Implement Proc#to_js and add ability to pass blocks to JS::Object#call (#36)

* Add Proc#to_js to allow passing functions as call arguments

* Allow passing blocks to JS::Object#call

* Use rb_abi_lend_object to keep reference to wrapped Proc

* Add test that holds wrapped Proc in a variable before calling it

* Add documentation for Proc#to_js

Author: richardboehme

ext/js/bindgen/rb-js-abi-host.wit

@@ -7,6 +7,7 @@ global-this: function() -> js-abi-value
 int-to-js-number: function(value: s32) -> js-abi-value
 string-to-js-string: function(value: string) -> js-abi-value
 bool-to-js-bool: function(value: bool) -> js-abi-value
+proc-to-js-function: function(value: u32) -> js-abi-value
 rb-object-to-js-rb-value: function(raw-rb-abi-value: u32) -> js-abi-value
 
 js-value-to-string: function(value: js-abi-value) -> string

ext/js/js-core.c

@@ -15,6 +15,7 @@ extern VALUE rb_cInteger;
 extern VALUE rb_cString;
 extern VALUE rb_cTrueClass;
 extern VALUE rb_cFalseClass;
+extern VALUE rb_cProc;
 
 // from js/js-core.c
 void rb_abi_lend_object(VALUE obj);
@@ -246,8 +247,12 @@ static VALUE _rb_js_obj_call(int argc, VALUE *argv, VALUE obj) {
   struct jsvalue *abi_method = check_jsvalue(method);
 
   rb_js_abi_host_list_js_abi_value_t abi_args;
-  abi_args.ptr = ALLOCA_N(rb_js_abi_host_js_abi_value_t, argc - 1);
-  abi_args.len = argc - 1;
+  int function_arguments_count = argc;
+  if(!rb_block_given_p())
+    function_arguments_count -= 1;
+
+  abi_args.ptr = ALLOCA_N(rb_js_abi_host_js_abi_value_t, function_arguments_count);
+  abi_args.len = function_arguments_count;
   for (int i = 1; i < argc; i++) {
     VALUE arg = _rb_js_try_convert(rb_mJS, argv[i]);
     if (arg == Qnil) {
@@ -256,6 +261,12 @@ static VALUE _rb_js_obj_call(int argc, VALUE *argv, VALUE obj) {
     }
     abi_args.ptr[i - 1] = check_jsvalue(arg)->abi;
   }
+
+  if(rb_block_given_p()) {
+    VALUE proc = rb_block_proc();
+    abi_args.ptr[function_arguments_count - 1] = check_jsvalue(_rb_js_try_convert(rb_mJS, proc))->abi;
+  }
+
   return jsvalue_s_new(
       rb_js_abi_host_reflect_apply(abi_method->abi, p->abi, &abi_args));
 }
@@ -365,6 +376,17 @@ static VALUE _rb_js_false_to_js(VALUE obj) {
   return jsvalue_s_new(rb_js_abi_host_bool_to_js_bool(false));
 }
 
+/*
+ * call-seq:
+ *   to_js -> JS::Object
+ *
+ *  Returns +self+ as a JS::Object.
+ */
+static VALUE _rb_js_proc_to_js(VALUE obj) {
+  rb_abi_lend_object(obj);
+  return jsvalue_s_new(rb_js_abi_host_proc_to_js_function((uint32_t) obj));
+}
+
 /*
  * JavaScript interoperations module
  */
@@ -395,4 +417,5 @@ void Init_js() {
   rb_define_method(rb_cString, "to_js", _rb_js_string_to_js, 0);
   rb_define_method(rb_cTrueClass, "to_js", _rb_js_true_to_js, 0);
   rb_define_method(rb_cFalseClass, "to_js", _rb_js_false_to_js, 0);
+  rb_define_method(rb_cProc, "to_js", _rb_js_proc_to_js, 0);
 }

packages/npm-packages/ruby-wasm-wasi/src/index.ts

@@ -94,12 +94,14 @@ export class RubyVM {
         boolToJsBool: (value) => {
           return value;
         },
+        procToJsFunction: (rawRbAbiValue) => {
+          const rbValue = this.rbValueofPointer(rawRbAbiValue);
+          return (...args) => {
+            rbValue.call('call', ...args.map(arg => this.wrap(arg)));
+          }
+        },
         rbObjectToJsRbValue: (rawRbAbiValue) => {
-          const abiValue = new (RbAbi.RbAbiValue as any)(
-            rawRbAbiValue,
-            this.guest
-          );
-          return new RbValue(abiValue, this, this.privateObject());
+          return this.rbValueofPointer(rawRbAbiValue);
         },
         jsValueToString: (value) => {
           // According to the [spec](https://tc39.es/ecma262/multipage/text-processing.html#sec-string-constructor-string-value)
@@ -216,6 +218,11 @@ export class RubyVM {
       exceptionFormatter: this.exceptionFormatter,
     };
   }
+
+  private rbValueofPointer(pointer: number): RbValue {
+    const abiValue = new (RbAbi.RbAbiValue as any)(pointer, this.guest);
+    return new RbValue(abiValue, this, this.privateObject());
+  }
 }
 
 /**

packages/npm-packages/ruby-wasm-wasi/test/js_from_rb.test.ts

@@ -122,6 +122,34 @@ describe("Manipulation of JS from Ruby", () => {
       expr: `JS.global[:Math].call(:min, JS.eval("return 1"), JS.eval("return 2"))`,
       result: 1,
     },
+    {
+      expr: `
+        function_to_call = JS.eval('return { a: (callback) => { callback(1) } }')
+        b = nil
+        function_to_call.call(:a, Proc.new { |a| b = a })
+        b
+      `,
+      result: 1
+    },
+    {
+      expr: `
+        function_to_call = JS.eval('return { a: (callback) => { callback(1) } }')
+        b = nil
+        function_to_call.call(:a) { |a| b = a }
+        b
+      `,
+      result: 1
+    },
+    {
+      expr: `
+        function_to_call = JS.eval('let callback; return { a: (c) => { callback = c }, b: () => { callback(1) } }')
+        b = nil
+        function_to_call.call(:a) { |a| b = a }
+        function_to_call.call(:b)
+        b
+      `,
+      result: 1
+    }
   ])(`JS::Object#call (%s)`, async (props) => {
     const vm = await initRubyVM();
     const result = vm.eval(`