index.d.ts

// DO NOT EDIT! This is a generated file. Edit the JSDoc in src/*.js instead and run 'npm run build:types'.

export as namespace protobuf;

/**
 * Provides common type definitions.
 * Can also be used to provide additional google types or your own custom types.
 * @param name Short name as in `google/protobuf/[name].proto` or full file name
 * @param json JSON definition within `google.protobuf` if a short name, otherwise the file's root definition
 */
export function common(name: string, json: { [k: string]: any }): void;

export namespace common {

    /** Properties of a google.protobuf.Any message. */
    interface IAny {
        typeUrl?: string;
        bytes?: Uint8Array;
    }

    /** Properties of a google.protobuf.Duration message. */
    interface IDuration {
        seconds?: (number|bigint);
        nanos?: number;
    }

    /** Properties of a google.protobuf.Timestamp message. */
    interface ITimestamp {
        seconds?: (number|bigint);
        nanos?: number;
    }

    /** Properties of a google.protobuf.Empty message. */
    interface IEmpty {
    }

    /** Properties of a google.protobuf.Struct message. */
    interface IStruct {
        fields?: { [k: string]: IValue };
    }

    /** Properties of a google.protobuf.Value message. */
    interface IValue {
        kind?: string;
        nullValue?: 0;
        numberValue?: number;
        stringValue?: string;
        boolValue?: boolean;
        structValue?: IStruct;
        listValue?: IListValue;
    }

    /** Properties of a google.protobuf.ListValue message. */
    interface IListValue {
        values?: IValue[];
    }

    /** Properties of a google.protobuf.DoubleValue message. */
    interface IDoubleValue {
        value?: number;
    }

    /** Properties of a google.protobuf.FloatValue message. */
    interface IFloatValue {
        value?: number;
    }

    /** Properties of a google.protobuf.Int64Value message. */
    interface IInt64Value {
        value?: (number|bigint);
    }

    /** Properties of a google.protobuf.UInt64Value message. */
    interface IUInt64Value {
        value?: (number|bigint);
    }

    /** Properties of a google.protobuf.Int32Value message. */
    interface IInt32Value {
        value?: number;
    }

    /** Properties of a google.protobuf.UInt32Value message. */
    interface IUInt32Value {
        value?: number;
    }

    /** Properties of a google.protobuf.BoolValue message. */
    interface IBoolValue {
        value?: boolean;
    }

    /** Properties of a google.protobuf.StringValue message. */
    interface IStringValue {
        value?: string;
    }

    /** Properties of a google.protobuf.BytesValue message. */
    interface IBytesValue {
        value?: Uint8Array;
    }

    /**
     * Gets the root definition of the specified common proto file.
     *
     * Bundled definitions are:
     * - google/protobuf/any.proto
     * - google/protobuf/duration.proto
     * - google/protobuf/empty.proto
     * - google/protobuf/field_mask.proto
     * - google/protobuf/struct.proto
     * - google/protobuf/timestamp.proto
     * - google/protobuf/wrappers.proto
     *
     * @param file Proto file name
     * @returns Root definition or `null` if not defined
     */
    function get(file: string): (INamespace|null);
}

/** Runtime message from/to plain object converters. */
export namespace converter {

    /**
     * Generates a plain object to runtime message converter specific to the specified message type.
     * @param mtype Message type
     * @returns Codegen instance
     */
    function fromObject(mtype: Type): Codegen;

    /**
     * Generates a runtime message to plain object converter specific to the specified message type.
     * @param mtype Message type
     * @returns Codegen instance
     */
    function toObject(mtype: Type): Codegen;
}

/**
 * Generates a decoder specific to the specified message type.
 * @param mtype Message type
 * @returns Codegen instance
 */
export function decoder(mtype: Type): Codegen;

/**
 * Generates an encoder specific to the specified message type.
 * @param mtype Message type
 * @returns Codegen instance
 */
export function encoder(mtype: Type): Codegen;

/** Reflected enum. */
export class Enum extends ReflectionObject {

    /**
     * Constructs a new enum instance.
     * @param name Unique name within its namespace
     * @param [values] Enum values as an object, by name
     * @param [options] Declared options
     * @param [comment] The comment for this enum
     * @param [comments] The value comments for this enum
     * @param [valuesOptions] The value options for this enum
     */
    constructor(name: string, values?: { [k: string]: number }, options?: { [k: string]: any }, comment?: string, comments?: { [k: string]: string }, valuesOptions?: ({ [k: string]: { [k: string]: any } }|undefined));

    /** Enum values by id. */
    public valuesById: { [k: number]: string };

    /** Enum values by name. */
    public values: { [k: string]: number };

    /** Enum comment text. */
    public comment: (string|null);

    /** Value comment texts, if any. */
    public comments: { [k: string]: string };

    /** Values options, if any */
    public valuesOptions?: { [k: string]: { [k: string]: any } };

    /** Reserved ranges, if any. */
    public reserved: (number[]|string)[];

    /**
     * Constructs an enum from an enum descriptor.
     * @param name Enum name
     * @param json Enum descriptor
     * @returns Created enum
     * @throws {TypeError} If arguments are invalid
     */
    public static fromJSON(name: string, json: IEnum): Enum;

    /**
     * Converts this enum to an enum descriptor.
     * @param [toJSONOptions] JSON conversion options
     * @returns Enum descriptor
     */
    public toJSON(toJSONOptions?: IToJSONOptions): IEnum;

    /**
     * Adds a value to this enum.
     * @param name Value name
     * @param id Value id
     * @param [comment] Comment, if any
     * @param {Object.<string, *>|undefined} [options] Options, if any
     * @returns `this`
     * @throws {TypeError} If arguments are invalid
     * @throws {Error} If there is already a value with this name or id
     */
    public add(name: string, id: number, comment?: string, options?: ({ [k: string]: any }|undefined)): Enum;

    /**
     * Removes a value from this enum
     * @param name Value name
     * @returns `this`
     * @throws {TypeError} If arguments are invalid
     * @throws {Error} If `name` is not a name of this enum
     */
    public remove(name: string): Enum;

    /**
     * Tests if the specified id is reserved.
     * @param id Id to test
     * @returns `true` if reserved, otherwise `false`
     */
    public isReservedId(id: number): boolean;

    /**
     * Tests if the specified name is reserved.
     * @param name Name to test
     * @returns `true` if reserved, otherwise `false`
     */
    public isReservedName(name: string): boolean;
}

/** Enum descriptor. */
export interface IEnum {

    /** Enum values */
    values: { [k: string]: number };

    /** Enum options */
    options?: { [k: string]: any };
}

/** Reflected message field. */
export class Field extends FieldBase {

    /**
     * Constructs a new message field instance. Note that {@link MapField|map fields} have their own class.
     * @param name Unique name within its namespace
     * @param id Unique id within its namespace
     * @param type Value type
     * @param [rule="optional"] Field rule
     * @param [extend] Extended type if different from parent
     * @param [options] Declared options
     */
    constructor(name: string, id: number, type: string, rule?: (string|{ [k: string]: any }), extend?: (string|{ [k: string]: any }), options?: { [k: string]: any });

    /**
     * Constructs a field from a field descriptor.
     * @param name Field name
     * @param json Field descriptor
     * @returns Created field
     * @throws {TypeError} If arguments are invalid
     */
    public static fromJSON(name: string, json: IField): Field;

    /** Determines whether this field is packed. Only relevant when repeated and working with proto2. */
    public readonly packed: boolean;

    /**
     * Field decorator (TypeScript).
     * @param fieldId Field id
     * @param fieldType Field type
     * @param [fieldRule="optional"] Field rule
     * @param [defaultValue] Default value
     * @returns Decorator function
     */
    public static d<T extends number | number[] | bigint | bigint[] | string | string[] | boolean | boolean[] | Uint8Array | Uint8Array[] | Buffer | Buffer[]>(fieldId: number, fieldType: ("double"|"float"|"int32"|"uint32"|"sint32"|"fixed32"|"sfixed32"|"int64"|"uint64"|"sint64"|"fixed64"|"sfixed64"|"string"|"bool"|"bytes"|object), fieldRule?: ("optional"|"required"|"repeated"), defaultValue?: T): FieldDecorator;

    /**
     * Field decorator (TypeScript).
     * @param fieldId Field id
     * @param fieldType Field type
     * @param [fieldRule="optional"] Field rule
     * @returns Decorator function
     */
    public static d<T extends Message<T>>(fieldId: number, fieldType: (Constructor<T>|string), fieldRule?: ("optional"|"required"|"repeated")): FieldDecorator;
}

/** Base class of all reflected message fields. This is not an actual class but here for the sake of having consistent type definitions. */
export class FieldBase extends ReflectionObject {

    /**
     * Not an actual constructor. Use {@link Field} instead.
     * @param name Unique name within its namespace
     * @param id Unique id within its namespace
     * @param type Value type
     * @param [rule="optional"] Field rule
     * @param [extend] Extended type if different from parent
     * @param [options] Declared options
     * @param [comment] Comment associated with this field
     */
    constructor(name: string, id: number, type: string, rule?: (string|{ [k: string]: any }), extend?: (string|{ [k: string]: any }), options?: { [k: string]: any }, comment?: string);

    /** Field type. */
    public type: string;

    /** Unique field id. */
    public id: number;

    /** Extended type if different from parent. */
    public extend?: string;

    /** Whether this field is required. */
    public required: boolean;

    /** Whether this field is optional. */
    public optional: boolean;

    /** Whether this field is repeated. */
    public repeated: boolean;

