- Author:
- David Nickerson <nickerso@users.sourceforge.net>
- Date:
- 2009-07-16 02:00:03+12:00
- Desc:
- the starting point for the HH tutorial example
- Permanent Source URI:
- https://models.fieldml.org/workspace/a1/rawfile/f6a8f90307388eb4b040ee3566b84d88b59247f7/dojo-presentation/js/dojo/dojox/lang/functional/curry.js
dojo.provide("dojox.lang.functional.curry");
dojo.require("dojox.lang.functional.lambda");
// This module adds high-level functions and related constructs:
// - currying and partial functions
// - argument pre-processing: mixer and flip
// Acknoledgements:
// - partial() is based on work by Oliver Steele
// (http://osteele.com/sources/javascript/functional/functional.js)
// which was published under MIT License
// Defined methods:
// - take any valid lambda argument as the functional argument
(function(){
var df = dojox.lang.functional, ap = Array.prototype;
var currying = function(/*Object*/ info){
return function(){ // Function
if(arguments.length + info.args.length < info.arity){
return currying({func: info.func, arity: info.arity,
args: ap.concat.apply(info.args, arguments)});
}
return info.func.apply(this, ap.concat.apply(info.args, arguments));
};
};
dojo.mixin(df, {
// currying and partial functions
curry: function(/*Function|String|Array*/ f, /*Number?*/ arity){
// summary: curries a function until the arity is satisfied, at
// which point it returns the calculated value.
f = df.lambda(f);
arity = typeof arity == "number" ? arity : f.length;
return currying({func: f, arity: arity, args: []}); // Function
},
arg: {}, // marker for missing arguments
partial: function(/*Function|String|Array*/ f){
// summary: creates a function where some arguments are bound, and
// some arguments (marked as dojox.lang.functional.arg) are will be
// accepted by the final function in the order they are encountered.
// description: This method is used to produce partially bound
// functions. If you want to change the order of arguments, use
// dojox.lang.functional.mixer() or dojox.lang.functional.flip().
var a = arguments, args = new Array(a.length - 1), p = [];
f = df.lambda(f);
for(var i = 1; i < a.length; ++i){
var t = a[i];
args[i - 1] = t;
if(t == df.arg){
p.push(i - 1);
}
}
return function(){ // Function
var t = ap.slice.call(args, 0); // clone the array
for(var i = 0; i < p.length; ++i){
t[p[i]] = arguments[i];
}
return f.apply(this, t);
};
},
// argument pre-processing
mixer: function(/*Function|String|Array*/ f, /*Array*/ mix){
// summary: changes the order of arguments using an array of
// numbers mix --- i-th argument comes from mix[i]-th place
// of supplied arguments.
f = df.lambda(f);
return function(){ // Function
var t = new Array(mix.length);
for(var i = 0; i < mix.length; ++i){
t[i] = arguments[mix[i]];
}
return f.apply(this, t);
};
},
flip: function(/*Function|String|Array*/ f){
// summary: changes the order of arguments by reversing their
// order.
f = df.lambda(f);
return function(){ // Function
// reverse arguments
var a = arguments, l = a.length - 1, t = new Array(l + 1), i;
for(i = 0; i <= l; ++i){
t[l - i] = a[i];
}
return f.apply(this, t);
};
}
});
})();
