==== Problem ====

`Implement a mathematical expression evaluator`

Basically take a string such as:

	"(45 - 5) / 10"

and find the result.  The engine must support basic substitution as well, example:

	"(width / 2) - offset"

Here are the rules:
	* you CAN NOT use python's eval() function
	* you CAN NOT use language XYZ's eval() function
	* support basic arithmetic operators +,-,*,/
	* support bracketed expressions
	* integer values (bonus: support decimal values)
	* positive integer values (bonus: support negative values)
	* evaluate from left to right (bonus: support proper order of operations)

Feel free to use whatever syntax you like for the variables
('variable', ${variable}, :variable, etc).

==== Examples ====

An example implementation might look like this:

	# prints 6
	print evaluate("10 - 6 + 2")

	# prints 2
	print evaluate("(10 - 6) / 2")

	# prints 4
	print evaluate("poo - 12 / 3", {poo: 24})



==== Solutions ====

=== Josh using Java ===

  * Source {{:codeapalooza:eval-0.3-src.zip|eval-0.3-src.zip}}
  * Binary {{:codeapalooza:eval.jar|eval.jar}}

To run this, use the following command line:

	java -jar eval.jar "2 + 2"

or to pass a set of variables, use ECMA style syntax

	java -jar eval.jar "poo + pee" "{poo: 2, pee: 4}"

=== Gabriel Using Python ===

  * Source {{:codeapalooza:calculator.zip|calculator.zip}}

Examples:

        python calc.py "2 + 2"
        python calc.py "2 + 3.5*(1 - 7e-3)"

With variable substitution:

        python calc.py "$poo + $pee" poo:2 pee:4

=== Jason Using Python ===

There are two files: the original, eval.py and the Gabriel modified eval2.py. eval2.py allows for spaces in equations and variable names that can be found within other variable names.

  * Source Source {{:codeapalooza:jason.zip|jason.zip}}

Examples:

        python eval.py 2 + 2
        python eval.py 2+3.5*(1-7e-3)

With variable substitution:

        python eval2.py "$poo + $pee" poo:2 pee:4