1 files changed, 101 insertions, 0 deletions
diff --git a/lib/chef/resource/conditional.rb b/lib/chef/resource/conditional.rb
new file mode 100644
index 0000000000..3f892af827
--- /dev/null
+++ b/lib/chef/resource/conditional.rb
@@ -0,0 +1,101 @@
+#
+# Author:: Daniel DeLeo (<dan@opscode.com>)
+# Copyright:: Copyright (c) 2011 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.
+#
+
+require 'chef/mixin/shell_out'
+
+class Chef
+  class Resource
+    class Conditional
+      include Chef::Mixin::ShellOut
+
+      # We only create these via the `not_if` or `only_if` constructors, and
+      # not the default constructor
+      class << self
+        private :new
+      end
+
+      def self.not_if(command=nil, command_opts={}, &block)
+        new(:not_if, command, command_opts, &block)
+      end
+
+      def self.only_if(command=nil, command_opts={}, &block)
+        new(:only_if, command, command_opts, &block)
+      end
+
+      attr_reader :positivity
+      attr_reader :command
+      attr_reader :command_opts
+      attr_reader :block
+
+      def initialize(positivity, command=nil, command_opts={}, &block)
+        @positivity = positivity
+        case command
+        when String
+          @command, @command_opts = command, command_opts
+          @block = nil
+        when nil
+          raise ArgumentError, "only_if/not_if requires either a command or a block" unless block_given?
+          @command, @command_opts = nil, nil
+          @block = block
+        else
+          raise ArgumentError, "Invalid only_if/not_if command: #{command.inspect} (#{command.class})"
+        end
+      end
+
+      def continue?
+        case @positivity
+        when :only_if
+          evaluate
+        when :not_if
+          !evaluate
+        else
+          raise "Cannot evaluate resource conditional of type #{@positivity}"
+        end
+      end
+
+      def evaluate
+        @command ? evaluate_command : evaluate_block
+      end
+
+      def evaluate_command
+        shell_out(@command, @command_opts).status.success?
+      rescue Chef::Exceptions::CommandTimeout
+        Chef::Log.warn "Command '#{@command}' timed out"
+        false
+      end
+
+      def evaluate_block
+        @block.call
+      end
+
+      def description
+        cmd_or_block = @command ? "command `#{@command}`" : "ruby block"
+        "#{@positivity} #{cmd_or_block}"
+      end
+
+      def to_text
+        if @command
+          "#{positivity} \"#{@command}\""
+        else
+          "#{@positivity} { #code block }"
+        end
+      end
+
+    end
+  end
+end