observer pattern through js watch

git-svn-id: svn://svn.open-ils.org/ILS/trunk@7201 dcc99617-32d9-48b4-a31d-7c20da2025e4

diff --git a/Open-ILS/xul/staff_client/chrome/content/OpenILS/data.js b/Open-ILS/xul/staff_client/chrome/content/OpenILS/data.js
index 2b6c7ca..3685ce0 100644 (file)
--- a/Open-ILS/xul/staff_client/chrome/content/OpenILS/data.js
+++ b/Open-ILS/xul/staff_client/chrome/content/OpenILS/data.js
@@ -14,6 +14,7 @@ OpenILS.data.prototype = {
        'list' : {},
        'hash' : {},
        'tree' : {},
+       'cached_request' : {},
 
        'temp' : '',
 
@@ -45,6 +46,98 @@ OpenILS.data.prototype = {
 
        },
 
+       // This should be invoked only once per application, in a persistant window
+       'init_observer_functions' : function() {
+               try {
+                       var obj = this;                         // OpenILS.data
+                       obj.observers = {};                     //
+                       obj.observers.id = 1;           // Unique id for each observer function added
+                       obj.observers.id2path = {}; // Lookup for full_path via observer id
+                       obj.observers.cache = {};       // Observer funcs go in here
+
+                       // For a given path, this executes all the registered observer funcs
+                       obj.observers.dispatch = function(full_path, old_value, new_value) {
+                               obj.error.sdump('D_OBSERVERS', 'entering observers.dispatch\nfull_path = ' + full_path + '\nold_value = ' + js2JSON(old_value) + '\nnew_value = ' + js2JSON(new_value) + '\n');
+                               try {
+                                       var path = full_path.split(/\./).pop();
+                                       for (var i in obj.observers.cache[full_path]) {
+                                               try {
+                                                       var o = obj.observers.cache[full_path][i];
+                                                       if (typeof o.func == 'function') o.func(path, old_value, new_value);
+                                               } catch(E) {
+                                                       obj.error.sdump('D_ERROR','Error in OpenILS.data.observers.dispatch(): ' + js2JSON(E) );
+                                               }
+                                       }
+                               } catch(E) {
+                                       obj.error.sdump('D_ERROR','Error in OpenILS.data.observers.dispatch(): ' + js2JSON(E) );
+                               }
+                       }
+
+                       // This registers an observer function for a given path
+                       obj.observers.add = function(full_path, func) {
+                               try {
+                                       obj.error.sdump('D_OBSERVERS', 'entering observers.add\nfull_path = ' + full_path + '\nfunc = ' + func + '\n');
+                                       netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
+                                       const OpenILS=new Components.Constructor("@mozilla.org/openils_data_cache;1", "nsIOpenILS");
+                                       var data_cache=new OpenILS( );
+                                       var stash = data_cache.wrappedJSObject.OpenILS.prototype.data;
+
+                                       var id = obj.observers.id++;
+                                       if (typeof obj.observers.cache[ full_path ] == 'undefined') obj.observers.cache[ full_path ] = {};
+                                       obj.observers.cache[ full_path ][ id ] = { 'func' : func, 'time_added' : new Date() };
+                                       obj.observers.id2path[ id ] = [ full_path ];
+
+                                       var path_list = full_path.split(/\./);
+                                       var observed_prop = path_list.pop();
+
+                                       // Convert soft path to object reference.  Error if any but the last node is undefined
+                                       for (var i in path_list) stash = stash[ path_list[i] ];
+                                       stash.watch(
+                                               observed_prop,
+                                               function(p,old_value,new_value) {
+                                                       obj.observers.dispatch(full_path,old_value,new_value);
+                                                       return new_value;
+                                               }
+                                       );
+
+                                       return id;
+                               } catch(E) {
+                                       obj.error.sdump('D_ERROR','Error in OpenILS.data.observers.add(): ' + js2JSON(E) );
+                               }
+                       }
+
+                       // This unregisters an observer function for a given observer id
+                       obj.observers.remove = function(id) {
+                               try {
+                                       obj.error.sdump('D_OBSERVERS', 'entering observers.remove\nid = ' + id + '\n');
+                                       var path = obj.observers.id2path[ id ];
+                                       delete obj.observers.cache[ path ][ id ];
+                                       delete obj.observers.id2path[ id ];
+                               } catch(E) {
+                                       obj.error.sdump('D_ERROR','Error in OpenILS.data.observers.remove(): ' + js2JSON(E) );
+                               }
+                       }
+
+                       // This purges observer functions for a given path
+                       obj.observers.purge = function(full_path) {
+                               obj.error.sdump('D_OBSERVERS', 'entering observers.purge\nfull_path = ' + full_path + '\n');
+                               try {
+                                       var remove_these = [];
+                                       for (var id in obj.observers.cache[ full_path ]) remove_these.push( id );
+                                       for (var id in remove_these) delete obj.observers.id2path[ id ];
+                                       delete obj.observers.cache[ full_path ];
+                               } catch(E) {
+                                       obj.error.sdump('D_ERROR','Error in OpenILS.data.observers.purge(): ' + js2JSON(E) );
+                               }
+                       }
+
+                       obj.stash('observers'); // make this accessible globally
+
+               } catch(E) {
+                       this.error.sdump('D_ERROR','Error in OpenILS.data.init_observer_functions(): ' + js2JSON(E) );
+               }
+       },
+
        'stash' : function () {
                try {
                        netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");