cxx-qt-gen: move signals away from an enum to an extern "C++" block

Related to #557

book/src/SUMMARY.md

@@ -20,7 +20,7 @@ SPDX-License-Identifier: MIT OR Apache-2.0
 - [QObject](./qobject/index.md)
     - [`#[cxx_qt::bridge]` - Bridge Macro](./qobject/bridge-macro.md)
     - [`#[cxx_qt::qobject]` - Defining QObjects](./qobject/qobject_struct.md)
-    - [`#[cxx_qt::qsignals]` - Signals enum](./qobject/signals_enum.md)
+    - [`#[cxx_qt::qsignals]` - Signals macro](./qobject/signals.md)
     - [`qobject::T` - The generated QObject](./qobject/generated-qobject.md)
     - [CxxQtThread](./qobject/cxxqtthread.md)
 - [Concepts](./concepts/index.md)

book/src/getting-started/1-qobjects-in-rust.md

@@ -47,7 +47,7 @@ Then you can use the afformentioned features with the help of more macros.
 - `#[cxx_qt::qobject]` - Expose a Rust struct to Qt as a QObject subclass.
     - `#[qproperty]` - Expose a field of the Rust struct to QML/C++ as a [`Q_PROPERTY`](https://doc.qt.io/qt-6/qtqml-cppintegration-exposecppattributes.html#exposing-properties).
     - `#[qinvokable]` - Expose a function on the QObject to QML and C++ as a [`Q_INVOKABLE`](https://doc.qt.io/qt-6/qtqml-cppintegration-exposecppattributes.html#exposing-methods-including-qt-slots).
-- `#[cxx_qt::qsignals(T)]` - Use an enum to define the [Signals](https://doc.qt.io/qt-6/signalsandslots.html#signals) of a QObject T.
+- `#[cxx_qt::qsignals]` - Use an enum to define the [Signals](https://doc.qt.io/qt-6/signalsandslots.html#signals) of a QObject T.
 
 CXX-Qt will then expand this Rust module into two separate parts:
 - C++ files that define a QObject subclass for each `#[cxx_qt::qobject]` marked struct.

book/src/qobject/index.md

@@ -15,7 +15,7 @@ For a simpler introduction, take a look at our [Getting Started guide](../gettin
 QObject Features and Parts:
   * [`#[cxx_qt::bridge]` - The macro around the module](./bridge-macro.md)
   * [`#[cxx_qt::qobject]` - Marking a Rust struct as a QObject](./qobject_struct.md)
-  * [`#[cxx_qt::qsignals(T)]` - An enum for defining signals](./signals_enum.md)
+  * [`#[cxx_qt::qsignals]` - A macro for defining signals](./signals.md)
   * [`qobject:T` - The generated QObject](./generated-qobject.md)
   * [`CxxQtThread` - Queueing closures onto the Qt event loop](./cxxqtthread.md)
 

book/src/qobject/signals_enum.md → book/src/qobject/signals.md

@@ -7,17 +7,14 @@ SPDX-License-Identifier: MIT OR Apache-2.0
 
 # Signals enum
 
-The `cxx_qt::qsignals(T)` attribute is used on an [enum](https://doc.rust-lang.org/book/ch06-01-defining-an-enum.html) to define [signals](https://doc.qt.io/qt-6/signalsandslots.html) for the QObject `T`.
+The `cxx_qt::qsignals` attribute is used on an `extern "C++"` block to define [signals](https://doc.qt.io/qt-6/signalsandslots.html) for the a QObject.
 
 ```rust,ignore,noplayground
-{{#include ../../../examples/qml_features/rust/src/signals.rs:book_signals_enum}}
+{{#include ../../../examples/qml_features/rust/src/signals.rs:book_signals_block}}
 ```
 
-For every enum variant, CXX-Qt will generate a signal on the corresponding QObject.
-If the enum variant has members, they will become the parameters for the corresponding signal.
-
-Because CXX-Qt needs to know the names of each parameter, only enum variants with named members are supported.
-The signal parameters are generated in order of appearance in the enum variant.
+For every function signature in the extern block, CXX-Qt will generate a signal on the corresponding QObject.
+If the function has parameters, they will become the parameters for the corresponding signal.
 
