Skip to content
Permalink
d385021675
Switch branches/tags
Go to file
 
 
Cannot retrieve contributors at this time
221 lines (197 sloc) 5.33 KB
module CodeRay
# = PluginHost
#
# A simple subclass/subfolder plugin system.
#
# Example:
# class Generators
# extend PluginHost
# plugin_path 'app/generators'
# end
#
# class Generator
# extend Plugin
# PLUGIN_HOST = Generators
# end
#
# class FancyGenerator < Generator
# register_for :fancy
# end
#
# Generators[:fancy] #-> FancyGenerator
# # or
# CodeRay.require_plugin 'Generators/fancy'
# # or
# Generators::Fancy
module PluginHost
# Raised if Encoders::[] fails because:
# * a file could not be found
# * the requested Plugin is not registered
PluginNotFound = Class.new LoadError
HostNotFound = Class.new LoadError
PLUGIN_HOSTS = []
PLUGIN_HOSTS_BY_ID = {} # dummy hash
# Loads all plugins using list and load.
def load_all
for plugin in list
load plugin
end
end
# Returns the Plugin for +id+.
#
# Example:
# yaml_plugin = MyPluginHost[:yaml]
def [] id, *args, &blk
plugin = validate_id(id)
begin
plugin = plugin_hash.[](plugin, *args, &blk)
end while plugin.is_a? String
plugin
end
alias load []
# Tries to +load+ the missing plugin by translating +const+ to the
# underscore form (eg. LinesOfCode becomes lines_of_code).
def const_missing const
id = const.to_s.
gsub(/([A-Z]+)([A-Z][a-z])/,'\1_\2').
gsub(/([a-z\d])([A-Z])/,'\1_\2').
downcase
load id
end
class << self
# Adds the module/class to the PLUGIN_HOSTS list.
def extended mod
PLUGIN_HOSTS << mod
end
end
# The path where the plugins can be found.
def plugin_path *args
unless args.empty?
@plugin_path = File.expand_path File.join(*args)
end
@plugin_path ||= ''
end
# Map a plugin_id to another.
#
# Usage: Put this in a file plugin_path/_map.rb.
#
# class MyColorHost < PluginHost
# map :navy => :dark_blue,
# :maroon => :brown,
# :luna => :moon
# end
def map hash
for from, to in hash
from = validate_id from
to = validate_id to
plugin_hash[from] = to unless plugin_hash.has_key? from
end
end
# Define the default plugin to use when no plugin is found
# for a given id, or return the default plugin.
#
# See also map.
#
# class MyColorHost < PluginHost
# map :navy => :dark_blue
# default :gray
# end
#
# MyColorHost.default # loads and returns the Gray plugin
def default id = nil
if id
id = validate_id id
raise "The default plugin can't be named \"default\"." if id == :default
plugin_hash[:default] = id
else
load :default
end
end
# Every plugin must register itself for +id+ by calling register_for,
# which calls this method.
#
# See Plugin#register_for.
def register plugin, id
plugin_hash[validate_id(id)] = plugin
end
# A Hash of plugion_id => Plugin pairs.
def plugin_hash
@plugin_hash ||= (@plugin_hash = make_plugin_hash).tap { load_plugin_map }
end
# Returns an array of all .rb files in the plugin path.
#
# The extension .rb is not included.
def list
Dir[path_to('*')].select do |file|
File.basename(file)[/^(?!_)\w+\.rb$/]
end.map do |file|
File.basename(file, '.rb').to_sym
end
end
# Returns an array of all Plugins.
#
# Note: This loads all plugins using load_all.
def all_plugins
load_all
plugin_hash.values.grep(Class)
end
# Loads the map file (see map).
#
# This is done automatically when plugin_path is called.
def load_plugin_map
mapfile = path_to '_map'
if File.exist? mapfile
require mapfile
true
else
false
end
end
protected
# Return a plugin hash that automatically loads plugins.
def make_plugin_hash
Hash.new do |h, plugin_id|
id = validate_id(plugin_id)
path = path_to id
begin
require path
rescue LoadError => boom
if h.has_key?(:default)
h[:default]
else
raise PluginNotFound, '%p could not load plugin %p: %s' % [self, id, boom]
end
else
# Plugin should have registered by now
if h.has_key? id
h[id]
else
raise PluginNotFound, "No #{self.name} plugin for #{id.inspect} found in #{path}."
end
end
end
end
# Returns the expected path to the plugin file for the given id.
def path_to plugin_id
File.join plugin_path, "#{plugin_id}.rb"
end
# Converts +id+ to a valid plugin ID String, or returns +nil+.
#
# Raises +ArgumentError+ for all other objects, or if the
# given String includes non-alphanumeric characters (\W).
def validate_id id
case id
when Symbol
id.to_s
when String
if id[/\w+/] == id
id.downcase
else
raise ArgumentError, "Invalid id given: #{id}"
end
else
raise ArgumentError, "Symbol or String expected, but #{id.class} given."
end
end
end
end