285 lines
6.8 KiB
Ruby
285 lines
6.8 KiB
Ruby
module CodeRay
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# = PluginHost
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#
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# A simple subclass/subfolder plugin system.
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#
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# Example:
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# class Generators
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# extend 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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# CodeRay.require_plugin 'Generators/fancy'
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# # or
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# 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 Plugin is not registered
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PluginNotFound = Class.new LoadError
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HostNotFound = Class.new LoadError
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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 load []
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# Tries to +load+ the missing plugin by translating +const+ to the
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# underscore form (eg. LinesOfCode becomes lines_of_code).
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def const_missing const
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id = const.to_s.
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gsub(/([A-Z]+)([A-Z][a-z])/,'\1_\2').
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gsub(/([a-z\d])([A-Z])/,'\1_\2').
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downcase
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load id
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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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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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end
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@plugin_path ||= ''
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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, or return the default plugin.
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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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#
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# MyColorHost.default # loads and returns the Gray plugin
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def default id = nil
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if id
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id = validate_id id
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raise "The default plugin can't be named \"default\"." if id == :default
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plugin_hash[:default] = id
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else
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load :default
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end
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end
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# Every plugin must register itself for +id+ by calling register_for,
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# which calls this method.
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#
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# See Plugin#register_for.
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def register plugin, id
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plugin_hash[validate_id(id)] = plugin
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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 ||= make_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').to_sym
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end
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end
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# Returns an array of all Plugins.
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#
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# Note: This loads all plugins using load_all.
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def all_plugins
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load_all
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plugin_hash.values.grep(Class)
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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_plugin_map
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mapfile = path_to '_map'
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@plugin_map_loaded = true
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if File.exist? mapfile
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require mapfile
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true
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else
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false
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end
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end
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protected
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# Return a plugin hash that automatically loads plugins.
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def make_plugin_hash
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@plugin_map_loaded ||= false
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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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raise LoadError, "#{path} not found" unless File.exist? path
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require path
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rescue LoadError => boom
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if @plugin_map_loaded
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if h.has_key?(:default)
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warn '%p could not load plugin %p; falling back to %p' % [self, id, h[:default]]
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h[:default]
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else
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raise PluginNotFound, '%p could not load plugin %p: %s' % [self, id, boom]
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end
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else
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load_plugin_map
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h[plugin_id]
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end
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else
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# Plugin should have registered by now
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if h.has_key? id
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h[id]
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else
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raise PluginNotFound, "No #{self.name} plugin for #{id.inspect} found in #{path}."
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end
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end
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end
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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.downcase.to_sym
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else
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raise ArgumentError, "Invalid id given: #{id}"
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end
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else
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raise ArgumentError, "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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# See CodeRay::PluginHost for examples.
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module Plugin
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attr_reader :plugin_id
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# Register this class for the given +id+.
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#
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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 id
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@plugin_id = id
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plugin_host.register self, id
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end
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# Returns the title of the plugin, or sets it to the
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# optional argument +title+.
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def title title = nil
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if title
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@title = title.to_s
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else
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@title ||= name[/([^:]+)$/, 1]
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end
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end
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# The PluginHost for this Plugin class.
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def plugin_host host = nil
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if host.is_a? PluginHost
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const_set :PLUGIN_HOST, host
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end
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self::PLUGIN_HOST
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end
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def aliases
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plugin_host.load_plugin_map
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plugin_host.plugin_hash.inject [] do |aliases, (key, _)|
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aliases << key if plugin_host[key] == self
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aliases
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end
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end
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end
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end
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