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/**
FUNCTIONAL
by Caio Chassot (http://v2studio.com/k/code/)
*/
/**
* this is used internally by each, map, combine, filter and reduce to accept
* strings as functions.
*
* if <b>fn</b> does not contain a return statement, a return keyword will be added
* before the last statement. the last statement is determined by removing the
* trailing semicolon (';') (if it exists) and then searching for the last
* semicolon, hence, caveats may apply (i.e. if the last statement has a
* string or regex containing the ';' character things will go wrong)
* @param args a string of comma separated names of the function arguments
* @param fn the function body
*/
function __strfn(args, fn) {
/**
* Internal function. Do not call it directly.
*/
function quote(s) { return '"' + s.replace(/"/g,'\\"') + '"' }
if (!/\breturn\b/.test(fn)) {
fn = fn.replace(/;\s*$/, '');
fn = fn.insert(fn.lastIndexOf(';')+1, ' return ');
}
return eval('new Function('
+ map(args.split(/\s*,\s*/), quote).join()
+ ','
+ quote(fn)
+ ')'
);
}
/**
* traverses <b>list</b>, applying <b>fn</b> to each item of <b>list</b>.
* see doc for <b>__strfn</b> for peculiarities about passing strings for <b>fn</b>
*
* <b>each</b> provides a safe way for traversing only an array's indexed items,
* ignoring its other properties. (as opposed to how for-in works)
* @param list anything that can be indexed and has a <b>length</b> property. usually an array.
* @param fn either a function, or a string containing a function body,
* in which case the name of the paremeters passed to it will be
* 'item', 'idx' and 'list'.
* @see #__strfn
*/
function each(list, fn) {
if (typeof(fn)=='string') return each(list, __strfn('item,idx,list', fn));
for (var i=0; i < list.length; i++) fn(list[i], i, list);
}
/**
* traverses <b>list</b>, applying <b>fn</b> to each item of <b>list</b>, returning an array
of values returned by <b>fn</b>
parameters work the same as for <b>each</b>, same <b>__strfn</b> caveats apply
if <b>fn</b> is not provided, the list item is returned itself. this is an easy
way to transform fake arrays (e.g. the arguments object of a function or
nodeList objects) into real javascript arrays.
e.g.: args = map(arguments)
If you don't care about map's return value, you should use <b>each</b>
this is a simplified version of python's map. parameter order is different,
only a single list (array) is accepted, and the parameters passed to [fn]
are different:
[fn] takes the current item, then, optionally, the current index and a
reference to the list (so that [fn] can modify list)
see <b>combine</b> if you want to pass multiple lists
*/
function map(list, fn) {
if (typeof(fn)=='string') return map(list, __strfn('item,idx,list', fn));
var result = [];
fn = fn || function(v) {return v};
for (var i=0; i < list.length; i++) result.push(fn(list[i], i, list));
return result;
}
/**
* combine will traverse all lists concurrently, passing each row if items as
parameters to <b>fn</b>
if <b>fn</b> is not provided, a function that returns a list containing each
item in the row is used.
if a list is smaller than the other, <b>null</b> is used in place of its missing
items
* @param list one or more lists (see <b>each</b> for definition of a list)
* @param fn Similar s <b>each</b> or <b>map</b>, a function or a string containing
a function body.
if a string is used, the name of parameters passed to the
created function will be the lowercase alphabet letters, in
order: a,b,c...
same <b>__strfn</b> caveats apply
* @see #each
* @see #__strfn
* @return an array of the values returned by calling <b>fn</b> for each row of items
*//*
function combine() {
var args = map(arguments);
var lists = map(args.slice(0,-1),'map(item)');
var fn = args.last();
var toplen = map(lists, "item.length").max();
var vals = [];
if (!fn) fn = function(){return map(arguments)};
if (typeof fn == 'string') {
if (lists.length > 26) throw 'string functions can take at most 26 lists';
var a = 'a'.charCodeAt(0);
fn = __strfn(map(range(a, a+lists.length),'String.fromCharCode(item)').join(','), fn);
}
map(lists, function(li) {
while (li.length < toplen) li.push(null);
map(li, function(item,ix){
if (ix < vals.length) vals[ix].push(item);
else vals.push([item]);
});
});
return map(vals, function(val) { return fn.apply(fn, val) });
}
/**
* returns an array of items in <b>list</b> for which <b>fn(item)</b> is true
parameters work the same as for <b>each</b>, same <b>__strfn</b> caveats apply
if <b>fn</b> is not specified the items are evaluated themselves, that is,
filter will return an array of the items in <b>list</b> which evaluate to true
this is a similar to python's filter, but parameter order is inverted
*//*
function filter(list, fn) {
if (typeof(fn)=='string') return filter(list, __strfn('item,idx,list', fn));
var result = [];
fn = fn || function(v) {return v};
map(list, function(item,idx,list) { if (fn(item,idx,list)) result.push(item) } );
return result;
}
/**
* similar to python's reduce. paremeter order inverted...
* @param list see doc for <b>each</b> to learn more about it
* @param initial TODO
* @param fn similar to <b>each</b> too, but in the case where it's a string,
the name of the paremeters passed to it will be 'a' and 'b'
same <b>__strfn</b> caveats apply
*//*
function reduce(list, initial, fn) {
if (undef(fn)) {
fn = initial;
// explicit <b>window</b> object so browsers that do not have an <b>undefined</b>
//keyword will evaluate to the (hopefully) undefined parameter
//<b>undefined</b> of <b>window</b>
initial = window.undefined;
}
if (typeof(fn)=='string') return reduce(list, initial, __strfn('a,b', fn));
if (isdef(initial)) list.splice(0,0,initial);
if (list.length===0) return false;
if (list.length===1) return list[0];
var result = list[0];
var i = 1;
while(i<list.length) result = fn(result,list[i++]);
return result;
}*/
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