Function instantiateMappedType

test/fixtures/snapshot/typescript.js:63499–63537

(type, mapper, aliasSymbol, aliasTypeArguments)

            return undefined;
        }
        function instantiateMappedType(type, mapper, aliasSymbol, aliasTypeArguments) {
            // For a homomorphic mapped type { [P in keyof T]: X }, where T is some type variable, the mapping
            // operation depends on T as follows:
            // * If T is a primitive type no mapping is performed and the result is simply T.
            // * If T is a union type we distribute the mapped type over the union.
            // * If T is an array we map to an array where the element type has been transformed.
            // * If T is a tuple we map to a tuple where the element types have been transformed.
            // * Otherwise we map to an object type where the type of each property has been transformed.
            // For example, when T is instantiated to a union type A | B, we produce { [P in keyof A]: X } |
            // { [P in keyof B]: X }, and when when T is instantiated to a union type A | undefined, we produce
            // { [P in keyof A]: X } | undefined.
            var typeVariable = getHomomorphicTypeVariable(type);
            if (typeVariable) {
                var mappedTypeVariable = instantiateType(typeVariable, mapper);
                if (typeVariable !== mappedTypeVariable) {
                    return mapTypeWithAlias(getReducedType(mappedTypeVariable), function (t) {
                        if (t.flags & (3 /* TypeFlags.AnyOrUnknown */ | 58982400 /* TypeFlags.InstantiableNonPrimitive */ | 524288 /* TypeFlags.Object */ | 2097152 /* TypeFlags.Intersection */) && t !== wildcardType && !isErrorType(t)) {
                            if (!type.declaration.nameType) {
                                var constraint = void 0;
                                if (isArrayType(t) || t.flags & 1 /* TypeFlags.Any */ && findResolutionCycleStartIndex(typeVariable, 4 /* TypeSystemPropertyName.ImmediateBaseConstraint */) < 0 &&
                                    (constraint = getConstraintOfTypeParameter(typeVariable)) && everyType(constraint, isArrayOrTupleType)) {
                                    return instantiateMappedArrayType(t, type, prependTypeMapping(typeVariable, t, mapper));
                                }
                                if (isGenericTupleType(t)) {
                                    return instantiateMappedGenericTupleType(t, type, typeVariable, mapper);
                                }
                                if (isTupleType(t)) {
                                    return instantiateMappedTupleType(t, type, prependTypeMapping(typeVariable, t, mapper));
                                }
                            }
                            return instantiateAnonymousType(type, prependTypeMapping(typeVariable, t, mapper));
                        }
                        return t;
                    }, aliasSymbol, aliasTypeArguments);
                }
            }
            // If the constraint type of the instantiation is the wildcard type, return the wildcard type.
            return instantiateType(getConstraintTypeFromMappedType(type), mapper) === wildcardType ? wildcardType : instantiateAnonymousType(type, mapper, aliasSymbol, aliasTypeArguments);
        }
        function getModifiedReadonlyState(state, modifiers) {
            return modifiers & 1 /* MappedTypeModifiers.IncludeReadonly */ ? true : modifiers & 2 /* MappedTypeModifiers.ExcludeReadonly */ ? false : state;
        }