From 49aa81b9ec5bdc3e9429540d0074a5f36a95234f Mon Sep 17 00:00:00 2001
From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Date: Fri, 17 Oct 2025 21:53:34 +0300
Subject: [PATCH] libcamera: value_node: Rework templates to prepare for
 mutable views
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ValueNode provides adapter classes to expose the object as an iteratable
list or dictionary. The Iterator and Adapter classes hardcode the
assumption that the ValueNode is const. To prepare for mutable views,
move the const specifier to the top-level DictAdapter and ListAdapter
class templates.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>
Reviewed-by: Isaac Scott <isaac.scott@ideasonboard.com>
---
 include/libcamera/internal/value_node.h | 54 ++++++++++++++++---------
 1 file changed, 35 insertions(+), 19 deletions(-)

diff --git a/include/libcamera/internal/value_node.h b/include/libcamera/internal/value_node.h
index bcf2c8ec..16e6660e 100644
--- a/include/libcamera/internal/value_node.h
+++ b/include/libcamera/internal/value_node.h
@@ -38,14 +38,14 @@ private:
 
 public:
 #ifndef __DOXYGEN__
-	template<typename Derived>
+	template<typename Derived, typename ContainerIterator>
 	class Iterator
 	{
 	public:
 		using difference_type = std::ptrdiff_t;
 		using iterator_category = std::forward_iterator_tag;
 
-		Iterator(typename ValueContainer::const_iterator it)
+		Iterator(ContainerIterator it)
 			: it_(it)
 		{
 		}
@@ -74,14 +74,14 @@ public:
 		}
 
 	protected:
-		ValueContainer::const_iterator it_;
+		ContainerIterator it_;
 	};
 
-	template<typename Iterator>
+	template<typename Iterator, typename Container>
 	class Adapter
 	{
 	public:
-		Adapter(const ValueContainer &container)
+		Adapter(Container &container)
 			: container_(container)
 		{
 		}
@@ -97,47 +97,63 @@ public:
 		}
 
 	protected:
-		const ValueContainer &container_;
+		Container &container_;
 	};
 
-	class ListIterator : public Iterator<ListIterator>
+	template<typename Value, typename ContainerIterator>
+	class ListIterator : public Iterator<ListIterator<Value, ContainerIterator>,
+					     ContainerIterator>
 	{
-	public:
-		using value_type = const ValueNode &;
-		using pointer = const ValueNode *;
-		using reference = value_type;
+	private:
+		using Base = Iterator<ListIterator<Value, ContainerIterator>,
+				      ContainerIterator>;
 
-		value_type operator*() const
+	public:
+		using value_type = Value;
+		using pointer = value_type *;
+		using reference = value_type &;
+
+		reference operator*() const
 		{
-			return *it_->value.get();
+			return *Base::it_->value.get();
 		}
 
 		pointer operator->() const
 		{
-			return it_->value.get();
+			return Base::it_->value.get();
 		}
 	};
 
-	class DictIterator : public Iterator<DictIterator>
+	template<typename Value, typename ContainerIterator>
+	class DictIterator : public Iterator<DictIterator<Value, ContainerIterator>,
+					     ContainerIterator>
 	{
+	private:
+		using Base = Iterator<DictIterator<Value, ContainerIterator>,
+				      ContainerIterator>;
+
 	public:
-		using value_type = std::pair<const std::string &, const ValueNode &>;
+		using value_type = std::pair<const std::string &, Value &>;
 		using pointer = value_type *;
 		using reference = value_type &;
 
 		value_type operator*() const
 		{
-			return { it_->key, *it_->value.get() };
+			return { Base::it_->key, *Base::it_->value.get() };
 		}
 	};
 
-	class DictAdapter : public Adapter<DictIterator>
+	class DictAdapter : public Adapter<DictIterator<const ValueNode,
+							ValueContainer::const_iterator>,
+					   const ValueContainer>
 	{
 	public:
 		using key_type = std::string;
 	};
 
-	class ListAdapter : public Adapter<ListIterator>
+	class ListAdapter : public Adapter<ListIterator<const ValueNode,
+							ValueContainer::const_iterator>,
+					   const ValueContainer>
 	{
 	};
 #endif /* __DOXYGEN__ */