//  Created by chris on 2007-03-16.
//  Copyright (c) 2007. All rights reserved.

function validate() {
	valid = true
  	formula = document.getElementById('formula').value
	formula = strip(formula)
  	if ( formula == "" ) {
  	  	alert("Please enter a formula.")
  	  	valid = false
	}
	var q = /.+\?/	
	if ( q.test(formula) ) {
		alert("Embedded questions are disallowed.")
		valid = false		
	}
  	if ( bracket_check(formula) == false ) {
    	alert("Your brackets are mismatched.")
	  	valid = false
    }
  	var others = /[^\(\)\,\w\~\&\|\>\<\=\^E\?-\s]/
  	if ( others.test(formula) ) {
    	alert("Your string contains foreign characters.")
		valid = false
  	}
	return valid
}

function bracket_check(formula) {
	var bracket_count = 0
	for (i = 0; i < formula.length; i++) {
		if ( formula.charAt(i) == "(" ) {
			bracket_count = bracket_count + 1
		}
		if ( formula.charAt(i) == ")" ) {
			bracket_count = bracket_count - 1   		
		}
	}
	if ( bracket_count == 0) {
		return true
	}
	else { return false }
}

function strip(formula) {
    while (formula.substring(0,1) == ' ') {
		formula = formula.substring(1);
	}
    while (formula.substring(formula.length-1,formula.length) == ' ') {
		formula = formula.substring(0, formula.length-1); 
	}
	return formula
}

function restart() {
	window.location = "index.cgi"
}