implementation of utility functions to handle collections (associative arrays) and implementation of design patterns (iterator, visitor and observer)

utils.js

@@ -1,14 +1,181 @@
 /**
- * The Phi Technology LLC, Steve L. Nyemba <steve@the-phi.com>
+* jxf version 0.9
- * Javascript-x
+* This file contains the compilation of utilities for miscellaneous/unsorted operations:
- * 
+*	casting
- * This is a utiliy class that is used across several namespaces because it implements handy utility functionalities and design patterns
+*	vector extraction from associative array
- */
+*	list of keys from an associative array
+*/
+
 if(!jx){
-    var jx = {}
+	var jx = {} ;
 }
-jx.utils = {} ;
+
+jx.utils={} ;
+
+/**
+* Extract an array from an array of associative arrays (map), 
+* This function can also perform a sort of join provided a set of keys (good for building a matrix)
+* @param key	key or column of the associative array
+* @param array	an array or associative arrays i.e [{}]
+*/
+jx.utils.vector=function(key,rec){
+	var vector = [] ;
+	var value;
+	for(var i=0; i < rec.length; i++){
+//		value = rec[i][key] ;	
+//                if(key.constructor == String){
+//                    vector.push( value ) ;
+//                }else
+                if(key.constructor == Array){
+                    value = []
+                    for(ii in key){
+                        value.push(rec[i][key[ii]])
+                    }
+                    
+                }else{
+                    value = rec[i][key] ;	
+                }
+            vector.push( value ) ;
+	}
+	return vector ;
+
+}//-- end jx.utils.vector(key,rec) 
+
+/**
+* Extract keys from an associative array
+* @param rec	associative array
+*/
+jx.utils.keys=function(rec){
+	var keys = [] ;
+	for(var id in rec){
+            
+		keys.push(id) ;
+	}
+	return keys ;
+}//-- end jx.utils.keys
+/**
+ * This function will returnt he unique elements of a list
+ * @param list  list of elements (duplicates are expected)
+ */
+jx.utils.unique = function (list){
+    var obj = {}
+    for(var i=0; i < list.length; i++){
+        obj[list[i]]= 1 ;
+    }
+    return jx.utils.keys(obj);
+}
+/**
+ * Implementation of a few standard design patterns. Their use is user/dependent
+ * For more information on how/when to use a design pattern please use google/wikipedia ;-)
+ */
 jx.utils.patterns = {}
-jx.utils.patterns.visitor = function(list,pointer){}
+jx.utils.patterns.visitor = function(list,pointer){
-jx.utils.patterns.iterator = function(list,ipointer){}
+	rlist = [] ;
+    for(var i=0; i < list.length; i++){       
+        value = pointer(list[i]) ;
+	if(value != null){
+		rlist.push(value) ;
+	}
+    }
+    return (rlist.length > 0)?rlist:list;
+}
+/**
+ * Implementation of an iterator design pattern: i.e we use a sequence of objects and call a given method on them
+ * This is a basic iterator design pattern 
+ */
+jx.utils.patterns.iterator = function(list,pointer){
+    for(var i=0; i < list.length; i++){
+        list[i][pointer]();
+    }
+}
+/**
+ * This is an implementation of an observer design pattern, the obervers will just have to call notify on the subject
+ * The observers' role is to render some stuff on the ui, having said this, this design pattern is suited for ui & asynchronous tasks
+ * @param lobservers	list of observers
+ * @param init			pointer to be called on each observer to trigger it
+ */
+jx.utils.patterns.observer = function(lobservers,init){
+	p = {} ;	//-- specification of the subject
+	p.index = 0;
+	p.nodes = lobservers ;
+	p.pointer = init;
+	p.notify = function(){
+		//
+		// This function is designed to be called by the observers
+		//
+		if( this.index < this.nodes.length){
+			this.start() ;
+		}
+	}
+	p.start = function(){
+		observer = this.nodes[this.index];
+		try{
+			observer[this.pointer](this) ;
+			++this.index;
+		}catch(e){
+			//
+			// if an exception was thrown, chances are were unable to increment and call notify
+			// In the spirit of "The show must go on", we will make the notify call here for the failed observer
+			//
+			++this.index ;
+			this.notify();
+			
+		}
+		
+	}
+	//
+	// let's fire the design pattern
+	//
+	p.start() ;
+}
+
+/**
+* Apply a function to an array (visitor-like design pattern)
+* @param fn	casting function on the vector or array of data
+* @param list	array of numeric data (hopefully)
+* @return 	array containing casted type
+*/
+jx.utils.cast = jx.utils.patterns.visitor ;
+
+/**
+* Print a dom object to system defined printer (Physical; Network or File)
+* @param id	id of a DOM object
+*/
+jx.utils.print = function(id){}
+
+/**
+* The following namespace handles searches in depth & in breath.
+*/
+jx.utils.search = function(id,keywords,attrib){
+	var lattr = null;
+	attrib = (attrib == null)?['innerHTML','value']:attrib;
+	if(attrib.constructor == Array){
+		lattr = attrib;
+	}else{
+		lattr = [attrib] ;
+	}
+
+	regex = keywords.toLowerCase();
+	ldoms = jx.dom.get.children(id) ;
+	//ldoms.push(document.getElementById(id)) ;
+	var imatch = function(_dom){
+		obj = null;
+		for(var j=0; j < lattr.length; j++){
+			id = lattr[j] ;
+			str = _dom[id] ;
+			str = (str != null)?str.toLowerCase():str;
+			if(str == null){
+				continue;
+			}else if(str.match(regex) != null){
+					obj = _dom.cloneNode(true) ;
+					
+				}
+
+		}
+		return obj;
+	}
+	lmatches = jx.utils.patterns.visitor(ldoms,imatch)
+	return lmatches ;
+}
 
+module.exports.utils = jx.utils ;