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//>>built
// wrapped by build app
define("dojox/lang/functional/binrec", ["dijit","dojo","dojox","dojo/require!dojox/lang/functional/lambda,dojox/lang/functional/util"], function(dijit,dojo,dojox){
dojo.provide("dojox.lang.functional.binrec");
dojo.require("dojox.lang.functional.lambda");
dojo.require("dojox.lang.functional.util");
// This module provides recursion combinators:
// - a binary recursion combinator.
// Acknoledgements:
// - recursion combinators are inspired by Manfred von Thun's article
// "Recursion Theory and Joy"
// (http://www.latrobe.edu.au/philosophy/phimvt/joy/j05cmp.html)
// Notes:
// - recursion combinators produce a function, which implements
// their respective recusion patterns. String lambdas are inlined, if possible.
(function(){
var df = dojox.lang.functional, inline = df.inlineLambda,
_x ="_x", _z_r_r_z_a = ["_z.r", "_r", "_z.a"];
df.binrec = function(
/*Function|String|Array*/ cond,
/*Function|String|Array*/ then,
/*Function|String|Array*/ before,
/*Function|String|Array*/ after){
// summary:
// Generates a function for the binary recursion pattern.
// All parameter functions are called in the context of "this" object.
// cond:
// The lambda expression, which is used to detect the termination of recursion.
// It accepts the same parameter as the generated recursive function itself.
// This function should return "true", if the recursion should be stopped,
// and the "then" part should be executed. Otherwise the recursion will proceed.
// then:
// The lambda expression, which is called upon termination of the recursion.
// It accepts the same parameters as the generated recursive function itself.
// The returned value will be returned as the value of the generated function.
// before:
// The lambda expression, which is called before the recursive step.
// It accepts the same parameter as the generated recursive function itself.
// The returned value should be an array of two variable, which are used to call
// the generated function recursively twice in row starting from the first item.
// above:
// The lambda expression, which is called after the recursive step.
// It accepts three parameters: two returned values from recursive steps, and
// the original array of parameters used with all other functions.
// The returned value will be returned as the value of the generated function.
var c, t, b, a, cs, ts, bs, as, dict1 = {}, dict2 = {},
add2dict = function(x){ dict1[x] = 1; };
if(typeof cond == "string"){
cs = inline(cond, _x, add2dict);
}else{
c = df.lambda(cond);
cs = "_c.apply(this, _x)";
dict2["_c=_t.c"] = 1;
}
if(typeof then == "string"){
ts = inline(then, _x, add2dict);
}else{
t = df.lambda(then);
ts = "_t.apply(this, _x)";
}
if(typeof before == "string"){
bs = inline(before, _x, add2dict);
}else{
b = df.lambda(before);
bs = "_b.apply(this, _x)";
dict2["_b=_t.b"] = 1;
}
if(typeof after == "string"){
as = inline(after, _z_r_r_z_a, add2dict);
}else{
a = df.lambda(after);
as = "_a.call(this, _z.r, _r, _z.a)";
dict2["_a=_t.a"] = 1;
}
var locals1 = df.keys(dict1), locals2 = df.keys(dict2),
f = new Function([], "var _x=arguments,_y,_z,_r".concat( // Function
locals1.length ? "," + locals1.join(",") : "",
locals2.length ? ",_t=_x.callee," + locals2.join(",") : "",
t ? (locals2.length ? ",_t=_t.t" : "_t=_x.callee.t") : "",
";while(!",
cs,
"){_r=",
bs,
";_y={p:_y,a:_r[1]};_z={p:_z,a:_x};_x=_r[0]}for(;;){do{_r=",
ts,
";if(!_z)return _r;while(\"r\" in _z){_r=",
as,
";if(!(_z=_z.p))return _r}_z.r=_r;_x=_y.a;_y=_y.p}while(",
cs,
");do{_r=",
bs,
";_y={p:_y,a:_r[1]};_z={p:_z,a:_x};_x=_r[0]}while(!",
cs,
")}"
));
if(c){ f.c = c; }
if(t){ f.t = t; }
if(b){ f.b = b; }
if(a){ f.a = a; }
return f;
};
})();
/*
For documentation only:
1) The original recursive version:
var binrec1 = function(cond, then, before, after){
var cond = df.lambda(cond),
then = df.lambda(then),
before = df.lambda(before),
after = df.lambda(after);
return function(){
if(cond.apply(this, arguments)){
return then.apply(this, arguments);
}
var args = before.apply(this, arguments);
var ret1 = arguments.callee.apply(this, args[0]);
var ret2 = arguments.callee.apply(this, args[1]);
return after.call(this, ret1, ret2, arguments);
};
};
2) The original iterative version (before minification and inlining):
var binrec2 = function(cond, then, before, after){
var cond = df.lambda(cond),
then = df.lambda(then),
before = df.lambda(before),
after = df.lambda(after);
return function(){
var top1, top2, ret, args = arguments;
// first part: start the pump
while(!cond.apply(this, args)){
ret = before.apply(this, args);
top1 = {prev: top1, args: ret[1]};
top2 = {prev: top2, args: args};
args = ret[0];
}
for(;;){
// second part: mop up
do{
ret = then.apply(this, args);
if(!top2){
return ret;
}
while("ret" in top2){
ret = after.call(this, top2.ret, ret, top2.args);
if(!(top2 = top2.prev)){
return ret;
}
}
top2.ret = ret;
args = top1.args;
top1 = top1.prev;
}while(cond.apply(this, args));
// first part (encore)
do{
ret = before.apply(this, args);
top1 = {prev: top1, args: ret[1]};
top2 = {prev: top2, args: args};
args = ret[0];
}while(!cond.apply(this, args));
}
};
};
*/
});
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