
						lexeme[i++] = b[offset++];
						break;
					case '_':
						state = 17;
						lexeme[i++] = b[offset++];
						break;
					case '#':
						state = 20;
						lexeme[i++] = b[offset++];
						break;
					case '[':
						state = 22;
						offset++;
						token.id = 20;
						token.lineNo = lineNo;
						token.name = "[";
						return token;
					case ']':
						state = 23;
						offset++;
						token.id = 21;
						token.lineNo = lineNo;
						token.name = "]";
						return token;
					case ';':
						state = 24;
						offset++;
						token.id = 26;
						token.lineNo = lineNo;
						token.name = ";";
						return token;
					case ':':
						state = 25;
						offset++;
						token.id = 27;
						token.lineNo = lineNo;
						token.name = ":";
						return token;
					case '.':
						state = 26;
						offset++;
						token.id = 28;
						token.lineNo = lineNo;
						token.name = ".";
						return token;
					case '(':
						state = 27;
						offset++;
						token.id = 30;
						token.lineNo = lineNo;
						token.name = "(";
						return token;
					case ')':
						state = 28;
						offset++;
						token.id = 31;
						token.lineNo = lineNo;
						token.name = ")";
						return token;
					case '+':
						state = 29;
						offset++;
						token.id = 38;
						token.lineNo = lineNo;
						token.name = "+";
						return token;
					case '-':
						state = 30;
						offset++;
						token.id = 39;
						token.lineNo = lineNo;
						token.name = "-";
						return token;
					case '*':
						state = 31;
						offset++;
						token.id = 40;
						token.lineNo = lineNo;
						token.name = "*";
						return token;
					case '/':
						state = 32;
						offset++;
						token.id = 41;
						token.lineNo = lineNo;
						token.name = "/";
						return token;
					case '&':
						state = 33;
						lexeme[i++] = b[offset++];
						break;
					case '@':
						state = 36;
						lexeme[i++] = b[offset++];
						break;
					case '~':
						state = 39;
						offset++;
						token.id = 48;
						token.lineNo = lineNo;
						token.name = "~";
						return token;
					case ',':
						state = 39;
						offset++;
						token.id = 56;
						token.lineNo = lineNo;
						token.name = ",";
						return token;
					case '=':
						state = 40;
						lexeme[i++] = b[offset++];
						break;
					case '>':
						state = 42;
						lexeme[i++] = b[offset++];
						break;
					case '!':
						state = 44;
						lexeme[i++] = b[offset++];
						break;
					case '\0':
						// printf("Scanning Complete!\n");
						token.id = 55;
						token.name = "$";
						token.lineNo = lineNo;
						return token;
					default:
						error_in_lexer = 1;
						printf("ERROR_2: Unknown Symbol <%c> at line<%d>\n",b[offset], lineNo);
						offset++;
						error = 1;
						break;
				}
				break;
			// comments
			case 2:
				while(b[offset++]!='\n')
				{
					if (offset == k || b[offset] == '\0'){
						// comment at end of file
						if (feof(fp)){
							break;
						}
						memset(b, 0, sizeof(b));
						fp = getStream(fp, b, k);
						offset = 0;
					}
				};
				token.id = 2;
				token.lineNo = lineNo;
				token.name = "COMMENT";
				lineNo++;
				return token;
			// <, <--, <=
			case 3:
				switch(b[offset]){
					case '-':
						if(offset + 2 < k && b[offset+1] == '-' && b[offset+2] == '-'){
							lexeme[i++] = b[offset++];
							lexeme[i++] = b[offset++];
							lexeme[i++] = b[offset++];
							i = 0;
							token.id = 1;
							token.lineNo=lineNo;
							strcpy(token.name, lexeme);
							memset(lexeme, 0, sizeof(lexeme));
							state = 6;
							return token;
						}
						else if(offset+2 <k && b[offset+1] == '-'){
							lexeme[i++] = b[offset++];
							lexeme[i++] = b[offset++];
							error_in_lexer = 1;
							printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
							error = 1;
							break;
						}
						else if(offset+2 <k){
							lexeme[i++] = b[offset++];
							error_in_lexer = 1;
							printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
							error = 1;
							break;
						}
						else if(offset + 1 < k && b[offset+1] == '-'){
							lexeme[i++] = b[offset++];
							lexeme[i++] = b[offset++];
							if(feof(fp)){
								error_in_lexer = 1;
								printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
								error = 1;
								break;
							}
							else{
								memset(b, 0, sizeof(b));
								fp = getStream(fp, b, k);
								offset=0;
								if(b[offset]=='-'){
									lexeme[i++] = b[offset++];
									token.id = 1;
									token.lineNo=lineNo;
									strcpy(token.name, lexeme);
									i = 0;
									memset(lexeme, 0 ,sizeof(lexeme));
									state =6;
									return token;
								}
								else{
									error_in_lexer = 1;
									printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
									error = 1;
									break;
								}
							}
						}
						else if(offset+1<k){
							lexeme[i++] = b[offset++];
							error_in_lexer = 1;
							printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
							error = 1;
							break;
						}
						else if(offset + 1==k){
							if (feof(fp)){
								//@gyani print offsets?
