%{
#include <stdio.h>
int yyerror(const char *);
int yylex();

char attr_buf[1024];
int attr_i;
%}


%union {
	long lval;
	double dval;
	char *sval;
	char cval;
}

%token PROLOG
%token S_TAG_OPEN E_TAG_OPEN TAG_CLOSE EMPTY_TAG_CLOSE
%token <sval> NAME
%token <cval> CHAR
%token <lval> INTEGER
%token <dval> DOUBLE
%token DATE;


%define parse.error verbose


%%


document: PROLOG element;

elements:
	element
	| elements element
	;

element:
	empty_tag
	| start_tag end_tag
	| start_tag content end_tag
	;

content:
	elements
	| integers
	| doubles
	| DATE
	;

empty_tag:
	S_TAG_OPEN NAME attributes EMPTY_TAG_CLOSE { printf("empty tag: %s\n", $2); }
	;

start_tag:
	S_TAG_OPEN NAME attributes TAG_CLOSE { printf("enter tag: %s\n", $2); }
	;

end_tag:
	E_TAG_OPEN NAME TAG_CLOSE { printf("exit tag: %s\n", $2); }
	;

attributes:
	| attribute
	| attributes attribute;
	;

attribute:
	NAME '=' '"' chars '"' { attr_buf[attr_i] = 0; printf("attribute: %s=%s\n", $1, attr_buf); attr_i = 0; }
	;

chars:
	| CHAR { attr_buf[attr_i] = $1; attr_i += 1; }
	| chars CHAR { attr_buf[attr_i] = $2; attr_i += 1; }
	;


integers:
	INTEGER
	| integers INTEGER
	;

doubles:
	DOUBLE
	| doubles DOUBLE
	;


%%


extern FILE *yyin;
extern int line_num;

int main()
{
	attr_i = 0;
	line_num = 0;
	yyin = fopen("in.xml", "r");
	if (yyin == NULL) {
		fprintf(stderr, "could not open file!\n");
		return -1;
	}
	do {
		yyparse();
	} while (!feof(yyin));

	return 0;
}


int yyerror(const char *msg)
{
	fprintf(stderr, "parse error on line %d: %s\n", line_num, msg);
	return 1;
}