Document CommandRegistry

src/atom.coffee

@@ -113,6 +113,9 @@ class Atom extends Model
   # Public: A {KeymapManager} instance
   keymaps: null
 
+  # Public: A {CommandRegistry} instance
+  commands: null
+
   # Public: A {MenuManager} instance
   menu: null
 

src/command-registry.coffee

@@ -7,6 +7,41 @@ SequenceCount = 0
 SpecificityCache = {}
 
 module.exports =
+
+# Experimental: Associates listener functions with commands in a
+# context-sensitive way using CSS selectors. You can access a global instance of
+# this class via `atom.commands`, and commands registered there will be
+# presented in the command palette.
+#
+# The global command registry facilitates a style of event handling known as
+# *event delegation* that was popularized by jQuery. Atom commands are expressed
+# as custom DOM events that can be invoked on the currently focused element via
+# a key binding or manually via the command palette. Rather than binding
+# listeners for command events directly to DOM nodes, you instead register
+# command event listeners globally on `atom.commands` and constrain them to
+# specific kinds of elements with CSS selectors.
+#
+# As the event bubbles upward through the DOM, all registered event listeners
+# with matching selectors are invoked in order of specificity. In the event of a
+# specificity tie, the most recently registered listener is invoked first. This
+# mirrors the "cascade" semantics of CSS. Event listeners are invoked in the
+# context of the current DOM node, meaning `this` always points at
+# `event.currentTarget`. As is normally the case with DOM events,
+# `stopPropagation` and `stopImmediatePropagation` can be used to terminate the
+# bubbling process and prevent invocation of additional listeners.
+#
+# ## Example
+#
+# Here is a command that inserts the current date in an editor:
+#
+# ```coffee
+# atom.commands.add '.editor',
+#   'user:insert-date': (event) ->
+#     editor = $(this).view().getModel()
+#     # soon the above above line will be:
+#     # editor = @getModel()
+#     editor.insertText(new Date().toLocaleString())
+# ```
 class CommandRegistry
   constructor: (@rootNode) ->
     @listenersByCommandName = {}
@@ -19,6 +54,31 @@ class CommandRegistry
       oldRootNode?.removeEventListener(commandName, @dispatchCommand, true)
       newRootNode?.addEventListener(commandName, @dispatchCommand, true)
 
+  # Public: Add one or more command listeners associated with a selector.
+  #
+  # ## Arguments: Registering One Command
+  #
+  # * `selector` A {String} containing a CSS selector matching elements on which
+  #   you want to handle the commands. The `,` combinator is not currently
+  #   supported.
+  # * `commandName` A {String} containing the name of a command you want to
+  #   handle such as `user:insert-date`.
+  # * `callback` A {Function} to call when the given command is invoked on an
+  #   element matching the selector. It will be called with `this` referencing
+  #   the matching DOM node.
+  #   * `event` A standard DOM event instance. Call `stopPropagation` or
+  #     `stopImmediatePropagation` to terminate bubbling early.
+  #
+  # ## Arguments: Registering Multiple Commands
+  #
+  # * `selector` A {String} containing a CSS selector matching elements on which
+  #   you want to handle the commands. The `,` combinator is not currently
+  #   supported.
+  # * `commands` An {Object} mapping command names like `user:insert-date` to
+  #   listener {Function}s.
+  #
+  # Returns a {Disposable} on which `.dispose()` can be called to remove the
+  # added command handler(s).
   add: (selector, commandName, callback) ->
     if typeof commandName is 'object'
       commands = commandName
@@ -69,6 +129,17 @@ class CommandRegistry
       break if currentTarget is @rootNode
       currentTarget = currentTarget.parentNode
 
+  # Public: Find all registered commands matching a query.
+  #
+  # * `params` An {Object} containing one or more of the following keys:
+  #   * `target` A DOM node that is the hypothetical target of a given command.
+  #
+  # Returns an {Array} of {Object}s containing the following keys:
+  #  * `name` The name of the command. For example, `user:insert-date`.
+  #  * `displayName` The display name of the command. For example,
+  #    `User: Insert Date`.
+  #  * `jQuery` Present if the command was registered with the legacy
+  #    `$::command` method.
   findCommands: ({target}) ->
     commands = []
     target = @rootNode unless @rootNode.contains(target)
@@ -97,6 +168,8 @@ class CommandRegistry
 
 class CommandListener
   constructor: (@selector, @callback) ->
+    console.log "calc specificity", @selector
+
     @specificity = (SpecificityCache[@selector] ?= specificity(@selector))
     @sequenceNumber = SequenceCount++