[libcamera-devel] [PATCH v3 01/16] libcamera: controls: Add a function to merge two control lists

[Jacopo Mondi]

From: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

Add a new ControlList::merge() function to merge two control lists. The
semantics is identical to std::unordered_map::merge(). This can be used
by pipeline handlers to merge metadata they populate with metadata
received from an IPA.

Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---
 include/libcamera/controls.h |  2 ++
 src/libcamera/controls.cpp   | 20 ++++++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/include/libcamera/controls.h b/include/libcamera/controls.h
index 1a5690a5ccbe..16726ce9b1ed 100644
--- a/include/libcamera/controls.h
+++ b/include/libcamera/controls.h
@@ -363,7 +363,9 @@ public:
 
 	bool empty() const { return controls_.empty(); }
 	std::size_t size() const { return controls_.size(); }
+
 	void clear() { controls_.clear(); }
+	void merge(ControlList &source);
 
 	bool contains(const ControlId &id) const;
 	bool contains(unsigned int id) const;
diff --git a/src/libcamera/controls.cpp b/src/libcamera/controls.cpp
index c58ed3946f3b..58555ea64c95 100644
--- a/src/libcamera/controls.cpp
+++ b/src/libcamera/controls.cpp
@@ -874,6 +874,26 @@ ControlList::ControlList(const ControlInfoMap &infoMap, ControlValidator *valida
  * \brief Removes all controls from the list
  */
 
+/**
+ * \brief Merge the \a source into the ControlList
+ * \param[in] source The ControlList to merge into this object
+ *
+ * Merging two control lists extracts elements from the \a source and insert
+ * them in *this. If the \a source contains elements whose key is already
+ * present in *this, then those elements are not extracted. The semantics is
+ * identical to std::unordered_map::merge() in that only internal pointers to
+ * nodes are updated, without copying or moving the elements.
+ *
+ * Only control lists created from the same ControlIdMap or ControlInfoMap may
+ * be merged. Attempting to do otherwise results in undefined behaviour.
+ */
+void ControlList::merge(ControlList &source)
+{
+	ASSERT(idmap_ == source.idmap_);
+
+	controls_.merge(source.controls_);
+}
+
 /**
  * \brief Check if the list contains a control with the specified \a id
  * \param[in] id The control ID
-- 
2.31.1