    /** Whether this field is a map or not. */
    public map: boolean;

    /** Message this field belongs to. */
    public message: (Type|null);

    /** OneOf this field belongs to, if any, */
    public partOf: (OneOf|null);

    /** The field type's default value. */
    public typeDefault: any;

    /** The field's default value on prototypes. */
    public defaultValue: any;

    /** Whether this field's value should be treated as a long. */
    public long: boolean;

    /** Whether this field's value is a buffer. */
    public bytes: boolean;

    /** Resolved type if not a basic type. */
    public resolvedType: (Type|Enum|null);

    /** Sister-field within the extended type if a declaring extension field. */
    public extensionField: (Field|null);

    /** Sister-field within the declaring namespace if an extended field. */
    public declaringField: (Field|null);

    /** Comment for this field. */
    public comment: (string|null);

    /**
     * Converts this field to a field descriptor.
     * @param [toJSONOptions] JSON conversion options
     * @returns Field descriptor
     */
    public toJSON(toJSONOptions?: IToJSONOptions): IField;

    /**
     * Resolves this field's type references.
     * @returns `this`
     * @throws {Error} If any reference cannot be resolved
     */
    public resolve(): Field;
}

/** Field descriptor. */
export interface IField {

    /** Field rule */
    rule?: string;

    /** Field type */
    type: string;

    /** Field id */
    id: number;

    /** Field options */
    options?: { [k: string]: any };
}

/** Extension field descriptor. */
export interface IExtensionField extends IField {

    /** Extended type */
    extend: string;
}

/**
 * Decorator function as returned by {@link Field.d} and {@link MapField.d} (TypeScript).
 * @param prototype Target prototype
 * @param fieldName Field name
 */
type FieldDecorator = (prototype: object, fieldName: string) => void;

/**
 * A node-style callback as used by {@link load} and {@link Root#load}.
 * @param error Error, if any, otherwise `null`
 * @param [root] Root, if there hasn't been an error
 */
type LoadCallback = (error: (Error|null), root?: Root) => void;

/**
 * Loads one or multiple .proto or preprocessed .json files into a common root namespace and calls the callback.
 * @param filename One or multiple files to load
 * @param root Root namespace, defaults to create a new one if omitted.
 * @param callback Callback function
 * @see {@link Root#load}
 */
export function load(filename: (string|string[]), root: Root, callback: LoadCallback): void;

/**
 * Loads one or multiple .proto or preprocessed .json files into a common root namespace and calls the callback.
 * @param filename One or multiple files to load
 * @param callback Callback function
 * @see {@link Root#load}
 */
export function load(filename: (string|string[]), callback: LoadCallback): void;

/**
 * Loads one or multiple .proto or preprocessed .json files into a common root namespace and returns a promise.
 * @param filename One or multiple files to load
 * @param [root] Root namespace, defaults to create a new one if omitted.
 * @returns Promise
 * @see {@link Root#load}
 */
export function load(filename: (string|string[]), root?: Root): Promise<Root>;

/**
 * Synchronously loads one or multiple .proto or preprocessed .json files into a common root namespace (node only).
 * @param filename One or multiple files to load
 * @param [root] Root namespace, defaults to create a new one if omitted.
 * @returns Root namespace
 * @throws {Error} If synchronous fetching is not supported (i.e. in browsers) or if a file's syntax is invalid
 * @see {@link Root#loadSync}
 */
export function loadSync(filename: (string|string[]), root?: Root): Root;

/** Build type, one of `"full"`, `"light"` or `"minimal"`. */
export const build: string;

/** Reconfigures the library according to the environment. */
export function configure(): void;

/** Reflected map field. */
export class MapField extends FieldBase {

    /**
     * Constructs a new map field instance.
     * @param name Unique name within its namespace
     * @param id Unique id within its namespace
     * @param keyType Key type
     * @param type Value type
     * @param [options] Declared options
     * @param [comment] Comment associated with this field
     */
    constructor(name: string, id: number, keyType: string, type: string, options?: { [k: string]: any }, comment?: string);

    /** Key type. */
    public keyType: string;

    /** Resolved key type if not a basic type. */
    public resolvedKeyType: (ReflectionObject|null);

    /**
     * Constructs a map field from a map field descriptor.
     * @param name Field name
     * @param json Map field descriptor
     * @returns Created map field
     * @throws {TypeError} If arguments are invalid
     */
    public static fromJSON(name: string, json: IMapField): MapField;

    /**
     * Converts this map field to a map field descriptor.
     * @param [toJSONOptions] JSON conversion options
     * @returns Map field descriptor
     */
    public toJSON(toJSONOptions?: IToJSONOptions): IMapField;

    /**
     * Map field decorator (TypeScript).
     * @param fieldId Field id
     * @param fieldKeyType Field key type
     * @param fieldValueType Field value type
     * @returns Decorator function
     */
    public static d<T extends { [key: string]: number | bigint | string | boolean | Uint8Array | Buffer | number[] | Message<{}> }>(fieldId: number, fieldKeyType: ("int32"|"uint32"|"sint32"|"fixed32"|"sfixed32"|"int64"|"uint64"|"sint64"|"fixed64"|"sfixed64"|"bool"|"string"), fieldValueType: ("double"|"float"|"int32"|"uint32"|"sint32"|"fixed32"|"sfixed32"|"int64"|"uint64"|"sint64"|"fixed64"|"sfixed64"|"bool"|"string"|"bytes"|object|Constructor<{}>)): FieldDecorator;
}

/** Map field descriptor. */
export interface IMapField extends IField {

    /** Key type */
    keyType: string;
}

/** Extension map field descriptor. */
export interface IExtensionMapField extends IMapField {

    /** Extended type */
    extend: string;
}

/** Abstract runtime message. */
export class Message<T extends object = object> {

    /**
     * Constructs a new message instance.
     * @param [properties] Properties to set
     */
    constructor(properties?: Properties<T>);

    /** Reference to the reflected type. */
    public static readonly $type: Type;

    /** Reference to the reflected type. */
    public readonly $type: Type;

    /**
     * Creates a new message of this type using the specified properties.
     * @param [properties] Properties to set
     * @returns Message instance
     */
    public static create<T extends Message<T>>(this: Constructor<T>, properties?: { [k: string]: any }): Message<T>;

    /**
     * Encodes a message of this type.
     * @param message Message to encode
     * @param [writer] Writer to use
     * @returns Writer
     */
    public static encode<T extends Message<T>>(this: Constructor<T>, message: (T|{ [k: string]: any }), writer?: Writer): Writer;

    /**
     * Encodes a message of this type preceeded by its length as a varint.
     * @param message Message to encode
     * @param [writer] Writer to use
     * @returns Writer
     */
    public static encodeDelimited<T extends Message<T>>(this: Constructor<T>, message: (T|{ [k: string]: any }), writer?: Writer): Writer;

    /**
     * Decodes a message of this type.
     * @param reader Reader or buffer to decode
     * @returns Decoded message
     */
    public static decode<T extends Message<T>>(this: Constructor<T>, reader: (Reader|Uint8Array)): T;

    /**
     * Decodes a message of this type preceeded by its length as a varint.
     * @param reader Reader or buffer to decode
     * @returns Decoded message
     */
    public static decodeDelimited<T extends Message<T>>(this: Constructor<T>, reader: (Reader|Uint8Array)): T;

    /**
     * Verifies a message of this type.
     * @param message Plain object to verify
     * @returns `null` if valid, otherwise the reason why it is not
     */
    public static verify(message: { [k: string]: any }): (string|null);

    /**
     * Creates a new message of this type from a plain object. Also converts values to their respective internal types.
     * @param object Plain object
     * @returns Message instance
     */
    public static fromObject<T extends Message<T>>(this: Constructor<T>, object: { [k: string]: any }): T;

    /**
     * Creates a plain object from a message of this type. Also converts values to other types if specified.
     * @param message Message instance
     * @param [options] Conversion options
     * @returns Plain object
     */
    public static toObject<T extends Message<T>>(this: Constructor<T>, message: T, options?: IConversionOptions): { [k: string]: any };

    /**
     * Converts this message to JSON.
     * @returns JSON object
     */
    public toJSON(): { [k: string]: any };
}

/** Reflected service method. */
export class Method extends ReflectionObject {

    /**
     * Constructs a new service method instance.
     * @param name Method name
     * @param type Method type, usually `"rpc"`
     * @param requestType Request message type
     * @param responseType Response message type
     * @param [requestStream] Whether the request is streamed
     * @param [responseStream] Whether the response is streamed
     * @param [options] Declared options
     * @param [comment] The comment for this method
     * @param [parsedOptions] Declared options, properly parsed into an object
     */
    constructor(name: string, type: (string|undefined), requestType: string, responseType: string, requestStream?: (boolean|{ [k: string]: any }), responseStream?: (boolean|{ [k: string]: any }), options?: { [k: string]: any }, comment?: string, parsedOptions?: { [k: string]: any });

    /** Method type. */
    public type: string;

    /** Request type. */
    public requestType: string;

    /** Whether requests are streamed or not. */
    public requestStream?: boolean;

    /** Response type. */
    public responseType: string;

    /** Whether responses are streamed or not. */
    public responseStream?: boolean;

    /** Resolved request type. */
    public resolvedRequestType: (Type|null);

    /** Resolved response type. */
    public resolvedResponseType: (Type|null);

    /** Comment for this method */
    public comment: (string|null);

    /** Options properly parsed into an object */
    public parsedOptions: any;

