Add @rust-attr on scturct (#2785)

Fixes: #2660

api/rs/slint/Cargo.toml

@@ -138,6 +138,8 @@ log = { version = "0.4.17", optional = true }
 [dev-dependencies]
 slint-build = { path = "../build" }
 i-slint-backend-testing = { version = "=1.0.3", path = "../../../internal/backends/testing" }
+serde_json = "1.0.96"
+serde = { version = "1.0.163", features = ["derive"] }
 
 [package.metadata.docs.rs]
 rustdoc-args = [

api/rs/slint/lib.rs

@@ -208,6 +208,26 @@ struct MyStruct {
 }
 ```
 
+The `.slint` file allows you to utilize Rust attributes and features for defining structures using the `@rust-attr()` directive.
+This enables you to customize the generated code by applying additional traits, derivations, or annotations.
+Consider the following structure defined in the `.slint` file with Rust attributes:
+```slint,ignore
+@rust-attr(derive(serde::Serialize, serde::Deserialize))
+struct MyStruct {
+    foo : i32,
+}
+```
+
+Based on this structure, the following Rust code would be generated:
+
+```rust
+#[derive(serde::Serialize, serde::Deserialize)]
+#[derive(Default, Clone, Debug, PartialEq)]
+struct MyStruct {
+    foo : i32,
+}
+```
+
 ## Exported Global singletons
 
 */

api/rs/slint/tests/simple_macro.rs

@@ -15,3 +15,19 @@ fn empty_stuff() {
     slint!(export struct Hei { abcd: bool });
     slint!(export global G { });
 }
+
+#[test]
+fn test_serialize_deserialize_struct() {
+    i_slint_backend_testing::init();
+    slint! {
+        @rust-attr(derive(serde::Serialize, serde::Deserialize))
+        export struct TestStruct {
+            foo: int,
+        }
+        export component Test { }
+    }
+    let data = TestStruct { foo: 1 };
+    let serialized = serde_json::to_string(&data).unwrap();
+    let deserialized: TestStruct = serde_json::from_str(&serialized).unwrap();
+    assert_eq!(data, deserialized);
+}

internal/compiler/expression_tree.rs

@@ -173,6 +173,7 @@ impl BuiltinFunction {
                     .collect(),
                     name: Some("Size".to_string()),
                     node: None,
+                    rust_attributes: None,
                 }),
                 args: vec![Type::Image],
             },
@@ -1027,7 +1028,7 @@ impl Expression {
                 },
                 (
                     Type::Struct { fields: ref left, .. },
-                    Type::Struct { fields: right, name, node: n },
+                    Type::Struct { fields: right, name, node: n, rust_attributes },
                 ) if left != right => {
                     if let Expression::Struct { mut values, .. } = self {
                         let mut new_values = HashMap::new();
@@ -1051,6 +1052,7 @@ impl Expression {
                                         fields: left.clone(),
                                         name: name.clone(),
                                         node: n.clone(),
+                                        rust_attributes: rust_attributes.clone(),
                                     },
                                 }),
                                 name: key.clone(),

internal/compiler/generator/cpp.rs

@@ -579,7 +579,7 @@ pub fn generate(doc: &Document) -> impl std::fmt::Display {
     }
 
     for ty in doc.root_component.used_types.borrow().structs.iter() {
-        if let Type::Struct { fields, name: Some(name), node: Some(node) } = ty {
+        if let Type::Struct { fields, name: Some(name), node: Some(node), .. } = ty {
             generate_struct(&mut file, name, fields, node);
         }
     }

internal/compiler/generator/rust.rs

@@ -25,6 +25,7 @@ use proc_macro2::{Ident, TokenStream};
 use quote::{format_ident, quote};
 use std::collections::BTreeMap;
 use std::num::NonZeroUsize;
+use std::str::FromStr;
 
 type EvaluationContext<'a> = llr_EvaluationContext<'a, TokenStream>;
 type ParentCtx<'a> = llr_ParentCtx<'a, TokenStream>;
@@ -139,8 +140,8 @@ pub fn generate(doc: &Document) -> TokenStream {
         .structs
         .iter()
         .filter_map(|ty| {
-            if let Type::Struct { fields, name: Some(name), node: Some(_) } = ty {
-                Some((ident(name), generate_struct(name, fields)))
+            if let Type::Struct { fields, name: Some(name), node: Some(_), rust_attributes } = ty {
+                Some((ident(name), generate_struct(name, fields, rust_attributes)))
             } else {
                 None
             }
@@ -422,12 +423,28 @@ fn generate_public_component(llr: &llr::PublicComponent) -> TokenStream {
     )
 }
 
-fn generate_struct(name: &str, fields: &BTreeMap<String, Type>) -> TokenStream {
+fn generate_struct(
+    name: &str,
+    fields: &BTreeMap<String, Type>,
+    rust_attributes: &Option<Vec<String>>,
+) -> TokenStream {
     let component_id = struct_name_to_tokens(name);
     let (declared_property_vars, declared_property_types): (Vec<_>, Vec<_>) =
         fields.iter().map(|(name, ty)| (ident(name), rust_primitive_type(ty).unwrap())).unzip();
 
+    let attributes = if let Some(feature) = rust_attributes {
+        let attr =
+            feature.iter().map(|f| match TokenStream::from_str(format!(r#"#[{}]"#, f).as_str()) {
+                Ok(eval) => eval,
+                Err(_) => quote! {},
+            });
+        quote! { #(#attr)* }
+    } else {
+        quote! {}
+    };
+
     quote! {
+        #attributes
         #[derive(Default, PartialEq, Debug, Clone)]
         pub struct #component_id {
             #(pub #declared_property_vars : #declared_property_types),*

internal/compiler/langtype.rs

@@ -60,6 +60,8 @@ pub enum Type {
         name: Option<String>,
         /// When declared in .slint, this is the node of the declaration.
