cxx_qt::Constructor: Add Rust generation

Author: LeonMatthesKDAB

crates/cxx-qt-gen/src/generator/rust/constructor.rs

@@ -0,0 +1,316 @@
+// SPDX-FileCopyrightText: 2023 Klarälvdalens Datakonsult AB, a KDAB Group company <[email protected]>
+// SPDX-FileContributor: Leon Matthes <[email protected]>
+//
+// SPDX-License-Identifier: MIT OR Apache-2.0
+
+use crate::{
+    generator::{
+        naming::{namespace::NamespaceName, qobject::QObjectName},
+        rust::{qobject::GeneratedRustQObjectBlocks, types},
+    },
+    parser::constructor::Constructor,
+};
+
+use convert_case::{Case, Casing};
+use proc_macro2::{Span, TokenStream};
+use quote::{format_ident, quote};
+use syn::{parse_quote, Ident, Result, Type};
+
+const CONSTRUCTOR_ARGUMENTS: &str = "CxxQtConstructorArguments";
+const BASE_ARGUMENTS: &str = "CxxQtConstructorBaseArguments";
+const NEW_ARGUMENTS: &str = "CxxQtConstructorNewArguments";
+const INITIALIZE_ARGUMENTS: &str = "CxxQtConstructorInitializeArguments";
+
+fn map_types<F: FnMut((usize, &Type)) -> TokenStream>(
+    args: &Option<Vec<Type>>,
+    f: F,
+) -> Vec<TokenStream> {
+    args.as_ref()
+        .map(|args| args.iter().enumerate().map(f).collect())
+        .unwrap_or_default()
+}
+
+fn extract_arguments_from_tuple(args: &Option<Vec<Type>>, tuple_name: Ident) -> Vec<TokenStream> {
+    map_types(args, |(index, _ty)| {
+        let arg_name = format_ident!("arg{index}");
+        let index = syn::LitInt::new(index.to_string().as_str(), Span::call_site());
+        quote! {
+            #arg_name: #tuple_name.#index
+        }
+    })
+}
+
+fn extract_arguments_from_struct(args: &Option<Vec<Type>>, struct_name: Ident) -> Vec<TokenStream> {
+    map_types(args, |(index, _ty)| {
+        let arg_name = format_ident!("arg{index}");
+        quote! {
+            #struct_name.#arg_name
+        }
+    })
+}
+
+fn argument_members(args: &Option<Vec<Type>>) -> Vec<TokenStream> {
+    map_types(args, |(index, ty)| {
+        let arg_name = format_ident!("arg{index}");
+        quote! {
+            #arg_name: #ty
+        }
+    })
+}
+
+fn generate_default_constructor(
+    qobject_idents: &QObjectName,
+    namespace: &NamespaceName,
+) -> GeneratedRustQObjectBlocks {
+    let rust_struct_ident = &qobject_idents.rust_struct.rust;
+    let create_rs_ident = format_ident!(
+        "create_rs_{object_name}",
+        object_name = rust_struct_ident.to_string().to_case(Case::Snake)
+    );
+    let namespace_internals = &namespace.internal;
+
+    GeneratedRustQObjectBlocks {
+        cxx_mod_contents: vec![parse_quote! {
+        extern "Rust" {
+            #[cxx_name = "createRs"]
+            #[namespace = #namespace_internals]
+            fn #create_rs_ident() -> Box<#rust_struct_ident>;
+        }
+        }],
+        cxx_qt_mod_contents: vec![parse_quote! {
+            /// Generated CXX-Qt method which creates a boxed rust struct of a QObject
+            pub fn #create_rs_ident() -> std::boxed::Box<#rust_struct_ident> {
+                core::default::Default::default()
+            }
+        }],
+    }
+}
+
+pub fn generate(
+    constructors: &[Constructor],
+    qobject_idents: &QObjectName,
+    namespace: &NamespaceName,
+) -> Result<GeneratedRustQObjectBlocks> {
+    if constructors.is_empty() {
+        return Ok(generate_default_constructor(qobject_idents, namespace));
+    }
+
+    let mut result = GeneratedRustQObjectBlocks::default();
+    let namespace_internals = &namespace.internal;
+    let rust_struct_name_rust = &qobject_idents.rust_struct.rust;
+    let rust_struct_name_snake = &qobject_idents
+        .rust_struct
+        .rust
+        .to_string()
+        .to_case(Case::Snake);
+    let qobject_name_rust = &qobject_idents.cpp_class.rust;
+
+    for (index, constructor) in constructors.iter().enumerate() {
+        let arguments_rust = format_ident!("{CONSTRUCTOR_ARGUMENTS}{rust_struct_name_rust}{index}");
+        let base_arguments_rust = format_ident!("{BASE_ARGUMENTS}{rust_struct_name_rust}{index}");
+        let new_arguments_rust = format_ident!("{NEW_ARGUMENTS}{rust_struct_name_rust}{index}");
+        let initialize_arguments_rust =
+            format_ident!("{INITIALIZE_ARGUMENTS}{rust_struct_name_rust}{index}");
+
+        let arguments_cxx = format!("{CONSTRUCTOR_ARGUMENTS}{index}");
+        let base_arguments_cxx = format!("{BASE_ARGUMENTS}{index}");
+        let new_arguments_cxx = format!("{NEW_ARGUMENTS}{index}");
+        let initialize_arguments_cxx = format!("{INITIALIZE_ARGUMENTS}{index}");
+
+        let base_argument_members = argument_members(&constructor.items.base_arguments);
+        let new_argument_members = argument_members(&constructor.items.new_arguments);
+        let initialize_argument_members = argument_members(&constructor.items.initialize_arguments);
+
+        let new_rust = format_ident!("new_rs_{rust_struct_name_snake}_{index}");
+        let new_cxx = format!("newRs{index}");
+
+        let initialize_rust = format_ident!("initialize_{rust_struct_name_snake}_{index}");
+        let initialize_cxx = format!("initialize{index}");
+
+        let route_arguments_rust =
+            format_ident!("route_arguments_{rust_struct_name_snake}_{index}");
+        let route_arguemnts_cxx = format!("routeArguments{index}");
+
+        let argument_types = &constructor.arguments;
+        let empty_vec = &Vec::new();
+        let base_argument_types = constructor
+            .items
+            .base_arguments
+            .as_ref()
+            .unwrap_or(empty_vec);
+        let new_argument_types = &constructor
+            .items
+            .new_arguments
+            .as_ref()
+            .unwrap_or(empty_vec);
+        let initialize_argument_types = &constructor
+            .items
+            .initialize_arguments
+            .as_ref()
+            .unwrap_or(empty_vec);
+
+        let passthrough_items = &constructor.items.passthrough;
+
+        let route_arguments_parameters: Vec<TokenStream> = constructor
+            .arguments
+            .iter()
+            .enumerate()
+            .map(|(index, ty)| {
+                let name = format_ident!("arg{index}");
+                quote! { #name: #ty }
+            })
+            .collect();
+        let route_arguments_safety = if constructor.arguments.iter().any(types::is_unsafe_cxx_type)
+        {
+            quote! { unsafe }
+        } else {
+            quote! {}
+        };
+
