Fix things mentioned during code review

Ref: https://github.com/dolphin-emu/dolphin/pull/4917

Source/Core/Common/Config/Layer.cpp

@@ -0,0 +1,148 @@
+// Copyright 2016 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#include <algorithm>
+#include <cstring>
+#include <map>
+
+#include "Common/Config/Config.h"
+#include "Common/Config/Layer.h"
+#include "Common/Config/Section.h"
+
+namespace Config
+{
+ConfigLayerLoader::ConfigLayerLoader(LayerType layer) : m_layer(layer)
+{
+}
+
+ConfigLayerLoader::~ConfigLayerLoader() = default;
+
+LayerType ConfigLayerLoader::GetLayer() const
+{
+  return m_layer;
+}
+
+Layer::Layer(LayerType type) : m_layer(type)
+{
+}
+
+Layer::Layer(std::unique_ptr<ConfigLayerLoader> loader)
+    : m_layer(loader->GetLayer()), m_loader(std::move(loader))
+{
+  Load();
+}
+
+Layer::~Layer()
+{
+  Save();
+}
+
+bool Layer::Exists(System system, const std::string& section_name, const std::string& key)
+{
+  Section* section = GetSection(system, section_name);
+  if (!section)
+    return false;
+  return section->Exists(key);
+}
+
+bool Layer::DeleteKey(System system, const std::string& section_name, const std::string& key)
+{
+  Section* section = GetSection(system, section_name);
+  if (!section)
+    return false;
+  return section->Delete(key);
+}
+
+Section* Layer::GetSection(System system, const std::string& section_name)
+{
+  for (auto& section : m_sections[system])
+    if (!strcasecmp(section.m_name.c_str(), section_name.c_str()))
+      return &section;
+  return nullptr;
+}
+
+Section* Layer::GetOrCreateSection(System system, const std::string& section_name)
+{
+  Section* section = GetSection(system, section_name);
+  if (!section)
+  {
+    if (m_layer == LayerType::Meta)
+      m_sections[system].emplace_back(RecursiveSection(m_layer, system, section_name));
+    else
+      m_sections[system].emplace_back(Section(m_layer, system, section_name));
+    section = &m_sections[system].back();
+  }
+  return section;
+}
+
+void Layer::Load()
+{
+  if (m_loader)
+    m_loader->Load(this);
+  ClearDirty();
+  InvokeConfigChangedCallbacks();
+}
+
+void Layer::Save()
+{
+  if (!m_loader || !IsDirty())
+    return;
+
+  m_loader->Save(this);
+  ClearDirty();
+  InvokeConfigChangedCallbacks();
+}
+
+LayerType Layer::GetLayer() const
+{
+  return m_layer;
+}
+
+const LayerMap& Layer::GetLayerMap() const
+{
+  return m_sections;
+}
+
+ConfigLayerLoader* Layer::GetLoader() const
+{
+  return m_loader.get();
+}
+
+bool Layer::IsDirty() const
+{
+  return std::any_of(m_sections.begin(), m_sections.end(), [](const auto& system) {
+    return std::any_of(system.second.begin(), system.second.end(),
+                       [](const auto& section) { return section.IsDirty(); });
+  });
+}
+
+void Layer::ClearDirty()
+{
+  std::for_each(m_sections.begin(), m_sections.end(), [](auto& system) {
+    std::for_each(system.second.begin(), system.second.end(),
+                  [](auto& section) { section.ClearDirty(); });
+  });
+}
+
+RecursiveLayer::RecursiveLayer() : Layer(LayerType::Meta)
+{
+}
+
+Section* RecursiveLayer::GetSection(System system, const std::string& section_name)
+{
+  // Always queries backwards recursively, so it doesn't matter if it exists or not on this layer
+  return GetOrCreateSection(system, section_name);
+}
+
+Section* RecursiveLayer::GetOrCreateSection(System system, const std::string& section_name)
+{
+  Section* section = Layer::GetSection(system, section_name);
+  if (!section)
+  {
+    m_sections[system].emplace_back(RecursiveSection(m_layer, system, section_name));
+    section = &m_sections[system].back();
+  }
+  return section;
+}
+}