    /**
     * Constructs a method from a method descriptor.
     * @param name Method name
     * @param json Method descriptor
     * @returns Created method
     * @throws {TypeError} If arguments are invalid
     */
    public static fromJSON(name: string, json: IMethod): Method;

    /**
     * Converts this method to a method descriptor.
     * @param [toJSONOptions] JSON conversion options
     * @returns Method descriptor
     */
    public toJSON(toJSONOptions?: IToJSONOptions): IMethod;
}

/** Method descriptor. */
export interface IMethod {

    /** Method type */
    type?: string;

    /** Request type */
    requestType: string;

    /** Response type */
    responseType: string;

    /** Whether requests are streamed */
    requestStream?: boolean;

    /** Whether responses are streamed */
    responseStream?: boolean;

    /** Method options */
    options?: { [k: string]: any };

    /** Method comments */
    comment: string;

    /** Method options properly parsed into an object */
    parsedOptions?: { [k: string]: any };
}

/** Reflected namespace. */
export class Namespace extends NamespaceBase {

    /**
     * Constructs a new namespace instance.
     * @param name Namespace name
     * @param [options] Declared options
     */
    constructor(name: string, options?: { [k: string]: any });

    /**
     * Constructs a namespace from JSON.
     * @param name Namespace name
     * @param json JSON object
     * @returns Created namespace
     * @throws {TypeError} If arguments are invalid
     */
    public static fromJSON(name: string, json: { [k: string]: any }): Namespace;

    /**
     * Converts an array of reflection objects to JSON.
     * @param array Object array
     * @param [toJSONOptions] JSON conversion options
     * @returns JSON object or `undefined` when array is empty
     */
    public static arrayToJSON(array: ReflectionObject[], toJSONOptions?: IToJSONOptions): ({ [k: string]: any }|undefined);

    /**
     * Tests if the specified id is reserved.
     * @param reserved Array of reserved ranges and names
     * @param id Id to test
     * @returns `true` if reserved, otherwise `false`
     */
    public static isReservedId(reserved: ((number[]|string)[]|undefined), id: number): boolean;

    /**
     * Tests if the specified name is reserved.
     * @param reserved Array of reserved ranges and names
     * @param name Name to test
     * @returns `true` if reserved, otherwise `false`
     */
    public static isReservedName(reserved: ((number[]|string)[]|undefined), name: string): boolean;
}

/** Base class of all reflection objects containing nested objects. This is not an actual class but here for the sake of having consistent type definitions. */
export abstract class NamespaceBase extends ReflectionObject {

    /** Nested objects by name. */
    public nested?: { [k: string]: ReflectionObject };

    /** Nested objects of this namespace as an array for iteration. */
    public readonly nestedArray: ReflectionObject[];

    /**
     * Converts this namespace to a namespace descriptor.
     * @param [toJSONOptions] JSON conversion options
     * @returns Namespace descriptor
     */
    public toJSON(toJSONOptions?: IToJSONOptions): INamespace;

    /**
     * Adds nested objects to this namespace from nested object descriptors.
     * @param nestedJson Any nested object descriptors
     * @returns `this`
     */
    public addJSON(nestedJson: { [k: string]: AnyNestedObject }): Namespace;

    /**
     * Gets the nested object of the specified name.
     * @param name Nested object name
     * @returns The reflection object or `null` if it doesn't exist
     */
    public get(name: string): (ReflectionObject|null);

    /**
     * Gets the values of the nested {@link Enum|enum} of the specified name.
     * This methods differs from {@link Namespace#get|get} in that it returns an enum's values directly and throws instead of returning `null`.
     * @param name Nested enum name
     * @returns Enum values
     * @throws {Error} If there is no such enum
     */
    public getEnum(name: string): { [k: string]: number };

    /**
     * Adds a nested object to this namespace.
     * @param object Nested object to add
     * @returns `this`
     * @throws {TypeError} If arguments are invalid
     * @throws {Error} If there is already a nested object with this name
     */
    public add(object: ReflectionObject): Namespace;

    /**
     * Removes a nested object from this namespace.
     * @param object Nested object to remove
     * @returns `this`
     * @throws {TypeError} If arguments are invalid
     * @throws {Error} If `object` is not a member of this namespace
     */
    public remove(object: ReflectionObject): Namespace;

    /**
     * Defines additial namespaces within this one if not yet existing.
     * @param path Path to create
     * @param [json] Nested types to create from JSON
     * @returns Pointer to the last namespace created or `this` if path is empty
     */
    public define(path: (string|string[]), json?: any): Namespace;

    /**
     * Resolves this namespace's and all its nested objects' type references. Useful to validate a reflection tree, but comes at a cost.
     * @returns `this`
     */
    public resolveAll(): Namespace;

    /**
     * Recursively looks up the reflection object matching the specified path in the scope of this namespace.
     * @param path Path to look up
     * @param filterTypes Filter types, any combination of the constructors of `protobuf.Type`, `protobuf.Enum`, `protobuf.Service` etc.
     * @param [parentAlreadyChecked=false] If known, whether the parent has already been checked
     * @returns Looked up object or `null` if none could be found
     */
    public lookup(path: (string|string[]), filterTypes: (any|any[]), parentAlreadyChecked?: boolean): (ReflectionObject|null);

    /**
     * Looks up the reflection object at the specified path, relative to this namespace.
     * @param path Path to look up
     * @param [parentAlreadyChecked=false] Whether the parent has already been checked
     * @returns Looked up object or `null` if none could be found
     */
    public lookup(path: (string|string[]), parentAlreadyChecked?: boolean): (ReflectionObject|null);

    /**
     * Looks up the {@link Type|type} at the specified path, relative to this namespace.
     * Besides its signature, this methods differs from {@link Namespace#lookup|lookup} in that it throws instead of returning `null`.
     * @param path Path to look up
     * @returns Looked up type
     * @throws {Error} If `path` does not point to a type
     */
    public lookupType(path: (string|string[])): Type;

    /**
     * Looks up the values of the {@link Enum|enum} at the specified path, relative to this namespace.
     * Besides its signature, this methods differs from {@link Namespace#lookup|lookup} in that it throws instead of returning `null`.
     * @param path Path to look up
     * @returns Looked up enum
     * @throws {Error} If `path` does not point to an enum
     */
    public lookupEnum(path: (string|string[])): Enum;

    /**
     * Looks up the {@link Type|type} or {@link Enum|enum} at the specified path, relative to this namespace.
     * Besides its signature, this methods differs from {@link Namespace#lookup|lookup} in that it throws instead of returning `null`.
     * @param path Path to look up
     * @returns Looked up type or enum
     * @throws {Error} If `path` does not point to a type or enum
     */
    public lookupTypeOrEnum(path: (string|string[])): Type;

    /**
     * Looks up the {@link Service|service} at the specified path, relative to this namespace.
     * Besides its signature, this methods differs from {@link Namespace#lookup|lookup} in that it throws instead of returning `null`.
     * @param path Path to look up
     * @returns Looked up service
     * @throws {Error} If `path` does not point to a service
     */
    public lookupService(path: (string|string[])): Service;
}

/** Namespace descriptor. */
export interface INamespace {

    /** Namespace options */
    options?: { [k: string]: any };

    /** Nested object descriptors */
    nested?: { [k: string]: AnyNestedObject };
}

/** Any extension field descriptor. */
type AnyExtensionField = (IExtensionField|IExtensionMapField);

/** Any nested object descriptor. */
type AnyNestedObject = (IEnum|IType|IService|AnyExtensionField|INamespace|IOneOf);

/** Base class of all reflection objects. */
export abstract class ReflectionObject {

    /** Options. */
    public options?: { [k: string]: any };

    /** Parsed Options. */
    public parsedOptions?: { [k: string]: any[] };

    /** Unique name within its namespace. */
    public name: string;

    /** Parent namespace. */
    public parent: (Namespace|null);

    /** Whether already resolved or not. */
    public resolved: boolean;

    /** Comment text, if any. */
    public comment: (string|null);

    /** Defining file name. */
    public filename: (string|null);

    /** Reference to the root namespace. */
    public readonly root: Root;

    /** Full name including leading dot. */
    public readonly fullName: string;

    /**
     * Converts this reflection object to its descriptor representation.
     * @returns Descriptor
     */
    public toJSON(): { [k: string]: any };

    /**
     * Called when this object is added to a parent.
     * @param parent Parent added to
     */
    public onAdd(parent: ReflectionObject): void;

    /**
     * Called when this object is removed from a parent.
     * @param parent Parent removed from
     */
    public onRemove(parent: ReflectionObject): void;

    /**
     * Resolves this objects type references.
     * @returns `this`
     */
    public resolve(): ReflectionObject;

    /**
     * Gets an option value.
     * @param name Option name
     * @returns Option value or `undefined` if not set
     */
    public getOption(name: string): any;

    /**
     * Sets an option.
     * @param name Option name
     * @param value Option value
     * @param [ifNotSet] Sets the option only if it isn't currently set
     * @returns `this`
     */
    public setOption(name: string, value: any, ifNotSet?: boolean): ReflectionObject;

    /**
     * Sets a parsed option.
     * @param name parsed Option name
     * @param value Option value
     * @param propName dot '.' delimited full path of property within the option to set. if undefined\empty, will add a new option with that value
     * @returns `this`
     */
    public setParsedOption(name: string, value: any, propName: string): ReflectionObject;

    /**
     * Sets multiple options.
     * @param options Options to set
     * @param [ifNotSet] Sets an option only if it isn't currently set
     * @returns `this`
     */
    public setOptions(options: { [k: string]: any }, ifNotSet?: boolean): ReflectionObject;

