handle/copyable: Implement copyable handle

This is a generic handle type that holds a resource and uses RAII to
call a user defined function when the resource is copied or destroyed.

Tested:
    Built and run through unit tests.

Change-Id: I3d23544b2e7c8d8c6686effc03b3b7433ea18bf5
Signed-off-by: William A. Kennington III <wak@google.com>

1 files changed, 347 insertions, 0 deletions

diff --git a/test/handle/copyable.cpp b/test/handle/copyable.cpp
new file mode 100644
index 0000000..6ce210f
--- /dev/null
+++ b/test/handle/copyable.cpp
@@ -0,0 +1,347 @@
+#include <gtest/gtest.h>
+#include <optional>
+#include <stdplus/handle/copyable.hpp>
+#include <string>
+#include <utility>
+#include <vector>
+
+namespace stdplus
+{
+namespace
+{
+
+static std::vector<int> reffed;
+static int stored_ref = 0;
+static std::vector<int> dropped;
+static int stored_drop = 0;
+
+int ref(const int& i)
+{
+    reffed.push_back(i);
+    return i + 1;
+}
+
+void drop(int&& i)
+{
+    dropped.push_back(std::move(i));
+}
+
+int ref(const int& i, std::string&, int& si)
+{
+    reffed.push_back(i);
+    // Make sure we can update the stored data
+    stored_ref = si++;
+    return i + 1;
+}
+
+void drop(int&& i, std::string&, int& si)
+{
+    dropped.push_back(std::move(i));
+    // Make sure we can update the stored data
+    stored_drop = si++;
+}
+
+using SimpleHandle = Copyable<int>::Handle<drop, ref>;
+using StoreHandle = Copyable<int, std::string, int>::Handle<drop, ref>;
+
+class CopyableHandleTest : public ::testing::Test
+{
+  protected:
+    void SetUp()
+    {
+        reffed.clear();
+        dropped.clear();
+    }
+
+    void TearDown()
+    {
+        EXPECT_TRUE(reffed.empty());
+        EXPECT_TRUE(dropped.empty());
+    }
+};
+
+TEST_F(CopyableHandleTest, EmptyNoStorage)
+{
+    SimpleHandle h(std::nullopt);
+    EXPECT_FALSE(h);
+    EXPECT_THROW(h.value(), std::bad_optional_access);
+    h.reset();
+    EXPECT_FALSE(h);
+    EXPECT_THROW(h.value(), std::bad_optional_access);
+}
+
+TEST_F(CopyableHandleTest, EmptyWithStorage)
+{
+    auto maybeV = std::nullopt;
+    StoreHandle h(maybeV, "str", 5);
+    EXPECT_FALSE(h);
+    EXPECT_THROW(h.value(), std::bad_optional_access);
+    h.reset(maybeV);
+    EXPECT_FALSE(h);
+    EXPECT_THROW(h.value(), std::bad_optional_access);
+}
+
+TEST_F(CopyableHandleTest, SimplePopulated)
+{
+    constexpr int expected = 3;
+    {
+        int val = expected;
+        SimpleHandle h(std::move(val));
+        EXPECT_TRUE(h);
+        EXPECT_EQ(expected, *h);
+        EXPECT_EQ(expected, h.value());
+        EXPECT_TRUE(dropped.empty());
+    }
+    EXPECT_EQ(std::vector{expected}, dropped);
+    dropped.clear();
+}
+
+TEST_F(CopyableHandleTest, OptionalPopulated)
+{
+    constexpr int expected = 3;
+    {
+        std::optional<int> maybeVal{expected};
+        SimpleHandle h(std::move(maybeVal));
+        EXPECT_TRUE(h);
+        EXPECT_EQ(expected, *h);
+        EXPECT_EQ(expected, h.value());
+        EXPECT_TRUE(dropped.empty());
+    }
+    EXPECT_TRUE(reffed.empty());
+    EXPECT_EQ(std::vector{expected}, dropped);
+    dropped.clear();
+    {
+        const std::optional<int> maybeVal{expected};
+        SimpleHandle h(maybeVal);
+        EXPECT_TRUE(h);
+        EXPECT_EQ(expected + 1, *h);
