1 files changed, 63 insertions, 0 deletions
diff --git a/priv/static/js/metricsgraphics/common/hooks.js b/priv/static/js/metricsgraphics/common/hooks.js
new file mode 100644
index 0000000..5f2adb5
--- /dev/null
+++ b/priv/static/js/metricsgraphics/common/hooks.js
@@ -0,0 +1,63 @@
+/**
+  Record of all registered hooks.
+  For internal use only.
+*/
+MG._hooks = {};
+
+/**
+  Add a hook callthrough to the stack.
+
+  Hooks are executed in the order that they were registered.
+*/
+MG.add_hook = function(name, func, context) {
+  var hooks;
+
+  if (!MG._hooks[name]) {
+    MG._hooks[name] = [];
+  }
+
+  hooks = MG._hooks[name];
+
+  var already_registered =
+    hooks.filter(function(hook) {
+      return hook.func === func;
+    })
+    .length > 0;
+
+  if (already_registered) {
+    throw 'That function is already registered.';
+  }
+
+  hooks.push({
+    func: func,
+    context: context
+  });
+};
+
+/**
+  Execute registered hooks.
+
+  Optional arguments
+*/
+MG.call_hook = function(name) {
+  var hooks = MG._hooks[name],
+    result = [].slice.apply(arguments, [1]),
+    processed;
+
+  if (hooks) {
+    hooks.forEach(function(hook) {
+      if (hook.func) {
+        var params = processed || result;
+
+        if (params && params.constructor !== Array) {
+          params = [params];
+        }
+
+        params = [].concat.apply([], params);
+        processed = hook.func.apply(hook.context, params);
+      }
+    });
+  }
+
+  return processed || result;
+};