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+#--
+# Copyright:: Copyright 2016, Chef Software, 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
+ # shared API between VividMash and ImmutableMash, writer code can be
+ # 'shared' to keep it logically in this file by adding them to the
+ # block list in ImmutableMash.
+ module CommonAPI
+ # method-style access to attributes
+
+ def valid_container?(obj, key)
+ return obj.is_a?(Hash) || (obj.is_a?(Array) && key.is_a?(Fixnum))
+ end
+
+ private :valid_container?
+
+ # - autovivifying / autoreplacing writer
+ # - non-container-ey intermediate objects are replaced with hashes
+ def write(*args, &block)
+ value = block_given? ? yield : args.pop
+ last = args.pop
+ prev_memo = prev_key = nil
+ chain = args.inject(self) do |memo, key|
+ if !valid_container?(memo, key)
+ prev_memo[prev_key] = {}
+ memo = prev_memo[prev_key]
+ end
+ prev_memo = memo
+ prev_key = key
+ memo[key]
+ end
+ if !valid_container?(chain, last)
+ prev_memo[prev_key] = {}
+ chain = prev_memo[prev_key]
+ end
+ chain[last] = value
+ end
+
+ # this autovivifies, but can throw NoSuchAttribute when trying to access #[] on
+ # something that is not a container ("schema violation" issues).
+ #
+ def write!(*args, &block)
+ value = block_given? ? yield : args.pop
+ last = args.pop
+ obj = args.inject(self) do |memo, key|
+ raise Chef::Exceptions::AttributeTypeMismatch unless valid_container?(memo, key)
+ memo[key]
+ end
+ raise Chef::Exceptions::AttributeTypeMismatch unless valid_container?(obj, last)
+ obj[last] = value
+ end
+
+ # FIXME:(?) does anyone need a non-autovivifying writer for attributes that throws exceptions?
+
+ # return true or false based on if the attribute exists
+ def exist?(*path)
+ path.inject(self) do |memo, key|
+ return false unless valid_container?(memo, key)
+ if memo.is_a?(Hash)
+ if memo.key?(key)
+ memo[key]
+ else
+ return false
+ end
+ elsif memo.is_a?(Array)
+ if memo.length > key
+ memo[key]
+ else
+ return false
+ end
+ end
+ end
+ return true
+ end
+
+ # this is a safe non-autovivifying reader that returns nil if the attribute does not exist
+ def read(*path)
+ begin
+ read!(*path)
+ rescue Chef::Exceptions::NoSuchAttribute
+ nil
+ end
+ end
+
+ # non-autovivifying reader that throws an exception if the attribute does not exist
+ def read!(*path)
+ raise Chef::Exceptions::NoSuchAttribute unless exist?(*path)
+ path.inject(self) do |memo, key|
+ memo[key]
+ end
+ end
+
+ # FIXME:(?) does anyone really like the autovivifying reader that we have and wants the same behavior? readers that write? ugh...
+
+ def unlink(*path, last)
+ hash = path.empty? ? self : read(*path)
+ return nil unless hash.is_a?(Hash) || hash.is_a?(Array)
+ root.top_level_breadcrumb ||= last
+ hash.delete(last)
+ end
+
+ def unlink!(*path)
+ raise Chef::Exceptions::NoSuchAttribute unless exist?(*path)
+ unlink(*path)
+ end
+
+ end
+ end
+end