Implement the named properties object

Author: TimothyGu

lib/constructs/interface.js

@@ -236,6 +236,10 @@ class Interface {
         throw new Error(msg);
       }
     }
+
+    if (utils.isGlobal(this.idl) && this.namedGetter) {
+      this.factory = true;
+    }
   }
 
   get supportsIndexedProperties() {
@@ -347,15 +351,19 @@ class Interface {
       `;
     }
 
+    if (utils.isGlobal(this.idl) && this.supportsNamedProperties) {
+      this.generateNamedPropertiesObject();
+      this.str += `Object.setPrototypeOf(${this.name}.prototype, namedPropertiesObject);`;
+    } else if (this.idl.inheritance) {
+      this.str += `Object.setPrototypeOf(${this.name}.prototype, ${this.idl.inheritance}.interface.prototype);`;
+    } else if (utils.getExtAttr(this.idl.extAttrs, "LegacyArrayClass")) {
+      this.str += `Object.setPrototypeOf(${this.name}.prototype, Array.prototype);`;
+    }
+
     if (this.idl.inheritance) {
       this.str += `
-        Object.setPrototypeOf(${this.name}.prototype, ${this.idl.inheritance}.interface.prototype);
         Object.setPrototypeOf(${this.name}, ${this.idl.inheritance}.interface);
       `;
-    } else if (utils.getExtAttr(this.idl.extAttrs, "LegacyArrayClass")) {
-      this.str += `
-        Object.setPrototypeOf(${this.name}.prototype, Array.prototype);
-      `;
     }
 
     this.str += `
@@ -544,6 +552,180 @@ class Interface {
     return conditions.join(" && ");
   }
 
+  generateNamedPropertiesObject() {
+    const proto = (() => {
+      if (this.idl.inheritance) {
+        return `${this.idl.inheritance}.interface.prototype`;
+      } else if (utils.getExtAttr(this.idl.extAttrs, "LegacyArrayClass")) {
+        return "Array.prototype";
+      }
+      return "Object.prototype";
+    })();
+
+    this.str += `
+      const namedPropertiesObject = new Proxy(Object.create(${proto}, {
+        [Symbol.toStringTag]: {
+          value: "${this.name}Properties",
+          writable: false,
+          enumerable: false,
+          configurable: true
+        }
+      }), {
+    `;
+
+    // [[SetPrototypeOf]]
+    this.str += `
+        setPrototypeOf() {
+          throw new TypeError("Immutable prototype object '#<${this.name}Properties>' cannot have their prototype set");
+        },
+    `;
+
+    // [[PreventExtensions]]
+    this.str += `
+        preventExtensions() {
+          return false;
+        },
+    `;
+
+    // [[GetOwnProperty]]
+    this.str += `
+        getOwnPropertyDescriptor(target, P) {
+          if (typeof P === "symbol") {
+            return Reflect.getOwnPropertyDescriptor(target, P);
+          }
+          const object = defaultPrivateData.globalObject;
+    `;
+
+    const func = this.namedGetter.name !== null ? `.${this.namedGetter.name}` : "[utils.namedGet]";
+    const enumerable = !utils.getExtAttr(this.idl.extAttrs, "LegacyUnenumerableNamedProperties");
+    let preamble = "";
+    const conditions = [];
+    if (utils.getExtAttr(this.namedGetter.extAttrs, "WebIDL2JSValueAsUnsupported")) {
+      this.str += `
+        const namedValue = object[impl]${func}(P);
+      `;
+      conditions.push(this._supportsPropertyName("object", "index", "namedValue"));
+      conditions.push(this._namedPropertyVisible("P", "object", true));
+    } else {
+      preamble = `
+        const namedValue = object[impl]${func}(P);
+      `;
+      conditions.push(this._namedPropertyVisible("P", "object", false));
+    }
+
+    this.str += `
+          if (${conditions.join(" && ")}) {
+            ${preamble}
+            return {
+              writable: true,
+              enumerable: ${enumerable},
+              configurable: true,
+              value: utils.tryWrapperForImpl(namedValue)
+            };
+          }
+          return Reflect.getOwnPropertyDescriptor(target, P);
+        },
+    `;
+
+    // [[DefineOwnProperty]]
+    this.str += `
+        defineProperty() {
+          return false;
+        },
+    `;
+
+    // [[HasProperty]]
+    this.str += `
+        has(target, P) {
+          if (typeof P === "symbol") {
+            return Reflect.has(target, P);
+          }
+          const desc = this.getOwnPropertyDescriptor(target, P);
+          if (desc !== undefined) {
+            return true;
+          }
+          const parent = Object.getPrototypeOf(target);
+          if (parent !== null) {
+            return Reflect.has(parent, P);
+          }
+          return false;
+        },
+    `;
+
+    // [[Get]]
+    this.str += `
+        get(target, P, receiver) {
+          if (typeof P === "symbol") {
+            return Reflect.get(target, P, receiver);
+          }
+          const desc = this.getOwnPropertyDescriptor(target, P);
+          if (desc === undefined) {
+            const parent = Object.getPrototypeOf(target);
+            if (parent === null) {
+              return undefined;
+            }
+            return Reflect.get(target, P, receiver);
+          }
+          if (!desc.get && !desc.set) {
+            return desc.value;
+          }
+          const getter = desc.get;
+          if (getter === undefined) {
+            return undefined;
+          }
+          return Reflect.apply(getter, receiver, []);
+        },
+    `;
+
+    // [[Set]]
+    this.str += `
+        set(target, P, V, receiver) {
+          if (typeof P === "symbol") {
+            return Reflect.set(target, P, V, receiver);
+          }
+          const ownDesc = this.getOwnPropertyDescriptor(P);
+          if (ownDesc === undefined) {
+            const parent = Reflect.getPrototypeOf(target);
+            // parent is never null.
+            return Reflect.set(parent, P, V, receiver);
+          }
+          // ownDesc.writable is always true.
+          if (!utils.isObject(receiver)) {
+            return false;
+          }
+          // If receiver is this Proxy object, the following will always return false. Problem is, receiver may not be
+          // this Proxy object.
+          const existingDesc = Reflect.getOwnPropertyDescriptor(receiver, P);
+          let valueDesc;
+          if (existingDesc !== undefined) {
+            if (existingDesc.get || existingDesc.set) {
+              return false;
+            }
+            if (!existingDesc.writable) {
+              return false;
+            }
+            valueDesc = { value: V };
+          } else {
+            valueDesc = { writable: true, enumerable: true, configurable: true, value: V };
+          }
+          return Reflect.defineProperty(receiver, P, valueDesc);
+        },
+    `;
+
+    // [[Delete]]
+    this.str += `
+        deleteProperty() {
+          return false;
+        },
+    `;
+
+    // [[OwnPropertyKeys]] not overriden
+
+    this.str += `
+      });
+    `;
+  }
+
   generateLegacyProxy() {
     const hasIndexedSetter = this.indexedSetter !== null;
     const hasNamedSetter = this.namedSetter !== null;