From f60a24e07da1b9948262ef0dc2f0a8ba33b8d569 Mon Sep 17 00:00:00 2001
From: Nicholas Van Sickle <nvsickle@amazon.com>
Date: Tue, 15 Feb 2022 15:55:12 -0800
Subject: [PATCH] Add support for Range-based DomPrefixTree construction, fix
 initializer_list

Signed-off-by: Nicholas Van Sickle <nvsickle@amazon.com>
---
 .../AzCore/AzCore/DOM/DomPrefixTree.h         | 22 +++++++++++++++---
 .../AzCore/AzCore/DOM/DomPrefixTree.inl       | 16 +++++++------
 .../AzCore/Tests/DOM/DomPrefixTreeTests.cpp   | 23 +++++++++++++++++++
 3 files changed, 51 insertions(+), 10 deletions(-)

diff --git a/Code/Framework/AzCore/AzCore/DOM/DomPrefixTree.h b/Code/Framework/AzCore/AzCore/DOM/DomPrefixTree.h
index 1322dbf843..4349783b8c 100644
--- a/Code/Framework/AzCore/AzCore/DOM/DomPrefixTree.h
+++ b/Code/Framework/AzCore/AzCore/DOM/DomPrefixTree.h
@@ -9,9 +9,10 @@
 #pragma once
 
 #include <AzCore/DOM/DomPath.h>
-#include <AzCore/std/containers/unordered_map.h>
 #include <AzCore/std/containers/stack.h>
+#include <AzCore/std/containers/unordered_map.h>
 #include <AzCore/std/optional.h>
+#include <AzCore/std/ranges/ranges.h>
 
 namespace AZ::Dom
 {
@@ -42,6 +43,19 @@ namespace AZ::Dom
         DomPrefixTree(const DomPrefixTree&) = default;
         DomPrefixTree(DomPrefixTree&&) = default;
         explicit DomPrefixTree(AZStd::initializer_list<AZStd::pair<Path, T>> init);
+        template<
+            class Range,
+            class = AZStd::enable_if_t<
+                AZStd::ranges::input_range<Range> &&
+                AZStd::convertible_to<AZStd::tuple_element_t<0, AZStd::ranges::range_value_t<Range>>, Path> &&
+                AZStd::convertible_to<AZStd::tuple_element_t<1, AZStd::ranges::range_value_t<Range>>, T>>>
+        explicit DomPrefixTree(Range&& range)
+        {
+            for (auto&& [path, value] : AZStd::forward<Range>(range))
+            {
+                SetValue(path, value);
+            }
+        }
 
         DomPrefixTree& operator=(const DomPrefixTree&) = default;
         DomPrefixTree& operator=(DomPrefixTree&&) = default;
@@ -55,10 +69,12 @@ namespace AZ::Dom
         //! \see ValueAtPath
         const T* ValueAtPath(const Path& path, PrefixTreeMatch match) const;
         //! Visits a path and returns the most specific matching value or some default value.
-        T ValueAtPathOrDefault(const Path& path, T&& defaultValue, PrefixTreeMatch match) const;
+        template<class Deduced>
+        T ValueAtPathOrDefault(const Path& path, Deduced&& defaultValue, PrefixTreeMatch match) const;
 
         //! Sets the value stored at path.
-        void SetValue(const Path& path, T&& value);
+        template<class Deduced>
+        void SetValue(const Path& path, Deduced&& value);
         //! Removes the value stored at path. If removeChildren is true, also removes any values stored at subpaths.
         void EraseValue(const Path& path, bool removedChildren = false);
         //! Removes all entries from this tree.
diff --git a/Code/Framework/AzCore/AzCore/DOM/DomPrefixTree.inl b/Code/Framework/AzCore/AzCore/DOM/DomPrefixTree.inl
index be129aa3e0..ea8745413c 100644
--- a/Code/Framework/AzCore/AzCore/DOM/DomPrefixTree.inl
+++ b/Code/Framework/AzCore/AzCore/DOM/DomPrefixTree.inl
@@ -13,9 +13,9 @@ namespace AZ::Dom
     template<class T>
     DomPrefixTree<T>::DomPrefixTree(AZStd::initializer_list<AZStd::pair<Path, T>> init)
     {
-        for (const auto& entry : init)
+        for (const auto& [path, value] : init)
         {
-            SetValue(entry.first, entry.second);
+            SetValue(path, value);
         }
     }
 
