From 0d78367b9abbb2468c398d51e11cc8f0573112e2 Mon Sep 17 00:00:00 2001
From: dehnert <dehnert@cs.rwth-aachen.de>
Date: Tue, 28 Nov 2017 08:53:24 +0100
Subject: [PATCH] Catching empty selection in getSubmatrix pointed out by Timo
 Gros

---
 src/storm/storage/SparseMatrix.cpp          | 1 +
 src/test/storm/storage/SparseMatrixTest.cpp | 8 +++++---
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/storm/storage/SparseMatrix.cpp b/src/storm/storage/SparseMatrix.cpp
index d4c9ba5ad..9d92d5e35 100644
--- a/src/storm/storage/SparseMatrix.cpp
+++ b/src/storm/storage/SparseMatrix.cpp
@@ -892,6 +892,7 @@ namespace storm {
         
         template<typename ValueType>
         SparseMatrix<ValueType> SparseMatrix<ValueType>::getSubmatrix(storm::storage::BitVector const& rowGroupConstraint, storm::storage::BitVector const& columnConstraint, std::vector<index_type> const& rowGroupIndices, bool insertDiagonalEntries) const {
+            STORM_LOG_THROW(!rowGroupConstraint.empty() && !columnConstraint.empty(), storm::exceptions::InvalidArgumentException, "Cannot build empty submatrix.");
             uint_fast64_t submatrixColumnCount = columnConstraint.getNumberOfSetBits();
             
             // Start by creating a temporary vector that stores for each index whose bit is set to true the number of
diff --git a/src/test/storm/storage/SparseMatrixTest.cpp b/src/test/storm/storage/SparseMatrixTest.cpp
index 1b468c318..1cb2ae9ca 100644
--- a/src/test/storm/storage/SparseMatrixTest.cpp
+++ b/src/test/storm/storage/SparseMatrixTest.cpp
@@ -331,13 +331,15 @@ TEST(SparseMatrix, Submatrix) {
     storm::storage::SparseMatrix<double> matrix;
     ASSERT_NO_THROW(matrix = matrixBuilder.build());
 
+    storm::storage::BitVector rowGroupConstraint(4);
+    storm::storage::BitVector columnConstraint(4);
+
+    ASSERT_THROW(matrix.getSubmatrix(true, rowGroupConstraint, columnConstraint), storm::exceptions::InvalidArgumentException);
+
     std::vector<uint_fast64_t> rowGroupIndices = {0, 1, 2, 4, 5};
     
-    storm::storage::BitVector rowGroupConstraint(4);
     rowGroupConstraint.set(2);
     rowGroupConstraint.set(3);
-    
-    storm::storage::BitVector columnConstraint(4);
     columnConstraint.set(0);
     columnConstraint.set(3);