Implement To/FromWasmAbi traits for boxed slices of JsValue wrappers

crates/backend/src/codegen.rs

@@ -624,7 +624,7 @@ impl ToTokens for ast::ImportType {
                 use wasm_bindgen::convert::{OptionIntoWasmAbi, OptionFromWasmAbi};
                 use wasm_bindgen::convert::RefFromWasmAbi;
                 use wasm_bindgen::describe::WasmDescribe;
-                use wasm_bindgen::{JsValue, JsCast};
+                use wasm_bindgen::{JsValue, JsCast, JsObject};
                 use wasm_bindgen::__rt::core;
 
                 impl WasmDescribe for #rust_name {
@@ -761,6 +761,8 @@ impl ToTokens for ast::ImportType {
                     }
                 }
 
+                impl JsObject for #rust_name {}
+
                 ()
             };
         })

crates/cli-support/src/descriptor.rs

@@ -86,7 +86,7 @@ pub struct Closure {
     pub mutable: bool,
 }
 
-#[derive(Copy, Clone, Debug)]
+#[derive(Clone, Debug)]
 pub enum VectorKind {
     I8,
     U8,
@@ -101,6 +101,7 @@ pub enum VectorKind {
     F64,
     String,
     Externref,
+    NamedExternref(String),
 }
 
 impl Descriptor {
@@ -193,6 +194,7 @@ impl Descriptor {
             Descriptor::F32 => Some(VectorKind::F32),
             Descriptor::F64 => Some(VectorKind::F64),
             Descriptor::Externref => Some(VectorKind::Externref),
+            Descriptor::NamedExternref(ref name) => Some(VectorKind::NamedExternref(name.clone())),
             _ => None,
         }
     }
@@ -240,21 +242,24 @@ impl Function {
 }
 
 impl VectorKind {
-    pub fn js_ty(&self) -> &str {
+    pub fn js_ty(&self) -> String {
         match *self {
-            VectorKind::String => "string",
-            VectorKind::I8 => "Int8Array",
-            VectorKind::U8 => "Uint8Array",
-            VectorKind::ClampedU8 => "Uint8ClampedArray",
-            VectorKind::I16 => "Int16Array",
-            VectorKind::U16 => "Uint16Array",
-            VectorKind::I32 => "Int32Array",
-            VectorKind::U32 => "Uint32Array",
-            VectorKind::I64 => "BigInt64Array",
-            VectorKind::U64 => "BigUint64Array",
-            VectorKind::F32 => "Float32Array",
-            VectorKind::F64 => "Float64Array",
-            VectorKind::Externref => "any[]",
+            VectorKind::String => "string".to_string(),
+            VectorKind::I8 => "Int8Array".to_string(),
+            VectorKind::U8 => "Uint8Array".to_string(),
+            VectorKind::ClampedU8 => "Uint8ClampedArray".to_string(),
+            VectorKind::I16 => "Int16Array".to_string(),
+            VectorKind::U16 => "Uint16Array".to_string(),
+            VectorKind::I32 => "Int32Array".to_string(),
+            VectorKind::U32 => "Uint32Array".to_string(),
+            VectorKind::I64 => "BigInt64Array".to_string(),
+            VectorKind::U64 => "BigUint64Array".to_string(),
+            VectorKind::F32 => "Float32Array".to_string(),
+            VectorKind::F64 => "Float64Array".to_string(),
+            VectorKind::Externref => "any[]".to_string(),
+            VectorKind::NamedExternref(ref name) => {
+                format!("({})[]", name)
+            }
         }
     }
 
@@ -273,6 +278,7 @@ impl VectorKind {
             VectorKind::F32 => 4,
             VectorKind::F64 => 8,
             VectorKind::Externref => 4,
+            VectorKind::NamedExternref(_) => 4,
         }
     }
 }