    /**
     * Converts this instance to its string representation.
     * @returns Class name[, space, full name]
     */
    public toString(): string;
}

/** Reflected oneof. */
export class OneOf extends ReflectionObject {

    /**
     * Constructs a new oneof instance.
     * @param name Oneof name
     * @param [fieldNames] Field names
     * @param [options] Declared options
     * @param [comment] Comment associated with this field
     */
    constructor(name: string, fieldNames?: (string[]|{ [k: string]: any }), options?: { [k: string]: any }, comment?: string);

    /** Field names that belong to this oneof. */
    public oneof: string[];

    /** Fields that belong to this oneof as an array for iteration. */
    public readonly fieldsArray: Field[];

    /** Comment for this field. */
    public comment: (string|null);

    /**
     * Constructs a oneof from a oneof descriptor.
     * @param name Oneof name
     * @param json Oneof descriptor
     * @returns Created oneof
     * @throws {TypeError} If arguments are invalid
     */
    public static fromJSON(name: string, json: IOneOf): OneOf;

    /**
     * Converts this oneof to a oneof descriptor.
     * @param [toJSONOptions] JSON conversion options
     * @returns Oneof descriptor
     */
    public toJSON(toJSONOptions?: IToJSONOptions): IOneOf;

    /**
     * Adds a field to this oneof and removes it from its current parent, if any.
     * @param field Field to add
     * @returns `this`
     */
    public add(field: Field): OneOf;

    /**
     * Removes a field from this oneof and puts it back to the oneof's parent.
     * @param field Field to remove
     * @returns `this`
     */
    public remove(field: Field): OneOf;

    /**
     * OneOf decorator (TypeScript).
     * @param fieldNames Field names
     * @returns Decorator function
     */
    public static d<T extends string>(...fieldNames: string[]): OneOfDecorator;
}

/** Oneof descriptor. */
export interface IOneOf {

    /** Oneof field names */
    oneof: string[];

    /** Oneof options */
    options?: { [k: string]: any };
}

/**
 * Decorator function as returned by {@link OneOf.d} (TypeScript).
 * @param prototype Target prototype
 * @param oneofName OneOf name
 */
type OneOfDecorator = (prototype: object, oneofName: string) => void;

/**
 * Parses the given .proto source and returns an object with the parsed contents.
 * @param source Source contents
 * @param [options] Parse options. Defaults to {@link parse.defaults} when omitted.
 * @returns Parser result
 */
export function parse(source: string, options?: IParseOptions): IParserResult;

/** Result object returned from {@link parse}. */
export interface IParserResult {

    /** Package name, if declared */
    package: (string|undefined);

    /** Imports, if any */
    imports: (string[]|undefined);

    /** Weak imports, if any */
    weakImports: (string[]|undefined);

    /** Syntax, if specified (either `"proto2"` or `"proto3"`) */
    syntax: (string|undefined);

    /** Populated root instance */
    root: Root;
}

/** Options modifying the behavior of {@link parse}. */
export interface IParseOptions {

    /** Keeps field casing instead of converting to camel case */
    keepCase?: boolean;

    /** Recognize double-slash comments in addition to doc-block comments. */
    alternateCommentMode?: boolean;

    /** Use trailing comment when both leading comment and trailing comment exist. */
    preferTrailingComment?: boolean;
}

/** Options modifying the behavior of JSON serialization. */
export interface IToJSONOptions {

    /** Serializes comments. */
    keepComments?: boolean;
}

/**
 * Parses the given .proto source and returns an object with the parsed contents.
 * @param source Source contents
 * @param root Root to populate
 * @param [options] Parse options. Defaults to {@link parse.defaults} when omitted.
 * @returns Parser result
 */
export function parse(source: string, root: Root, options?: IParseOptions): IParserResult;

/** Wire format reader using `Uint8Array` if available, otherwise `Array`. */
export class Reader {

    /**
     * Constructs a new reader instance using the specified buffer.
     * @param buffer Buffer to read from
     */
    constructor(buffer: Uint8Array);

    /** Read buffer. */
    public buf: Uint8Array;

    /** Read buffer position. */
    public pos: number;

    /** Read buffer length. */
    public len: number;

    /**
     * Creates a new reader using the specified buffer.
     * @param buffer Buffer to read from
     * @returns A {@link BufferReader} if `buffer` is a Buffer, otherwise a {@link Reader}
     * @throws {Error} If `buffer` is not a valid buffer
     */
    public static create(buffer: (Uint8Array|Buffer)): (Reader|BufferReader);

    /**
     * Reads a varint as an unsigned 32 bit value.
     * @returns Value read
     */
    public uint32(): number;

    /**
     * Reads a varint as a signed 32 bit value.
     * @returns Value read
     */
    public int32(): number;

    /**
     * Reads a zig-zag encoded varint as a signed 32 bit value.
     * @returns Value read
     */
    public sint32(): number;

    /**
     * Reads a varint as a boolean.
     * @returns Value read
     */
    public bool(): boolean;

    /**
     * Reads fixed 32 bits as an unsigned 32 bit integer.
     * @returns Value read
     */
    public fixed32(): number;

    /**
     * Reads fixed 32 bits as a signed 32 bit integer.
     * @returns Value read
     */
    public sfixed32(): number;

    /**
     * Reads a varint as a signed 64 bit value.
     * @returns Value read
     */
    public int64(): bigint;

    /**
     * Reads a varint as an unsigned 64 bit value.
     * @returns Value read
     */
    public uint64(): bigint;

    /**
     * Reads a zig-zag encoded varint as a signed 64 bit value.
     * @returns Value read
     */
    public sint64(): bigint;

    /**
     * Reads fixed 64 bits.
     * @returns Value read
     */
    public fixed64(): bigint;

    /**
     * Reads zig-zag encoded fixed 64 bits.
     * @returns Value read
     */
    public sfixed64(): bigint;

    /**
     * Reads a float (32 bit) as a number.
     * @returns Value read
     */
    public float(): number;

    /**
     * Reads a double (64 bit float) as a number.
     * @returns Value read
     */
    public double(): number;

    /**
     * Reads a sequence of bytes preceeded by its length as a varint.
     * @returns Value read
     */
    public bytes(): Uint8Array;

    /**
     * Reads a string preceeded by its byte length as a varint.
     * @returns Value read
     */
    public string(): string;

    /**
     * Skips the specified number of bytes if specified, otherwise skips a varint.
     * @param [length] Length if known, otherwise a varint is assumed
     * @returns `this`
     */
    public skip(length?: number): Reader;

    /**
     * Skips the next element of the specified wire type.
     * @param wireType Wire type received
     * @returns `this`
     */
    public skipType(wireType: number): Reader;
}

/** Wire format reader using node buffers. */
export class BufferReader extends Reader {

    /**
     * Constructs a new buffer reader instance.
     * @param buffer Buffer to read from
     */
    constructor(buffer: Buffer);

    /**
     * Reads a sequence of bytes preceeded by its length as a varint.
     * @returns Value read
     */
    public bytes(): Buffer;
}

/** Root namespace wrapping all types, enums, services, sub-namespaces etc. that belong together. */
export class Root extends NamespaceBase {

    /**
     * Constructs a new root namespace instance.
     * @param [options] Top level options
     */
    constructor(options?: { [k: string]: any });

    /** Deferred extension fields. */
    public deferred: Field[];

    /** Resolved file names of loaded files. */
    public files: string[];

    /**
     * Loads a namespace descriptor into a root namespace.
     * @param json Nameespace descriptor
     * @param [root] Root namespace, defaults to create a new one if omitted
     * @returns Root namespace
     */
    public static fromJSON(json: INamespace, root?: Root): Root;

    /**
     * Resolves the path of an imported file, relative to the importing origin.
     * This method exists so you can override it with your own logic in case your imports are scattered over multiple directories.
     * @param origin The file name of the importing file
     * @param target The file name being imported
     * @returns Resolved path to `target` or `null` to skip the file
     */
    public resolvePath(origin: string, target: string): (string|null);

    /**
     * Fetch content from file path or url
     * This method exists so you can override it with your own logic.
     * @param path File path or url
     * @param callback Callback function
     */
    public fetch(path: string, callback: FetchCallback): void;

    /**
     * Loads one or multiple .proto or preprocessed .json files into this root namespace and calls the callback.
     * @param filename Names of one or multiple files to load
     * @param options Parse options
     * @param callback Callback function
     */
    public load(filename: (string|string[]), options: IParseOptions, callback: LoadCallback): void;

    /**
     * Loads one or multiple .proto or preprocessed .json files into this root namespace and calls the callback.
     * @param filename Names of one or multiple files to load
     * @param callback Callback function
     */
    public load(filename: (string|string[]), callback: LoadCallback): void;

    /**
     * Loads one or multiple .proto or preprocessed .json files into this root namespace and returns a promise.
     * @param filename Names of one or multiple files to load
     * @param [options] Parse options. Defaults to {@link parse.defaults} when omitted.
     * @returns Promise
     */
    public load(filename: (string|string[]), options?: IParseOptions): Promise<Root>;

    /**
     * Synchronously loads one or multiple .proto or preprocessed .json files into this root namespace (node only).
     * @param filename Names of one or multiple files to load
     * @param [options] Parse options. Defaults to {@link parse.defaults} when omitted.
     * @returns Root namespace
     * @throws {Error} If synchronous fetching is not supported (i.e. in browsers) or if a file's syntax is invalid
     */
    public loadSync(filename: (string|string[]), options?: IParseOptions): Root;
}

