cxx-qt-lib: add support for QByteArray

Related to KDAB#291

CHANGELOG.md

@@ -17,7 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## Added
 
 - Support for container types: `QSet<T>`, `QHash<K, V>`
-- Support for further types: `QModelIndex`
+- Support for further types: `QByteArray`, `QModelIndex`
 
 ### Fixed
 

crates/cxx-qt-lib-headers/include/qbytearray.h

@@ -0,0 +1,27 @@
+// clang-format off
+// SPDX-FileCopyrightText: 2022 Klarälvdalens Datakonsult AB, a KDAB Group company <[email protected]>
+// clang-format on
+// SPDX-FileContributor: Andrew Hayzen <[email protected]>
+//
+// SPDX-License-Identifier: MIT OR Apache-2.0
+#pragma once
+
+#include <QByteArray>
+
+#include "rust/cxx.h"
+
+template<>
+struct rust::IsRelocatable<QByteArray> : std::true_type
+{
+};
+
+namespace rust {
+namespace cxxqtlib1 {
+
+QByteArray
+qbytearrayFromRustString(rust::Str string);
+rust::String
+qbytearrayToRustString(const QByteArray& string);
+
+}
+}

crates/cxx-qt-lib-headers/src/lib.rs

@@ -14,6 +14,7 @@ static HEADERS: [(&str, &str); 20] = [
     (include_str!("../include/common.h"), "common.h"),
     (include_str!("../include/convert.h"), "convert.h"),
     (include_str!("../include/cxxqt_thread.h"), "cxxqt_thread.h"),
+    (include_str!("../include/qbytearray.h"), "qbytearray.h"),
     (include_str!("../include/qcolor.h"), "qcolor.h"),
     (include_str!("../include/qdate.h"), "qdate.h"),
     (include_str!("../include/qdatetime.h"), "qdatetime.h"),

crates/cxx-qt-lib/build.rs

@@ -19,6 +19,7 @@ fn main() {
     );
 
     let rust_bridges = [
+        "qbytearray",
         "qcolor",
         "qdate",
         "qdatetime",
@@ -68,6 +69,7 @@ fn main() {
     );
 
     let cpp_files = [
+        "qbytearray",
         "qcolor",
         "qdate",
         "qdatetime",

crates/cxx-qt-lib/src/types/mod.rs

@@ -3,6 +3,9 @@
 //
 // SPDX-License-Identifier: MIT OR Apache-2.0
 
+mod qbytearray;
+pub use qbytearray::QByteArray;
+
 mod qcolor;
 pub use qcolor::QColor;
 

crates/cxx-qt-lib/src/types/qbytearray.cpp

@@ -0,0 +1,54 @@
+// clang-format off
+// SPDX-FileCopyrightText: 2022 Klarälvdalens Datakonsult AB, a KDAB Group company <[email protected]>
+// clang-format on
+// SPDX-FileContributor: Andrew Hayzen <[email protected]>
+//
+// SPDX-License-Identifier: MIT OR Apache-2.0
+#include "cxx-qt-lib/qbytearray.h"
+
+#include "assertion_utils.h"
+
+// The layout has changed between Qt 5 and Qt 6
+//
+// Qt5 QByteArray has one pointer as a member
+// https://code.qt.io/cgit/qt/qtbase.git/tree/src/corelib/text/qbytearray.h?h=v5.15.6-lts-lgpl#n470
+//
+// Qt6 QByteArray has one member, which contains two pointers and a size_t
+// https://code.qt.io/cgit/qt/qtbase.git/tree/src/corelib/text/qbytearray.h?h=v6.2.4#n91
+// DataPointer is then a QByteArrayData, which is a QArrayDataPointer<char>
+// https://code.qt.io/cgit/qt/qtbase.git/tree/src/corelib/tools/qarraydatapointer.h?h=v6.2.4#n390
+#if (QT_VERSION >= QT_VERSION_CHECK(6, 0, 0))
+assert_alignment_and_size(QByteArray,
+                          alignof(std::size_t),
+                          sizeof(std::size_t[3]));
+#else
+assert_alignment_and_size(QByteArray,
+                          alignof(std::size_t),
+                          sizeof(std::size_t));
+#endif
+
+static_assert(!std::is_trivially_copy_assignable<QByteArray>::value);
+static_assert(!std::is_trivially_copy_constructible<QByteArray>::value);
+
+static_assert(!std::is_trivially_destructible<QByteArray>::value);
+
+static_assert(QTypeInfo<QByteArray>::isRelocatable);
+
+namespace rust {
+namespace cxxqtlib1 {
+
+QByteArray
+qbytearrayFromRustString(rust::Str string)
+{
+  // Note that rust::Str here is borrowed
+  return QByteArray(string.data(), string.size());
+}
+
+rust::String
+qbytearrayToRustString(const QByteArray& byteArray)
+{
+  return rust::String(byteArray.constData(), byteArray.size());
+}
+
+}
+}

