| 1 | {"version":3,"file":"subclassing.js","sourceRoot":"","sources":["../../../src/utilities/observables/subclassing.ts"],"names":[],"mappings":"AAAA,OAAO,EAAE,UAAU,EAAE,MAAM,cAAc,CAAC;AAC1C,OAAO,EAAE,YAAY,EAAE,MAAM,kBAAkB,CAAC;AAUhD,MAAM,UAAU,qBAAqB,CAEnC,QAAW;IACX,SAAS,GAAG,CAAC,GAAoB;QAI/B,MAAM,CAAC,cAAc,CAAC,QAAQ,EAAE,GAAG,EAAE,EAAE,KAAK,EAAE,UAAU,EAAE,CAAC,CAAC;IAC9D,CAAC;IACD,IAAI,YAAY,IAAI,MAAM,CAAC,OAAO,EAAE;QAClC,GAAG,CAAC,MAAM,CAAC,OAAO,CAAC,CAAC;KACrB;IAID,GAAG,CAAC,WAAW,CAAC,CAAC;IACjB,OAAO,QAAQ,CAAC;AAClB,CAAC","sourcesContent":["import { Observable } from \"./Observable\";\nimport { canUseSymbol } from \"../common/canUse\";\n\n// Generic implementations of Observable.prototype methods like map and\n// filter need to know how to create a new Observable from an Observable\n// subclass (like Concast or ObservableQuery). Those methods assume\n// (perhaps unwisely?) that they can call the subtype's constructor with a\n// Subscriber function, even though the subclass constructor might expect\n// different parameters. Defining this static Symbol.species property on\n// the subclass is a hint to generic Observable code to use the default\n// constructor instead of trying to do `new Subclass(observer => ...)`.\nexport function fixObservableSubclass<\n S extends new (...args: any[]) => Observable<any>,\n>(subclass: S): S {\n function set(key: symbol | string) {\n // Object.defineProperty is necessary because the Symbol.species\n // property is a getter by default in modern JS environments, so we\n // can't assign to it with a normal assignment expression.\n Object.defineProperty(subclass, key, { value: Observable });\n }\n if (canUseSymbol && Symbol.species) {\n set(Symbol.species);\n }\n // The \"@@species\" string is used as a fake Symbol.species value in some\n // polyfill systems (including the SymbolSpecies variable used by\n // zen-observable), so we should set it as well, to be safe.\n set(\"@@species\");\n return subclass;\n}\n"]} |