Merge pull request #5163 from vespa-engine/havardpe/unconstify

added unconstify for ConstArrayRef -> ArrayRef conversion

4 files changed, 71 insertions, 0 deletions

diff --git a/vespalib/CMakeLists.txt b/vespalib/CMakeLists.txt
index 9e11562c0b0..9ef6daea91c 100644
--- a/vespalib/CMakeLists.txt
+++ b/vespalib/CMakeLists.txt
@@ -17,6 +17,7 @@ vespa_define_module(
     src/tests/approx
     src/tests/array
     src/tests/arrayqueue
+    src/tests/arrayref
     src/tests/barrier
     src/tests/benchmark_timer
     src/tests/box
diff --git a/vespalib/src/tests/arrayref/CMakeLists.txt b/vespalib/src/tests/arrayref/CMakeLists.txt
new file mode 100644
index 00000000000..c851ff3e277
--- /dev/null
+++ b/vespalib/src/tests/arrayref/CMakeLists.txt
@@ -0,0 +1,8 @@
+# Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+vespa_add_executable(vespalib_arrayref_test_app TEST
+    SOURCES
+    arrayref_test.cpp
+    DEPENDS
+    vespalib
+)
+vespa_add_test(NAME vespalib_arrayref_test_app COMMAND vespalib_arrayref_test_app)
diff --git a/vespalib/src/tests/arrayref/arrayref_test.cpp b/vespalib/src/tests/arrayref/arrayref_test.cpp
new file mode 100644
index 00000000000..ad11d9b6ba4
--- /dev/null
+++ b/vespalib/src/tests/arrayref/arrayref_test.cpp
@@ -0,0 +1,56 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#include <vespa/vespalib/testkit/test_kit.h>
+#include <vespa/vespalib/util/arrayref.h>
+
+using namespace vespalib;
+
+TEST("require that default constructors create references to empty arrays") {
+    ArrayRef<int> array_ref;
+    ConstArrayRef<int> const_ref;
+    EXPECT_EQUAL(array_ref.size(), 0u);
+    EXPECT_EQUAL(array_ref.begin(), array_ref.end());
+    EXPECT_EQUAL(const_ref.size(), 0u);
+    EXPECT_EQUAL(const_ref.begin(), const_ref.end());
+}
+
+TEST("require that data can be referenced") {
+    std::vector<int> data({1,2,3});
+    ArrayRef<int> array_ref(data);
+    ConstArrayRef<int> const_ref(data);
+    EXPECT_EQUAL(array_ref.size(), 3u);
+    EXPECT_EQUAL(array_ref.end() - array_ref.begin(), 3);
+    EXPECT_EQUAL(array_ref[1], 2);
+    EXPECT_EQUAL(const_ref.size(), 3u);
+    EXPECT_EQUAL(const_ref.end() - const_ref.begin(), 3);
+    EXPECT_EQUAL(const_ref[2], 3);
+}
+
+TEST("require that non-const array ref can be written to") {
+    std::vector<int> data({1,2,3});
+    ArrayRef<int> array_ref(data);
+    array_ref[1] = 5;
+    EXPECT_EQUAL(data[1], 5);
+}
+
+TEST("require that references can be constified") {
+    std::vector<int> data({1,2,3});
+    const ArrayRef<int> array_ref(data);
+    ConstArrayRef<int> const_ref(array_ref);
+    EXPECT_EQUAL(const_ref.size(), 3u);
+    EXPECT_EQUAL(const_ref.end() - const_ref.begin(), 3);
+    EXPECT_EQUAL(const_ref[2], 3);    
+}
+
+TEST("require that references can be unconstified") {
+    std::vector<int> data({1,2,3});
+    const ConstArrayRef<int> const_ref(data);
+    ArrayRef<int> array_ref = unconstify(const_ref);
+    EXPECT_EQUAL(array_ref.size(), 3u);
+    EXPECT_EQUAL(array_ref.end() - array_ref.begin(), 3);
+    EXPECT_EQUAL(array_ref[1], 2);
+    array_ref[1] = 5;
+    EXPECT_EQUAL(data[1], 5);
+}
+
+TEST_MAIN() { TEST_RUN_ALL(); }
diff --git a/vespalib/src/vespa/vespalib/util/arrayref.h b/vespalib/src/vespa/vespalib/util/arrayref.h
index edda3d7b0c6..186316c10d3 100644
--- a/vespalib/src/vespa/vespalib/util/arrayref.h
+++ b/vespalib/src/vespa/vespalib/util/arrayref.h
@@ -46,4 +46,10 @@ private:
     size_t   _sz;
 };
 
+// const-cast for array references; use with care
+template <typename T>
+ArrayRef<T> unconstify(const ConstArrayRef<T> &ref) {
+    return ArrayRef<T>(const_cast<T*>(&ref[0]), ref.size());
+}
+
 }