								lexeme[i++] = b[offset++];
								error_in_lexer = 1;
								printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
								error = 1;
								break;
							}
							memset(b, 0, sizeof(b));
							fp = getStream(fp, b, k);
							offset=0;
							// come back here
							if(b[offset] == '-' && b[offset+1] == '-'){
								lexeme[i++] = b[offset++];
								lexeme[i++] = b[offset++];
								i = 0;
								token.id = 1;
								token.lineNo=lineNo;
								token.name = "<---";
								memset(lexeme, 0 ,sizeof(lexeme));
								state = 6;
								return token;
							}
							else if (b[offset] == '-'){
								lexeme[i++] = b[offset++];
								lexeme[i++] = b[offset++];
								error_in_lexer = 1;
								printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
								error=1;
								break;
							}
							else {
								lexeme[i++] = b[offset++];
								error_in_lexer = 1;
								printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
								error=1;
								break;
							}
						}
						else{
							lexeme[i++] = b[offset++];
							error_in_lexer = 1;
							printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
							error=1;
							break;
						}
						break;
					case '=':
						offset++;
						token.id = 50;
						token.lineNo = lineNo;
						token.name = "<=";
						state = 7;
						return token;
					default:
						//offset not increased in this case as the character isn't parsed and will be parsed later.
						token.id= 49;
						token.lineNo= lineNo;
						token.name = "<";
						state = 3;
						return token;
				}
				break;
			//field id and all keywords except _main
			case 8:
				while(97 <= b[offset] && b[offset] <= 122){
					lexeme[i++] = b[offset++];
					if (offset == k || b[offset] == '\0'){
						if (feof(fp)){
							break;
						}
						memset(b, 0, sizeof(b));
						fp = getStream(fp, b, k);
						offset=0;
					}
				}
				if(strcmp(lexeme,"with")==0){
					token.id = 9;
					token.lineNo = lineNo;
					strcpy(token.name, lexeme);
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(strcmp(lexeme, "parameters")==0){
					token.id = 10;
					token.lineNo = lineNo;
					strcpy(token.name, lexeme);
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(strcmp(lexeme, "end")==0){
					token.id = 11;
					token.lineNo = lineNo;
					strcpy(token.name, lexeme);
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(strcmp(lexeme, "while")==0){
					token.id = 12;
					token.lineNo = lineNo;
					strcpy(token.name, lexeme);
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(strcmp(lexeme, "int")==0){
					token.id = 13;
					token.lineNo = lineNo;
					strcpy(token.name, lexeme);
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(strcmp(lexeme, "real")==0){
					token.id = 14;
					token.lineNo = lineNo;
					strcpy(token.name, lexeme);
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(strcmp(lexeme, "type")==0){
					token.id = 15;
					token.lineNo = lineNo;
					strcpy(token.name, lexeme);
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(strcmp(lexeme, "global")==0){
					token.id = 17;
					token.lineNo = lineNo;
					strcpy(token.name, lexeme);
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(strcmp(lexeme, "parameter")==0){
					token.id = 18;
					token.lineNo = lineNo;
					strcpy(token.name, lexeme);
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(strcmp(lexeme, "list")==0){
					token.id = 19;
					token.lineNo = lineNo;
					strcpy(token.name, lexeme);
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(strcmp(lexeme, "input")==0){
					token.id = 22;
					token.lineNo = lineNo;
					strcpy(token.name, lexeme);
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(strcmp(lexeme, "output")==0){
					token.id = 23;
					token.lineNo = lineNo;
					strcpy(token.name, lexeme);
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(strcmp(lexeme, "endwhile")==0){
					token.id = 29;
					token.lineNo = lineNo;
					strcpy(token.name, lexeme);
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(strcmp(lexeme, "if")==0){
					token.id = 32;
					token.lineNo = lineNo;
					strcpy(token.name, lexeme);
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(strcmp(lexeme, "then")==0){
					token.id = 33;
					token.lineNo = lineNo;
					strcpy(token.name, lexeme);
