Implement a basic event dispatcher

lib/uh/wm.rb

@@ -1,6 +1,7 @@
 require 'uh'
 
 require 'uh/wm/cli'
+require 'uh/wm/dispatcher'
 require 'uh/wm/env'
 require 'uh/wm/manager'
 require 'uh/wm/runner'

lib/uh/wm/dispatcher.rb

@@ -0,0 +1,27 @@
+module Uh
+  module WM
+    class Dispatcher
+      attr_reader :hooks
+
+      def initialize hooks = Hash.new
+        @hooks = hooks
+      end
+
+      def [] *key
+        @hooks[translate_key key] or []
+      end
+
+      def on *key, &block
+        @hooks[translate_key key] ||= []
+        @hooks[translate_key key] << block
+      end
+
+
+      private
+
+      def translate_key key
+        key.one? ? key[0] : key
+      end
+    end
+  end
+end

spec/uh/wm/dispatcher_spec.rb

@@ -0,0 +1,44 @@
+module Uh
+  module WM
+    RSpec.describe Dispatcher do
+      let(:hooks)           { {} }
+      subject(:dispatcher)  { described_class.new hooks }
+
+      describe '#[]' do
+        context 'when given key for existing hook' do
+          let(:hooks) { { hook_key: [:hook] } }
+
+          it 'returns registered hooks for this key' do
+            expect(dispatcher[:hook_key]).to eq [:hook]
+          end
+        end
+
+        context 'when given multiple keys for existing hook' do
+          let(:hooks) { { %i[hook key] => [:hook] } }
+
+          it 'returns registered hooks for this key' do
+            expect(dispatcher[:hook, :key]).to eq [:hook]
+          end
+        end
+
+        context 'when given key for unknown hook' do
+          it 'returns an empty array' do
+            expect(dispatcher[:unknown_hook]).to eq []
+          end
+        end
+      end
+
+      describe '#on' do
+        it 'registers given hook for given key' do
+          dispatcher.on(:hook_key) { :hook }
+          expect(dispatcher.hooks[:hook_key]).to be
+        end
+
+        it 'registers given hook for given multiple keys' do
+          dispatcher.on(:hook, :key) { :hook }
+          expect(dispatcher.hooks[%i[hook key]]).to be
+        end
+      end
+    end
+  end
+end