implement the construction of Simple LR parsing table

I have an idea I can do it by hand but i am not able to implement via program
I need help with construction of Simple LR parsing table given the grammar productions in a file
I am not able to implement the closure, goto and to find the sets of items construction my main problem is the position of parser that is . how to implement this.

please help me I am ready to forgo anything for this. please get me started my posting some code for these functions and combining them for building the slr parsing table

if anybody needs the algorithms simple google of construction of slr parsing table will give the algorithms clearly if anybody wants the dragon book that is compilers book I am pleased to upload.

I know how to separate identifiers ,keywords,operators from a file given the productions in a file.I have posted the code.

#include<stdio.h>
#include<conio.h>
#include<string.h>
main()
{
char exp[500];
char op[21]={'+','-','*','/','%','^','[',']','(',')','{','}','=',';','<','>','#',',','&','"','|'};
char keys[30][30]={"if","while","for","do","include","printf","main","void","scanf","getch","int","char","break","continue","case","const","default","else","double","float","void","isaplha","isdigit","strcmp"};
char token[20];
int i,j,pos,k,h,m,len,c=0,g;
FILE *fp;
FILE *fp1;
int p=0;
clrscr();
fp=fopen("C:\\users\\nasch\\data.c","r");
fp1=fopen("C:\\users\\nasch\\result.txt","w");
while(!feof(fp))
{
p++;
if(fgets(exp,500,fp)!=NULL)
{
len=strlen(exp);
for(i=0;i<=len;i++)
{
if(isalpha(exp[i]))
{
pos=i;
g=i;
while(isalpha(exp[g])||isdigit(exp[g]))
g++;
for(j=0;j<20;j++)
token[j]=NULL;
k=0;
for(j=pos;j<g;j++)
{
3
token[k]=exp[j];
k++;
}
c=0;
if((strcmp(token,"stdio")==0)||(strcmp(token,"conio")==0)||(strcmp(token,"string")==0))
{
fprintf(fp1,"%s.h is a header file\n",token);
g=g+2;
}
else
{
fprintf(fp1,"%s",token);
for(m=0;m<30;m++)
{
if(strcmp(token,keys[m])==0)
c++;
}
if(c==0)
fprintf(fp1," - It is a identifier\n");
else
fprintf(fp1," - It is a key word\n");
}
i=g-1;
}
else if(isdigit(exp[i]))
{
while(isdigit(exp[i+1]))
{
fprintf(fp1,"%c",exp[i]);
i++;
}
fprintf(fp1,"%c",exp[i]);
fprintf(fp1," - It is a digit\n");
}
else
{
if(exp[i]=='+'||exp[i]=='-'||exp[i]=='='||exp[i]=='|'||exp[i]=='<'||exp[i]=='>'||exp[i]=='!')
{
4
i++;
if(exp[i]=='+'||exp[i]=='-'||exp[i]=='='||exp[i]=='|')
fprintf(fp1,"%c%c - It is an operator\n",exp[i-1],exp[i]);
else
{
fprintf(fp1,"%c - It is an operator\n",exp[i-1]);
i--;
}
}
else
{
for(h=0;h<21;h++)
{
if(exp[i]==op[h])
{
fprintf(fp1,"%c - It is an operator\n",op[h]);
break;
}
}
}
}
}
}
}
getch();
}

                                              

1:
2:
3:
4:
5:
6:
7:
8:
9:
10:
11:
12:
13:
14:
15:
16:
17:
18:
19:
20:
21:
22:
23:
24:
25:
26:
27:
28:
29:
30:
31:
32:
33:
34:
35:
36:
37:
38:
39:
40:
41:
42:
43:
44:
45:
46:
47:
48:
49:
50:
51:
52:
53:
54:
55:
56:
57:
58:
59:
60:
61:
62:
63:
64:
65:
66:
67:
68:
69:
70:
71:
72:
73:
74:
75:
76:
77:
78:
79:
80:
81:
82:
83:
84:
85:
86:
87:
88:
89:
90:
91:
92:
93:
94:
95:
96:
97:
98:
99:
100:
101:

This is completely unformatted code.  It does not even compile.

You are asking for help on an advanced subject, LR parser generators, and you are posting code that has no indentation code and does not compile.
 

It compiles i just forgot to add <ctype.h> and just a typo mistake was there i corrected now I post after correcting