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(strcmp(lexeme, "endif")==0){
					token.id = 34;
					token.lineNo = lineNo;
					strcpy(token.name, lexeme);
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(strcmp(lexeme, "read")==0){
					token.id = 35;
					token.lineNo = lineNo;
					strcpy(token.name, lexeme);
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(strcmp(lexeme, "write")==0){
					token.id = 36;
					token.lineNo = lineNo;
					strcpy(token.name, lexeme);
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(strcmp(lexeme, "return")==0){
					token.id = 37;
					token.lineNo = lineNo;
					strcpy(token.name, lexeme);
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(strcmp(lexeme, "call")==0){
					token.id = 42;
					token.lineNo = lineNo;
					strcpy(token.name, lexeme);
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(strcmp(lexeme, "record")==0){
					token.id = 43;
					token.lineNo = lineNo;
					strcpy(token.name, lexeme);
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(strcmp(lexeme, "endrecord")==0){
					token.id = 44;
					token.lineNo = lineNo;
					strcpy(token.name, lexeme);
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(strcmp(lexeme, "else")==0){
					token.id = 45;
					token.lineNo = lineNo;
					strcpy(token.name, lexeme);
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else{
					token.id = 3;
					token.lineNo=lineNo;
					strcpy(token.name, lexeme);
					// empty the lexeme array
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				break;
			//b-d was encountered, so one of fieldid or id
			case 9:
				//a-z
				if (97 <= b[offset] && b[offset]<= 122){
					state = 8;
					lexeme[i++] = b[offset++];
					break;
				}
				// some number comes up
				else if(48 <= b[offset] && b[offset]<=57){
					state = 10;
					lexeme[i++] = b[offset++];
					break;
				}
				//something random pops in, we are in a final state so thngs are good
				else{
					token.id = 3;
					token.lineNo=lineNo;
					strcpy(token.name, lexeme);
					memset(lexeme, 0, sizeof(lexeme));
					i=0;
					return token;
				}
				break;
			case 10:
				//id is being processed
				switch(b[offset]){
					case 'b':
					case 'c':
					case 'd':
						state = 11;
						lexeme[i++] = b[offset++];
						break;
					case '0':
					case '1':
					case '2':
					case '3':
					case '4':
					case '5':
					case '6':
					case '7':
					case '8':
						state = 12;
						lexeme[i++] = b[offset++];
						break;
					default:
						token.id = 4;
						strcpy(token.name, lexeme);
						token.lineNo = lineNo;
						memset(lexeme, 0, sizeof(lexeme));
						i=0;
						return token;
				}
				break;
			case 11:
				//something between b,c and d
				while(98<=b[offset] && b[offset]<=100){
					lexeme[i++] = b[offset++];
					if (offset == k || b[offset] == '\0'){
						if (feof(fp)){
							break;
						}
						memset(b, 0, sizeof(b));
						fp = getStream(fp, b, k);
						offset=0;
					}
				}
				if (b[offset] != '\0' && offset != k && 48 <=b[offset] && b[offset]<=57){
					state = 12;
					lexeme[i++] = b[offset++];
					break;
				}
				else{
					// something apart form b-d, number showed up, abhi tak ka jitna useful hai
					//usko send as token, not increased offset as current char is weird and will be parsed in the next run
					token.id = 4;
					strcpy(token.name, lexeme);
					token.lineNo = lineNo;
					memset(lexeme, 0, sizeof(lexeme));
					i=0;
					return token;
				}
				break;
			case 12:
				while(48<= b[offset] &&  b[offset]<=57){
					lexeme[i++] = b[offset++];
					if (offset == k || b[offset] == '\0'){
						if (feof(fp)){
							break;
						}
						memset(b, 0, sizeof(b));
						fp = getStream(fp, b, k);
						offset=0;
					}
				}
				// minimum length of 20 is enforced automatically, as it will be detected as fieldid
				if(strlen(lexeme) > 20){
					error_in_lexer = 1;
					printf("Error_1:Identifier at line<%d> is longer than the prescribed length of 20 characters.\n", lineNo);
					error = 1;
					break;
				}
				token.id = 4;
				strcpy(token.name, lexeme);
				token.lineNo = lineNo;
				memset(lexeme, 0, sizeof(lexeme));
				i = 0;
				return token;
				break;
			case 13:
				//integer number that may become rnum
				while(48<= b[offset]&& b[offset]<=57){
					lexeme[i++] = b[offset++];
					if (offset == k || b[offset] == '\0'){
						if (feof(fp)){
