1 files changed, 109 insertions, 0 deletions
diff --git a/lib/blink/elements.rb b/lib/blink/elements.rb
new file mode 100644
index 000000000..64fac9b24
--- /dev/null
+++ b/lib/blink/elements.rb
@@ -0,0 +1,109 @@
+#!/usr/local/bin/ruby -w
+
+# $Id$
+
+# the definition of our state tree
+# the base class for both leaves and branches, and the base class for each
+# of them, also
+
+require 'blink'
+require 'blink/statechange'
+
+#---------------------------------------------------------------
+class Blink::Element
+    attr_accessor :noop
+
+    #---------------------------------------------------------------
+    @@interface_methods = [
+        :retrieve, :insync?, :sync, :fqpath, :evaluate, :refresh
+    ]
+
+    @@interface_methods.each { |method|
+        self.send(:define_method,method) {
+            raise "%s has not overridden %s" % [self.class,method]
+        }
+    }
+
+    class Blink::Element::Branch
+        attr_accessor :children, :parent, :states
+
+		#---------------------------------------------------------------
+        # iterate across all children, and then iterate across states
+        # we do children first so we're sure that all dependent objects
+        # are checked first
+        def each
+            [@children,@states].each { |child|
+                yield child
+            }
+        end
+		#---------------------------------------------------------------
+
+		#---------------------------------------------------------------
+        # this method is responsible for collecting state changes
+        # we always descend into the children before we evaluate our current
+        # states
+        def evaluate(transaction)
+            self.each { |child| child.evaluate }
+        end
+		#---------------------------------------------------------------
+
+		#---------------------------------------------------------------
+        def initialize
+            @childary = []
+            @childhash = {}
+            @states = []
+            @parent = nil
+        end
+		#---------------------------------------------------------------
+
+		#---------------------------------------------------------------
+        # this method is responsible for handling changes in dependencies
+        # for instance, restarting a service if a config file is changed
+        # in general, we just hand the method up to our parent, but for
+        # objects that might need to refresh, they'll override this method
+        # XXX at this point, if all dependent objects change, then this method
+        # might get called for each change
+        def refresh(transaction)
+            unless @parent.nil?
+                @parent.refresh(transaction)
+            end
+        end
+		#---------------------------------------------------------------
+    end
+
+    #---------------------------------------------------------------
+    class Blink::Element::Leaf
+        attr_accessor :is, :should, :parent
+
+        #---------------------------------------------------------------
+        # this assumes the controlling process will actually execute the change
+        # which will demonstrably not work with states that are part of a larger
+        # whole, like FileRecordStates
+        def evaluate(transaction)
+            self.retrieve
+            transaction.change(Blink::StateChange.new(state)) unless self.insync?
+        end
+        #---------------------------------------------------------------
+
+		#---------------------------------------------------------------
+        def initialize
+            @is = nil
+            @should = nil
+            @parent = nil
+        end
+		#---------------------------------------------------------------
+
+		#---------------------------------------------------------------
+        def refresh(transaction)
+            self.retrieve
+
+            # we definitely need some way to batch these refreshes, so a
+            # given object doesn't get refreshed multiple times in a single
+            # run
+            @parent.refresh
+        end
+		#---------------------------------------------------------------
+    end
+    #---------------------------------------------------------------
+end
+#---------------------------------------------------------------