/**
 * Named roots.
 * This is where pbjs stores generated structures (the option `-r, --root` specifies a name).
 * Can also be used manually to make roots available across modules.
 */
export let roots: { [k: string]: Root };

/** Streaming RPC helpers. */
export namespace rpc {

    /**
     * A service method callback as used by {@link rpc.ServiceMethod|ServiceMethod}.
     *
     * Differs from {@link RPCImplCallback} in that it is an actual callback of a service method which may not return `response = null`.
     * @param error Error, if any
     * @param [response] Response message
     */
    type ServiceMethodCallback<TRes extends Message<TRes>> = (error: (Error|null), response?: TRes) => void;

    /**
     * A service method part of a {@link rpc.Service} as created by {@link Service.create}.
     * @param request Request message or plain object
     * @param [callback] Node-style callback called with the error, if any, and the response message
     * @returns Promise if `callback` has been omitted, otherwise `undefined`
     */
    type ServiceMethod<TReq extends Message<TReq>, TRes extends Message<TRes>> = (request: (TReq|Properties<TReq>), callback?: rpc.ServiceMethodCallback<TRes>) => Promise<Message<TRes>>;

    /** An RPC service as returned by {@link Service#create}. */
    class Service extends util.EventEmitter {

        /**
         * Constructs a new RPC service instance.
         * @param rpcImpl RPC implementation
         * @param [requestDelimited=false] Whether requests are length-delimited
         * @param [responseDelimited=false] Whether responses are length-delimited
         */
        constructor(rpcImpl: RPCImpl, requestDelimited?: boolean, responseDelimited?: boolean);

        /** RPC implementation. Becomes `null` once the service is ended. */
        public rpcImpl: (RPCImpl|null);

        /** Whether requests are length-delimited. */
        public requestDelimited: boolean;

        /** Whether responses are length-delimited. */
        public responseDelimited: boolean;

        /**
         * Calls a service method through {@link rpc.Service#rpcImpl|rpcImpl}.
         * @param method Reflected or static method
         * @param requestCtor Request constructor
         * @param responseCtor Response constructor
         * @param request Request message or plain object
         * @param callback Service callback
         */
        public rpcCall<TReq extends Message<TReq>, TRes extends Message<TRes>>(method: (Method|rpc.ServiceMethod<TReq, TRes>), requestCtor: Constructor<TReq>, responseCtor: Constructor<TRes>, request: (TReq|Properties<TReq>), callback: rpc.ServiceMethodCallback<TRes>): void;

        /**
         * Ends this service and emits the `end` event.
         * @param [endedByRPC=false] Whether the service has been ended by the RPC implementation.
         * @returns `this`
         */
        public end(endedByRPC?: boolean): rpc.Service;
    }
}

/**
 * RPC implementation passed to {@link Service#create} performing a service request on network level, i.e. by utilizing http requests or websockets.
 * @param method Reflected or static method being called
 * @param requestData Request data
 * @param callback Callback function
 */
type RPCImpl = (method: (Method|rpc.ServiceMethod<Message<{}>, Message<{}>>), requestData: Uint8Array, callback: RPCImplCallback) => void;

/**
 * Node-style callback as used by {@link RPCImpl}.
 * @param error Error, if any, otherwise `null`
 * @param [response] Response data or `null` to signal end of stream, if there hasn't been an error
 */
type RPCImplCallback = (error: (Error|null), response?: (Uint8Array|null)) => void;

/** Reflected service. */
export class Service extends NamespaceBase {

    /**
     * Constructs a new service instance.
     * @param name Service name
     * @param [options] Service options
     * @throws {TypeError} If arguments are invalid
     */
    constructor(name: string, options?: { [k: string]: any });

    /** Service methods. */
    public methods: { [k: string]: Method };

    /**
     * Constructs a service from a service descriptor.
     * @param name Service name
     * @param json Service descriptor
     * @returns Created service
     * @throws {TypeError} If arguments are invalid
     */
    public static fromJSON(name: string, json: IService): Service;

    /**
     * Converts this service to a service descriptor.
     * @param [toJSONOptions] JSON conversion options
     * @returns Service descriptor
     */
    public toJSON(toJSONOptions?: IToJSONOptions): IService;

    /** Methods of this service as an array for iteration. */
    public readonly methodsArray: Method[];

    /**
     * Creates a runtime service using the specified rpc implementation.
     * @param rpcImpl RPC implementation
     * @param [requestDelimited=false] Whether requests are length-delimited
     * @param [responseDelimited=false] Whether responses are length-delimited
     * @returns RPC service. Useful where requests and/or responses are streamed.
     */
    public create(rpcImpl: RPCImpl, requestDelimited?: boolean, responseDelimited?: boolean): rpc.Service;
}

/** Service descriptor. */
export interface IService extends INamespace {

    /** Method descriptors */
    methods: { [k: string]: IMethod };
}

/**
 * Gets the next token and advances.
 * @returns Next token or `null` on eof
 */
type TokenizerHandleNext = () => (string|null);

/**
 * Peeks for the next token.
 * @returns Next token or `null` on eof
 */
type TokenizerHandlePeek = () => (string|null);

/**
 * Pushes a token back to the stack.
 * @param token Token
 */
type TokenizerHandlePush = (token: string) => void;

/**
 * Skips the next token.
 * @param expected Expected token
 * @param [optional=false] If optional
 * @returns Whether the token matched
 * @throws {Error} If the token didn't match and is not optional
 */
type TokenizerHandleSkip = (expected: string, optional?: boolean) => boolean;

/**
 * Gets the comment on the previous line or, alternatively, the line comment on the specified line.
 * @param [line] Line number
 * @returns Comment text or `null` if none
 */
type TokenizerHandleCmnt = (line?: number) => (string|null);

/** Handle object returned from {@link tokenize}. */
export interface ITokenizerHandle {

    /** Gets the next token and advances (`null` on eof) */
    next: TokenizerHandleNext;

    /** Peeks for the next token (`null` on eof) */
    peek: TokenizerHandlePeek;

    /** Pushes a token back to the stack */
    push: TokenizerHandlePush;

    /** Skips a token, returns its presence and advances or, if non-optional and not present, throws */
    skip: TokenizerHandleSkip;

    /** Gets the comment on the previous line or the line comment on the specified line, if any */
    cmnt: TokenizerHandleCmnt;

    /** Current line number */
    line: number;
}

/**
 * Tokenizes the given .proto source and returns an object with useful utility functions.
 * @param source Source contents
 * @param alternateCommentMode Whether we should activate alternate comment parsing mode.
 * @returns Tokenizer handle
 */
export function tokenize(source: string, alternateCommentMode: boolean): ITokenizerHandle;

export namespace tokenize {

    /**
     * Unescapes a string.
     * @param str String to unescape
     * @returns Unescaped string
     */
    function unescape(str: string): string;
}

/** Reflected message type. */
export class Type extends NamespaceBase {

    /**
     * Constructs a new reflected message type instance.
     * @param name Message name
     * @param [options] Declared options
     */
    constructor(name: string, options?: { [k: string]: any });

    /** Message fields. */
    public fields: { [k: string]: Field };

    /** Oneofs declared within this namespace, if any. */
    public oneofs: { [k: string]: OneOf };

    /** Extension ranges, if any. */
    public extensions: number[][];

    /** Reserved ranges, if any. */
    public reserved: (number[]|string)[];

    /** Message fields by id. */
    public readonly fieldsById: { [k: number]: Field };

    /** Fields of this message as an array for iteration. */
    public readonly fieldsArray: Field[];

    /** Oneofs of this message as an array for iteration. */
    public readonly oneofsArray: OneOf[];

    /**
     * The registered constructor, if any registered, otherwise a generic constructor.
     * Assigning a function replaces the internal constructor. If the function does not extend {@link Message} yet, its prototype will be setup accordingly and static methods will be populated. If it already extends {@link Message}, it will just replace the internal constructor.
     */
    public ctor: Constructor<{}>;

    /**
     * Generates a constructor function for the specified type.
     * @param mtype Message type
     * @returns Codegen instance
     */
    public static generateConstructor(mtype: Type): Codegen;

    /**
     * Creates a message type from a message type descriptor.
     * @param name Message name
     * @param json Message type descriptor
     * @returns Created message type
     */
    public static fromJSON(name: string, json: IType): Type;

    /**
     * Converts this message type to a message type descriptor.
     * @param [toJSONOptions] JSON conversion options
     * @returns Message type descriptor
     */
    public toJSON(toJSONOptions?: IToJSONOptions): IType;

    /**
     * Adds a nested object to this type.
     * @param object Nested object to add
     * @returns `this`
     * @throws {TypeError} If arguments are invalid
     * @throws {Error} If there is already a nested object with this name or, if a field, when there is already a field with this id
     */
    public add(object: ReflectionObject): Type;

    /**
     * Removes a nested object from this type.
     * @param object Nested object to remove
     * @returns `this`
     * @throws {TypeError} If arguments are invalid
     * @throws {Error} If `object` is not a member of this type
     */
    public remove(object: ReflectionObject): Type;

    /**
     * Tests if the specified id is reserved.
     * @param id Id to test
     * @returns `true` if reserved, otherwise `false`
     */
    public isReservedId(id: number): boolean;

    /**
     * Tests if the specified name is reserved.
     * @param name Name to test
     * @returns `true` if reserved, otherwise `false`
     */
    public isReservedName(name: string): boolean;

    /**
     * Creates a new message of this type using the specified properties.
     * @param [properties] Properties to set
     * @returns Message instance
     */
    public create(properties?: { [k: string]: any }): Message<{}>;