         node: Option<syntax_nodes::ObjectType>,
+        /// deriven
+        rust_attributes: Option<Vec<String>>,
     },
     Enumeration(Rc<Enumeration>),
 
@@ -104,8 +106,8 @@ impl core::cmp::PartialEq for Type {
             Type::Easing => matches!(other, Type::Easing),
             Type::Brush => matches!(other, Type::Brush),
             Type::Array(a) => matches!(other, Type::Array(b) if a == b),
-            Type::Struct { fields, name, node: _ } => {
-                matches!(other, Type::Struct{fields: f, name: n, node: _} if fields == f && name == n)
+            Type::Struct { fields, name, node: _, rust_attributes: _ } => {
+                matches!(other, Type::Struct{fields:f,name:n,node:_, rust_attributes: _ } if fields == f && name == n)
             }
             Type::Enumeration(lhs) => matches!(other, Type::Enumeration(rhs) if lhs == rhs),
             Type::UnitProduct(a) => matches!(other, Type::UnitProduct(b) if a == b),

internal/compiler/layout.rs

@@ -460,6 +460,7 @@ pub fn layout_info_type() -> Type {
             .collect(),
         name: Some("LayoutInfo".into()),
         node: None,
+        rust_attributes: None,
     }
 }
 

internal/compiler/llr/lower_expression.rs

@@ -398,6 +398,7 @@ pub fn lower_animation(a: &PropertyAnimation, ctx: &ExpressionContext<'_>) -> An
             fields: animation_fields().collect(),
             name: Some("PropertyAnimation".into()),
             node: None,
+            rust_attributes: None,
         }
     }
 
@@ -435,6 +436,7 @@ pub fn lower_animation(a: &PropertyAnimation, ctx: &ExpressionContext<'_>) -> An
                     .collect(),
                     name: None,
                     node: None,
+                    rust_attributes: None,
                 },
                 values: IntoIterator::into_iter([
                     ("0".to_string(), get_anim),
@@ -661,6 +663,7 @@ fn box_layout_data(
         .collect(),
         name: Some("BoxLayoutCellData".into()),
         node: None,
+        rust_attributes: None,
     };
 
     if repeater_count == 0 {
@@ -747,6 +750,7 @@ pub(super) fn grid_layout_cell_data_ty() -> Type {
         .collect(),
         name: Some("GridLayoutCellData".into()),
         node: None,
+        rust_attributes: None,
     }
 }
 
@@ -843,6 +847,7 @@ fn compile_path(path: &crate::expression_tree::Path, ctx: &ExpressionContext) ->
                     fields: Default::default(),
                     name: Some("PathElement".to_owned()),
                     node: None,
+                    rust_attributes: None,
                 },
                 values: elements,
                 as_model: false,
@@ -866,6 +871,7 @@ fn compile_path(path: &crate::expression_tree::Path, ctx: &ExpressionContext) ->
                             .collect(),
                         name: element.element_type.native_class.cpp_type.clone(),
                         node: None,
+                        rust_attributes: None,
                     };
 
                     llr_Expression::Struct {
@@ -917,6 +923,7 @@ fn compile_path(path: &crate::expression_tree::Path, ctx: &ExpressionContext) ->
                         .collect(),
                         name: None,
                         node: None,
+                        rust_attributes: None,
                     },
                     values: IntoIterator::into_iter([
                         (
@@ -960,5 +967,8 @@ fn make_struct(
         values.insert(name.to_string(), expr);
     }
 
-    llr_Expression::Struct { ty: Type::Struct { fields, name: Some(name), node: None }, values }
+    llr_Expression::Struct {
+        ty: Type::Struct { fields, name: Some(name), node: None, rust_attributes: None },
+        values,
+    }
 }

internal/compiler/load_builtins.rs

@@ -36,7 +36,7 @@ pub fn load_builtins(register: &mut TypeRegister) {
     // parse structs
     for s in doc.StructDeclaration().chain(doc.ExportsList().flat_map(|e| e.StructDeclaration())) {
         let external_name = identifier_text(&s.DeclaredIdentifier()).unwrap();
-        let mut ty = object_tree::type_struct_from_node(s.ObjectType(), &mut diag, register);
+        let mut ty = object_tree::type_struct_from_node(s.ObjectType(), &mut diag, register, None);