crates/cli-support/src/externref.rs

@@ -351,31 +351,31 @@ fn module_needs_externref_metadata(aux: &WasmBindgenAux, section: &NonstandardWi
         };
         instructions.iter().any(|instr| match instr.instr {
             VectorToMemory {
-                kind: VectorKind::Externref,
+                kind: VectorKind::Externref | VectorKind::NamedExternref(_),
                 ..
             }
             | MutableSliceToMemory {
-                kind: VectorKind::Externref,
+                kind: VectorKind::Externref | VectorKind::NamedExternref(_),
                 ..
             }
             | OptionVector {
-                kind: VectorKind::Externref,
+                kind: VectorKind::Externref | VectorKind::NamedExternref(_),
                 ..
             }
             | VectorLoad {
-                kind: VectorKind::Externref,
+                kind: VectorKind::Externref | VectorKind::NamedExternref(_),
                 ..
             }
             | OptionVectorLoad {
-                kind: VectorKind::Externref,
+                kind: VectorKind::Externref | VectorKind::NamedExternref(_),
                 ..
             }
             | View {
-                kind: VectorKind::Externref,
+                kind: VectorKind::Externref | VectorKind::NamedExternref(_),
                 ..
             }
             | OptionView {
-                kind: VectorKind::Externref,
+                kind: VectorKind::Externref | VectorKind::NamedExternref(_),
                 ..
             } => true,
             _ => false,

crates/cli-support/src/js/binding.rs

@@ -762,7 +762,7 @@ fn instruction(js: &mut JsBuilder, instr: &Instruction, log_error: &mut bool) ->
 
         Instruction::VectorToMemory { kind, malloc, mem } => {
             let val = js.pop();
-            let func = js.cx.pass_to_wasm_function(*kind, *mem)?;
+            let func = js.cx.pass_to_wasm_function(kind.clone(), *mem)?;
             let malloc = js.cx.export_name_of(*malloc);
             let i = js.tmp();
             js.prelude(&format!(
@@ -805,7 +805,7 @@ fn instruction(js: &mut JsBuilder, instr: &Instruction, log_error: &mut bool) ->
         }
 
         Instruction::OptionVector { kind, mem, malloc } => {
-            let func = js.cx.pass_to_wasm_function(*kind, *mem)?;
+            let func = js.cx.pass_to_wasm_function(kind.clone(), *mem)?;
             js.cx.expose_is_like_none();
             let i = js.tmp();
             let malloc = js.cx.export_name_of(*malloc);
@@ -832,7 +832,7 @@ fn instruction(js: &mut JsBuilder, instr: &Instruction, log_error: &mut bool) ->
             // a length. These two pointer/length values get pushed onto the
             // value stack.
             let val = js.pop();
-            let func = js.cx.pass_to_wasm_function(*kind, *mem)?;
+            let func = js.cx.pass_to_wasm_function(kind.clone(), *mem)?;
             let malloc = js.cx.export_name_of(*malloc);
             let i = js.tmp();
             js.prelude(&format!(
@@ -850,7 +850,7 @@ fn instruction(js: &mut JsBuilder, instr: &Instruction, log_error: &mut bool) ->
             // original mutable slice with any modifications, and then free the
             // Rust-backed memory.
             let free = js.cx.export_name_of(*free);
-            let get = js.cx.memview_function(*kind, *mem);
+            let get = js.cx.memview_function(kind.clone(), *mem);
             js.finally(&format!(
                 "
                     {val}.set({get}().subarray(ptr{i} / {size}, ptr{i} / {size} + len{i}));
@@ -1003,7 +1003,7 @@ fn instruction(js: &mut JsBuilder, instr: &Instruction, log_error: &mut bool) ->
         Instruction::VectorLoad { kind, mem, free } => {
             let len = js.pop();
             let ptr = js.pop();
-            let f = js.cx.expose_get_vector_from_wasm(*kind, *mem)?;
+            let f = js.cx.expose_get_vector_from_wasm(kind.clone(), *mem)?;
             let i = js.tmp();
             let free = js.cx.export_name_of(*free);
             js.prelude(&format!("var v{} = {}({}, {}).slice();", i, f, ptr, len));
@@ -1020,7 +1020,7 @@ fn instruction(js: &mut JsBuilder, instr: &Instruction, log_error: &mut bool) ->
         Instruction::OptionVectorLoad { kind, mem, free } => {
             let len = js.pop();
             let ptr = js.pop();
-            let f = js.cx.expose_get_vector_from_wasm(*kind, *mem)?;
+            let f = js.cx.expose_get_vector_from_wasm(kind.clone(), *mem)?;
             let i = js.tmp();
             let free = js.cx.export_name_of(*free);
             js.prelude(&format!("let v{};", i));
@@ -1040,14 +1040,14 @@ fn instruction(js: &mut JsBuilder, instr: &Instruction, log_error: &mut bool) ->
         Instruction::View { kind, mem } => {
             let len = js.pop();
             let ptr = js.pop();
-            let f = js.cx.expose_get_vector_from_wasm(*kind, *mem)?;
+            let f = js.cx.expose_get_vector_from_wasm(kind.clone(), *mem)?;
             js.push(format!("{f}({ptr}, {len})", ptr = ptr, len = len, f = f));
         }
 
