111 lines
3.7 KiB
JavaScript
111 lines
3.7 KiB
JavaScript
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if(!dojo._hasResource["dojox.lang.functional.lambda"]){ //_hasResource checks added by build. Do not use _hasResource directly in your code.
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dojo._hasResource["dojox.lang.functional.lambda"] = true;
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dojo.provide("dojox.lang.functional.lambda");
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// This module adds high-level functions and related constructs:
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// - anonymous functions built from the string
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// Acknoledgements:
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// - lambda() is based on work by Oliver Steele
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// (http://osteele.com/sources/javascript/functional/functional.js)
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// which was published under MIT License
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// Notes:
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// - lambda() produces functions, which after the compilation step are
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// as fast as regular JS functions (at least theoretically).
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// Lambda input values:
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// - returns functions unchanged
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// - converts strings to functions
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// - converts arrays to a functional composition
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(function(){
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var df = dojox.lang.functional;
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// split() is augmented on IE6 to ensure the uniform behavior
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var split = "ab".split(/a*/).length > 1 ? String.prototype.split :
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function(sep){
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var r = this.split.call(this, sep),
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m = sep.exec(this);
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if(m && m.index == 0){ r.unshift(""); }
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return r;
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};
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var lambda = function(/*String*/ s){
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var args = [], sects = split.call(s, /\s*->\s*/m);
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if(sects.length > 1){
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while(sects.length){
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s = sects.pop();
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args = sects.pop().split(/\s*,\s*|\s+/m);
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if(sects.length){ sects.push("(function(" + args + "){return (" + s + ")})"); }
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}
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}else if(s.match(/\b_\b/)){
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args = ["_"];
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}else{
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var l = s.match(/^\s*(?:[+*\/%&|\^\.=<>]|!=)/m),
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r = s.match(/[+\-*\/%&|\^\.=<>!]\s*$/m);
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if(l || r){
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if(l){
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args.push("$1");
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s = "$1" + s;
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}
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if(r){
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args.push("$2");
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s = s + "$2";
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}
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}else{
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// the point of the long regex below is to exclude all well-known
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// lower-case words from the list of potential arguments
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var vars = s.
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replace(/(?:\b[A-Z]|\.[a-zA-Z_$])[a-zA-Z_$\d]*|[a-zA-Z_$][a-zA-Z_$\d]*:|this|true|false|null|undefined|typeof|instanceof|in|delete|new|void|arguments|decodeURI|decodeURIComponent|encodeURI|encodeURIComponent|escape|eval|isFinite|isNaN|parseFloat|parseInt|unescape|dojo|dijit|dojox|window|document|'(?:[^'\\]|\\.)*'|"(?:[^"\\]|\\.)*"/g, "").
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match(/([a-z_$][a-z_$\d]*)/gi) || [];
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var t = {};
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dojo.forEach(vars, function(v){
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if(!(v in t)){
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args.push(v);
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t[v] = 1;
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}
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});
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}
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}
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return {args: args, body: "return (" + s + ");"}; // Object
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};
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var compose = function(/*Array*/ a){
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return a.length ?
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function(){
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var i = a.length - 1, x = df.lambda(a[i]).apply(this, arguments);
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for(--i; i >= 0; --i){ x = df.lambda(a[i]).call(this, x); }
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return x;
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}
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:
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// identity
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function(x){ return x; };
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};
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dojo.mixin(df, {
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// lambda
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buildLambda: function(/*String*/ s){
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// summary: builds a function from a snippet, returns a string,
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// which represents the function.
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// description: This method returns a textual representation of a function
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// built from the snippet. It is meant to be evaled in the proper context,
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// so local variables can be pulled from the environment.
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s = lambda(s);
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return "function(" + s.args.join(",") + "){" + s.body + "}"; // String
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},
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lambda: function(/*Function|String|Array*/ s){
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// summary: builds a function from a snippet, or array (composing), returns
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// a function object; functions are passed through unmodified.
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// description: This method is used to normalize a functional representation
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// (a text snippet, an array, or a function) to a function object.
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if(typeof s == "function"){ return s; }
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if(s instanceof Array){ return compose(s); }
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s = lambda(s);
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return new Function(s.args, s.body); // Function
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}
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});
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})();
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}
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