crates/cxx-qt-lib/src/types/qbytearray.rs

@@ -0,0 +1,111 @@
+// SPDX-FileCopyrightText: 2022 Klarälvdalens Datakonsult AB, a KDAB Group company <[email protected]>
+// SPDX-FileContributor: Andrew Hayzen <[email protected]>
+//
+// SPDX-License-Identifier: MIT OR Apache-2.0
+use cxx::{type_id, ExternType};
+use std::mem::MaybeUninit;
+
+#[cxx::bridge]
+mod ffi {
+    unsafe extern "C++" {
+        include!("cxx-qt-lib/qbytearray.h");
+
+        type QByteArray = super::QByteArray;
+    }
+
+    #[namespace = "rust::cxxqtlib1"]
+    unsafe extern "C++" {
+        include!("cxx-qt-lib/common.h");
+
+        #[doc(hidden)]
+        #[rust_name = "qbytearray_drop"]
+        fn drop(string: &mut QByteArray);
+
+        #[doc(hidden)]
+        #[rust_name = "qbytearray_default"]
+        fn construct() -> QByteArray;
+        #[doc(hidden)]
+        #[rust_name = "qbytearray_from_rust_string"]
+        fn qbytearrayFromRustString(string: &str) -> QByteArray;
+        #[doc(hidden)]
+        #[rust_name = "qbytearray_clone"]
+        fn construct(string: &QByteArray) -> QByteArray;
+
+        #[doc(hidden)]
+        #[rust_name = "qbytearray_to_rust_string"]
+        fn qbytearrayToRustString(string: &QByteArray) -> String;
+    }
+}
+
+/// The QByteArray class provides an array of bytes.
+pub struct QByteArray {
+    /// The layout has changed between Qt 5 and Qt 6
+    ///
+    /// Qt5 QByteArray has one pointer as a member
+    /// Qt6 QByteArray has one member, which contains two pointers and a size_t
+    #[cfg(qt_version_major = "5")]
+    _space: MaybeUninit<usize>,
+    #[cfg(qt_version_major = "6")]
+    _space: MaybeUninit<[usize; 3]>,
+}
+
+impl Clone for QByteArray {
+    /// Constructs a copy of other.
+    ///
+    /// This operation takes constant time, because QByteArray is implicitly shared.
+    /// This makes returning a QByteArray from a function very fast.
+    /// If a shared instance is modified, it will be copied (copy-on-write), and that takes linear time.
+    fn clone(&self) -> Self {
+        ffi::qbytearray_clone(self)
+    }
+}
+
+impl Default for QByteArray {
+    /// Constructs an empty byte array.
+    fn default() -> Self {
+        ffi::qbytearray_default()
+    }
+}
+
+impl std::fmt::Display for QByteArray {
+    /// Convert the QByteArray to a Rust string
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        write!(f, "{}", <&QByteArray as Into<String>>::into(self))
+    }
+}
+
+impl Drop for QByteArray {
+    /// Destroys the byte array.
+    fn drop(&mut self) {
+        ffi::qbytearray_drop(self)
+    }
+}
+
+impl From<&str> for QByteArray {
+    /// Constructs a QByteArray from a Rust string
+    fn from(str: &str) -> Self {
+        ffi::qbytearray_from_rust_string(str)
+    }
+}
+
+impl From<&String> for QByteArray {
+    /// Constructs a QByteArray from a Rust string
+    fn from(str: &String) -> Self {
+        ffi::qbytearray_from_rust_string(str)
+    }
+}
+
+impl From<&QByteArray> for String {
+    /// Convert the QByteArray to a Rust string
+    fn from(qbytearray: &QByteArray) -> Self {
+        ffi::qbytearray_to_rust_string(qbytearray)
+    }
+}
+
+// Safety:
+//
+// Static checks on the C++ side to ensure the size is the same.
+unsafe impl ExternType for QByteArray {
+    type Id = type_id!("QByteArray");
+    type Kind = cxx::kind::Trivial;
+}

tests/qt_types_standalone/CMakeLists.txt

@@ -41,6 +41,7 @@ target_link_libraries(${CRATE} INTERFACE
 add_executable(${APP_NAME}
     cpp/cxxqtconvert.h
     cpp/main.cpp
+    cpp/qbytearray.h
     cpp/qcolor.h
     cpp/qdate.h
     cpp/qdatetime.h

tests/qt_types_standalone/cpp/main.cpp

@@ -8,6 +8,7 @@
 #include <QtTest/QTest>
 
 #include "cxxqtconvert.h"
+#include "qbytearray.h"
 #include "qcolor.h"
 #include "qdate.h"
 #include "qdatetime.h"
@@ -38,6 +39,7 @@ main(int argc, char* argv[])
   };
 
   runTest(QScopedPointer<QObject>(new CxxQtConvertTest));
+  runTest(QScopedPointer<QObject>(new QByteArrayTest));
   runTest(QScopedPointer<QObject>(new QColorTest));
   runTest(QScopedPointer<QObject>(new QDateTest));
   runTest(QScopedPointer<QObject>(new QDateTimeTest));

