Containers: better diagnostics for ArrayView::slice() assertions.

Python-like. I like.
mosra · Mar 29, 2017 · 0bd7984 · 0bd7984
1 parent 2b688e5
commit 0bd7984
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Showing 2 changed files with 13 additions and 6 deletions.
diff --git a/src/Corrade/Containers/ArrayView.h b/src/Corrade/Containers/ArrayView.h
@@ -560,13 +560,19 @@ template<class U, std::size_t size, class T> StaticArrayView<size*sizeof(T)/size
 
 template<class T> ArrayView<T> ArrayView<T>::slice(T* begin, T* end) const {
     CORRADE_ASSERT(_data <= begin && begin <= end && end <= _data + _size,
-        "Containers::ArrayView::slice(): slice out of range", nullptr);
+        "Containers::ArrayView::slice(): slice [" << Utility::Debug::nospace
+        << begin - _data << Utility::Debug::nospace << ":"
+        << Utility::Debug::nospace << end - _data << Utility::Debug::nospace
+        << "] out of range for" << _size << "elements", nullptr);
     return ArrayView<T>{begin, std::size_t(end - begin)};
 }
 
 template<class T> template<std::size_t viewSize> StaticArrayView<viewSize, T> ArrayView<T>::slice(T* begin) const {
     CORRADE_ASSERT(_data <= begin && begin + viewSize <= _data + _size,
-        "Containers::ArrayView::slice(): slice out of range", nullptr);
+        "Containers::ArrayView::slice(): slice [" << Utility::Debug::nospace
+        << begin - _data << Utility::Debug::nospace << ":"
+        << Utility::Debug::nospace << begin + viewSize - _data << Utility::Debug::nospace
+        << "] out of range for" << _size << "elements", nullptr);
     return StaticArrayView<viewSize, T>{begin};
 }
 

diff --git a/src/Corrade/Containers/Test/ArrayViewTest.cpp b/src/Corrade/Containers/Test/ArrayViewTest.cpp
@@ -305,10 +305,11 @@ void ArrayViewTest::sliceInvalid() {
     a.slice(a + 2, a + 1);
     a.slice<5>(1);
 
-    CORRADE_COMPARE(out.str(), "Containers::ArrayView::slice(): slice out of range\n"
-                               "Containers::ArrayView::slice(): slice out of range\n"
-                               "Containers::ArrayView::slice(): slice out of range\n"
-                               "Containers::ArrayView::slice(): slice out of range\n");
+    CORRADE_COMPARE(out.str(),
+        "Containers::ArrayView::slice(): slice [-1:0] out of range for 5 elements\n"
+        "Containers::ArrayView::slice(): slice [5:6] out of range for 5 elements\n"
+        "Containers::ArrayView::slice(): slice [2:1] out of range for 5 elements\n"
+        "Containers::ArrayView::slice(): slice [1:6] out of range for 5 elements\n");
 }
 
 void ArrayViewTest::sliceNullptr() {