Issue 4125 - [emscripten] Convert filter classes to C++

lib/filterClassesNew.js

Index: lib/filterClassesNew.js
===================================================================
new file mode 100644
--- /dev/null
+++ b/lib/filterClassesNew.js
@@ -0,0 +1,46 @@
+"use strict";
+
+let {_Filter_FromText, _Filter_Normalize, _Filter_get_type} = require("./compiled");
+let {wrapCall, stringArg, stringResult} = require("./compiledTools");
+let constructors = Object.create(null);
+
+function filterResult(call)
+{
+  return function()
+  {
+    let result = call.apply(this, arguments);
+    let type = _Filter_get_type(result);
+    if (type in constructors)
+      return new (constructors[type])(result);
+    else
+      throw new Error("Unexpected filter type " + type);
+  };
+}
+
+function createFilterClass(superclass, type, typeId)
+{
+  let result = function(pointer)
+  {
+    this._pointer = pointer;
+  };
+  if (superclass)
+    result.prototype = Object.create(superclass);
+  if (type)
+    Object.defineProperty(result.prototype, "type", {get: () => type, enumerable: true});
+  if (typeId)
+    constructors[typeId] = result;
+  return result;
+}
+
+exports.Filter = createFilterClass();
+exports.Filter.fromText = wrapCall(filterResult(stringArg(0, _Filter_FromText)));
+exports.Filter.normalize = wrapCall(stringResult(stringArg(0, _Filter_Normalize)));
+
+exports.InvalidFilter = createFilterClass(exports.Filter, "invalid", 1);
+exports.CommentFilter = createFilterClass(exports.Filter, "comment", 2);
+exports.RegExpFilter = createFilterClass(exports.Filter, "blocking", 3);
+exports.WhiteListFilter = createFilterClass(exports.RegExpFilter, "whitelist", 4);
+exports.ElemHideBase = createFilterClass(exports.Filter);
+exports.ElemHideFilter = createFilterClass(exports.ElemHideBase, "elemhide", 5);
+exports.ElemHideException = createFilterClass(exports.ElemHideException, "elemhideexception", 6);
+exports.CSSPropertyFilter = createFilterClass(exports.ElemHideBase, "cssproperty", 7);