         if let Type::Struct { name, .. } = &mut ty {
             *name = Some(
                 parse_annotation("name", &s.ObjectType())

internal/compiler/object_tree.rs

@@ -7,7 +7,7 @@
 
 // cSpell: ignore qualname
 
-use itertools::Either;
+use itertools::{Either, Itertools};
 
 use crate::diagnostics::{BuildDiagnostics, SourceLocation, Spanned};
 use crate::expression_tree::{self, BindingExpression, Expression, Unit};
@@ -77,7 +77,21 @@ impl Document {
             |n: syntax_nodes::StructDeclaration,
              diag: &mut BuildDiagnostics,
              local_registry: &mut TypeRegister| {
-                let mut ty = type_struct_from_node(n.ObjectType(), diag, local_registry);
+                let rust_attributes: Vec<String> = n
+                    .children()
+                    .filter(|child| child.kind() == SyntaxKind::AtRustAttr)
+                    .map(|child| {
+                        let mut text = child.text().to_string();
+                        text.pop();
+                        text
+                    })
+                    .collect_vec();
+                let mut ty = type_struct_from_node(
+                    n.ObjectType(),
+                    diag,
+                    local_registry,
+                    Some(rust_attributes),
+                );
                 if let Type::Struct { name, .. } = &mut ty {
                     *name = parser::identifier_text(&n.DeclaredIdentifier());
                 } else {
@@ -1630,7 +1644,7 @@ pub fn type_from_node(
         }
         prop_type
     } else if let Some(object_node) = node.ObjectType() {
-        type_struct_from_node(object_node, diag, tr)
+        type_struct_from_node(object_node, diag, tr, None)
     } else if let Some(array_node) = node.ArrayType() {
         Type::Array(Box::new(type_from_node(array_node.Type(), diag, tr)))
     } else {
@@ -1644,6 +1658,7 @@ pub fn type_struct_from_node(
     object_node: syntax_nodes::ObjectType,
     diag: &mut BuildDiagnostics,
     tr: &TypeRegister,
+    rust_attributes: Option<Vec<String>>,
 ) -> Type {
     let fields = object_node
         .ObjectTypeMember()
@@ -1654,7 +1669,7 @@ pub fn type_struct_from_node(
             )
         })
         .collect();
-    Type::Struct { fields, name: None, node: Some(object_node) }
+    Type::Struct { fields, name: None, node: Some(object_node), rust_attributes }
 }
 
 fn animation_element_from_node(

internal/compiler/parser.rs

@@ -422,8 +422,9 @@ declare_syntax! {
         /// `[ type ]`
         ArrayType -> [ Type ],
         /// `struct Foo := { ... }
-        StructDeclaration -> [DeclaredIdentifier, ObjectType],
-
+        StructDeclaration -> [DeclaredIdentifier, ObjectType, ?AtRustAttr],
+        /// `@rust-attr(...)`
+        AtRustAttr -> [],
     }
 }
 

internal/compiler/parser/document.rs

@@ -4,6 +4,7 @@
 use super::element::{parse_element, parse_element_content};
 use super::prelude::*;
 use super::r#type::parse_struct_declaration;
+use crate::parser::r#type::parse_rustattr;
 
 #[cfg_attr(test, parser_test)]
 /// ```test,Document
@@ -45,6 +46,35 @@ pub fn parse_document(p: &mut impl Parser) -> bool {
                     break;
                 }
             }
+            "@" if p.nth(1).as_str() == "rust-attr" => {
+                let mut is_export = false;
+                let mut i = 0;
+                loop {
+                    let value = p.nth(i);
+                    if value.as_str() == ")" && p.nth(i + 1).as_str() == "export" {
+                        is_export = true;
+                        break;
+                    } else if (value.as_str() == ")"
+                        && p.nth(i + 1).as_str() != "struct"
+                        && p.nth(i + 1).as_str() != "export"
+                        && p.nth(i + 1).as_str() != ")")
+                        || (value.as_str() == ")" && p.nth(i + 1).as_str() == "struct")
+                    {
+                        break;
+                    }
+                    i += 1;
+                }
+                if is_export {
+                    let mut p = p.start_node(SyntaxKind::ExportsList);
+                    if !parse_rustattr(&mut *p) {
