Add more utility traits and funtions to boa_interop (#3773)

* Add more utility traits and funtions to boa_interop

* cargo clippy

* Readd the safe version for Fn which also implements Copy

* Use a new trait for converting a Rust type to a JsResult<JsValue>

* cargo clippy

* Add a test for returning result and Fn()

* Seal both IntoJsFunction and IntoJsFunctionUnsafe

* Try Borrowing and return a nice error instead of panicking

* Address comments

* Rename into_js_function to into_js_function_copied

* Move TryIntoJsResult to boa_engine

* Move JsRest to be at the end only of arguments and add JsAll

* use from_copy_closure and remove unsafe

core/engine/src/lib.rs

@@ -141,6 +141,22 @@ pub use prelude::*;
 /// The result of a Javascript expression is represented like this so it can succeed (`Ok`) or fail (`Err`)
 pub type JsResult<T> = StdResult<T, JsError>;
 
+/// Create a [`JsResult`] from a Rust value. This trait is used to
+/// convert Rust types to JS types, including [`JsResult`] of
+/// Rust values and [`JsValue`]s.
+///
+/// This trait is implemented for any that can be converted into a [`JsValue`].
+pub trait TryIntoJsResult {
+    /// Try to convert a Rust value into a `JsResult<JsValue>`.
+    ///
+    /// # Errors
+    /// Any parsing errors that may occur during the conversion, or any
+    /// error that happened during the call to a function.
+    fn try_into_js_result(self, context: &mut Context) -> JsResult<JsValue>;
+}
+
+mod try_into_js_result_impls;
+
 /// A utility trait to make working with function arguments easier.
 pub trait JsArgs {
     /// Utility function to `get` a parameter from a `[JsValue]` or default to `JsValue::Undefined`

core/engine/src/try_into_js_result_impls.rs

@@ -0,0 +1,33 @@
+//! Declare implementations of [`TryIntoJsResult`] trait for various types.
+
+use crate::{Context, JsResult, JsValue, TryIntoJsResult};
+
+impl<T> TryIntoJsResult for T
+where
+    T: Into<JsValue>,
+{
+    fn try_into_js_result(self, _cx: &mut Context) -> JsResult<JsValue> {
+        Ok(self.into())
+    }
+}
+
+impl<T> TryIntoJsResult for Option<T>
+where
+    T: TryIntoJsResult,
+{
+    fn try_into_js_result(self, cx: &mut Context) -> JsResult<JsValue> {
+        match self {
+            Some(value) => value.try_into_js_result(cx),
+            None => Ok(JsValue::undefined()),
+        }
+    }
+}
+
+impl<T> TryIntoJsResult for JsResult<T>
+where
+    T: TryIntoJsResult,
+{
+    fn try_into_js_result(self, cx: &mut Context) -> JsResult<JsValue> {
+        self.and_then(|value| value.try_into_js_result(cx))
+    }
+}

