Math Parser //JavaScript Repository

Description

Mathematical expression parser.
Created: 2005.08.20 - Modified 2006.05.05

``````//+ Carlos R. L. Rodrigues
//@ http://jsfromhell.com/classes/math-parser [rev. #3]

MathParser = function(){
var o = this, p = o.operator = {};
p["+"] = function(n, m){return n + m;}
p["-"] = function(n, m){return n - m;}
p["*"] = function(n, m){return n * m;}
p["/"] = function(m, n){return n / m;}
p["%"] = function(m, n){return n % m;}
p["^"] = function(m, n){return Math.pow(n, m);}
p["~"] = function(m, n){return Math.sqrt(n, m);}
o.custom = {}, p.f = function(s, n){
if(Math[s]) return Math[s](n);
else if(o.custom[s]) return o.custom[s].apply(o, n);
else throw new Error("Function \"" + s + "\" not defined.");
}, o.add = function(n, f){this.custom[n] = f;}
}
MathParser.prototype.eval = function(e, ig){
var v = [], p = [], i, _, a, c = 0, s = 0, x, t = !ig ? e.indexOf("^") : -1, d = null;
var cp = e, e = e.split(""), n = "0123456789.", o = "+-/*^%~", f = this.operator;
if(t + 1)
do{
for(a = "", _ = t - 1;  _ && o.indexOf(e[_]) < 0; a += e[_], e[_--] = ""); a += "^";
for(_ = t + 1, i = e.length; _ < i && o.indexOf(e[_]) < 0; a += e[_], e[_++] = "");
e = e.slice(0, t).concat((this.eval(a, 1) + "").split("")).concat(e.slice(t + 1));
}
while(t = cp.indexOf("^", ++t) + 1);
for(i = 0, l = e.length; i < l; i++){
if(o.indexOf(e[i]) > -1)
e[i] == "-" && (s > 1 || d === null) && ++s, !s && d !== null && (p.push(e[i]), s = 2), "+-".indexOf(e[i]) < (d = null) && (c = 1);
else if(a = n.indexOf(e[i]) + 1 ? e[i++] : ""){
while(n.indexOf(e[i]) + 1) a += e[i++];
v.push(d = (s & 1 ? -1 : 1) * a), c && v.push(f[p.pop()](v.pop(), v.pop())) && (c = 0), --i, s = 0;
}
}
for(c = v[0], i = 0, l = p.length; l--; c = f[p[i]](c, v[++i]));
return c;
}
MathParser.prototype.parse = function(e){
var p = [], f = [], ag, n, c, a, o = this, v = "0123456789.+-*/^%~(, )";
for(var x, i = 0, l = e.length; i < l; i++){
if(v.indexOf(c = e.charAt(i)) < 0){
for(a = c; v.indexOf(c = e.charAt(++i)) < 0; a += c); f.push((--i, a));
}
else if(!(c == "(" && p.push(i)) && c == ")"){
if(a = e.slice(0, (n = p.pop()) - (x = v.indexOf(e.charAt(n - 1)) < 0 ? y = (c = f.pop()).length : 0)), x)
for(var j = (ag = e.slice(n, ++i).split(",")).length; j--; ag[j] = o.eval(ag[j]));
l = (e = a + (x ? o.operator.f(c, ag) : o.eval(e.slice(n, ++i))) + e.slice(i)).length, i -= i - n + c.length;
}
}
return o.eval(e);
}``````

Example (Example)

``````<form id="math" action="">
<fieldset>
<legend>MathParser</legend>
<label>Express?o</label><input type="text" name="exp" value="userFunction(1, 1) + 1" /><br /><br />
<input type="submit" value="MathParser.parse()" />
</fieldset>
</form>

<script type="text/javascript">
//<![CDATA[

var parser = new MathParser(), f = document.forms.math;

return n + m;
});

try{
}catch(e){
}
return false;
});

//]]>
</script>``````

Help

Constructor

MathParser(void)
Generates an instance of MathParser.

Methods

MathParser.parse(expression: String): Number
Parses a set of pre-defined commands to make a mathematical expression.
expression
mathematical expression that will be parsed
MathParser.add(name: String, handler: Function(args): Number): void
Adds a customized function to the parser.
name
name that should be used in the expression to call the user function
handler
function that will receive the arguments, it must return a number

Basic operations

( and )
Precedence operator
+
-
Subtraction
*
Multiplication
/
Division
^
Power
~
Square Root
%
Division Reminder

Functions

The class has access to all functions defined in the Math object.

abs
Returns the absolute value of a number
acos
Returns the arccosine of a number
asin
Returns the arcsine of a number
atan
Returns the arctangent of a number
ceil
Returns the smallest integer greater than or equal to its numeric argument
cos
Returns the cosine of a number
exp
Returns e (the base of natural logarithms) raised to a power
floor
Returns the greatest integer less than or equal to its numeric argument
log
Returns the natural logarithm of a number
round
Returns a supplied numeric expression rounded to the nearest integer
sin
Returns the sine of a number
tan
Returns the tangent of a number