flattener

/*
Assignment...

Write some code, that will flatten an array of arbitrarily nested arrays of integers into a flat array of integers. 
e.g. [[1,2,[3]],4] -> [1,2,3,4]. 

Your solution should be a link to a gist on gist.github.com with your implementation.

When writing this code, you can use any language you're comfortable with. The code must be well tested and documented 
if necessary, and in general please treat the quality of the code as if it was ready to ship to production.

Try to avoid using language defined methods like Ruby's Array#flatten.*

*/


/*
Solution....

    by chadsteele.com

    I'm assuming this simple function would be included in a larger library, but for now, 
    I'll limit the scope to "tools".

    You can execute in a browser or running >node test.js  in your console

	I'm also not depending on any external libraries although a production solution should 
    also not using prototypes, etc. to protect the global namespace
*/


tools = {

    flatten: (ary, result) => {
        result = result || [];
        if (!Array.isArray(ary)){
            result.push(ary);
            return result;
        }

        ary.map(i => {
            tools.flatten(i,result);
        });

        return result;
    },

    isEqual: (a, b) => {
        if (a.length !== b.length) return false;
        for (var i = 0; i < a.length; i++) {
            if (a[i] != b[i]) return false;
        }
        return true;
    },

    assert: (msg, expr) => {
        if (expr) console.log('PASS ' + msg);
        else console.log('FAIL ' + msg);
        return expr;
    },

    selfTest: () =>{

        var allPassed = true;

        //test the example
        allPassed &= tools.assert("[[1,2,[3]],4] -> [1,2,3,4]", tools.isEqual([1, 2, 3, 4], tools.flatten([[1, 2, [3]], 4])));

        //add strings
        allPassed &= tools.assert("['one',[1,2,[3,'three']],4,[[[['five']]]]] -> ['one',1, 2, 3,'three', 4,'five']", tools.isEqual(['one',1, 2, 3,'three', 4,'five'], tools.flatten(['one',[1,2,[3,'three']],4,[[[['five']]]]])));
        
        // test crazy deep nesting with values, strings, and arrays
        var crazy = "[1,[2,[3,[4,[5,[6,[7,[8,[9,['ten',[1,[2,[3,[4,[5,[6,[7,[8,[9,['twenty',[1,[2,[3,[4,[5,[6,[7,[8,[9,['thirty',[1,[2,[3,[4,[5,[6,[7,[8,[9,['forty',[1,[2,[3,[4,[5,[6,[7,[8,[9,['fifty'],1],2],3],4],5],6],7],8],9],'sixty'],1],2],3],4],5],6],7],8],9],70],1],2],3],4],5],6],7],8],9],80]]]]]]]]]]]]]]]]]]]]";
        var flatcrazy = "[1,2,3,4,5,6,7,8,9,'ten',1,2,3,4,5,6,7,8,9,'twenty',1,2,3,4,5,6,7,8,9,'thirty',1,2,3,4,5,6,7,8,9,'forty',1,2,3,4,5,6,7,8,9,'fifty',1,2,3,4,5,6,7,8,9,'sixty',1,2,3,4,5,6,7,8,9,70,1,2,3,4,5,6,7,8,9,80]";
        
        allPassed &= tools.assert(crazy + ' -> ' + flatcrazy, tools.isEqual(eval(flatcrazy), tools.flatten(eval(crazy))));

        //test that it fails too
        allPassed &= tools.assert('[1,2,3] <> ' + crazy, !tools.isEqual([1,2,3], tools.flatten(eval(crazy))));

        //extra crazy
        crazy = eval(crazy);
        flatcrazy = eval(flatcrazy);
        crazy = [crazy,[crazy, crazy], crazy, [[flatcrazy]]];
        flatcrazy = flatcrazy.concat(flatcrazy,flatcrazy,flatcrazy,flatcrazy);
        allPassed &= tools.assert('extra crazy', tools.isEqual(flatcrazy, tools.flatten(crazy)));

        
        // test that objects, don't confuse it
        allPassed &= tools.assert('{ one:[1], two:[2], three:[3]} <> [1,2,3]', !tools.isEqual({ one:[1], two:[2], three:[3]},[1,2,3]));
        allPassed &= tools.assert('[{one:1,two:2,three:3}] <> [1,2,3]', !tools.isEqual([{one:1,two:2,three:3}],[1,2,3]));
        allPassed &= tools.assert('[{one:1,two:2,three:3}] -> [{one:1,two:2,three:3}]', !tools.isEqual([{one:1,two:2,three:3}],[{one:1,two:2,three:3}]));

        //test empty arrays
        var empty = '[[[[[[[[[[[[[[[[[[[[]]]]]]]]]]]]]]]]]]]]';
        allPassed &= tools.assert('[] -> ' + empty, tools.isEqual([], tools.flatten(eval(empty))));
        
        if (allPassed) console.log("Yay!  All selftests passed!");

        return allPassed;

    }

}


tools.selfTest();