ipa: libipa: vector: Add mutable x(), y() and z() accessors

The x(), y() and z() functions of the Vector class are convenience
accessors for the first, second and third element of the vector
respectively, meant to improve readability of class users when a vector
represents coordinates in 1D, 2D or 3D space. Those accessors are
limited to immutable access to the vector elements, as they return a
copy. Extend the API with mutable accessors.

The immutable accessors are modified to return a reference to the vector
elements instead of a copy for consistency. As they are inline
functions, this should make no difference in terms of performance as the
compiler can perform the same optimizations in their case.

While at it, reorder functions to declare operators before other member
functions, to be consistent with the usual coding style.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Milan Zamazal <mzamazal@redhat.com>

2 files changed, 58 insertions, 42 deletions

diff --git a/src/ipa/libipa/vector.cpp b/src/ipa/libipa/vector.cpp
index bd00b019..b650fcc1 100644
--- a/src/ipa/libipa/vector.cpp
+++ b/src/ipa/libipa/vector.cpp
@@ -53,24 +53,6 @@ namespace ipa {
  */
 
 /**
- * \fn Vector::x()
- * \brief Convenience function to access the first element of the vector
- * \return The first element of the vector
- */
-
-/**
- * \fn Vector::y()
- * \brief Convenience function to access the second element of the vector
- * \return The second element of the vector
- */
-
-/**
- * \fn Vector::z()
- * \brief Convenience function to access the third element of the vector
- * \return The third element of the vector
- */
-
-/**
  * \fn Vector::operator-() const
  * \brief Negate a Vector by negating both all of its coordinates
  * \return The negated vector
@@ -112,6 +94,39 @@ namespace ipa {
  */
 
 /**
+ * \fn constexpr T &Vector::x()
+ * \brief Convenience function to access the first element of the vector
+ * \return The first element of the vector
+ */
+
+/**
+ * \fn constexpr T &Vector::y()
+ * \brief Convenience function to access the second element of the vector
+ * \return The second element of the vector
+ */
+
+/**
+ * \fn constexpr T &Vector::z()
+ * \brief Convenience function to access the third element of the vector
+ * \return The third element of the vector
+ */
+
+/**
+ * \fn constexpr const T &Vector::x() const
+ * \copydoc Vector::x()
+ */
+
+/**
+ * \fn constexpr const T &Vector::y() const
+ * \copydoc Vector::y()
+ */
+
+/**
+ * \fn constexpr const T &Vector::z() const
+ * \copydoc Vector::z()
+ */
+
+/**
  * \fn Vector::length2()
  * \brief Get the squared length of the vector
  * \return The squared length of the vector
diff --git a/src/ipa/libipa/vector.h b/src/ipa/libipa/vector.h
index 8612a06a..b91e50b2 100644
--- a/src/ipa/libipa/vector.h
+++ b/src/ipa/libipa/vector.h
@@ -53,30 +53,6 @@ public:
 		return data_[i];
 	}
 
-#ifndef __DOXYGEN__
-	template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 1>>
-#endif /* __DOXYGEN__ */
-	constexpr T x() const
-	{
-		return data_[0];
-	}
-
-#ifndef __DOXYGEN__
-	template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 2>>
-#endif /* __DOXYGEN__ */
-	constexpr T y() const
-	{
-		return data_[1];
-	}
-
-#ifndef __DOXYGEN__
-	template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 3>>
-#endif /* __DOXYGEN__ */
-	constexpr T z() const
-	{
-		return data_[2];
-	}
-
 	constexpr Vector<T, Rows> operator-() const
 	{
 		Vector<T, Rows> ret;
@@ -125,6 +101,31 @@ public:
 		return ret;
 	}
 
+#ifndef __DOXYGEN__
+	template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 1>>
+#endif /* __DOXYGEN__ */
+	constexpr const T &x() const { return data_[0]; }
+#ifndef __DOXYGEN__
+	template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 2>>
+#endif /* __DOXYGEN__ */
+	constexpr const T &y() const { return data_[1]; }
+#ifndef __DOXYGEN__
+	template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 3>>
+#endif /* __DOXYGEN__ */
+	constexpr const T &z() const { return data_[2]; }
+#ifndef __DOXYGEN__
+	template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 1>>
+#endif /* __DOXYGEN__ */
+	constexpr T &x() { return data_[0]; }
+#ifndef __DOXYGEN__
+	template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 2>>
+#endif /* __DOXYGEN__ */
+	constexpr T &y() { return data_[1]; }
+#ifndef __DOXYGEN__
+	template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 3>>
+#endif /* __DOXYGEN__ */
+	constexpr T &z() { return data_[2]; }
+
 	constexpr double length2() const
 	{
 		double ret = 0;