+                        break;
+                    }
+                } else {
+                    if !parse_rustattr(&mut *p) {
+                        break;
+                    }
+                }
+            }
             _ => {
                 if !parse_component(&mut *p) {
                     break;

internal/compiler/parser/type.rs

@@ -85,3 +85,57 @@ pub fn parse_struct_declaration(p: &mut impl Parser) -> bool {
     parse_type_object(&mut *p);
     true
 }
+
+pub fn parse_rustattr(p: &mut impl Parser) -> bool {
+    let checkpoint = p.checkpoint();
+    debug_assert_eq!(p.peek().as_str(), "@");
+    p.consume(); // "@"
+    if p.peek().as_str() != "rust-attr" {
+        p.expect(SyntaxKind::AtRustAttr);
+    }
+    p.consume(); // "rust-attr"
+    p.expect(SyntaxKind::LParent);
+    parse_parentheses(&mut *p);
+    if p.peek().as_str() == "export" {
+        p.consume();
+    }
+    let mut p = p.start_node_at(checkpoint, SyntaxKind::StructDeclaration);
+    p.consume(); // "struct"
+    {
+        let mut p = p.start_node(SyntaxKind::DeclaredIdentifier);
+        p.expect(SyntaxKind::Identifier);
+    }
+
+    if p.peek().kind() == SyntaxKind::ColonEqual {
+        p.warning("':=' to declare a struct is deprecated. Remove the ':='");
+        p.consume();
+    }
+
+    parse_type_object(&mut *p);
+    true
+}
+
+fn parse_parentheses(p: &mut impl Parser) -> bool {
+    let mut p = p.start_node(SyntaxKind::AtRustAttr);
+    let mut opened = 0;
+    let mut closed = 0;
+    while closed <= opened {
+        if p.peek().kind() == SyntaxKind::LParent {
+            opened += 1;
+        }
+        if p.peek().kind() == SyntaxKind::RParent {
+            closed += 1;
+        }
+        if closed == opened && opened != 0 && closed != 0 && p.peek().kind() != SyntaxKind::RParent
+        {
+            p.error("Parse error: `)` or `,`");
+            return false;
+        }
+        p.consume();
+    }
+    if p.peek().as_str() != "struct" && p.peek().as_str() != "export" {
+        p.error("Parse error: expected `struct` or `export`");
+        return false;
+    }
+    true
+}

internal/compiler/passes/compile_paths.rs

@@ -139,6 +139,7 @@ fn compile_path_from_string_literal(
         .collect(),
         name: Some("Point".into()),
         node: None,
+        rust_attributes: None,
     };
 
     let mut points = Vec::new();

internal/compiler/passes/resolving.rs

@@ -969,6 +969,7 @@ impl Expression {
             fields: values.iter().map(|(k, v)| (k.clone(), v.ty())).collect(),
             name: None,
             node: None,
+            rust_attributes: None,
         };
         Expression::Struct { ty, values }
     }
@@ -1030,8 +1031,14 @@ impl Expression {
                             fields: mut result_fields,
                             name: result_name,
                             node: result_node,
+                            rust_attributes,
+                        },
+                        Type::Struct {
+                            fields: elem_fields,
+                            name: elem_name,
+                            node: elem_node,
+                            rust_attributes: deriven,
                         },
-                        Type::Struct { fields: elem_fields, name: elem_name, node: elem_node },
                     ) => {
                         for (elem_name, elem_ty) in elem_fields.into_iter() {
                             match result_fields.entry(elem_name) {
@@ -1052,6 +1059,7 @@ impl Expression {
                             name: result_name.or(elem_name),
                             fields: result_fields,
                             node: result_node.or(elem_node),
+                            rust_attributes: rust_attributes.or(deriven),
                         }
                     }
                     (Type::Color, Type::Brush) | (Type::Brush, Type::Color) => Type::Brush,

internal/interpreter/highlight.rs

@@ -355,6 +355,7 @@ fn add_highlight_items(doc: &Document) {
                         .collect(),
                     name: None,
                     node: None,
+                    rust_attributes: None,
                 }
                 .into(),
             ),