From 6105f44a460e5b720fd03a272cadf4b120a62bd7 Mon Sep 17 00:00:00 2001
From: Gabriel Ozouf <gabriel.ozouf@numworks.com>
Date: Mon, 21 Sep 2020 15:35:44 +0200
Subject: [PATCH] [escher/toolbox_message_tree] Add indirection

The children of a ToolboxMessageTree object can be stored as a simple
pointer, representing an array of all the children stored consecutively,
or as a double pointer, representing an array storing the addresses of
all children.

Change-Id: I10134684963aaafc635aaf9a2374d0f3c32d3d0c
---
 escher/include/escher/toolbox_message_tree.h | 38 +++++++++++++++++---
 1 file changed, 34 insertions(+), 4 deletions(-)

diff --git a/escher/include/escher/toolbox_message_tree.h b/escher/include/escher/toolbox_message_tree.h
index 835bccde5..1e17b83b0 100644
--- a/escher/include/escher/toolbox_message_tree.h
+++ b/escher/include/escher/toolbox_message_tree.h
@@ -10,7 +10,7 @@ public:
         label,
         text,
         (insertedText == (I18n::Message)0) ? label : insertedText,
-        nullptr,
+        static_cast<ToolboxMessageTree *>(0),
         0,
         stripInsertedText);
   };
@@ -24,7 +24,19 @@ public:
         N,
         true);
   }
-  const MessageTree * childAtIndex(int index) const override { return &m_children[index]; }
+  template <int N>
+  constexpr static ToolboxMessageTree Node(I18n::Message label, const ToolboxMessageTree * (&children)[N]) {
+    return ToolboxMessageTree(
+        label,
+        (I18n::Message)0,
+        (I18n::Message)0,
+        children,
+        N,
+        true);
+  }
+  const MessageTree * childAtIndex(int index) const override {
+    return m_childrenConsecutive ? m_children.m_direct + index : m_children.m_indirect[index];
+  }
   I18n::Message text() const { return m_text; }
   I18n::Message insertedText() const { return m_insertedText; }
   bool stripInsertedText() const { return m_stripInsertedText; }
@@ -34,12 +46,30 @@ private:
     m_children(children),
     m_text(text),
     m_insertedText(insertedText),
-    m_stripInsertedText(stripInsertedText)
+    m_stripInsertedText(stripInsertedText),
+    m_childrenConsecutive(true)
   {}
-  const ToolboxMessageTree * m_children;
+  constexpr ToolboxMessageTree(I18n::Message label, I18n::Message text, I18n::Message insertedText, const ToolboxMessageTree ** children, int numberOfChildren, bool stripInsertedText) :
+    MessageTree(label, numberOfChildren),
+    m_children(children),
+    m_text(text),
+    m_insertedText(insertedText),
+    m_stripInsertedText(stripInsertedText),
+    m_childrenConsecutive(false)
+  {}
+
+  union Children {
+  public:
+    constexpr Children(const ToolboxMessageTree * children) : m_direct(children) {}
+    constexpr Children(const ToolboxMessageTree ** children) : m_indirect(children) {}
+    const ToolboxMessageTree * m_direct;
+    const ToolboxMessageTree ** m_indirect;
+  };
+  const Children m_children;
   I18n::Message m_text;
   I18n::Message m_insertedText;
   bool m_stripInsertedText;
+  const bool m_childrenConsecutive;
 };
 
 #endif