 If a signal is defined on the base class of the QObject then `#[inherit]` can be used to indicate to CXX-Qt that the `Q_SIGNAL` does not need to be created in C++.
 
@@ -60,18 +57,16 @@ In this case, it is no longer possible to disconnect later.
 
 ## Emitting a signal
 
-For every generated QObject [`qobject::T`](./generated-qobject.md) that has a signals enum, CXX-Qt will generate an `emit` function:
-``` rust,ignore,noplayground
-fn emit(self: Pin<&mut Self>, signal: /*Signals enum*/)
-```
-`emit` can therefore be called from any mutable `#[qinvokable]`.
+Call the function signature defined in the `extern "C++` block to emit the signal.
+
+Note that these are defined on the generated QObject [`qobject::T`](./generated-qobject.md), so can be called from any mutable `#[qinvokable]`.
 
-The `emit` function will immediately emit the signal.
+The function will immediately emit the signal.
 Depending on the connection type, the connected slots will be called either immediately or from the event loop (See [the different connection types](https://doc.qt.io/qt-6/qt.html#ConnectionType-enum)).
-To queue the call to `emit` until the next cycle of the Qt event loop, you can use the [`CxxQtThread`](./cxxqtthread.md).
+To queue the call until the next cycle of the Qt event loop, you can use the [`CxxQtThread`](./cxxqtthread.md).
 
 ### [Example](https://github.com/KDAB/cxx-qt/blob/main/examples/qml_features/rust/src/signals.rs)
+
 ```rust,ignore,noplayground
 {{#include ../../../examples/qml_features/rust/src/signals.rs:book_macro_code}}
 ```
-

crates/cxx-qt-gen/src/generator/cpp/property/mod.rs

@@ -4,7 +4,7 @@
 // SPDX-License-Identifier: MIT OR Apache-2.0
 
 use crate::generator::{
-    cpp::{qobject::GeneratedCppQObjectBlocks, types::CppType},
+    cpp::{qobject::GeneratedCppQObjectBlocks, signal::generate_cpp_signals, types::CppType},
     naming::{property::QPropertyName, qobject::QObjectName},
 };
 use crate::parser::{cxxqtdata::ParsedCxxMappings, property::ParsedQProperty};
@@ -22,7 +22,9 @@ pub fn generate_cpp_properties(
     lock_guard: Option<&str>,
 ) -> Result<GeneratedCppQObjectBlocks> {
     let mut generated = GeneratedCppQObjectBlocks::default();
+    let mut signals = vec![];
     let qobject_ident = qobject_idents.cpp_class.cpp.to_string();
+
     for property in properties {
         // Cache the idents as they are used in multiple places
         let idents = QPropertyName::from(property);
@@ -41,9 +43,16 @@ pub fn generate_cpp_properties(
             &cxx_ty,
             lock_guard,
         ));
-        generated.methods.push(signal::generate(&idents));
+        signals.push(signal::generate(&idents, qobject_idents));
     }
 
+    generated.append(&mut generate_cpp_signals(
+        &signals,
+        qobject_idents,
+        cxx_mappings,
+        lock_guard,
+    )?);
+
     Ok(generated)
 }
 
@@ -88,7 +97,7 @@ mod tests {
         assert_str_eq!(generated.metaobjects[1], "Q_PROPERTY(::std::unique_ptr<QColor> opaqueProperty READ getOpaqueProperty WRITE setOpaqueProperty NOTIFY opaquePropertyChanged)");
 
         // methods
-        assert_eq!(generated.methods.len(), 6);
+        assert_eq!(generated.methods.len(), 10);
         let (header, source) = if let CppFragment::Pair { header, source } = &generated.methods[0] {
             (header, source)
         } else {
@@ -127,13 +136,8 @@ mod tests {
                 }
                 "#}
         );
-        let header = if let CppFragment::Header(header) = &generated.methods[2] {
-            header
-        } else {
-            panic!("Expected header!")
-        };
-        assert_str_eq!(header, "Q_SIGNAL void trivialPropertyChanged();");
-        let (header, source) = if let CppFragment::Pair { header, source } = &generated.methods[3] {
+
+        let (header, source) = if let CppFragment::Pair { header, source } = &generated.methods[2] {
             (header, source)
         } else {
             panic!("Expected pair!")
@@ -154,7 +158,7 @@ mod tests {
             "#}
         );
 
