From ee3e8c46dcf226705f1b8c3eb5df49c405337d66 Mon Sep 17 00:00:00 2001
From: Paul Beckingham <paul@beckingham.net>
Date: Fri, 28 Apr 2017 12:42:19 -0400
Subject: [PATCH] DOM: Stubbed DOM tree

---
 src/DOM.cpp | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/DOM.h   | 17 +++++++++++++
 2 files changed, 86 insertions(+)

diff --git a/src/DOM.cpp b/src/DOM.cpp
index 8fd8c7274..06f770e53 100644
--- a/src/DOM.cpp
+++ b/src/DOM.cpp
@@ -435,3 +435,72 @@ bool getDOM (const std::string& name, const Task& task, Variant& value)
 }
 
 ////////////////////////////////////////////////////////////////////////////////
+// DOM Class
+//
+// References are paths into a tree structure. For example:
+//
+//   1.due.month.number
+//   1.due.day.number
+//
+// Are represented internally as:
+//
+//   1
+//   +- due
+//     +- day
+//     | +- number
+//     +- month
+//       +- number
+//
+// The tree is augmented by other elements:
+//
+//   1
+//   +- due
+//   | +- day
+//   | | +- number
+//   | +- month
+//   |   +- number
+//   +- system
+//      +- os
+//
+// Each node in the tree has a name ("due", "system", "day"), and each node may
+// have a data source attached to it.
+//
+// The DOM class is independent of the project, in that it knows nothing about
+// the internal data or program structure. It knows only that certain DOM path
+// elements have handlers which will provide the data.
+//
+// The DOM class is therefore responsible for maintaining a tree of named nodes
+// with associated proividers. When a reference value is requested, the DOM
+// class will decompose the reference path, and navigate the tree to the lowest
+// level provider, and call it.
+//
+// This makes the DOM class a reusible object.
+
+////////////////////////////////////////////////////////////////////////////////
+bool DOM::valid (const std::string& reference) const
+{
+  return false;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+Variant DOM::get (const std::string& reference) const
+{
+  Variant v ("");
+
+  // Find the provider.
+  // TODO Start at the root of the tree.
+  for (const auto& element : decomposeReference (reference))
+  {
+    // TODO If tree contains a named node 'element', capture the provider, if any.
+  }
+
+  return v;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+std::vector <std::string> DOM::decomposeReference (const std::string& reference) const
+{
+  return split (reference, '.');
+}
+
+////////////////////////////////////////////////////////////////////////////////
diff --git a/src/DOM.h b/src/DOM.h
index f1cdef7a6..2f6d0704e 100644
--- a/src/DOM.h
+++ b/src/DOM.h
@@ -28,10 +28,27 @@
 #define INCLUDED_DOM
 
 #include <string>
+#include <Tree.h>
 #include <Variant.h>
 #include <Task.h>
 
+// 2017-04-22 Deprecated.
 bool getDOM (const std::string&, Variant&);
 bool getDOM (const std::string&, const Task&, Variant&);
 
+// DOM Tree
+class DOM;
+
+class DOM
+{
+public:
+  void addSource (const std::string&, bool (*)(const std::string&, Variant&));
+  bool valid (const std::string&) const;
+  Variant get (const Task&, const std::string&) const;
+  Variant get (const std::string&) const;
+
+private:
+  std::vector <std::string> decomposeReference (const std::string&) const;
+};
+
 #endif