    /**
     * Sets up {@link Type#encode|encode}, {@link Type#decode|decode} and {@link Type#verify|verify}.
     * @returns `this`
     */
    public setup(): Type;

    /**
     * Encodes a message of this type. Does not implicitly {@link Type#verify|verify} messages.
     * @param message Message instance or plain object
     * @param [writer] Writer to encode to
     * @returns writer
     */
    public encode(message: (Message<{}>|{ [k: string]: any }), writer?: Writer): Writer;

    /**
     * Encodes a message of this type preceeded by its byte length as a varint. Does not implicitly {@link Type#verify|verify} messages.
     * @param message Message instance or plain object
     * @param [writer] Writer to encode to
     * @returns writer
     */
    public encodeDelimited(message: (Message<{}>|{ [k: string]: any }), writer?: Writer): Writer;

    /**
     * Decodes a message of this type.
     * @param reader Reader or buffer to decode from
     * @param [length] Length of the message, if known beforehand
     * @returns Decoded message
     * @throws {Error} If the payload is not a reader or valid buffer
     * @throws {util.ProtocolError<{}>} If required fields are missing
     */
    public decode(reader: (Reader|Uint8Array), length?: number): Message<{}>;

    /**
     * Decodes a message of this type preceeded by its byte length as a varint.
     * @param reader Reader or buffer to decode from
     * @returns Decoded message
     * @throws {Error} If the payload is not a reader or valid buffer
     * @throws {util.ProtocolError} If required fields are missing
     */
    public decodeDelimited(reader: (Reader|Uint8Array)): Message<{}>;

    /**
     * Verifies that field values are valid and that required fields are present.
     * @param message Plain object to verify
     * @returns `null` if valid, otherwise the reason why it is not
     */
    public verify(message: { [k: string]: any }): (null|string);

    /**
     * Creates a new message of this type from a plain object. Also converts values to their respective internal types.
     * @param object Plain object to convert
     * @returns Message instance
     */
    public fromObject(object: { [k: string]: any }): Message<{}>;

    /**
     * Creates a plain object from a message of this type. Also converts values to other types if specified.
     * @param message Message instance
     * @param [options] Conversion options
     * @returns Plain object
     */
    public toObject(message: Message<{}>, options?: IConversionOptions): { [k: string]: any };

    /**
     * Type decorator (TypeScript).
     * @param [typeName] Type name, defaults to the constructor's name
     * @returns Decorator function
     */
    public static d<T extends Message<T>>(typeName?: string): TypeDecorator<T>;
}

/** Message type descriptor. */
export interface IType extends INamespace {

    /** Oneof descriptors */
    oneofs?: { [k: string]: IOneOf };

    /** Field descriptors */
    fields: { [k: string]: IField };

    /** Extension ranges */
    extensions?: number[][];

    /** Reserved ranges */
    reserved?: number[][];

    /** Whether a legacy group or not */
    group?: boolean;
}

/** Conversion options as used by {@link Type#toObject} and {@link Message.toObject}. */
export interface IConversionOptions {

    /**
     * Long conversion type.
     * Valid values are `String` and `BigInt` (the global types).
     * Defaults to copy the present value.
     */
    longs?: Function;

    /**
     * Enum value conversion type.
     * Only valid value is `String` (the global type).
     * Defaults to copy the present value, which is the numeric id.
     */
    enums?: Function;

    /**
     * Bytes value conversion type.
     * Valid values are `Array` and (a base64 encoded) `String` (the global types).
     * Defaults to copy the present value, which usually is a Buffer under node and an Uint8Array in the browser.
     */
    bytes?: Function;

    /** Also sets default values on the resulting object */
    defaults?: boolean;

    /** Sets empty arrays for missing repeated fields even if `defaults=false` */
    arrays?: boolean;

    /** Sets empty objects for missing map fields even if `defaults=false` */
    objects?: boolean;

    /** Includes virtual oneof properties set to the present field's name, if any */
    oneofs?: boolean;

    /** Performs additional JSON compatibility conversions, i.e. NaN and Infinity to strings */
    json?: boolean;
}

/**
 * Decorator function as returned by {@link Type.d} (TypeScript).
 * @param target Target constructor
 */
type TypeDecorator<T extends Message<T>> = (target: Constructor<T>) => void;

/** Common type constants. */
export namespace types {

    /** Basic type wire types. */
    const basic: {
        "double": number,
        "float": number,
        "int32": number,
        "uint32": number,
        "sint32": number,
        "fixed32": number,
        "sfixed32": number,
        "int64": number,
        "uint64": number,
        "sint64": number,
        "fixed64": number,
        "sfixed64": number,
        "bool": number,
        "string": number,
        "bytes": number
    };

    /** Basic type defaults. */
    const defaults: {
        "double": number,
        "float": number,
        "int32": number,
        "uint32": number,
        "sint32": number,
        "fixed32": number,
        "sfixed32": number,
        "int64": number,
        "uint64": number,
        "sint64": number,
        "fixed64": number,
        "sfixed64": number,
        "bool": boolean,
        "string": string,
        "bytes": number[],
        "message": null
    };

    /** Basic long type wire types. */
    const long: {
        "int64": number,
        "uint64": number,
        "sint64": number,
        "fixed64": number,
        "sfixed64": number
    };

    /** Allowed types for map keys with their associated wire type. */
    const mapKey: {
        "int32": number,
        "uint32": number,
        "sint32": number,
        "fixed32": number,
        "sfixed32": number,
        "int64": number,
        "uint64": number,
        "sint64": number,
        "fixed64": number,
        "sfixed64": number,
        "bool": number,
        "string": number
    };

    /** Allowed types for packed repeated fields with their associated wire type. */
    const packed: {
        "double": number,
        "float": number,
        "int32": number,
        "uint32": number,
        "sint32": number,
        "fixed32": number,
        "sfixed32": number,
        "int64": number,
        "uint64": number,
        "sint64": number,
        "fixed64": number,
        "sfixed64": number,
        "bool": number
    };
}

/** Constructor type. */
export interface Constructor<T> extends Function {
    new(...params: any[]): T; prototype: T;
}

/** Properties type. */
type Properties<T> = { [P in keyof T]?: T[P] };

/**
 * Any compatible Buffer instance.
 * This is a minimal stand-alone definition of a Buffer instance. The actual type is that exported by node's typings.
 */
export interface Buffer extends Uint8Array {
}

/**
 * A OneOf getter as returned by {@link util.oneOfGetter}.
 * @returns Set field name, if any
 */
type OneOfGetter = () => (string|undefined);

/**
 * A OneOf setter as returned by {@link util.oneOfSetter}.
 * @param value Field name
 */
type OneOfSetter = (value: (string|undefined)) => void;

/** Various utility functions. */
export namespace util {

    /** Helper class for working with the low and high bits of a 64 bit value. */
    class LongBits {

        /**
         * Constructs new long bits.
         * @param lo Low 32 bits, unsigned
         * @param hi High 32 bits, unsigned
         */
        constructor(lo: number, hi: number);

        /** Low bits. */
        public lo: number;

        /** High bits. */
        public hi: number;

        /** Zero bits. */
        public static zero: util.LongBits;

        /**
         * Constructs new long bits from the specified number.
         * @param value Value
         * @returns Instance
         */
        public static fromBigInt(value: number): util.LongBits;

        /**
         * Constructs new long bits from the specified number.
         * @param value Value
         * @returns Instance
         */
        public static fromNumber(value: number): util.LongBits;

        /**
         * Constructs new long bits from a number, long or string.
         * @param value Value
         * @returns Instance
         */
        public static from(value: (bigint|number|string|object)): util.LongBits;

        /**
         * Converts this long bits to a possibly unsafe JavaScript number.
         * @param [unsigned=false] Whether unsigned or not
         * @returns Possibly unsafe number
         */
        public toBigInt(unsigned?: boolean): number;

        /**
         * Zig-zag encodes this long bits.
         * @returns `this`
         */
        public zzEncode(): util.LongBits;

        /**
         * Zig-zag decodes this long bits.
         * @returns `this`
         */
        public zzDecode(): util.LongBits;

        /**
         * Calculates the length of this longbits when encoded as a varint.
         * @returns Length
         */
        public length(): number;
    }

    /** Whether running within node or not. */
    let isNode: boolean;

    /** Global object reference. */
    let global: object;

    /** An immuable empty array. */
    const emptyArray: any[];

    /** An immutable empty object. */
    const emptyObject: object;

    /**
     * Tests if the specified value is an integer.
     * @param value Value to test
     * @returns `true` if the value is an integer
     */
    function isInteger(value: any): boolean;

    /**
     * Tests if the specified value is a string.
     * @param value Value to test
     * @returns `true` if the value is a string
     */
    function isString(value: any): boolean;

    /**
     * Tests if the specified value is a non-null object.
     * @param value Value to test
     * @returns `true` if the value is a non-null object
     */
    function isObject(value: any): boolean;

    /**
     * Checks if a property on a message is considered to be present.
     * This is an alias of {@link util.isSet}.
     * @param obj Plain object or message instance
     * @param prop Property name
     * @returns `true` if considered to be present, otherwise `false`
     */
    function isset(obj: object, prop: string): boolean;

    /**
     * Checks if a property on a message is considered to be present.
     * @param obj Plain object or message instance
     * @param prop Property name
     * @returns `true` if considered to be present, otherwise `false`
     */
    function isSet(obj: object, prop: string): boolean;

