stream

gistfile1.js

function stream(initArr, fn){
    initArr = Array.prototype.slice.call(initArr||[],0);
    initArr._fn = fn;
    return initArr;
}
function streamRef(arr, i){
    if(arr[i])return arr[i];
    if(!arr._fn)return null;
    while(arr._fn&&arr.length<=i){
        var res = arr._fn(arr[arr.length-1], arr);
        if(res=== null){
            arr._fn = null;
            return null;
        }
        else arr[arr.length] = res;
    }
    return (arr.length<=i)?null:arr[i];
}
function streamFilter(arr, fn, initArr){
    var i = 0;
    return stream(initArr||[], function(){
        var res;
        do{
            res = streamRef(arr, i++);
        }while(res&&!fn(res));
        return res;
    })
}
function streamMap(arr, fn, initArr){
    var i = 0;
    return stream(initArr||[], function(){
        return fn(streamRef(arr, i++));
    })
}
function streamEach(arr, fn){
    var i = 0, res;
    while((res = streamRef(arr,i++))!== null)
        fn(res, i-1, arr);
}