329 lines
7.3 KiB
Ruby
329 lines
7.3 KiB
Ruby
module CodeRay
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# = PluginHost
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#
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# $Id: plugin.rb 220 2007-01-01 02:58:58Z murphy $
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#
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# A simple subclass plugin system.
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#
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# Example:
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# class Generators < PluginHost
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# plugin_path 'app/generators'
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# end
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#
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# class Generator
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# extend Plugin
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# PLUGIN_HOST = Generators
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# end
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#
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# class FancyGenerator < Generator
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# register_for :fancy
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# end
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#
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# Generators[:fancy] #-> FancyGenerator
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# # or
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# require_plugin 'Generators/fancy'
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module PluginHost
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# Raised if Encoders::[] fails because:
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# * a file could not be found
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# * the requested Encoder is not registered
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PluginNotFound = Class.new Exception
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HostNotFound = Class.new Exception
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PLUGIN_HOSTS = []
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PLUGIN_HOSTS_BY_ID = {} # dummy hash
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# Loads all plugins using list and load.
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def load_all
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for plugin in list
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load plugin
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end
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end
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# Returns the Plugin for +id+.
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#
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# Example:
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# yaml_plugin = MyPluginHost[:yaml]
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def [] id, *args, &blk
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plugin = validate_id(id)
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begin
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plugin = plugin_hash.[] plugin, *args, &blk
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end while plugin.is_a? Symbol
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plugin
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end
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# Alias for +[]+.
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alias load []
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def require_helper plugin_id, helper_name
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path = path_to File.join(plugin_id, helper_name)
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require path
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end
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class << self
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# Adds the module/class to the PLUGIN_HOSTS list.
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def extended mod
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PLUGIN_HOSTS << mod
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end
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# Warns you that you should not #include this module.
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def included mod
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warn "#{name} should not be included. Use extend."
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end
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# Find the PluginHost for host_id.
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def host_by_id host_id
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unless PLUGIN_HOSTS_BY_ID.default_proc
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ph = Hash.new do |h, a_host_id|
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for host in PLUGIN_HOSTS
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h[host.host_id] = host
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end
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h.fetch a_host_id, nil
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end
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PLUGIN_HOSTS_BY_ID.replace ph
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end
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PLUGIN_HOSTS_BY_ID[host_id]
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end
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end
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# The path where the plugins can be found.
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def plugin_path *args
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unless args.empty?
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@plugin_path = File.expand_path File.join(*args)
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load_map
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end
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@plugin_path
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end
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# The host's ID.
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#
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# If PLUGIN_HOST_ID is not set, it is simply the class name.
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def host_id
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if self.const_defined? :PLUGIN_HOST_ID
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self::PLUGIN_HOST_ID
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else
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name
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end
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end
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# Map a plugin_id to another.
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#
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# Usage: Put this in a file plugin_path/_map.rb.
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#
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# class MyColorHost < PluginHost
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# map :navy => :dark_blue,
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# :maroon => :brown,
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# :luna => :moon
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# end
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def map hash
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for from, to in hash
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from = validate_id from
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to = validate_id to
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plugin_hash[from] = to unless plugin_hash.has_key? from
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end
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end
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# Define the default plugin to use when no plugin is found
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# for a given id.
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#
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# See also map.
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#
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# class MyColorHost < PluginHost
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# map :navy => :dark_blue
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# default :gray
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# end
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def default id
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id = validate_id id
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plugin_hash[nil] = id
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end
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# Every plugin must register itself for one or more
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# +ids+ by calling register_for, which calls this method.
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#
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# See Plugin#register_for.
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def register plugin, *ids
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for id in ids
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unless id.is_a? Symbol
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raise ArgumentError,
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"id must be a Symbol, but it was a #{id.class}"
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end
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plugin_hash[validate_id(id)] = plugin
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end
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end
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# A Hash of plugion_id => Plugin pairs.
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def plugin_hash
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@plugin_hash ||= create_plugin_hash
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end
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# Returns an array of all .rb files in the plugin path.
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#
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# The extension .rb is not included.