         Instruction::OptionView { kind, mem } => {
             let len = js.pop();
             let ptr = js.pop();
-            let f = js.cx.expose_get_vector_from_wasm(*kind, *mem)?;
+            let f = js.cx.expose_get_vector_from_wasm(kind.clone(), *mem)?;
             js.push(format!(
                 "{ptr} === 0 ? undefined : {f}({ptr}, {len})",
                 ptr = ptr,
@@ -1226,7 +1226,7 @@ fn adapter2ts(ty: &AdapterType, dst: &mut String) {
         AdapterType::String => dst.push_str("string"),
         AdapterType::Externref => dst.push_str("any"),
         AdapterType::Bool => dst.push_str("boolean"),
-        AdapterType::Vector(kind) => dst.push_str(kind.js_ty()),
+        AdapterType::Vector(kind) => dst.push_str(&kind.js_ty()),
         AdapterType::Option(ty) => {
             adapter2ts(ty, dst);
             dst.push_str(" | undefined");

crates/cli-support/src/js/mod.rs

@@ -1621,6 +1621,7 @@ impl<'a> Context<'a> {
             VectorKind::F32 => self.expose_f32_memory(memory),
             VectorKind::F64 => self.expose_f64_memory(memory),
             VectorKind::Externref => self.expose_uint32_memory(memory),
+            VectorKind::NamedExternref(_) => self.expose_uint32_memory(memory),
         }
     }
 
@@ -1842,6 +1843,7 @@ impl<'a> Context<'a> {
             VectorKind::F32 => self.expose_pass_array_f32_to_wasm(memory),
             VectorKind::F64 => self.expose_pass_array_f64_to_wasm(memory),
             VectorKind::Externref => self.expose_pass_array_jsvalue_to_wasm(memory),
+            VectorKind::NamedExternref(_) => self.expose_pass_array_jsvalue_to_wasm(memory),
         }
     }
 
@@ -1864,6 +1866,7 @@ impl<'a> Context<'a> {
             VectorKind::F32 => self.expose_get_array_f32_from_wasm(memory),
             VectorKind::F64 => self.expose_get_array_f64_from_wasm(memory),
             VectorKind::Externref => self.expose_get_array_js_value_from_wasm(memory)?,
+            VectorKind::NamedExternref(_) => self.expose_get_array_js_value_from_wasm(memory)?,
         })
     }
 

crates/cli-support/src/wit/incoming.rs

@@ -121,7 +121,7 @@ impl InstructionBuilder<'_, '_> {
                     format_err!("unsupported argument type for calling Rust function from JS {:?}", arg)
                 })?;
                 self.instruction(
-                    &[AdapterType::Vector(kind)],
+                    &[AdapterType::Vector(kind.clone())],
                     Instruction::VectorToMemory {
                         kind,
                         malloc: self.cx.malloc()?,
@@ -198,7 +198,7 @@ impl InstructionBuilder<'_, '_> {
                 })?;
                 if mutable {
                     self.instruction(
-                        &[AdapterType::Vector(kind)],
+                        &[AdapterType::Vector(kind.clone())],
                         Instruction::MutableSliceToMemory {
                             kind,
                             malloc: self.cx.malloc()?,
@@ -209,7 +209,7 @@ impl InstructionBuilder<'_, '_> {
                     );
                 } else {
                     self.instruction(
-                        &[AdapterType::Vector(kind)],
+                        &[AdapterType::Vector(kind.clone())],
                         Instruction::VectorToMemory {
                             kind,
                             malloc: self.cx.malloc()?,
@@ -322,7 +322,7 @@ impl InstructionBuilder<'_, '_> {
                 let malloc = self.cx.malloc()?;
                 let mem = self.cx.memory()?;
                 self.instruction(
-                    &[AdapterType::Vector(kind).option()],
+                    &[AdapterType::Vector(kind.clone()).option()],
                     Instruction::OptionVector { kind, malloc, mem },
                     &[AdapterType::I32, AdapterType::I32],
                 );