tests/qt_types_standalone/cpp/qbytearray.h

@@ -0,0 +1,55 @@
+// clang-format off
+// SPDX-FileCopyrightText: 2022 Klarälvdalens Datakonsult AB, a KDAB Group company <[email protected]>
+// clang-format on
+// SPDX-FileContributor: Andrew Hayzen <[email protected]>
+//
+// SPDX-License-Identifier: MIT OR Apache-2.0
+#pragma once
+
+#include <QtCore/QByteArray>
+#include <QtTest/QTest>
+
+#include "cxx-qt-gen/qbytearray_cxx.cxx.h"
+
+class QByteArrayTest : public QObject
+{
+  Q_OBJECT
+
+private Q_SLOTS:
+  void construct()
+  {
+    QFETCH(bool, slice);
+    const auto s = construct_qbytearray(slice);
+    QCOMPARE(s, QByteArrayLiteral("String constructed by Rust"));
+  }
+
+  void construct_data()
+  {
+    QTest::addColumn<bool>("slice");
+
+    QTest::newRow("From &str") << true;
+    QTest::newRow("From String") << false;
+  }
+
+  void read()
+  {
+    const auto s = QByteArrayLiteral("String constructed by C++");
+    QVERIFY(read_qbytearray(s));
+  }
+
+  void clone()
+  {
+    auto s = QByteArrayLiteral("String constructed by C++");
+    const auto c = clone_qbytearray(s);
+    QCOMPARE(c, QByteArrayLiteral("String constructed by C++"));
+  }
+
+  void modify_rust() { QVERIFY(can_handle_qbytearray_change()); }
+
+  void modify_updates_cpp()
+  {
+    auto s = QByteArrayLiteral("String constructed by C++");
+    modify_qbytearray(s);
+    QCOMPARE(s, QByteArrayLiteral("Updated string value"));
+  }
+};

tests/qt_types_standalone/rust/build.rs

@@ -7,6 +7,7 @@ use cxx_qt_build::CxxQtBuilder;
 
 fn main() {
     CxxQtBuilder::new()
+        .file("src/qbytearray.rs")
         .file("src/qcolor.rs")
         .file("src/qdate.rs")
         .file("src/qdatetime.rs")

tests/qt_types_standalone/rust/src/lib.rs

@@ -4,6 +4,7 @@
 //
 // SPDX-License-Identifier: MIT OR Apache-2.0
 
+mod qbytearray;
 mod qcolor;
 mod qdate;
 mod qdatetime;

tests/qt_types_standalone/rust/src/qbytearray.rs

@@ -0,0 +1,59 @@
+// SPDX-FileCopyrightText: 2022 Klarälvdalens Datakonsult AB, a KDAB Group company <[email protected]>
+// SPDX-FileContributor: Andrew Hayzen <[email protected]>
+// SPDX-FileContributor: Gerhard de Clercq <[email protected]>
+//
+// SPDX-License-Identifier: MIT OR Apache-2.0
+
+use cxx_qt_lib::QByteArray;
+
+#[cxx::bridge]
+mod qbytearray_cxx {
+    unsafe extern "C++" {
+        include!("cxx-qt-lib/qbytearray.h");
+
+        type QByteArray = cxx_qt_lib::QByteArray;
+    }
+
+    extern "Rust" {
+        fn construct_qbytearray(slice: bool) -> QByteArray;
+        fn read_qbytearray(s: &QByteArray) -> bool;
+        fn modify_qbytearray(s: Pin<&mut QByteArray>);
+        fn can_handle_qbytearray_change() -> bool;
+        fn clone_qbytearray(s: &QByteArray) -> QByteArray;
+    }
+}
+
+fn construct_qbytearray(slice: bool) -> QByteArray {
+    if slice {
+        QByteArray::from("String constructed by Rust")
+    } else {
+        let rs_string = "String constructed by Rust".to_owned();
+        QByteArray::from(&rs_string)
+    }
+}
+
+fn read_qbytearray(s: &cxx_qt_lib::QByteArray) -> bool {
+    let rs = s.to_string();
+    rs == "String constructed by C++"
+}
+
+fn modify_qbytearray(mut s: std::pin::Pin<&mut cxx_qt_lib::QByteArray>) {
+    *s = QByteArray::from("Updated string value");
+}
+
+fn can_handle_qbytearray_change() -> bool {
+    let long_s = "Very very long string that is hopefully long enough to allocate and get Valgrind's attention :)";
+    let long_s_ptr = QByteArray::from(long_s);
+
+    let short_s = "Short string";
+    let mut short_s_ptr = QByteArray::from(short_s);
+    assert!(short_s_ptr.to_string() == short_s);
+
+    short_s_ptr = long_s_ptr;
+
+    short_s_ptr.to_string() == long_s
+}
+
+fn clone_qbytearray(s: &QByteArray) -> QByteArray {
+    s.clone()
+}