chore: improve internal webidl functions (#9606)

2 files changed, 125 insertions, 12 deletions

diff --git a/op_crates/web/00_webidl.js b/op_crates/web/00_webidl.js
index 8831cb71e..ab3047391 100644
--- a/op_crates/web/00_webidl.js
+++ b/op_crates/web/00_webidl.js
@@ -14,7 +14,7 @@
     return new ErrorType(
       `${opts.prefix ? opts.prefix + ": " : ""}${
         opts.context ? opts.context : "Value"
-      } ${message}.`,
+      } ${message}`,
     );
   }
 
@@ -602,7 +602,7 @@
         opts.prefix ? opts.prefix + ": " : ""
       }${required} argument${
         required === 1 ? "" : "s"
-      }, but only ${length} present.`;
+      } required, but only ${length} present.`;
       throw new TypeError(errMsg);
     }
   }
@@ -637,13 +637,15 @@
             esMemberValue = esDict[key];
           }
 
+          const context = `'${key}' of '${name}'${
+            opts.context ? ` (${opts.context})` : ""
+          }`;
+
           if (esMemberValue !== undefined) {
             const converter = member.converter;
             const idlMemberValue = converter(esMemberValue, {
               ...opts,
-              context: `${key} of '${name}'${
-                opts.context ? `(${opts.context})` : ""
-              }`,
+              context,
             });
             idlDict[key] = idlMemberValue;
           } else if ("defaultValue" in member) {
@@ -651,8 +653,10 @@
             const idlMemberValue = defaultValue;
             idlDict[key] = idlMemberValue;
           } else if (member.required) {
-            throw new TypeError(
-              `can not be converted to '${name}' because ${key} is required in '${name}'.`,
+            throw makeException(
+              TypeError,
+              `can not be converted to '${name}' because '${key}' is required in '${name}'.`,
+              { ...opts },
             );
           }
         }
@@ -670,10 +674,10 @@
       const S = String(V);
 
       if (!E.has(S)) {
-        throw makeException(
-          TypeError,
-          `The provided value '${V}' is not a valid enum value of type ${name}.`,
-          opts,
+        throw new TypeError(
+          `${
+            opts.prefix ? opts.prefix + ": " : ""
+          }The provided value '${S}' is not a valid enum value of type ${name}.`,
         );
       }
 
@@ -694,6 +698,72 @@
     };
   }
 
+  // https://heycam.github.io/webidl/#es-sequence
+  function createSequenceConverter(converter) {
+    return function (V, opts = {}) {
+      if (typeof V !== "object") {
+        throw makeException(
+          TypeError,
+          "can not be converted to sequence.",
+          opts,
+        );
+      }
+      const iter = V?.[Symbol.iterator]?.();
+      if (iter === undefined) {
+        throw makeException(
+          TypeError,
+          "can not be converted to sequence.",
+          opts,
+        );
+      }
+      const array = [];
+      while (true) {
+        const res = iter?.next?.();
+        if (res === undefined) {
+          throw makeException(
+            TypeError,
+            "can not be converted to sequence.",
+            opts,
+          );
+        }
+        if (res.done === true) break;
+        const val = converter(res.value, {
+          ...opts,
+          context: `${opts.context}, index ${array.length}`,
+        });
+        array.push(val);
+      }
+      return array;
+    };
+  }
+
+  const brand = Symbol("[[webidl.brand]]");
+
+  function createInterfaceConverter(name, prototype) {
+    return (V, opts) => {
+      if (!(V instanceof prototype) || V[brand] !== brand) {
+        throw makeException(TypeError, `is not of type ${name}.`, opts);
+      }
+      return V;
+    };
+  }
+
+  function createBranded(Type) {
+    const t = Object.create(Type.prototype);
+    t[brand] = brand;
+    return t;
+  }
+
+  function assertBranded(self, prototype) {
+    if (!(self instanceof prototype) || self[brand] !== brand) {
+      throw new TypeError("Illegal invocation");
+    }
+  }
+
+  function illegalConstructor() {
+    throw new TypeError("Illegal constructor");
+  }
+
   window.__bootstrap ??= {};
   window.__bootstrap.webidl = {
     converters,
@@ -701,5 +771,11 @@
     createDictionaryConverter,
     createEnumConverter,
     createNullableConverter,
+    createSequenceConverter,
+    createInterfaceConverter,
+    brand,
+    createBranded,
+    assertBranded,
+    illegalConstructor,
   };
 })(this);
diff --git a/op_crates/web/internal.d.ts b/op_crates/web/internal.d.ts
index 04fc061bb..d43332e4b 100644
--- a/op_crates/web/internal.d.ts
+++ b/op_crates/web/internal.d.ts
@@ -191,6 +191,8 @@ declare namespace globalThis {
          * Convert a value into a `VoidFunction` (() => void).
          */
         VoidFunction(v: any, opts?: ValueConverterOpts): () => void;
+
+        [type: string]: (v: any, opts: ValueConverterOpts) => any;
       };
 
       /**
@@ -205,7 +207,7 @@ declare namespace globalThis {
       declare interface DictionaryMember {
         key: string;
         converter: (v: any, opts: ValueConverterOpts) => any;
-        defaultValue?: boolean;
+        defaultValue?: any;
         required?: boolean;
       }
 
@@ -231,6 +233,41 @@ declare namespace globalThis {
       declare function createNullableConverter<T>(
         converter: (v: any, opts: ValueConverterOpts) => T,
       ): (v: any, opts: ValueConverterOpts) => T | null;
+
+      /**
+       * Create a converter that converts a sequence of the inner type.
+       */
+      declare function createSequenceConverter<T>(
+        converter: (v: any, opts: ValueConverterOpts) => T,
+      ): (v: any, opts: ValueConverterOpts) => T[];
+
+      /**
+       * Throw an illegal constructor error.
+       */
+      declare function illegalConstructor(): never;
+
+      /**
+       * The branding symbol.
+       */
+      declare const brand: unique symbol;
+
+      /**
+       * Create a branded instance of an interface.
+       */
+      declare function createBranded(self: any): any;
+
+      /**
+       * Assert that self is branded.
+       */
+      declare function assertBranded(self: any, type: any): void;
+
+      /**
+       * Create a converter for interfaces.
+       */
+      declare function createInterfaceConverter(
+        name: string,
+        prototype: any,
+      ): (v: any, opts: ValueConverterOpts) => any;
     }
 
     declare var url: {