-        let (header, source) = if let CppFragment::Pair { header, source } = &generated.methods[4] {
+        let (header, source) = if let CppFragment::Pair { header, source } = &generated.methods[3] {
             (header, source)
         } else {
             panic!("Expected pair!")
@@ -175,12 +179,105 @@ mod tests {
             "#}
         );
 
-        let header = if let CppFragment::Header(header) = &generated.methods[5] {
+        let header = if let CppFragment::Header(header) = &generated.methods[4] {
+            header
+        } else {
+            panic!("Expected header!")
+        };
+        assert_str_eq!(header, "Q_SIGNAL void trivialPropertyChanged();");
+
+        let (header, source) = if let CppFragment::Pair { header, source } = &generated.methods[5] {
+            (header, source)
+        } else {
+            panic!("Expected Pair")
+        };
+        assert_str_eq!(header, "void emitTrivialPropertyChanged();");
+        assert_str_eq!(
+            source,
+            indoc! {r#"
+            void
+            MyObject::emitTrivialPropertyChanged()
+            {
+                Q_EMIT trivialPropertyChanged();
+            }
+            "#}
+        );
+
+        let (header, source) = if let CppFragment::Pair { header, source } = &generated.methods[6] {
+            (header, source)
+        } else {
+            panic!("Expected Pair")
+        };
+        assert_str_eq!(
+            header,
+            "::QMetaObject::Connection trivialPropertyChangedConnect(::rust::Fn<void(MyObject&)> func, ::Qt::ConnectionType type);"
+        );
+        assert_str_eq!(
+            source,
+            indoc! {r#"
+            ::QMetaObject::Connection
+            MyObject::trivialPropertyChangedConnect(::rust::Fn<void(MyObject&)> func, ::Qt::ConnectionType type)
+            {
+                return ::QObject::connect(this,
+                        &MyObject::trivialPropertyChanged,
+                        this,
+                        [&, func = ::std::move(func)]() {
+                          // ::std::lock_guard
+                          func(*this);
+                        }, type);
+            }
+            "#}
+        );
+
+        let header = if let CppFragment::Header(header) = &generated.methods[7] {
             header
         } else {
             panic!("Expected header!")
         };
         assert_str_eq!(header, "Q_SIGNAL void opaquePropertyChanged();");
+
+        let (header, source) = if let CppFragment::Pair { header, source } = &generated.methods[8] {
+            (header, source)
+        } else {
+            panic!("Expected Pair")
+        };
+        assert_str_eq!(header, "void emitOpaquePropertyChanged();");
+        assert_str_eq!(
+            source,
+            indoc! {r#"
+            void
+            MyObject::emitOpaquePropertyChanged()
+            {
+                Q_EMIT opaquePropertyChanged();
+            }
+            "#}
+        );
+
+        let (header, source) = if let CppFragment::Pair { header, source } = &generated.methods[9] {
+            (header, source)
+        } else {
+            panic!("Expected Pair")
+        };
+        assert_str_eq!(
+            header,
+            "::QMetaObject::Connection opaquePropertyChangedConnect(::rust::Fn<void(MyObject&)> func, ::Qt::ConnectionType type);"
+        );
+        assert_str_eq!(
+            source,
+            indoc! {r#"
+            ::QMetaObject::Connection
+            MyObject::opaquePropertyChangedConnect(::rust::Fn<void(MyObject&)> func, ::Qt::ConnectionType type)
+            {
+                return ::QObject::connect(this,
+                        &MyObject::opaquePropertyChanged,
+                        this,
+                        [&, func = ::std::move(func)]() {
+                          // ::std::lock_guard
+                          func(*this);
+                        }, type);
+            }
+            "#}
+        );
     }
 
     #[test]
@@ -210,7 +307,7 @@ mod tests {
         assert_str_eq!(generated.metaobjects[0], "Q_PROPERTY(A1 mappedProperty READ getMappedProperty WRITE setMappedProperty NOTIFY mappedPropertyChanged)");
 