#include<stdio.h>
#include<conio.h>
#include<string.h>
#include<ctype.h>
void main()
{
char exp[500];
char op[21]={'+','-','*','/','%','^','[',']','(',')','{','}','=',';','<','>','#',',','&','"','|'};
char keys[30][30]={"if","while","for","do","include","printf","main","void","scanf","getch","int","char","break","continue","case","const","default","else","double","float","void","isaplha","isdigit","strcmp"};
char token[20];
int i,j,pos,k,h,m,len,c=0,g;
FILE *fp;
FILE *fp1;
int p=0;
clrscr();
fp=fopen("C:\\users\\nasch\\data.c","r");
fp1=fopen("C:\\users\\nasch\\result.txt","w");
  while(!feof(fp))
{
  p++;
	  if(fgets(exp,500,fp)!=NULL)
	{
	  len=strlen(exp);
 for(i=0;i<=len;i++)
{
	if(isalpha(exp[i]))
  {
	pos=i;
	g=i;
	  while(isalpha(exp[g])||isdigit(exp[g]))
			g++;
		 for(j=0;j<20;j++)
		 token[j]=NULL;
	k=0;
		 for(j=pos;j<g;j++)
	 {
		 token[k]=exp[j];
		 k++;
	 }
		c=0;
	  if((strcmp(token,"stdio")==0)||(strcmp(token,"conio")==0)||(strcmp(token,"string")==0))
	  {
		 fprintf(fp1,"%s.h is a header file\n",token);
		 g=g+2;
	  }
	  else
	  {
		fprintf(fp1,"%s",token);
		for(m=0;m<30;m++)
	  {
		 if(strcmp(token,keys[m])==0)
		  c++;
	  }
 if(c==0)
	fprintf(fp1," - It is a identifier\n");
 else
	fprintf(fp1," - It is a key word\n");
	 }
 i=g-1;
  }
			else if(isdigit(exp[i]))
		{
			  while(isdigit(exp[i+1]))
			{
			  fprintf(fp1,"%c",exp[i]);
			  i++;
			}
	fprintf(fp1,"%c",exp[i]);
	fprintf(fp1," - It is a digit\n");
  }
	else
  {
	 if(exp[i]=='+'||exp[i]=='-'||exp[i]=='='||exp[i]=='|'||exp[i]=='<'||exp[i]=='>'||exp[i]=='!')
	  {
		  i++;
			  if(exp[i]=='+'||exp[i]=='-'||exp[i]=='='||exp[i]=='|')
			  fprintf(fp1,"%c%c - It is an operator\n",exp[i-1],exp[i]);
			  else
			 {
			  fprintf(fp1,"%c - It is an operator\n",exp[i-1]);
			  i--;
			 }
	  }
  else
 {
	for(h=0;h<21;h++)
  {
	  if(exp[i]==op[h])
	 {
		fprintf(fp1,"%c - It is an operator\n",op[h]);
		  break;
	 }
  }
 }
}
}
}
}
getch();
}

                                              

1:
2:
3:
4:
5:
6:
7:
8:
9:
10:
11:
12:
13:
14:
15:
16:
17:
18:
19:
20:
21:
22:
23:
24:
25:
26:
27:
28:
29:
30:
31:
32:
33:
34:
35:
36:
37:
38:
39:
40:
41:
42:
43:
44:
45:
46:
47:
48:
49:
50:
51:
52:
53:
54:
55:
56:
57:
58:
59:
60:
61:
62:
63:
64:
65:
66:
67:
68:
69:
70:
71:
72:
73:
74:
75:
76:
77:
78:
79:
80:
81:
82:
83:
84:
85:
86:
87:
88:
89:
90:
91:
92:
93:
94:
95:
96:
97:
98:
99:
100:

please don't forgot my fopen function arguments refers to my system so u have to create a new file and give the new pathname in the arguments same for the other

I'm sorry. I gave up trying to read your code about half way through. It's impossible to read, as the indentation changes with each line in a completely inconsistent way. Please clean up your code - you'll do yourself (and us) a big favor, and make your code a lot easier to read/maintain.

From what I did read, it seems like you have to be able to parse C code. Are you sure that that's what you need to do (not just a small subset of C for example) ? Writing a parser for C is by no means a simple task (especially if you can't make use of parser generators like yacc and lexer generators like lex).

Can you post the exact wording of your assignment ? And also give us a bit of background on your C programming experience ?

In my assignment there is no need to parse C code, All I have to do is construct Simple LR parsing table for a given Grammar production in a file and parse the input string given using the table

I posted the code in reply to expert mrjoltcola who asked to parse a grammer production.

I have modified and again i am posting i have also hand coded the table and parsed the given string that i have attached in a different file I have attached also the grammar productions for which I have to construct Simple LR parsing table.I am not very good in C programming I know the syntax of C well
Please help me in constructing the Simple LR parsing table.

Actually what I have done is I saw the productions i worked in my note how to construct the table though it is there in the book and without constructing the Simple LR parsing table using a C program I have parsed the string using those arrays which I have to actually implement using C program

Could I get back on Friday evening in India time because I have two exams on Thursday and Friday.

There is still the problem of constructing the closure, goto and to find the sets of items construction.
I have not constructed the parsing table i have just used the table in the book and parsed the string

I hope i am clear

I probably need the yacc source code or some Simple LR parser table construction source code

Well my question is still:

Must you hand-construct a parser, or must you write a parser generator, like yacc?

I can't use Yacc parser. but probably the source code might help me to construct Simple LR parsing table

Thats not my question.

