#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#define MAX_PRODUCTIONS 100
#define MAX_WORD_LENGTH 100
typedef char Symbol;

Symbol read_sym(FILE* file){
	Symbol s;
 	fscanf(file,"%c",&s);
 	return s;
}


int is_terminal(Symbol s){
	return (islower(s));
}

int is_nonterminal(Symbol s){
	return (isupper(s));
}

int is_prodsym(Symbol s){
	return (s == '>');
}

int is_end_of_prod(Symbol s){
	return (s == '\n');
}

void print_sym (Symbol s){
	printf("%c ",s);
}

typedef struct{
	Symbol word [MAX_WORD_LENGTH];
	unsigned length;
} Word;

void print_word (Word* w){
	int i;
	for (i=0; i < w->length; i++)
	print_sym(w->word[i]);
}

typedef struct{
	Word left;
	Word right;
} Production;

void print_production (Production* p){
	print_word(&p->left);
	printf (" --> ");
	print_word(&p->right);
}

typedef struct{
	Production productions[MAX_PRODUCTIONS];
	unsigned numprod;
} Grammar;

void print_grammar(Grammar* g){
   int i;
	if (g == NULL) printf ("Errore! Grammatica non valida! \n");
	else{
		printf ("Numero di produzioni: %d\n", g->numprod);
		for (i=0; i<g->numprod; i++){
			print_production(&g->productions[i]);
			printf ("\n");
		}
	}
}


Grammar* load_grammar(FILE* file, Grammar* g){
	Symbol s;
	enum States {START,LEFT,RIGHT,ERROR};
	enum States current_state = START;
	Production* p;
	g->numprod = 0;
	while (current_state != ERROR && !feof(file))
		s = read_sym(file);
	if feof(file) return 0 ;
	switch(current_state){
		case START:
			if (is_terminal(s) || is_nonterminal(s)){
				current_state = LEFT;
				p = &(g->productions[g->numprod++]);
				p->left.length = 0;
				p->left.word[p->left.length++] = s;
			}else current_state = ERROR;
		break;
		case LEFT:
   		if (is_terminal(s) || is_nonterminal(s)){
				current_state = LEFT;
				p->left.word[p->left.length++] = s;
	 		}else if (is_prodsym(s)){
						current_state = RIGHT;
	 					p->right.length = 0;
   				}else current_state = ERROR;
	 	break;
		case RIGHT:
	 		if (is_terminal(s) || is_nonterminal(s)){
	 			current_state = RIGHT;
	 			(*p).right.word[p->right.length++] = s;
	 		}else if (is_end_of_prod(s)){
	 					current_state = START;
	 				}else current_state = ERROR;
	 	break;
   }
   if (current_state == START || current_state == RIGHT) return g;
   else return NULL;
}

int main(int argc, char *argv[]){
char* filename = argv[1];
FILE* gram_file;
Grammar grammar;
	 if (filename == 0){
	 	printf("nome file non specificato \n");
      system("PAUSE");
	 	return -1;
	 }
	 gram_file = fopen("C:\mygrammar.txt","r");
	 if (gram_file == NULL){
	 	printf("nome di file errato\n");
      system("PAUSE");
	 	return -1;
	 }
	print_grammar(load_grammar(gram_file,&grammar));
	fclose(gram_file);
	system("PAUSE");
	return 0;
}