         // methods
-        assert_eq!(generated.methods.len(), 3);
+        assert_eq!(generated.methods.len(), 5);
         let (header, source) = if let CppFragment::Pair { header, source } = &generated.methods[0] {
             (header, source)
         } else {
@@ -252,5 +349,48 @@ mod tests {
             panic!("Expected header!")
         };
         assert_str_eq!(header, "Q_SIGNAL void mappedPropertyChanged();");
+
+        let (header, source) = if let CppFragment::Pair { header, source } = &generated.methods[3] {
+            (header, source)
+        } else {
+            panic!("Expected Pair")
+        };
+        assert_str_eq!(header, "void emitMappedPropertyChanged();");
+        assert_str_eq!(
+            source,
+            indoc! {r#"
+            void
+            MyObject::emitMappedPropertyChanged()
+            {
+                Q_EMIT mappedPropertyChanged();
+            }
+            "#}
+        );
+
+        let (header, source) = if let CppFragment::Pair { header, source } = &generated.methods[4] {
+            (header, source)
+        } else {
+            panic!("Expected Pair")
+        };
+        assert_str_eq!(
+            header,
+            "::QMetaObject::Connection mappedPropertyChangedConnect(::rust::Fn<void(MyObject&)> func, ::Qt::ConnectionType type);"
+        );
+        assert_str_eq!(
+            source,
+            indoc! {r#"
+            ::QMetaObject::Connection
+            MyObject::mappedPropertyChangedConnect(::rust::Fn<void(MyObject&)> func, ::Qt::ConnectionType type)
+            {
+                return ::QObject::connect(this,
+                        &MyObject::mappedPropertyChanged,
+                        this,
+                        [&, func = ::std::move(func)]() {
+                          // ::std::lock_guard
+                          func(*this);
+                        }, type);
+            }
+            "#}
+        );
     }
 }

crates/cxx-qt-gen/src/generator/cpp/property/signal.rs

@@ -3,12 +3,27 @@
 //
 // SPDX-License-Identifier: MIT OR Apache-2.0
 
-use crate::generator::naming::property::QPropertyName;
-use crate::CppFragment;
+use syn::ForeignItemFn;
 
-pub fn generate(idents: &QPropertyName) -> CppFragment {
-    CppFragment::Header(format!(
-        "Q_SIGNAL void {ident_notify}();",
-        ident_notify = idents.notify.cpp
-    ))
+use crate::{
+    generator::naming::{property::QPropertyName, qobject::QObjectName},
+    parser::signals::ParsedSignal,
+};
+
+pub fn generate(idents: &QPropertyName, qobject_idents: &QObjectName) -> ParsedSignal {
+    // We build our signal in the generation phase as we need to use the naming
+    // structs to build the signal name
+    let cpp_class_rust = &qobject_idents.cpp_class.rust;
+    let notify_cpp = &idents.notify.cpp;
+    let notify_rust_str = idents.notify.rust.to_string();
+    let method: ForeignItemFn = syn::parse_quote! {
+        #[doc = "Notify for the Q_PROPERTY"]
+        #[rust_name = #notify_rust_str]
+        fn #notify_cpp(self: Pin<&mut #cpp_class_rust>);
+    };
+    ParsedSignal::from_property_method(
+        method,
+        idents.notify.clone(),
+        qobject_idents.cpp_class.rust.clone(),
+    )
 }

crates/cxx-qt-gen/src/generator/cpp/qobject.rs

@@ -116,14 +116,12 @@ impl GeneratedCppQObject {
             cxx_mappings,
             lock_guard,
         )?);
-        if let Some(signals_enum) = &qobject.signals {
-            generated.blocks.append(&mut generate_cpp_signals(
-                &signals_enum.signals,
-                &qobject_idents,
-                cxx_mappings,
-                lock_guard,
-            )?);
-        }
+        generated.blocks.append(&mut generate_cpp_signals(
+            &qobject.signals,
+            &qobject_idents,
+            cxx_mappings,
+            lock_guard,
+        )?);
         generated.blocks.append(&mut inherit::generate(
             &qobject.inherited_methods,
             &qobject.base_class,