							break;
						}
						memset(b, 0, sizeof(b));
						fp = getStream(fp, b, k);
						offset=0;
					}
				}
				if(b[offset] != '\0' && offset != k && b[offset] == '.'){
					state = 14;
					lexeme[i++] = b[offset++];
					break;
				}
				token.id = 5;
				strcpy(token.name, lexeme);
				token.lineNo = lineNo;
				memset(lexeme, 0, sizeof(lexeme));
				return token;
			case 14:
				//real number
				if(offset+1!=k){
					if (48 <= b[offset] && b[offset]<=57 && 48 <= b[offset+1] && b[offset+1]<=57){
						state = 16;
						lexeme[i++] = b[offset++];
						lexeme[i++] = b[offset++];
						token.id = 6;
						strcpy(token.name, lexeme);
						//@gyani line nu dec kia, why
						token.lineNo=lineNo;
						i = 0;
						memset(lexeme, 0, sizeof(lexeme));
						return token;
					}
					else if(48 <= b[offset] && b[offset]<=57){
						state = 15;
						lexeme[i++] = b[offset++];
						error_in_lexer = 1;
						printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
						error = 1;
						break;
					}
					else{
						error_in_lexer = 1;
						printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
						error =1;
						break;
					}
				}
				else if(offset+1==k){
					if(48 <= b[offset] && b[offset]<=57){
						state = 15;
						lexeme[i++] = b[offset++];
						if (feof(fp)){
							error_in_lexer = 1;
							printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
							error =1;
							break;
						}
						memset(b, 0, sizeof(b));
						fp = getStream(fp, b, k);
						offset=0;
						if (48 <= b[offset] && b[offset]<=57){
							state = 16;
							lexeme[i++] = b[offset++];
							token.id = 6;
							strcpy(token.name, lexeme);
							token.lineNo = lineNo;
							i = 0;
							memset(lexeme, 0, sizeof(lexeme));
							return token;
						}
						else{
							error_in_lexer = 1;
							printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
							error=1;
							break;
						}
					}
				}
				else{
					error_in_lexer = 1;
					printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
					error = 1;
					break;
				}
				break;
			case 17:
				if ((65 <=b[offset] && b[offset] <= 90) || (97 <=b[offset] && b[offset] <= 122)){
					lexeme[i++] = b[offset++];
					state = 18;
					break;
				}
				else{
					error_in_lexer = 1;
					printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
					error = 1;
					break;
				}
				break;
			case 18:
				while((65 <=b[offset] && b[offset] <= 90) || (97 <=b[offset] && b[offset] <= 122)){
					lexeme[i++] = b[offset++];
					if(offset==k){
						if (feof(fp)){
							break;
						}
						memset(b, 0, sizeof(b));
						fp = getStream(fp, b, k);
						offset=0;
					}
				}
				if(strlen(lexeme) > 30){
					error_in_lexer = 1;
					printf("Error_6:Function Identifier at line<%d> is longer than the prescribed length of 30 characters.\n", lineNo);
					error = 1;
					break;
				}
				if(b[offset] != '\0' && offset != k  && 48 <=b[offset] && b[offset] <= 57){
					lexeme[i++] =b[offset++];
					state = 19;
					break;
				}
				// offset already has been increased
				else if(strcmp("_main", lexeme) == 0){
					token.id = 16;
					strcpy(token.name, lexeme);
					token.lineNo = lineNo;
					i=0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else{
					token.id = 7;
					strcpy(token.name, lexeme);
					token.lineNo =lineNo;
					i =0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				break;
			case 19:
				while(48 <=b[offset] && b[offset] <= 57){
					lexeme[i++] = b[offset++];
					if(offset==k){
						if (feof(fp)){
							break;
						}
						memset(b, 0, sizeof(b));
						fp = getStream(fp, b, k);
						offset=0;
					}
				}
				token.id = 7;
				strcpy(token.name, lexeme);
				token.lineNo =lineNo;
				i=0;
				memset(lexeme, 0, sizeof(lexeme));
				return token;
				break;
			case 20:
				if(97<=b[offset] && b[offset]<= 122){
					while(97<=b[offset] && b[offset]<= 122){
						lexeme[i++] = b[offset++];
						if(offset == k){
							if(feof(fp)){
								break;
							}
							memset(b, 0, sizeof(b));
							fp = getStream(fp, b, k);
							offset=0;
						}
					}
					state = 21;
					token.id = 8;
					strcpy(token.name, lexeme);
					token.lineNo = lineNo;
					i = 0;
					memset(lexeme, 0 , sizeof(lexeme));
					return token;
				}
				else {
					error_in_lexer = 1;
					printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