+        let assign_arguments = constructor
+            .arguments
+            .iter()
+            .enumerate()
+            .map(|(index, _ty)| {
+                let name = format_ident!("arg{index}");
+                quote! { #name }
+            })
+            .collect::<Vec<_>>();
+
+        let init_new_arguments = extract_arguments_from_tuple(
+            &constructor.items.new_arguments,
+            format_ident!("new_arguments"),
+        );
+        let init_initialize_arguments = extract_arguments_from_tuple(
+            &constructor.items.initialize_arguments,
+            format_ident!("initialize_arguments"),
+        );
+        let init_base_arguments = extract_arguments_from_tuple(
+            &constructor.items.base_arguments,
+            format_ident!("base_arguments"),
+        );
+
+        let extract_new_arguments = extract_arguments_from_struct(
+            &constructor.items.new_arguments,
+            format_ident!("new_arguments"),
+        );
+
+        let extract_initialize_arguments = extract_arguments_from_struct(
+            &constructor.items.initialize_arguments,
+            format_ident!("initialize_arguments"),
+        );
+
+        result.cxx_mod_contents.append(&mut vec![
+            parse_quote! {
+                #[namespace = #namespace_internals]
+                #[cxx_name = #arguments_cxx]
+                #[doc(hidden)]
+                struct #arguments_rust {
+                    baseArguments: #base_arguments_rust,
+                    newArguments: #new_arguments_rust,
+                    initializeArguments: #initialize_arguments_rust,
+                }
+            },
+            parse_quote! {
+                #[namespace = #namespace_internals]
+                #[cxx_name = #base_arguments_cxx]
+                #[doc(hidden)]
+                struct #base_arguments_rust {
+                    #(#base_argument_members,)*
+                    notEmpty: i8 // Make sure there's always at least one struct member, as CXX
+                                 // doesn't support empty shared structs.
+                }
+            },
+            parse_quote! {
+                #[namespace = #namespace_internals]
+                #[cxx_name = #new_arguments_cxx]
+                #[doc(hidden)]
+                struct #new_arguments_rust {
+                    #(#new_argument_members,)*
+                    notEmpty: i8 // Make sure there's always at least one struct member, as CXX
+                                 // doesn't support empty shared structs.
+                }
+            },
+            parse_quote! {
+                #[namespace = #namespace_internals]
+                #[cxx_name = #initialize_arguments_cxx]
+                #[doc(hidden)]
+                struct #initialize_arguments_rust {
+                    #(#initialize_argument_members,)*
+                    notEmpty: i8 // Make sure there's always at least one struct member, as CXX
+                                 // doesn't support empty shared structs.
+                }
+            },
+            parse_quote! {
+                extern "Rust" {
+                    #[namespace = #namespace_internals]
+                    #[cxx_name = #route_arguemnts_cxx]
+                    // This function needs to marked unsafe, as some arguments may be pointers.
+                    #route_arguments_safety fn #route_arguments_rust(#(#route_arguments_parameters),*) -> #arguments_rust;
+
+                    #[namespace = #namespace_internals]
+                    #[cxx_name = #new_cxx]
+                    fn #new_rust(args: #new_arguments_rust) -> Box<#rust_struct_name_rust>;
+
+                    #[namespace = #namespace_internals]
+                    #[cxx_name = #initialize_cxx]
+                    fn #initialize_rust(qobject: Pin<&mut #qobject_name_rust>, args: #initialize_arguments_rust);
+                }
+            },
+        ]);
+        result.cxx_qt_mod_contents.append(&mut vec![parse_quote! {
+            #[doc(hidden)]
+            pub fn #route_arguments_rust(#(#route_arguments_parameters),*) -> #arguments_rust {
+                // These variables won't be used if the corresponding argument list is empty.
+                #[allow(unused_variable)]
+                let (
+                    new_arguments,
+                    base_arguments,
+                    initialize_arguments
+                    ) = <#qobject_name_rust as cxx_qt::Constructor<(#(#argument_types,)*)>>
+                                    ::route_arguments((#(#assign_arguments,)*));
+                #arguments_rust {
+                    baseArguments: #base_arguments_rust {
+                        #(#init_base_arguments,)*
+                        notEmpty: 0
+                    },
+                    initializeArguments: #initialize_arguments_rust {
+                        #(#init_initialize_arguments,)*
+                        notEmpty: 0
+                    },
+                    newArguments: #new_arguments_rust {
+                        #(#init_new_arguments,)*
+                        notEmpty: 0
+                    },
+                }
+            }
+        },
+        parse_quote! {
+            #[doc(hidden)]
+            pub fn #new_rust(new_arguments: #new_arguments_rust) -> std::boxed::Box<#rust_struct_name_rust> {
+                let new_arguments = (#(#extract_new_arguments,)*);
+                std::boxed::Box::new(<#qobject_name_rust as cxx_qt::Constructor<(#(#argument_types,)*)>>::new(new_arguments))
+            }
+        },
+        parse_quote! {
+            #[doc(hidden)]
+            pub fn #initialize_rust(
+                qobject: core::pin::Pin<&mut #qobject_name_rust>,
+                initialize_arguments: #initialize_arguments_rust
+            ) {
+                let initialize_arguments = (#(#extract_initialize_arguments,)*);
+                <#qobject_name_rust as cxx_qt::Constructor<(#(#argument_types,)*)>>::initialize(qobject, initialize_arguments)
+            }
+        },
+        parse_quote! {
+            impl cxx_qt::Constructor<(#(#argument_types,)*)> for #qobject_name_rust {
+                type NewArguments = (#(#new_argument_types,)*);
+                type InitializeArguments = (#(#initialize_argument_types,)*);
+                type BaseArguments = (#(#base_argument_types,)*);
+
+                #(#passthrough_items)*
+            }
+        }])
+    }
+    Ok(result)
+}

