first commit

lib/knife/event.lua

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+-- require('mobdebug').start()
+
+-- Event module
+local Event = {}
+
+-- Event handler registry
+Event.handlers = {}
+
+-- Remove an event handler from the registry
+local function remove (self)
+    if not self.isRegistered then
+        return self
+    end
+    if self.prevHandler then
+        self.prevHandler.nextHandler = self.nextHandler
+    end
+    if self.nextHandler then
+        self.nextHandler.prevHandler = self.prevHandler
+    end
+    if Event.handlers[self.name] == self then
+        Event.handlers[self.name] = self.nextHandler
+    end
+    self.prevHandler = nil
+    self.nextHandler = nil
+    self.isRegistered = false
+
+    return self
+end
+
+-- Insert an event handler into the registry
+local function register (self)
+    if self.isRegistered then
+        return self
+    end
+    self.nextHandler = Event.handlers[self.name]
+    if self.nextHandler then
+        self.nextHandler.prevHandler = self
+    end
+    Event.handlers[self.name] = self
+    self.isRegistered = true
+
+    return self
+end
+
+-- Create an event handler
+local function Handler (name, callback)
+    return {
+        name = name,
+        callback = callback,
+        isRegistered = false,
+        remove = remove,
+        register = register
+    }
+end
+
+
+
+-- Create and register a new event handler
+function Event.on (name, callback)
+    return register(Handler(name, callback))
+end
+
+-- Dispatch an event
+function Event.dispatch (name, ...)
+    local handler = Event.handlers[name]
+
+    while handler do
+        if handler.callback(...) == false then
+            return handler
+        end
+        handler = handler.nextHandler
+    end
+end
+
+local function isCallable (value)
+    return type(value) == 'function' or
+        getmetatable(value) and getmetatable(value).__call
+end
+
+-- Inject a dispatcher into a table.
+local function hookDispatcher (t, key)
+    local original = t[key]
+
+    if isCallable(original) then
+        t[key] = function (...)
+            original(...)
+            return Event.dispatch(key, ...)
+        end
+    else
+        t[key] = function (...)
+            return Event.dispatch(key, ...)
+        end
+    end
+end
+
+-- Inject dispatchers into a table. Examples:
+-- Event.hook(love.handlers)
+-- Event.hook(love, { 'load', 'update', 'draw' })
+function Event.hook (t, keys)
+    if keys then
+        for _, key in ipairs(keys) do
+            hookDispatcher(t, key)
+        end
+    else
+        for key in pairs(t) do
+            hookDispatcher(t, key)
+        end
+    end
+end
+
+return Event