					error = 1;
					break;
				}
				break;
			case 33:
				if(offset+1==k && b[offset]=='&'){
					lexeme[i++] = b[offset++];
					state = 34;
					if(feof(fp)){
						error_in_lexer = 1;
						printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
						error = 1;
						break;
					}
					memset(b, 0, sizeof(b));
					fp = getStream(fp, b, k);
					offset=0;
					if(b[offset] == '&'){
						state = 35;
						lexeme[i++] = b[offset++];
						i = 0;
						token.id = 46;
						strcpy(token.name, lexeme);
						token.lineNo = lineNo;
						memset(lexeme, 0, sizeof(lexeme));
						return token;
					}
					else{
						error_in_lexer = 1;
						printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
						error = 1;
						break;
					}
				}
				else if (offset+1 ==k ){
					error_in_lexer = 1;
					printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
					error = 1;
					break;
				}
				else if(b[offset] == '&' && b[offset+1] == '&'){
					state =35;
					lexeme[i++] = b[offset++];
					lexeme[i++] = b[offset++];
					token.id = 46;
					strcpy(token.name, lexeme);
					token.lineNo = lineNo;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(b[offset] == '&'){
						lexeme[i++] = b[offset++];
						error_in_lexer = 1;
						printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
						error = 1;
						break;
				}
				else{
					error_in_lexer = 1;
					printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
					error = 1;
					break;
				}
				break;
			case 36:
				if(offset+1==k && b[offset]=='@'){
					lexeme[i++] = b[offset++];
					state = 37;
					if(feof(fp)){
						error_in_lexer = 1;
						printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
						error = 1;
						break;
					}
					memset(b, 0, sizeof(b));
					fp = getStream(fp, b, k);
					offset=0;
					if(b[offset] == '@'){
						state = 38;
						lexeme[i++] = b[offset++];
						i = 0;
						token.id = 47;
						strcpy(token.name, lexeme);
						token.lineNo = lineNo;
						memset(lexeme, 0, sizeof(lexeme));
						return token;
					}
					else{
						error_in_lexer = 1;
						printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
						error = 1;
						break;
					}
				}
				else if (offset+1 == k ){
					error_in_lexer = 1;
					printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
					error = 1;
					break;
				}
				else if(b[offset] == '@' && b[offset+1] == '@'){
					state = 38;
					lexeme[i++] = b[offset++];
					lexeme[i++] = b[offset++];
					token.id = 47;
					strcpy(token.name, lexeme);
					token.lineNo = lineNo;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else if(b[offset] == '@'){
					error_in_lexer = 1;
					lexeme[i++] = b[offset++];
					printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
					error = 1;
					break;
				}
				else{
					error_in_lexer = 1;
					printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
					error = 1;
					break;
				}
				break;
			case 40:
				if(b[offset] == '='){
					state = 41;
					lexeme[i++] = b[offset++];
					token.id = 51;
					strcpy(token.name, lexeme);
					token.lineNo = lineNo;
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else{
					error_in_lexer = 1;
					printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
					error = 1;
					break;
				}
				break;
			case 42:
				if(b[offset] == '='){
					state = 43;
					lexeme[i++] = b[offset++];
					token.id = 53;
					strcpy(token.name, lexeme);
					token.lineNo = lineNo;
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else{
					token.id = 52;
					strcpy(token.name, lexeme);
					token.lineNo = lineNo;
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				break;
			case 44:
				if(b[offset] == '='){
					state = 45;
					lexeme[i++] = b[offset++];
					token.id = 54;
					strcpy(token.name, lexeme);
					token.lineNo = lineNo;
					i = 0;
					memset(lexeme, 0, sizeof(lexeme));
					return token;
				}
				else{
					error_in_lexer = 1;
					printf("ERROR_3: Unknown pattern <%s> at line number <%d>\n", lexeme, lineNo);
					error = 1;
					break;
				}
				break;
			default:
				printf("Illegal state %d reached! How?", state);
				error = 1;
				break;
		}//end switch
		if(error==1){
			error = 0;
			state = 1;
			i = 0;
			memset(lexeme, 0, sizeof(lexeme));
		}
	}
	//end while
}//end getNextToken