crates/cxx-qt-gen/src/generator/rust/mod.rs

@@ -3,6 +3,7 @@
 //
 // SPDX-License-Identifier: MIT OR Apache-2.0
 
+pub mod constructor;
 pub mod fragment;
 pub mod inherit;
 pub mod invokable;

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

@@ -7,7 +7,7 @@ use crate::{
     generator::{
         naming::{namespace::NamespaceName, qobject::QObjectName},
         rust::{
-            fragment::RustFragmentPair, inherit, invokable::generate_rust_invokables,
+            constructor, fragment::RustFragmentPair, inherit, invokable::generate_rust_invokables,
             property::generate_rust_properties, signals::generate_rust_signals, threading,
         },
     },
@@ -130,6 +130,12 @@ impl GeneratedRustQObject {
                 });
         }
 
+        generated.blocks.append(&mut constructor::generate(
+            &qobject.constructors,
+            &qobject_idents,
+            &namespace_idents,
+        )?);
+
         Ok(generated)
     }
 }
@@ -256,7 +262,7 @@ mod tests {
 
         let rust = GeneratedRustQObject::from(parser.cxx_qt_data.qobjects.values().next().unwrap())
             .unwrap();
-        assert_eq!(rust.blocks.cxx_mod_contents.len(), 3);
+        assert_eq!(rust.blocks.cxx_mod_contents.len(), 4);
         assert_tokens_eq(
             &rust.blocks.cxx_mod_contents[0],
             quote! {
@@ -289,5 +295,15 @@ mod tests {
                 }
             },
         );
+        assert_tokens_eq(
+            &rust.blocks.cxx_mod_contents[3],
+            quote! {
+                extern "Rust" {
+                    #[cxx_name = "createRs"]
+                    #[namespace = "cxx_qt::cxx_qt_my_object"]
+                    fn create_rs_my_object() -> Box<MyObject>;
+                }
+            },
+        );
     }
 }