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Diffstat (limited to 'lib/chef/node/attribute_collections.rb')
| -rw-r--r-- | lib/chef/node/attribute_collections.rb | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/lib/chef/node/attribute_collections.rb b/lib/chef/node/attribute_collections.rb new file mode 100644 index 0000000000..521687e8df --- /dev/null +++ b/lib/chef/node/attribute_collections.rb @@ -0,0 +1,191 @@ +#-- +# Author:: Daniel DeLeo (<dan@opscode.com>) +# Copyright:: Copyright (c) 2012 Opscode, Inc. +# License:: Apache License, Version 2.0 +# +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. +# + +class Chef + class Node + + # == AttrArray + # AttrArray is identical to Array, except that it keeps a reference to the + # "root" (Chef::Node::Attribute) object, and will trigger a cache + # invalidation on that object when mutated. + class AttrArray < Array + + MUTATOR_METHODS = [ + :<<, + :[]=, + :clear, + :collect!, + :compact!, + :default=, + :default_proc=, + :delete, + :delete_at, + :delete_if, + :fill, + :flatten!, + :insert, + :keep_if, + :map!, + :merge!, + :pop, + :push, + :update, + :reject!, + :reverse!, + :replace, + :select!, + :shift, + :slice!, + :sort!, + :sort_by!, + :uniq!, + :unshift + ] + + # For all of the methods that may mutate an Array, we override them to + # also invalidate the cached merged_attributes on the root + # Node::Attribute object. + MUTATOR_METHODS.each do |mutator| + class_eval(<<-METHOD_DEFN) + def #{mutator}(*args, &block) + root.reset_cache + super + end + METHOD_DEFN + end + + attr_reader :root + + def initialize(root, data) + @root = root + super(data) + end + + end + + # == VividMash + # VividMash is identical to a Mash, with a few exceptions: + # * It has a reference to the root Chef::Node::Attribute to which it + # belongs, and will trigger cache invalidation on that object when + # mutated. + # * It auto-vivifies, that is a reference to a missing element will result + # in the creation of a new VividMash for that key. (This only works when + # using the element reference method, `[]` -- other methods, such as + # #fetch, work as normal). + # * It supports a set_unless flag (via the root Attribute object) which + # allows `||=` style behavior (`||=` does not work with + # auto-vivification). This is only implemented for #[]=; methods such as + # #store work as normal. + # * attr_accessor style element set and get are supported via method_missing + class VividMash < Mash + attr_reader :root + + # Methods that mutate a VividMash. Each of them is overridden so that it + # also invalidates the cached merged_attributes on the root Attribute + # object. + MUTATOR_METHODS = [ + :clear, + :delete, + :delete_if, + :keep_if, + :merge!, + :update, + :reject!, + :replace, + :select!, + :shift + ] + + # For all of the mutating methods on Mash, override them so that they + # also invalidate the cached `merged_attributes` on the root Attribute + # object. + MUTATOR_METHODS.each do |mutator| + class_eval(<<-METHOD_DEFN) + def #{mutator}(*args, &block) + root.reset_cache + super + end + METHOD_DEFN + end + + def initialize(root, data={}) + @root = root + super(data) + end + + def [](key) + value = super + if !key?(key) + value = self.class.new(root) + self[key] = value + else + value + end + end + + def []=(key, value) + if set_unless? && key?(key) + self[key] + else + root.reset_cache + super + end + end + + alias :attribute? :has_key? + + def method_missing(symbol, *args) + if args.empty? + self[symbol] + elsif symbol.to_s =~ /=$/ + key_to_set = symbol.to_s[/^(.+)=$/, 1] + self[key_to_set] = (args.length == 1 ? args[0] : args) + else + raise NoMethodError, "Undefined node attribute or method `#{symbol}' on `node'. To set an attribute, use `#{symbol}=value' instead." + end + end + + def set_unless? + @root.set_unless? + end + + def convert_key(key) + super + end + + # Mash uses #convert_value to mashify values on input. + # We override it here to convert hash or array values to VividMash or + # AttrArray for consistency and to ensure that the added parts of the + # attribute tree will have the correct cache invalidation behavior. + def convert_value(value) + case value + when VividMash + value + when Hash + VividMash.new(root, value) + when Array + AttrArray.new(root, value) + else + value + end + end + + end + + end +end |