Add [ImplicitThis] behaviour (#166)

Author: ExE-Boss

lib/constructs/attribute.js

@@ -23,19 +23,15 @@ class Attribute {
 
     const onInstance = utils.isOnInstance(this.idl, this.interface.idl);
 
-    let objName = `this`;
-    if (onInstance) { // we're in a setup method
-      objName = `obj`;
-    }
     let brandCheck = `
-      if (!this || !exports.is(this)) {
+      if (!exports.is(esValue)) {
         throw new TypeError("Illegal invocation");
       }
     `;
-    let getterBody = `return utils.tryWrapperForImpl(${objName}[impl]["${this.idl.name}"]);`;
-    let setterBody = `${objName}[impl]["${this.idl.name}"] = V;`;
+    let getterBody = `return utils.tryWrapperForImpl(esValue[impl]["${this.idl.name}"]);`;
+    let setterBody = `esValue[impl]["${this.idl.name}"] = V;`;
     if (conversions[this.idl.idlType.idlType]) {
-      getterBody = `return ${objName}[impl]["${this.idl.name}"];`;
+      getterBody = `return esValue[impl]["${this.idl.name}"];`;
     }
 
     const addMethod = this.static ?
@@ -51,8 +47,8 @@ class Attribute {
         throw new Error("Unknown reflector type: " + this.idl.idlType.idlType);
       }
       const attrName = shouldReflect.rhs && shouldReflect.rhs.value.replace(/_/g, "-") || this.idl.name;
-      getterBody = reflector[this.idl.idlType.idlType].get(objName, attrName.toLowerCase());
-      setterBody = reflector[this.idl.idlType.idlType].set(objName, attrName.toLowerCase());
+      getterBody = reflector[this.idl.idlType.idlType].get("esValue", attrName.toLowerCase());
+      setterBody = reflector[this.idl.idlType.idlType].set("esValue", attrName.toLowerCase());
     }
 
     if (utils.getExtAttr(this.idl.extAttrs, "LenientThis")) {
@@ -71,6 +67,7 @@ class Attribute {
     }
 
     addMethod(this.idl.name, [], `
+      const esValue = this !== null && this !== undefined ? this : globalObject;
       ${brandCheck}
       ${getterBody}
     `, "get", { configurable });
@@ -95,19 +92,22 @@ class Attribute {
       }
 
       addMethod(this.idl.name, ["V"], `
+        const esValue = this !== null && this !== undefined ? this : globalObject;
         ${brandCheck}
         ${idlConversion}
         ${setterBody}
       `, "set", { configurable });
     } else if (utils.getExtAttr(this.idl.extAttrs, "PutForwards")) {
       addMethod(this.idl.name, ["V"], `
+        const esValue = this !== null && this !== undefined ? this : globalObject;
         ${brandCheck}
         this.${this.idl.name}.${utils.getExtAttr(this.idl.extAttrs, "PutForwards").rhs.value} = V;
       `, "set", { configurable });
     } else if (utils.getExtAttr(this.idl.extAttrs, "Replaceable")) {
       addMethod(this.idl.name, ["V"], `
+        const esValue = this !== null && this !== undefined ? this : globalObject;
         ${brandCheck}
-        Object.defineProperty(this, "${this.idl.name}", {
+        Object.defineProperty(esValue, "${this.idl.name}", {
           configurable: true,
           enumerable: true,
           value: V,
@@ -118,10 +118,12 @@ class Attribute {
 
     if (!this.static && this.idl.special === "stringifier") {
       addMethod("toString", [], `
-        if (!this || !exports.is(this)) {
+        const esValue = this;
+        if (!exports.is(esValue)) {
           throw new TypeError("Illegal invocation");
         }
-        ${getterBody};
+
+        ${getterBody}
       `, "regular", { configurable, writable: configurable });
     }
 

lib/constructs/interface.js

@@ -1128,12 +1128,12 @@ class Interface {
         const obj = exports.create(globalObject, constructorArgs, privateData);
         return utils.implForWrapper(obj);
       };
-      exports._internalSetup = function _internalSetup(obj) {
+      exports._internalSetup = function _internalSetup(obj, globalObject) {
     `;
 
     if (this.idl.inheritance) {
       this.str += `
-        ${this.idl.inheritance}._internalSetup(obj);
+        ${this.idl.inheritance}._internalSetup(obj, globalObject);
       `;
     }
 
@@ -1144,7 +1144,7 @@ class Interface {
       exports.setup = function setup(obj, globalObject, constructorArgs = [], privateData = {}) {
         privateData.wrapper = obj;
 
-        exports._internalSetup(obj);
+        exports._internalSetup(obj, globalObject);
         Object.defineProperty(obj, impl, {
           value: new Impl.implementation(globalObject, constructorArgs, privateData),
           configurable: true

lib/constructs/operation.js

@@ -62,13 +62,14 @@ class Operation {
 
     if (!this.static) {
       str += `
-        if (!this || !exports.is(this)) {
+        const esValue = this !== null && this !== undefined ? this : globalObject;
+        if (!exports.is(esValue)) {
           throw new TypeError("Illegal invocation");
         }
       `;
     }
 
-    const callOn = this.static ? "Impl.implementation" : "this[impl]";
+    const callOn = this.static ? "Impl.implementation" : `esValue[impl]`;
     // In case of stringifiers, use the named implementation function rather than hardcoded "toString".
     // All overloads will have the same name, so pick the first one.
     const implFunc = this.idls[0].name || this.name;