+        EXPECT_EQ(expected + 1, h.value());
+        EXPECT_EQ(std::vector{expected}, reffed);
+        reffed.clear();
+        EXPECT_TRUE(dropped.empty());
+    }
+    EXPECT_EQ(std::vector{expected + 1}, dropped);
+    dropped.clear();
+}
+
+TEST_F(CopyableHandleTest, SimplePopulatedWithStorage)
+{
+    constexpr int expected = 3;
+    {
+        StoreHandle h(expected, std::string{"str"}, 5);
+        EXPECT_TRUE(h);
+        EXPECT_EQ(expected + 1, *h);
+        EXPECT_EQ(expected + 1, h.value());
+        EXPECT_EQ(5, stored_ref);
+        EXPECT_EQ(std::vector{expected}, reffed);
+        reffed.clear();
+        EXPECT_TRUE(dropped.empty());
+    }
+    EXPECT_EQ(6, stored_drop);
+    EXPECT_EQ(std::vector{expected + 1}, dropped);
+    dropped.clear();
+}
+
+TEST_F(CopyableHandleTest, ResetPopulatedWithStorage)
+{
+    constexpr int expected = 3;
+    const std::string s{"str"};
+    StoreHandle h(int{expected}, s, 5);
+    EXPECT_TRUE(dropped.empty());
+    h.reset(std::nullopt);
+    EXPECT_FALSE(h);
+    EXPECT_THROW(h.value(), std::bad_optional_access);
+    EXPECT_EQ(5, stored_drop);
+    EXPECT_EQ(std::vector{expected}, dropped);
+    dropped.clear();
+}
+
+TEST_F(CopyableHandleTest, ResetNewPopulated)
+{
+    constexpr int expected = 3, expected2 = 10;
+    {
+        SimpleHandle h(int{expected});
+        EXPECT_TRUE(dropped.empty());
+        h.reset(int{expected2});
+        EXPECT_TRUE(h);
+        EXPECT_EQ(expected2, *h);
+        EXPECT_EQ(expected2, h.value());
+        EXPECT_EQ(std::vector{expected}, dropped);
+        dropped.clear();
+    }
+    EXPECT_EQ(std::vector{expected2}, dropped);
+    dropped.clear();
+}
+
+TEST_F(CopyableHandleTest, ResetCopyPopulated)
+{
+    constexpr int expected = 3, expected2 = 10;
+    {
+        SimpleHandle h(int{expected});
+        EXPECT_TRUE(reffed.empty());
+        EXPECT_TRUE(dropped.empty());
+        const std::optional<int> maybe2{expected2};
+        h.reset(maybe2);
+        EXPECT_TRUE(h);
+        EXPECT_EQ(expected2 + 1, *h);
+        EXPECT_EQ(expected2 + 1, h.value());
+        EXPECT_EQ(std::vector{expected2}, reffed);
+        reffed.clear();
+        EXPECT_EQ(std::vector{expected}, dropped);
+        dropped.clear();
+    }
+    EXPECT_EQ(std::vector{expected2 + 1}, dropped);
+    dropped.clear();
+}
+
+TEST_F(CopyableHandleTest, ResetCopyPopulatedWithStorage)
+{
+    constexpr int expected = 3, expected2 = 10;
+    {
+        StoreHandle h(int{expected}, "str", 5);
+        EXPECT_TRUE(dropped.empty());
+        h.reset(expected2);
+        EXPECT_TRUE(h);
+        EXPECT_EQ(expected2 + 1, *h);
+        EXPECT_EQ(expected2 + 1, h.value());
+        EXPECT_EQ(5, stored_ref);
+        EXPECT_EQ(std::vector{expected2}, reffed);
+        reffed.clear();
+        EXPECT_EQ(6, stored_drop);
+        EXPECT_EQ(std::vector{expected}, dropped);
+        dropped.clear();
+    }
+    EXPECT_EQ(7, stored_drop);
+    EXPECT_EQ(std::vector{expected2 + 1}, dropped);
+    dropped.clear();
+}
+
+TEST_F(CopyableHandleTest, MoveConstructWithStorage)
+{
+    constexpr int expected = 3;
+    StoreHandle h1(int{expected}, "str", 5);
+    {
+        StoreHandle h2(std::move(h1));
+        EXPECT_TRUE(dropped.empty());
+        EXPECT_FALSE(h1);
+        EXPECT_THROW(h1.value(), std::bad_optional_access);
