- 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/listcomp.js
dojo.provide("dojox.lang.functional.listcomp");
// This module adds high-level functions and related constructs:
// - list comprehensions similar to JavaScript 1.7
// Notes:
// - listcomp() produces functions, which after the compilation step are
// as fast as regular JS functions (at least theoretically).
(function(){
var g_re = /\bfor\b|\bif\b/gm;
var listcomp = function(/*String*/ s){
var frag = s.split(g_re), act = s.match(g_re),
head = ["var r = [];"], tail = [];
for(var i = 0; i < act.length;){
var a = act[i], f = frag[++i];
if(a == "for" && !/^\s*\(\s*(;|var)/.test(f)){
f = f.replace(/^\s*\(/, "(var ");
}
head.push(a, f, "{");
tail.push("}");
}
return head.join("") + "r.push(" + frag[0] + ");" + tail.join("") + "return r;"; // String
};
dojo.mixin(dojox.lang.functional, {
buildListcomp: function(/*String*/ s){
// summary: builds a function from a text snippet, which represents a valid
// JS 1.7 list comprehension, returns a string, which represents the function.
// description: This method returns a textual representation of a function
// built from the list comprehension text snippet (conformant to JS 1.7).
// It is meant to be evaled in the proper context, so local variable can be
// pulled from the environment.
return "function(){" + listcomp(s) + "}"; // String
},
compileListcomp: function(/*String*/ s){
// summary: builds a function from a text snippet, which represents a valid
// JS 1.7 list comprehension, returns a function object.
// description: This method returns a function built from the list
// comprehension text snippet (conformant to JS 1.7). It is meant to be
// reused several times.
return new Function([], listcomp(s)); // Function
},
listcomp: function(/*String*/ s){
// summary: executes the list comprehension building an array.
return (new Function([], listcomp(s)))(); // Array
}
});
})();