crates/cli-support/src/wit/outgoing.rs

@@ -139,7 +139,11 @@ impl InstructionBuilder<'_, '_> {
                 let free = self.cx.free()?;
                 self.instruction(
                     &[AdapterType::I32, AdapterType::I32],
-                    Instruction::VectorLoad { kind, mem, free },
+                    Instruction::VectorLoad {
+                        kind: kind.clone(),
+                        mem,
+                        free,
+                    },
                     &[AdapterType::Vector(kind)],
                 );
             }
@@ -196,7 +200,10 @@ impl InstructionBuilder<'_, '_> {
                 let mem = self.cx.memory()?;
                 self.instruction(
                     &[AdapterType::I32, AdapterType::I32],
-                    Instruction::View { kind, mem },
+                    Instruction::View {
+                        kind: kind.clone(),
+                        mem,
+                    },
                     &[AdapterType::Vector(kind)],
                 );
             }
@@ -313,7 +320,11 @@ impl InstructionBuilder<'_, '_> {
                 let free = self.cx.free()?;
                 self.instruction(
                     &[AdapterType::I32, AdapterType::I32],
-                    Instruction::OptionVectorLoad { kind, mem, free },
+                    Instruction::OptionVectorLoad {
+                        kind: kind.clone(),
+                        mem,
+                        free,
+                    },
                     &[AdapterType::Vector(kind).option()],
                 );
             }
@@ -355,7 +366,10 @@ impl InstructionBuilder<'_, '_> {
                 let mem = self.cx.memory()?;
                 self.instruction(
                     &[AdapterType::I32, AdapterType::I32],
-                    Instruction::OptionView { kind, mem },
+                    Instruction::OptionView {
+                        kind: kind.clone(),
+                        mem,
+                    },
                     &[AdapterType::Vector(kind).option()],
                 );
             }

src/cast.rs

@@ -1,4 +1,4 @@
-use crate::JsValue;
+use crate::{describe::WasmDescribe, JsValue};
 
 /// A trait for checked and unchecked casting between JS types.
 ///
@@ -154,3 +154,7 @@ where
     /// won't need to call this.
     fn unchecked_from_js_ref(val: &JsValue) -> &Self;
 }
+
+/// Trait implemented for wrappers around `JsValue`s generated by `#[wasm_bindgen]`.
+#[doc(hidden)]
+pub trait JsObject: JsCast + WasmDescribe {}

src/convert/slices.rs

@@ -4,6 +4,7 @@ use std::prelude::v1::*;
 use core::slice;
 use core::str;
 
+use crate::cast::JsObject;
 use crate::convert::OptionIntoWasmAbi;
 use crate::convert::{FromWasmAbi, IntoWasmAbi, RefFromWasmAbi, RefMutFromWasmAbi, WasmAbi};
 use cfg_if::cfg_if;
@@ -270,4 +271,41 @@ if_std! {
         #[inline]
         fn is_none(slice: &WasmSlice) -> bool { slice.ptr == 0 }
     }
+
+    impl<T> IntoWasmAbi for Box<[T]> where T: JsObject {
+        type Abi = WasmSlice;
+
+        #[inline]
+        fn into_abi(self) -> WasmSlice {
+            let ptr = self.as_ptr();
+            let len = self.len();
+            mem::forget(self);
+            WasmSlice {
+                ptr: ptr.into_abi(),
+                len: len as u32,
+            }
+        }
+    }
+
+    impl<T> OptionIntoWasmAbi for Box<[T]> where T: JsObject {
+        #[inline]
+        fn none() -> WasmSlice { null_slice() }
+    }
+
+    impl<T> FromWasmAbi for Box<[T]> where T: JsObject {
+        type Abi = WasmSlice;
+
+        #[inline]
+        unsafe fn from_abi(js: WasmSlice) -> Self {
+            let ptr = <*mut JsValue>::from_abi(js.ptr);
+            let len = js.len as usize;
+            let vec: Vec<T> = Vec::from_raw_parts(ptr, len, len).drain(..).map(|js_value| T::unchecked_from_js(js_value)).collect();
+            return vec.into_boxed_slice();
+        }
+    }
+
+    impl<T> OptionFromWasmAbi for Box<[T]> where T: JsObject {
+        #[inline]
+        fn is_none(slice: &WasmSlice) -> bool { slice.ptr == 0 }
+    }
 }

src/lib.rs

@@ -62,7 +62,7 @@ pub mod convert;
 pub mod describe;
 
 mod cast;
-pub use crate::cast::JsCast;
+pub use crate::cast::{JsCast, JsObject};
 
 if_std! {
     extern crate std;