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def list
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Dir[path_to('*')].select do |file|
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File.basename(file)[/^(?!_)\w+\.rb$/]
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end.map do |file|
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File.basename file, '.rb'
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end
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end
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# Makes a map of all loaded plugins.
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def inspect
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map = plugin_hash.dup
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map.each do |id, plugin|
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map[id] = plugin.to_s[/(?>[\w_]+)$/]
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end
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"#{name}[#{host_id}]#{map.inspect}"
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end
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protected
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# Created a new plugin list and stores it to @plugin_hash.
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def create_plugin_hash
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@plugin_hash =
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Hash.new do |h, plugin_id|
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id = validate_id(plugin_id)
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path = path_to id
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begin
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require path
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rescue LoadError => boom
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if h.has_key? nil # default plugin
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h[id] = h[nil]
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else
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raise PluginNotFound, 'Could not load plugin %p: %s' % [id, boom]
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end
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else
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# Plugin should have registered by now
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unless h.has_key? id
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raise PluginNotFound,
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"No #{self.name} plugin for #{id.inspect} found in #{path}."
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end
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end
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h[id]
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end
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end
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# Loads the map file (see map).
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#
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# This is done automatically when plugin_path is called.
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def load_map
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mapfile = path_to '_map'
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if File.exist? mapfile
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require mapfile
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elsif $DEBUG
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warn 'no _map.rb found for %s' % name
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end
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end
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# Returns the Plugin for +id+.
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# Use it like Hash#fetch.
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#
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# Example:
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# yaml_plugin = MyPluginHost[:yaml, :default]
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def fetch id, *args, &blk
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plugin_hash.fetch validate_id(id), *args, &blk
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end
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# Returns the expected path to the plugin file for the given id.
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def path_to plugin_id
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File.join plugin_path, "#{plugin_id}.rb"
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end
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# Converts +id+ to a Symbol if it is a String,
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# or returns +id+ if it already is a Symbol.
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#
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# Raises +ArgumentError+ for all other objects, or if the
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# given String includes non-alphanumeric characters (\W).
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def validate_id id
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if id.is_a? Symbol or id.nil?
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id
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elsif id.is_a? String
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if id[/\w+/] == id
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id.to_sym
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else
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raise ArgumentError, "Invalid id: '#{id}' given."
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end
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else
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raise ArgumentError,
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"String or Symbol expected, but #{id.class} given."
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end
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end
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end
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# = Plugin
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#
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# Plugins have to include this module.
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#
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# IMPORTANT: use extend for this module.
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#
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# Example: see PluginHost.
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module Plugin
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def included mod
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warn "#{name} should not be included. Use extend."
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end
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# Register this class for the given langs.
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# Example:
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# class MyPlugin < PluginHost::BaseClass
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# register_for :my_id
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# ...
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# end
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#
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# See PluginHost.register.
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def register_for *ids
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plugin_host.register self, *ids
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end
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# The host for this Plugin class.
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def plugin_host host = nil
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if host and not host.is_a? PluginHost
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raise ArgumentError,
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"PluginHost expected, but #{host.class} given."
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end
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self.const_set :PLUGIN_HOST, host if host
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self::PLUGIN_HOST
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end
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# Require some helper files.
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#
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# Example:
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#
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# class MyPlugin < PluginHost::BaseClass
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# register_for :my_id
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# helper :my_helper
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#
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# The above example loads the file myplugin/my_helper.rb relative to the
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# file in which MyPlugin was defined.
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def helper *helpers
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for helper in helpers
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self::PLUGIN_HOST.require_helper plugin_id, helper.to_s
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end
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end
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# Returns the pulgin id used by the engine.
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def plugin_id
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name[/[\w_]+$/].downcase
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end
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end
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# Convenience method for plugin loading.
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# The syntax used is:
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#
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# CodeRay.require_plugin '<Host ID>/<Plugin ID>'
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#
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# Returns the loaded plugin.
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def require_plugin path
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host_id, plugin_id = path.split '/', 2
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host = PluginHost.host_by_id(host_id)
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raise PluginHost::HostNotFound,
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"No host for #{host_id.inspect} found." unless host
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host.load plugin_id
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end
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end |