core/interop/src/into_js_function_impls.rs

@@ -0,0 +1,240 @@
+//! Implementations of the `IntoJsFunction` trait for various function signatures.
+
+use std::cell::RefCell;
+
+use boa_engine::{js_string, Context, JsError, NativeFunction, TryIntoJsResult};
+
+use crate::private::IntoJsFunctionSealed;
+use crate::{IntoJsFunctionCopied, JsRest, TryFromJsArgument, UnsafeIntoJsFunction};
+
+/// A token to represent the context argument in the function signature.
+/// This should not be used directly and has no external meaning.
+#[derive(Debug, Copy, Clone)]
+pub struct ContextArgToken;
+
+macro_rules! impl_into_js_function {
+    ($($id: ident: $t: ident),*) => {
+        impl<$($t,)* R, T> IntoJsFunctionSealed<($($t,)*), R> for T
+        where
+            $($t: TryFromJsArgument + 'static,)*
+            R: TryIntoJsResult,
+            T: FnMut($($t,)*) -> R + 'static
+        {}
+
+        impl<$($t,)* R, T> IntoJsFunctionSealed<($($t,)* ContextArgToken,), R> for T
+        where
+            $($t: TryFromJsArgument + 'static,)*
+            R: TryIntoJsResult,
+            T: FnMut($($t,)* &mut Context) -> R + 'static
+        {}
+
+        impl<$($t,)* R, T> IntoJsFunctionSealed<($($t,)* JsRest,), R> for T
+        where
+            $($t: TryFromJsArgument + 'static,)*
+            R: TryIntoJsResult,
+            T: FnMut($($t,)* JsRest) -> R + 'static
+        {}
+
+        impl<$($t,)* R, T> IntoJsFunctionSealed<($($t,)* JsRest, ContextArgToken), R> for T
+        where
+            $($t: TryFromJsArgument + 'static,)*
+            R: TryIntoJsResult,
+            T: FnMut($($t,)* JsRest, &mut Context) -> R + 'static
+        {}
+
+        impl<$($t,)* R, T> UnsafeIntoJsFunction<($($t,)*), R> for T
+        where
+            $($t: TryFromJsArgument + 'static,)*
+            R: TryIntoJsResult,
+            T: FnMut($($t,)*) -> R + 'static,
+        {
+            #[allow(unused_variables)]
+            unsafe fn into_js_function_unsafe(self, _context: &mut Context) -> NativeFunction {
+                let s = RefCell::new(self);
+                unsafe {
+                    NativeFunction::from_closure(move |this, args, ctx| {
+                        let rest = args;
+                        $(
+                            let ($id, rest) = $t::try_from_js_argument(this, rest, ctx)?;
+                        )*
+                        match s.try_borrow_mut() {
+                            Ok(mut r) => r( $($id,)* ).try_into_js_result(ctx),
+                            Err(_) => {
+                                Err(JsError::from_opaque(js_string!("recursive calls to this function not supported").into()))
+                            }
+                        }
+                    })
+                }
+            }
+        }
+
+        impl<$($t,)* R, T> UnsafeIntoJsFunction<($($t,)* JsRest,), R> for T
+        where
+            $($t: TryFromJsArgument + 'static,)*
+            R: TryIntoJsResult,
+            T: FnMut($($t,)* JsRest) -> R + 'static,
+        {
+            #[allow(unused_variables)]
+            unsafe fn into_js_function_unsafe(self, _context: &mut Context) -> NativeFunction {
+                let s = RefCell::new(self);
+                unsafe {
+                    NativeFunction::from_closure(move |this, args, ctx| {
+                        let rest = args;
+                        $(
+                            let ($id, rest) = $t::try_from_js_argument(this, rest, ctx)?;
+                        )*
+                        match s.try_borrow_mut() {
+                            Ok(mut r) => r( $($id,)* rest.into() ).try_into_js_result(ctx),
+                            Err(_) => {
+                                Err(JsError::from_opaque(js_string!("recursive calls to this function not supported").into()))
+                            }
+                        }
+                    })
+                }
+            }
+        }
+
+        impl<$($t,)* R, T> UnsafeIntoJsFunction<($($t,)* ContextArgToken,), R> for T
+        where
+            $($t: TryFromJsArgument + 'static,)*
+            R: TryIntoJsResult,
+            T: FnMut($($t,)* &mut Context) -> R + 'static,
+        {
+            #[allow(unused_variables)]
+            unsafe fn into_js_function_unsafe(self, _context: &mut Context) -> NativeFunction {
+                let s = RefCell::new(self);
+                unsafe {
+                    NativeFunction::from_closure(move |this, args, ctx| {
+                        let rest = args;
+                        $(
+                            let ($id, rest) = $t::try_from_js_argument(this, rest, ctx)?;
+                        )*
+                        let r = s.borrow_mut()( $($id,)* ctx);
+                        r.try_into_js_result(ctx)
+                    })
+                }
+            }
+        }
+
+        impl<$($t,)* R, T> UnsafeIntoJsFunction<($($t,)* JsRest, ContextArgToken), R> for T
+        where
+            $($t: TryFromJsArgument + 'static,)*
+            R: TryIntoJsResult,
