peterjaric/LICENSE.txt

## README.md

      
    Raw
  

              README.md
            
          
    RPN

Evaluates well-formed reverse polish notation expressions (http://en.wikipedia.org/wiki/Reverse_Polish_notation).
Input

Strings with tokens separated by single spaces. Tokens are operators or operands. Operators are +, -, * or /. Operands are integers or floats (e.g. 7, 3.23, -1e9).
Output

The value of the evaluated expression.
Examples

"1 1 +" -> 2
"5 8 -" -> -3
"2 3 7 + -" -> -8
"5 3 * 5 +" -> 20

  
## annotated.js
function(a,                                     // The input string
         b) {                                   // Placeholder var that will become the stack
  return (b = [])[                              // Create an empty stack, and later return its 0th element (*)
           a.replace(/\S+/g,                    // For each token (everything that does not
                                                // contain spaces) in the string,
                     function(c) {              // inspect and act on it:
                       b.push(                  // Something will always be pushed to the stack:
                         +c ||                  // If it is a number (an operand), push the number itself.
                         eval(                  // Else it is an operator.
                           b.pop(a = b.pop()) + // Pop the topmost element and save it in a.
                                                // Then pop the next element and
                           c +                  // apply the operator together with the
                           a))                  // previously saved element.
                     }),
           0]                                   // (*) After going through all tokens, index the 0th element
                                                //     of the stack. This is the result of the expression.
}

## index.js
function(a,b){return(b=[])[a.replace(/\S+/g,function(c){b.push(+c==c?c:eval(b.pop(a=b.pop())+c+a))}),0]}

## LICENSE.txt
            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
                    Version 2, December 2004

 Copyright (C) 2011 YOUR_NAME_HERE <YOUR_URL_HERE>

 Everyone is permitted to copy and distribute verbatim or modified
 copies of this license document, and changing it is allowed as long
 as the name is changed.

            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION

  0. You just DO WHAT THE FUCK YOU WANT TO.

## package.json
{
  "name": "rpn",

  "description": "Reverse Polish Notation expression evaluator",

  "keywords": [
    "expression",
    "parser",
    "rpn",
    "evaluator"
  ]
}

## test.html
<!DOCTYPE html>
<title>RPN</title>
<div>Expected value: <b>3, -4, -8, 14</b></div>
<div>Actual value: <b id="ret"></b></div>
<script>
  // write a small example that shows off the API for your example
  // and tests it in one fell swoop.

  var myFunction = function(a,b){return(b=[])[a.replace(/\S+/g,function(c){b.push(+c==c?c:eval(b.pop(a=b.pop())+c+a))}),0]}

  document.getElementById( "ret" ).innerHTML = [myFunction('1 2 +'), myFunction('2 6 -'), myFunction('2 3 7 + -'), myFunction('5 1 2 + 4 * + 3 -')].join(', ');
</script>
	function(a, // The input string
	b) { // Placeholder var that will become the stack
	return (b = [])[ // Create an empty stack, and later return its 0th element (*)
	a.replace(/\S+/g, // For each token (everything that does not
	// contain spaces) in the string,
	function(c) { // inspect and act on it:
	b.push( // Something will always be pushed to the stack:
	+c \|\| // If it is a number (an operand), push the number itself.
	eval( // Else it is an operator.
	b.pop(a = b.pop()) + // Pop the topmost element and save it in a.
	// Then pop the next element and
	c + // apply the operator together with the
	a)) // previously saved element.
	}),
	0] // (*) After going through all tokens, index the 0th element
	// of the stack. This is the result of the expression.
	}
	DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
	Version 2, December 2004

	Copyright (C) 2011 YOUR_NAME_HERE <YOUR_URL_HERE>

	Everyone is permitted to copy and distribute verbatim or modified
	copies of this license document, and changing it is allowed as long
	as the name is changed.

	DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
	TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION

	0. You just DO WHAT THE FUCK YOU WANT TO.
	{
	"name": "rpn",

	"description": "Reverse Polish Notation expression evaluator",

	"keywords": [
	"expression",
	"parser",
	"rpn",
	"evaluator"
	]
	}
	<!DOCTYPE html>
	<title>RPN</title>
	<div>Expected value: <b>3, -4, -8, 14</b></div>
	<div>Actual value: <b id="ret"></b></div>
	<script>
	// write a small example that shows off the API for your example
	// and tests it in one fell swoop.

	var myFunction = function(a,b){return(b=[])[a.replace(/\S+/g,function(c){b.push(+c==c?c:eval(b.pop(a=b.pop())+c+a))}),0]}

	document.getElementById( "ret" ).innerHTML = [myFunction('1 2 +'), myFunction('2 6 -'), myFunction('2 3 7 + -'), myFunction('5 1 2 + 4 * + 3 -')].join(', ');
	</script>