Which must you implement for your project?
1) A hand-coded parser?
2) A yacc? (parser generator)

I don't get what is hand-coded parser if you mean it is a slr parser which we have to implement on our own  in some programming language then yes

I can't use yacc ( parser generator)

I didn't ask if you could USE yacc, I asked if you had to _write_ a yacc.

A parser and a parser generator are not the same thing. Believe it or not, some 4th and 5th year students actually do implement "yacc".

But, it sounds like you have to hand-code a parser. I'm glad, at least, as its a much more reasonable task. :)

I am in second year engineering, could you help me now how to proceed in this SLR table construction

Maybe if you posted the exact wording of your assignment (like I asked earlier), we could avoid all this confusion about what actually needs to be done.

Could you do that ?


You mention that you don't have to parse C, but the code you posted starts out by doing exactly that (it seems to try to parse C standard headers like stdio.h etc., and try to match C specific keywords like if, while, etc.) ... So, you can understand my confusion.

I actually have done that in response to expert mrjoltcola who asked me if i could parse a general grammar that's what i understood so I took C generally and i did that

I told my madam that i am unable to do and i showed her what i had done so she now asks me to do using YACC.
I have never used it, I just know it is a parser generator I will try to find information on it with the books available with me i have to do it on Friday as i have two exams

Sorry if i am not clear with my question,as well with YACC as I didn't know what it was sorry for my ignorance.I have posted again the question.

Implement the construction of SLR Parsing table for a given Grammar productions given in a file and then parse the input string using the table.You can use YACC that's what she told me today.
I think YACC uses LALR parsing table so please forgive me if there is anything wrong with my understanding of the question.
 

>> Implement the construction of SLR Parsing table for a given Grammar productions given in a file and then parse the input string using the table.

Is this file of "grammar productions" fixed, or does your program have to be able to support any such file that is passed to it as argument ?
If it's fixed, then can you post it ? If not, then you need to at least know the format of the file.

If I understand the assignment correctly, then I'm not sure whether yacc would help you here, as it seems this is simply an exercise of implementing a few simple grammar rules as an SLR  parser.


Now, I'll assume (correct me if I'm wrong) that you need to implement it for these rules :

        E'->E              //This is augmentation for this grammar
        E->E+T
        E->T
        T->T*F
        T->F
        F->(E)
        F->id

and that 'id' is defined as an easily recognizable series of characters (like alphanumeric "words", separated by whitespace). Is that right ?

If so, what you have to do, is construct the parse table for the above rules, and implement it so it can be used by your code. Then you simply read the input data, get the different tokens from it (id's), and use the parse table to match the rules.

Actually my problem is i am not experienced to implement the construction of SLR parsing table even for the fixed productions in a file the same productions you have given and let id be defined as only digits.
the problem of constructing the closure, goto and to find the sets of items construction is proving difficult for me because of use of recursive functions and finding insufficient time because of other subjects.

So I have asked madam to do something and I asked her if i could use YACC, she replied yes. Now if i am using YACC and if the productions are fixed then i don't think the project will be worth so i assume they are not fixed and they could give any grammar production in the file.

>>So I have asked madam to do something and I asked her if i could use YACC, she replied yes. Now if i am using YACC and if the productions are fixed then i don't think the project will be worth so i assume they are not fixed and they could give any grammar production in the

She may mean that you may use YACC to construct the parser for the grammar file itself, but not the target input. But you still have to create the parsing table. What do you think? Can you she clarify?

I do not know anything about YACC to be frank and I am not able to understand your question forgive me if i am ignorant, Actually thanks to you that is why i asked if i could use YACC and she told yes though she did not agree first.

>>I do not know anything about YACC to be frank and I am not able to understand your question forgive me if i am ignorant

Nothing wrong with ignorance, we are all ignorant of many things.

However, I feel that this subject level is overly advanced for your current skill level in C and Yacc. I am surprised that you are given such an advanced task as a year 2 engineering student. I do not suggest that you should give up, but given the constraints of Experts Exchange, I cannot give you code to start with. So I advise you to seek assistance from your Professor or Madam on this, and return to us when you have a clearer understanding of both the problem and the tools to use to accomplish it, and give us a place to start so that we can help you.

Good luck.

>> Actually my problem is i am not experienced to implement the construction of SLR parsing table

You mentioned earlier that you could do it on paper.
If you know how to do it on paper, then you know how to do it in code. Just take it step by step. Start by constructing the parse table based on the given rules. Can you do that, and post it here ?

Sorry I had exam so could not reply quicker, Doing them by hand is easy the book tells first compute closure, In paper we follow the steps , there is initialization , we list the productions the .(dot) means the position of parser and recursive means we do it again and again till some condition. It is easy, Now you try to implement this using C code I know for you experts it is piece of cake but for me I have a mind block to be frank no time also and then combining each of these type functions so that they produce the table for me looks very tough, I know we have to split them into modules ,etc but still.

So that's why I think i'l use YACC. First i will read about it and then come back here

I have another exam so i will read on Friday. Please remember me when I get back here.