+            T: FnMut($($t,)* JsRest, &mut Context) -> R + 'static,
+        {
+            #[allow(unused_variables)]
+            unsafe fn into_js_function_unsafe(self, _context: &mut Context) -> NativeFunction {
+                let s = RefCell::new(self);
+                unsafe {
+                    NativeFunction::from_closure(move |this, args, ctx| {
+                        let rest = args;
+                        $(
+                            let ($id, rest) = $t::try_from_js_argument(this, rest, ctx)?;
+                        )*
+                        let r = s.borrow_mut()( $($id,)* rest.into(), ctx);
+                        r.try_into_js_result(ctx)
+                    })
+                }
+            }
+        }
+
+        // Safe versions for `Fn(..) -> ...`.
+        impl<$($t,)* R, T> IntoJsFunctionCopied<($($t,)*), R> for T
+        where
+            $($t: TryFromJsArgument + 'static,)*
+            R: TryIntoJsResult,
+            T: Fn($($t,)*) -> R + 'static + Copy,
+        {
+            #[allow(unused_variables)]
+            fn into_js_function_copied(self, _context: &mut Context) -> NativeFunction {
+                let s = self;
+                NativeFunction::from_copy_closure(move |this, args, ctx| {
+                    let rest = args;
+                    $(
+                        let ($id, rest) = $t::try_from_js_argument(this, rest, ctx)?;
+                    )*
+                    let r = s( $($id,)* );
+                    r.try_into_js_result(ctx)
+                })
+            }
+        }
+
+        impl<$($t,)* R, T> IntoJsFunctionCopied<($($t,)* JsRest,), R> for T
+        where
+            $($t: TryFromJsArgument + 'static,)*
+            R: TryIntoJsResult,
+            T: Fn($($t,)* JsRest) -> R + 'static + Copy,
+        {
+            #[allow(unused_variables)]
+            fn into_js_function_copied(self, _context: &mut Context) -> NativeFunction {
+                let s = self;
+                NativeFunction::from_copy_closure(move |this, args, ctx| {
+                    let rest = args;
+                    $(
+                        let ($id, rest) = $t::try_from_js_argument(this, rest, ctx)?;
+                    )*
+                    let r = s( $($id,)* rest.into() );
+                    r.try_into_js_result(ctx)
+                })
+            }
+        }
+
+        impl<$($t,)* R, T> IntoJsFunctionCopied<($($t,)* ContextArgToken,), R> for T
+        where
+            $($t: TryFromJsArgument + 'static,)*
+            R: TryIntoJsResult,
+            T: Fn($($t,)* &mut Context) -> R + 'static + Copy,
+        {
+            #[allow(unused_variables)]
+            fn into_js_function_copied(self, _context: &mut Context) -> NativeFunction {
+                let s = self;
+                NativeFunction::from_copy_closure(move |this, args, ctx| {
+                    let rest = args;
+                    $(
+                        let ($id, rest) = $t::try_from_js_argument(this, rest, ctx)?;
+                    )*
+                    let r = s( $($id,)* ctx);
+                    r.try_into_js_result(ctx)
+                })
+            }
+        }
+
+        impl<$($t,)* R, T> IntoJsFunctionCopied<($($t,)* JsRest, ContextArgToken), R> for T
+        where
+            $($t: TryFromJsArgument + 'static,)*
+            R: TryIntoJsResult,
+            T: Fn($($t,)* JsRest, &mut Context) -> R + 'static + Copy,
+        {
+            #[allow(unused_variables)]
+            fn into_js_function_copied(self, _context: &mut Context) -> NativeFunction {
+                let s = self;
+                NativeFunction::from_copy_closure(move |this, args, ctx| {
+                    let rest = args;
+                    $(
+                        let ($id, rest) = $t::try_from_js_argument(this, rest, ctx)?;
+                    )*
+                    let r = s( $($id,)* rest.into(), ctx);
+                    r.try_into_js_result(ctx)
+                })
+            }
+        }
+    };
+}
+
+// Currently implemented up to 12 arguments. The empty argument list
+// is implemented separately above.
+// Consider that JsRest and JsThis are part of this list, but Context
+// is not, as it is a special specialization of the template.
+impl_into_js_function!();
+impl_into_js_function!(a: A);
+impl_into_js_function!(a: A, b: B);
+impl_into_js_function!(a: A, b: B, c: C);
+impl_into_js_function!(a: A, b: B, c: C, d: D);
+impl_into_js_function!(a: A, b: B, c: C, d: D, e: E);
+impl_into_js_function!(a: A, b: B, c: C, d: D, e: E, f: F);
+impl_into_js_function!(a: A, b: B, c: C, d: D, e: E, f: F, g: G);
+impl_into_js_function!(a: A, b: B, c: C, d: D, e: E, f: F, g: G, h: H);
+impl_into_js_function!(a: A, b: B, c: C, d: D, e: E, f: F, g: G, h: H, i: I);
+impl_into_js_function!(a: A, b: B, c: C, d: D, e: E, f: F, g: G, h: H, i: I, j: J);
+impl_into_js_function!(a: A, b: B, c: C, d: D, e: E, f: F, g: G, h: H, i: I, j: J, k: K);
+impl_into_js_function!(a: A, b: B, c: C, d: D, e: E, f: F, g: G, h: H, i: I, j: J, k: K, l: L);