From c3dd709c0a625f896241791c1386aa77a3cdfa10 Mon Sep 17 00:00:00 2001
From: Jack Wrenn <me@jswrenn.com>
Date: Sat, 10 Nov 2018 18:02:52 -0500
Subject: [PATCH] Implements `Extend` for `Matrix<N, Dim, Dynamic>`.

Extends a matrix with new columns populated from an iterator.
---
 src/base/edition.rs    | 48 ++++++++++++++++++++++++++++++++++++++++++
 src/base/matrix_vec.rs | 18 ++++++++++++++++
 2 files changed, 66 insertions(+)

diff --git a/src/base/edition.rs b/src/base/edition.rs
index 0ae9c35f..4a99b77f 100644
--- a/src/base/edition.rs
+++ b/src/base/edition.rs
@@ -703,3 +703,51 @@ unsafe fn extend_rows<N: Scalar>(
         );
     }
 }
+
+/// Extend the number of columns of the `Matrix` with elements from
+/// a given iterator.
+impl<N, R, S> Extend<N> for Matrix<N, R, Dynamic, S>
+where
+    N: Scalar,
+    R: Dim,
+    S: Extend<N>,
+{
+    /// Extend the number of columns of the `Matrix` with elements
+    /// from the given iterator.
+    ///
+    /// # Example
+    /// ```
+    /// use nalgebra::{Dynamic, Matrix, MatrixMN, Matrix3};
+    ///
+    /// let data = vec![0, 1, 2,      // column 1
+    ///                 3, 4, 5];     // column 2
+    ///
+    /// let mut matrix : MatrixMN<_, Dynamic, Dynamic> =
+    ///   Matrix::from_vec_generic(Dynamic::new(3), Dynamic::new(2), data);
+    ///
+    /// matrix.extend(vec![6, 7, 8]); // column 3
+    ///
+    /// assert!(matrix.eq(&Matrix3::new(0, 3, 6,
+    ///                                 1, 4, 7,
+    ///                                 2, 5, 8)));
+    /// ```
+    ///
+    /// # Panics
+    /// This function panics if the number of elements yielded by the
+    /// given iterator is not a multiple of the number of rows of the
+    /// `Matrix`.
+    ///
+    /// ```should_panic
+    /// # use nalgebra::{Dynamic, Matrix, MatrixMN, Matrix3, U3};
+    /// let data = vec![0, 1, 2,  // column 1
+    ///                 3, 4, 5]; // column 2
+    ///
+    /// let mut matrix : MatrixMN<_, U3, Dynamic> =
+    ///   Matrix::from_vec_generic(U3, Dynamic::new(2), data);
+    ///
+    /// matrix.extend(vec![6, 7, 8, 9]); // column 3
+    /// ```
+    fn extend<I: IntoIterator<Item=N>>(&mut self, iter: I) {
+        self.data.extend(iter);
+    }
+}
diff --git a/src/base/matrix_vec.rs b/src/base/matrix_vec.rs
index 73b77609..8dfd940e 100644
--- a/src/base/matrix_vec.rs
+++ b/src/base/matrix_vec.rs
@@ -240,3 +240,21 @@ unsafe impl<N: Scalar, R: DimName> ContiguousStorage<N, R, Dynamic> for MatrixVe
 
 unsafe impl<N: Scalar, R: DimName> ContiguousStorageMut<N, R, Dynamic> for MatrixVec<N, R, Dynamic> where DefaultAllocator: Allocator<N, R, Dynamic, Buffer = Self>
 {}
+
+impl<N, R: Dim> Extend<N> for MatrixVec<N, R, Dynamic>
+{
+    /// Extends the number of columns of the `MatrixVec` with elements
+    /// from the given iterator.
+    ///
+    /// # Panics
+    /// This function panics if the number of elements yielded by the
+    /// given iterator is not a multiple of the number of rows of the
+    /// `MatrixVec`.
+    fn extend<I: IntoIterator<Item=N>>(&mut self, iter: I)
+    {
+        self.data.extend(iter);
+        self.ncols = Dynamic::new(self.data.len() / self.nrows.value());
+        assert!(self.data.len() % self.nrows.value() == 0,
+          "The number of elements produced by the given iterator was not a multiple of the number of rows.");
+    }
+}