introduce signal, start using in history; use consts for signal name

introduces two new modules:
scripts/consts.js
scripts/signal.js

signal is a thin wrapper for jquery('window').on and
jquery('window').trigger, which seems like an adaquete signal library -
there are faster things around, but why introduce another dependency.

4 files changed, 36 insertions, 6 deletions

diff --git a/scripts/consts.js b/scripts/consts.js
new file mode 100644
index 00000000..927a30d3
--- /dev/null
+++ b/scripts/consts.js
@@ -0,0 +1,5 @@
+define('consts', function() {
+    return {
+        RECORD_LINKS: 'record_links',
+    };
+});
diff --git a/scripts/history.js b/scripts/history.js
index a3127c75..e99cbb08 100644
--- a/scripts/history.js
+++ b/scripts/history.js
@@ -15,11 +15,16 @@
 // ReferenceError: __commandLineAPI is not defined
 //var ActionEnum = Enum();
 
-define('history', ['FileSaver'], function(saveAs) {
+define('history', ['jquery', 'FileSaver', 'consts', 'signal'],
+    function($, saveAs, consts, signal) {
 
 function History(user) {
+    var that = this;
     this.records = [];
     this.user = user;
+    signal.slot(consts.RECORD_LINKS, function(obj) {
+        return that.record_links(obj)
+    });
 }
 
 var ACTION_KEYSTROKES = 'ACTION_KEYSTROKES';
diff --git a/scripts/rhizicore.js b/scripts/rhizicore.js
index cdffde64..1b4bcbb3 100644
--- a/scripts/rhizicore.js
+++ b/scripts/rhizicore.js
@@ -1,8 +1,8 @@
 "use strict"
 
 define('rhizicore',
-['jquery', 'd3', 'util', 'history', 'textanalysis'],
-function($, d3, util, history, textanalysis) {
+['jquery', 'd3', 'consts', 'signal', 'util', 'history', 'textanalysis'],
+function($, d3, consts, signal, util, history, textanalysis) {
 var History = history.History;
 var addednodes = [];
 
@@ -260,9 +260,7 @@ function myGraph(el) {
                 "state": state
             };
             links.push(link);
-            if (this.history !== undefined) {
-                this.history.record_links([link]);
-            }
+            signal.signal(consts.RECORD_LINKS, [[link]]);
         } else {
             found.name = name;
             found.state = state;
diff --git a/scripts/signal.js b/scripts/signal.js
new file mode 100644
index 00000000..49c5afd3
--- /dev/null
+++ b/scripts/signal.js
@@ -0,0 +1,22 @@
+/*
+ * Signal/slot (i.e. blackboard pattern) for rhizi.
+ *
+ * This is a thin wrapper over jquery right now.
+ * But just keeping it here to make any future change of implementation slightly
+ * easier.
+ */
+
+define('signal', ['jquery'], function($) {
+    function slot(name, handler) {
+        $(window).on(name, function(e, args) {
+            handler(args);
+        });
+    };
+    function signal(name, obj) {
+        $(window).trigger(name, obj);
+    }
+    return {
+        'slot': slot,
+        'signal': signal
+    };
+})