+        EXPECT_TRUE(h2);
+        EXPECT_EQ(expected, *h2);
+        EXPECT_EQ(expected, h2.value());
+    }
+    EXPECT_EQ(5, stored_drop);
+    EXPECT_EQ(std::vector{expected}, dropped);
+    dropped.clear();
+}
+
+TEST_F(CopyableHandleTest, MoveAssignWithStorage)
+{
+    constexpr int expected = 3, expected2 = 10;
+    {
+        StoreHandle h1(int{expected}, "str", 5);
+        StoreHandle h2(int{expected2}, "str", 10);
+        EXPECT_TRUE(dropped.empty());
+
+        h2 = std::move(h1);
+        EXPECT_EQ(10, stored_drop);
+        EXPECT_EQ(std::vector{expected2}, dropped);
+        dropped.clear();
+        EXPECT_FALSE(h1);
+        EXPECT_THROW(h1.value(), std::bad_optional_access);
+        EXPECT_TRUE(h2);
+        EXPECT_EQ(expected, *h2);
+        EXPECT_EQ(expected, h2.value());
+    }
+    EXPECT_EQ(5, stored_drop);
+    EXPECT_EQ(std::vector{expected}, dropped);
+    dropped.clear();
+}
+
+TEST_F(CopyableHandleTest, CopyConstructSrcEmptyWithStorage)
+{
+    StoreHandle h1(std::nullopt, "str", 5);
+    StoreHandle h2(h1);
+}
+
+TEST_F(CopyableHandleTest, CopyConstructWithStorage)
+{
+    constexpr int expected = 3;
+    StoreHandle h1(int{expected}, "str", 5);
+    StoreHandle h2(h1);
+    EXPECT_EQ(5, stored_ref);
+    EXPECT_EQ(std::vector{expected}, reffed);
+    reffed.clear();
+
+    h1.reset();
+    EXPECT_EQ(5, stored_drop);
+    EXPECT_EQ(std::vector{expected}, dropped);
+    dropped.clear();
+    h2.reset();
+    EXPECT_EQ(6, stored_drop);
+    EXPECT_EQ(std::vector{expected + 1}, dropped);
+    dropped.clear();
+}
+
+TEST_F(CopyableHandleTest, CopyAssignBothEmptyWithStorage)
+{
+    StoreHandle h1(std::nullopt, "str", 5);
+    StoreHandle h2(std::nullopt, "str", 10);
+    h2 = h1;
+}
+
+TEST_F(CopyableHandleTest, CopyAssignSrcEmptyWithStorage)
+{
+    constexpr int expected = 3;
+    StoreHandle h1(std::nullopt, "str", 5);
+    StoreHandle h2(int{expected}, "str", 10);
+    h2 = h1;
+    EXPECT_EQ(10, stored_drop);
+    EXPECT_EQ(std::vector{expected}, dropped);
+    dropped.clear();
+}
+
+TEST_F(CopyableHandleTest, CopyAssignDstEmptyWithStorage)
+{
+    constexpr int expected = 3;
+    StoreHandle h1(int{expected}, "str", 5);
+    StoreHandle h2(std::nullopt, "str", 10);
+    h2 = h1;
+    EXPECT_EQ(5, stored_ref);
+    EXPECT_EQ(std::vector{expected}, reffed);
+    reffed.clear();
+
+    h1.reset();
+    EXPECT_EQ(5, stored_drop);
+    EXPECT_EQ(std::vector{expected}, dropped);
+    dropped.clear();
+    h2.reset();
+    EXPECT_EQ(6, stored_drop);
+    EXPECT_EQ(std::vector{expected + 1}, dropped);
+    dropped.clear();
+}
+
+TEST_F(CopyableHandleTest, CopyAssignWithStorage)
+{
+    constexpr int expected = 3, expected2 = 15;
+    StoreHandle h1(int{expected}, "str", 5);
+    StoreHandle h2(int{expected2}, "str", 10);
+    h2 = h1;
+    EXPECT_EQ(10, stored_drop);
+    EXPECT_EQ(std::vector{expected2}, dropped);
+    dropped.clear();
+    EXPECT_EQ(5, stored_ref);
+    EXPECT_EQ(std::vector{expected}, reffed);
+    reffed.clear();
+
+    h1.reset();
+    EXPECT_EQ(5, stored_drop);
+    EXPECT_EQ(std::vector{expected}, dropped);
+    dropped.clear();
+    h2.reset();
+    EXPECT_EQ(6, stored_drop);
+    EXPECT_EQ(std::vector{expected + 1}, dropped);
+    dropped.clear();
+}
+
+} // namespace
+} // namespace stdplus