@@ -158,7 +158,7 @@ namespace AZ::Dom
         return result;
     }
 
-    template <class T>
+    template<class T>
     const T* DomPrefixTree<T>::ValueAtPath(const Path& path, PrefixTreeMatch match) const
     {
         // Const coerce the ValueAtPath result, which doesn't mutate but returns a mutable pointer
@@ -166,14 +166,16 @@ namespace AZ::Dom
     }
 
     template<class T>
-    T DomPrefixTree<T>::ValueAtPathOrDefault(const Path& path, T&& defaultValue, PrefixTreeMatch match) const
+    template<class Deduced>
+    T DomPrefixTree<T>::ValueAtPathOrDefault(const Path& path, Deduced&& defaultValue, PrefixTreeMatch match) const
     {
         const T* value = ValueAtPath(path, match);
-        return value == nullptr ? AZStd::forward<T>(defaultValue) : *value;
+        return value == nullptr ? AZStd::forward<Deduced>(defaultValue) : *value;
     }
 
     template<class T>
-    void DomPrefixTree<T>::SetValue(const Path& path, T&& value)
+    template<class Deduced>
+    void DomPrefixTree<T>::SetValue(const Path& path, Deduced&& value)
     {
         Node* node = &m_rootNode;
         for (const PathEntry& entry : path)
@@ -181,7 +183,7 @@ namespace AZ::Dom
             // Get or create an entry in this node
             node = &node->m_values[entry];
         }
-        node->m_data = AZStd::forward<T>(value);
+        node->m_data = AZStd::forward<Deduced>(value);
     }
 
     template<class T>
diff --git a/Code/Framework/AzCore/Tests/DOM/DomPrefixTreeTests.cpp b/Code/Framework/AzCore/Tests/DOM/DomPrefixTreeTests.cpp
index 49496b44f8..e79c18aa72 100644
--- a/Code/Framework/AzCore/Tests/DOM/DomPrefixTreeTests.cpp
+++ b/Code/Framework/AzCore/Tests/DOM/DomPrefixTreeTests.cpp
@@ -13,6 +13,29 @@ namespace AZ::Dom::Tests
 {
     using DomPrefixTreeTests = DomTestFixture;
 
+    TEST_F(DomPrefixTreeTests, InitializeFromInitializerList)
+    {
+        DomPrefixTree<int> tree({
+            { Path(), 0 },
+            { Path("/foo/bar"), 1 },
+        });
+
+        EXPECT_EQ(0, *tree.ValueAtPath(Path(), PrefixTreeMatch::ExactPath));
+        EXPECT_EQ(1, *tree.ValueAtPath(Path("/foo/bar"), PrefixTreeMatch::ExactPath));
+    }
+
+    TEST_F(DomPrefixTreeTests, InitializeFromRange)
+    {
+        AZStd::vector<AZStd::pair<Path, int>> container({
+            { Path(), 21 },
+            { Path("/foo/bar"), 42 },
+        });
+        DomPrefixTree<int> tree(container);
+
+        EXPECT_EQ(21, *tree.ValueAtPath(Path(), PrefixTreeMatch::ExactPath));
+        EXPECT_EQ(42, *tree.ValueAtPath(Path("/foo/bar"), PrefixTreeMatch::ExactPath));
+    }
+
     TEST_F(DomPrefixTreeTests, GetAndSetRoot)
     {
         DomPrefixTree<AZStd::string> tree;