    /** Node's Buffer class if available. */
    let Buffer: Constructor<Buffer>;

    /**
     * Creates a new buffer of whatever type supported by the environment.
     * @param [sizeOrArray=0] Buffer size or number array
     * @returns Buffer
     */
    function newBuffer(sizeOrArray?: (number|number[])): (Uint8Array|Buffer);

    /** Array implementation used in the browser. `Uint8Array` if supported, otherwise `Array`. */
    let Array: Constructor<Uint8Array>;

    /** Regular expression used to verify 2 bit (`bool`) map keys. */
    const key2Re: RegExp;

    /** Regular expression used to verify 32 bit (`int32` etc.) map keys. */
    const key32Re: RegExp;

    /** Regular expression used to verify 64 bit (`int64` etc.) map keys. */
    const key64Re: RegExp;

    /**
     * Merges the properties of the source object into the destination object.
     * @param dst Destination object
     * @param src Source object
     * @param [ifNotSet=false] Merges only if the key is not already set
     * @returns Destination object
     */
    function merge(dst: { [k: string]: any }, src: { [k: string]: any }, ifNotSet?: boolean): { [k: string]: any };

    /**
     * Converts the first character of a string to lower case.
     * @param str String to convert
     * @returns Converted string
     */
    function lcFirst(str: string): string;

    /**
     * Creates a custom error constructor.
     * @param name Error name
     * @returns Custom error constructor
     */
    function newError(name: string): Constructor<Error>;

    /** Error subclass indicating a protocol specifc error. */
    class ProtocolError<T extends Message<T>> extends Error {

        /**
         * Constructs a new protocol error.
         * @param message Error message
         * @param [properties] Additional properties
         */
        constructor(message: string, properties?: { [k: string]: any });

        /** So far decoded message instance. */
        public instance: Message<T>;
    }

    /**
     * Builds a getter for a oneof's present field name.
     * @param fieldNames Field names
     * @returns Unbound getter
     */
    function oneOfGetter(fieldNames: string[]): OneOfGetter;

    /**
     * Builds a setter for a oneof's present field name.
     * @param fieldNames Field names
     * @returns Unbound setter
     */
    function oneOfSetter(fieldNames: string[]): OneOfSetter;

    /**
     * Default conversion options used for {@link Message#toJSON} implementations.
     *
     * These options are close to proto3's JSON mapping with the exception that internal types like Any are handled just like messages. More precisely:
     *
     * - Longs become strings
     * - Enums become string keys
     * - Bytes become base64 encoded strings
     * - (Sub-)Messages become plain objects
     * - Maps become plain objects with all string keys
     * - Repeated fields become arrays
     * - NaN and Infinity for float and double fields become strings
     *
     * @see https://developers.google.com/protocol-buffers/docs/proto3?hl=en#json
     */
    let toJSONOptions: IConversionOptions;

    /** Node's fs module if available. */
    let fs: { [k: string]: any };

    /**
     * Converts an object's values to an array.
     * @param object Object to convert
     * @returns Converted array
     */
    function toArray(object: { [k: string]: any }): any[];

    /**
     * Converts an array of keys immediately followed by their respective value to an object, omitting undefined values.
     * @param array Array to convert
     * @returns Converted object
     */
    function toObject(array: any[]): { [k: string]: any };

    /**
     * Tests whether the specified name is a reserved word in JS.
     * @param name Name to test
     * @returns `true` if reserved, otherwise `false`
     */
    function isReserved(name: string): boolean;

    /**
     * Returns a safe property accessor for the specified property name.
     * @param prop Property name
     * @returns Safe accessor
     */
    function safeProp(prop: string): string;

    /**
     * Converts the first character of a string to upper case.
     * @param str String to convert
     * @returns Converted string
     */
    function ucFirst(str: string): string;

    /**
     * Converts a string to camel case.
     * @param str String to convert
     * @returns Converted string
     */
    function camelCase(str: string): string;

    /**
     * Compares reflected fields by id.
     * @param a First field
     * @param b Second field
     * @returns Comparison value
     */
    function compareFieldsById(a: Field, b: Field): number;

    /**
     * Decorator helper for types (TypeScript).
     * @param ctor Constructor function
     * @param [typeName] Type name, defaults to the constructor's name
     * @returns Reflected type
     */
    function decorateType<T extends Message<T>>(ctor: Constructor<T>, typeName?: string): Type;

    /**
     * Decorator helper for enums (TypeScript).
     * @param object Enum object
     * @returns Reflected enum
     */
    function decorateEnum(object: object): Enum;

    /**
     * Sets the value of a property by property path. If a value already exists, it is turned to an array
     * @param dst Destination object
     * @param path dot '.' delimited path of the property to set
     * @param value the value to set
     * @returns Destination object
     */
    function setProperty(dst: { [k: string]: any }, path: string, value: object): { [k: string]: any };

    /** Decorator root (TypeScript). */
    let decorateRoot: Root;

    /**
     * Returns a promise from a node-style callback function.
     * @param fn Function to call
     * @param ctx Function context
     * @param params Function arguments
     * @returns Promisified function
     */
    function asPromise(fn: asPromiseCallback, ctx: any, ...params: any[]): Promise<any>;

    /** A minimal base64 implementation for number arrays. */
    namespace base64 {

        /**
         * Calculates the byte length of a base64 encoded string.
         * @param string Base64 encoded string
         * @returns Byte length
         */
        function length(string: string): number;

        /**
         * Encodes a buffer to a base64 encoded string.
         * @param buffer Source buffer
         * @param start Source start
         * @param end Source end
         * @returns Base64 encoded string
         */
        function encode(buffer: Uint8Array, start: number, end: number): string;

        /**
         * Decodes a base64 encoded string to a buffer.
         * @param string Source string
         * @param buffer Destination buffer
         * @param offset Destination offset
         * @returns Number of bytes written
         * @throws {Error} If encoding is invalid
         */
        function decode(string: string, buffer: Uint8Array, offset: number): number;

        /**
         * Tests if the specified string appears to be base64 encoded.
         * @param string String to test
         * @returns `true` if probably base64 encoded, otherwise false
         */
        function test(string: string): boolean;
    }

    /**
     * Begins generating a function.
     * @param functionParams Function parameter names
     * @param [functionName] Function name if not anonymous
     * @returns Appender that appends code to the function's body
     */
    function codegen(functionParams: string[], functionName?: string): Codegen;

    namespace codegen {

        /** When set to `true`, codegen will log generated code to console. Useful for debugging. */
        let verbose: boolean;
    }

    /**
     * Begins generating a function.
     * @param [functionName] Function name if not anonymous
     * @returns Appender that appends code to the function's body
     */
    function codegen(functionName?: string): Codegen;

    /** A minimal event emitter. */
    class EventEmitter {

        /** Constructs a new event emitter instance. */
        constructor();

        /**
         * Registers an event listener.
         * @param evt Event name
         * @param fn Listener
         * @param [ctx] Listener context
         * @returns `this`
         */
        public on(evt: string, fn: EventEmitterListener, ctx?: any): this;

        /**
         * Removes an event listener or any matching listeners if arguments are omitted.
         * @param [evt] Event name. Removes all listeners if omitted.
         * @param [fn] Listener to remove. Removes all listeners of `evt` if omitted.
         * @returns `this`
         */
        public off(evt?: string, fn?: EventEmitterListener): this;

        /**
         * Emits an event by calling its listeners with the specified arguments.
         * @param evt Event name
         * @param args Arguments
         * @returns `this`
         */
        public emit(evt: string, ...args: any[]): this;
    }

    /** Reads / writes floats / doubles from / to buffers. */
    namespace float {

        /**
         * Writes a 32 bit float to a buffer using little endian byte order.
         * @param val Value to write
         * @param buf Target buffer
         * @param pos Target buffer offset
         */
        function writeFloatLE(val: number, buf: Uint8Array, pos: number): void;

        /**
         * Writes a 32 bit float to a buffer using big endian byte order.
         * @param val Value to write
         * @param buf Target buffer
         * @param pos Target buffer offset
         */
        function writeFloatBE(val: number, buf: Uint8Array, pos: number): void;

        /**
         * Reads a 32 bit float from a buffer using little endian byte order.
         * @param buf Source buffer
         * @param pos Source buffer offset
         * @returns Value read
         */
        function readFloatLE(buf: Uint8Array, pos: number): number;

        /**
         * Reads a 32 bit float from a buffer using big endian byte order.
         * @param buf Source buffer
         * @param pos Source buffer offset
         * @returns Value read
         */
        function readFloatBE(buf: Uint8Array, pos: number): number;

        /**
         * Writes a 64 bit double to a buffer using little endian byte order.
         * @param val Value to write
         * @param buf Target buffer
         * @param pos Target buffer offset
         */
        function writeDoubleLE(val: number, buf: Uint8Array, pos: number): void;

        /**
         * Writes a 64 bit double to a buffer using big endian byte order.
         * @param val Value to write
         * @param buf Target buffer
         * @param pos Target buffer offset
         */
        function writeDoubleBE(val: number, buf: Uint8Array, pos: number): void;

        /**
         * Reads a 64 bit double from a buffer using little endian byte order.
         * @param buf Source buffer
         * @param pos Source buffer offset
         * @returns Value read
         */
        function readDoubleLE(buf: Uint8Array, pos: number): number;

        /**
         * Reads a 64 bit double from a buffer using big endian byte order.
         * @param buf Source buffer
         * @param pos Source buffer offset
         * @returns Value read
         */
        function readDoubleBE(buf: Uint8Array, pos: number): number;
    }

    /**
     * Fetches the contents of a file.
     * @param filename File path or url
     * @param options Fetch options
     * @param callback Callback function
     */
    function fetch(filename: string, options: IFetchOptions, callback: FetchCallback): void;

    /**
     * Fetches the contents of a file.
     * @param path File path or url
     * @param callback Callback function
     */
    function fetch(path: string, callback: FetchCallback): void;

    /**
     * Fetches the contents of a file.
     * @param path File path or url
     * @param [options] Fetch options
     * @returns Promise
     */
    function fetch(path: string, options?: IFetchOptions): Promise<(string|Uint8Array)>;

    /**
     * Requires a module only if available.
     * @param moduleName Module to require
     * @returns Required module if available and not empty, otherwise `null`
     */
    function inquire(moduleName: string): object;

    /** A minimal path module to resolve Unix, Windows and URL paths alike. */
    namespace path {

        /**
         * Tests if the specified path is absolute.
         * @param path Path to test
         * @returns `true` if path is absolute
         */
        function isAbsolute(path: string): boolean;

        /**
         * Normalizes the specified path.
         * @param path Path to normalize
         * @returns Normalized path
         */
        function normalize(path: string): string;

        /**
         * Resolves the specified include path against the specified origin path.
         * @param originPath Path to the origin file
         * @param includePath Include path relative to origin path
         * @param [alreadyNormalized=false] `true` if both paths are already known to be normalized
         * @returns Path to the include file
         */
        function resolve(originPath: string, includePath: string, alreadyNormalized?: boolean): string;
    }

    /**
     * A general purpose buffer pool.
     * @param alloc Allocator
     * @param slice Slicer
     * @param [size=8192] Slab size
     * @returns Pooled allocator
     */
    function pool(alloc: PoolAllocator, slice: PoolSlicer, size?: number): PoolAllocator;

    /** A minimal UTF8 implementation for number arrays. */
    namespace utf8 {

        /**
         * Calculates the UTF8 byte length of a string.
         * @param string String
         * @returns Byte length
         */
        function length(string: string): number;

        /**
         * Reads UTF8 bytes as a string.
         * @param buffer Source buffer
         * @param start Source start
         * @param end Source end
         * @returns String read
         */
        function read(buffer: Uint8Array, start: number, end: number): string;

        /**
         * Writes a string as UTF8 bytes.
         * @param string Source string
         * @param buffer Destination buffer
         * @param offset Destination offset
         * @returns Bytes written
         */
        function write(string: string, buffer: Uint8Array, offset: number): number;
    }
}

/**
 * Generates a verifier specific to the specified message type.
 * @param mtype Message type
 * @returns Codegen instance
 */
export function verifier(mtype: Type): Codegen;

/** Wrappers for common types. */
export const wrappers: { [k: string]: IWrapper };

/**
 * From object converter part of an {@link IWrapper}.
 * @param object Plain object
 * @returns Message instance
 */
type WrapperFromObjectConverter = (this: Type, object: { [k: string]: any }) => Message<{}>;

/**
 * To object converter part of an {@link IWrapper}.
 * @param message Message instance
 * @param [options] Conversion options
 * @returns Plain object
 */
type WrapperToObjectConverter = (this: Type, message: Message<{}>, options?: IConversionOptions) => { [k: string]: any };

/** Common type wrapper part of {@link wrappers}. */
export interface IWrapper {

    /** From object converter */
    fromObject?: WrapperFromObjectConverter;

    /** To object converter */
    toObject?: WrapperToObjectConverter;
}

/** Wire format writer using `Uint8Array` if available, otherwise `Array`. */
export class Writer {

    /** Constructs a new writer instance. */
    constructor();

    /** Current length. */
    public len: number;

    /** Operations head. */
    public head: object;

    /** Operations tail */
    public tail: object;

    /** Linked forked states. */
    public states: (object|null);

    /**
     * Creates a new writer.
     * @returns A {@link BufferWriter} when Buffers are supported, otherwise a {@link Writer}
     */
    public static create(): (BufferWriter|Writer);

    /**
     * Allocates a buffer of the specified size.
     * @param size Buffer size
     * @returns Buffer
     */
    public static alloc(size: number): Uint8Array;

    /**
     * Writes an unsigned 32 bit value as a varint.
     * @param value Value to write
     * @returns `this`
     */
    public uint32(value: number): Writer;

    /**
     * Writes a signed 32 bit value as a varint.
     * @param value Value to write
     * @returns `this`
     */
    public int32(value: number): Writer;

    /**
     * Writes a 32 bit value as a varint, zig-zag encoded.
     * @param value Value to write
     * @returns `this`
     */
    public sint32(value: number): Writer;

    /**
     * Writes an unsigned 64 bit value as a varint.
     * @param value Value to write
     * @returns `this`
     * @throws {TypeError} If `value` is a string and no long library is present.
     */
    public uint64(value: (bigint|number|string)): Writer;

    /**
     * Writes a signed 64 bit value as a varint.
     * @param value Value to write
     * @returns `this`
     * @throws {TypeError} If `value` is a string and no long library is present.
     */
    public int64(value: (bigint|number|string)): Writer;

    /**
     * Writes a signed 64 bit value as a varint, zig-zag encoded.
     * @param value Value to write
     * @returns `this`
     * @throws {TypeError} If `value` is a string and no long library is present.
     */
    public sint64(value: (bigint|number|string)): Writer;

    /**
     * Writes a boolish value as a varint.
     * @param value Value to write
     * @returns `this`
     */
    public bool(value: boolean): Writer;

    /**
     * Writes an unsigned 32 bit value as fixed 32 bits.
     * @param value Value to write
     * @returns `this`
     */
    public fixed32(value: number): Writer;

    /**
     * Writes a signed 32 bit value as fixed 32 bits.
     * @param value Value to write
     * @returns `this`
     */
    public sfixed32(value: number): Writer;

    /**
     * Writes an unsigned 64 bit value as fixed 64 bits.
     * @param value Value to write
     * @returns `this`
     * @throws {TypeError} If `value` is a string and no long library is present.
     */
    public fixed64(value: (bigint|number|string)): Writer;

    /**
     * Writes a signed 64 bit value as fixed 64 bits.
     * @param value Value to write
     * @returns `this`
     * @throws {TypeError} If `value` is a string and no long library is present.
     */
    public sfixed64(value: (bigint|number|string)): Writer;

    /**
     * Writes a float (32 bit).
     * @param value Value to write
     * @returns `this`
     */
    public float(value: number): Writer;

    /**
     * Writes a double (64 bit float).
     * @param value Value to write
     * @returns `this`
     */
    public double(value: number): Writer;

    /**
     * Writes a sequence of bytes.
     * @param value Buffer or base64 encoded string to write
     * @returns `this`
     */
    public bytes(value: (Uint8Array|string)): Writer;

    /**
     * Writes a string.
     * @param value Value to write
     * @returns `this`
     */
    public string(value: string): Writer;

    /**
     * Forks this writer's state by pushing it to a stack.
     * Calling {@link Writer#reset|reset} or {@link Writer#ldelim|ldelim} resets the writer to the previous state.
     * @returns `this`
     */
    public fork(): Writer;

    /**
     * Resets this instance to the last state.
     * @returns `this`
     */
    public reset(): Writer;

    /**
     * Resets to the last state and appends the fork state's current write length as a varint followed by its operations.
     * @returns `this`
     */
    public ldelim(): Writer;

    /**
     * Finishes the write operation.
     * @returns Finished buffer
     */
    public finish(): Uint8Array;
}

/** Wire format writer using node buffers. */
export class BufferWriter extends Writer {

    /** Constructs a new buffer writer instance. */
    constructor();

    /**
     * Allocates a buffer of the specified size.
     * @param size Buffer size
     * @returns Buffer
     */
    public static alloc(size: number): Buffer;

    /**
     * Finishes the write operation.
     * @returns Finished buffer
     */
    public finish(): Buffer;
}

/**
 * Callback as used by {@link util.asPromise}.
 * @param error Error, if any
 * @param params Additional arguments
 */
type asPromiseCallback = (error: (Error|null), ...params: any[]) => void;

/**
 * Appends code to the function's body or finishes generation.
 * @param [formatStringOrScope] Format string or, to finish the function, an object of additional scope variables, if any
 * @param [formatParams] Format parameters
 * @returns Itself or the generated function if finished
 * @throws {Error} If format parameter counts do not match
 */
type Codegen = (formatStringOrScope?: (string|{ [k: string]: any }), ...formatParams: any[]) => (Codegen|Function);

/**
 * Event listener as used by {@link util.EventEmitter}.
 * @param args Arguments
 */
type EventEmitterListener = (...args: any[]) => void;

/**
 * Node-style callback as used by {@link util.fetch}.
 * @param error Error, if any, otherwise `null`
 * @param [contents] File contents, if there hasn't been an error
 */
type FetchCallback = (error: Error, contents?: string) => void;

/** Options as used by {@link util.fetch}. */
export interface IFetchOptions {

    /** Whether expecting a binary response */
    binary?: boolean;

    /** If `true`, forces the use of XMLHttpRequest */
    xhr?: boolean;
}

/**
 * An allocator as used by {@link util.pool}.
 * @param size Buffer size
 * @returns Buffer
 */
type PoolAllocator = (size: number) => Uint8Array;

/**
 * A slicer as used by {@link util.pool}.
 * @param start Start offset
 * @param end End offset
 * @returns Buffer slice
 */
type PoolSlicer = (this: Uint8Array, start: number, end: number) => Uint8Array;