Class PbfReader

Protobuffer Reader

Description

Create a new PBF instance read to it. Follows the early Protobuf spec supporting various types of encoding including messages (which are usually representative of class objects).

Usage

Reading:

const data = fs.readFileSync(path);
const pbf = new Pbf(data);
// start reading here

Hierarchy (View Summary)

Constructors

constructor

Methods

destroy readBoolean readBytes readDouble readFields readFixed32 readFixed64 readFloat readMessage readPackedBoolean readPackedDouble readPackedFixed32 readPackedFixed64 readPackedFloat readPackedSFixed32 readPackedSFixed64 readPackedSVarint readPackedVarint readSFixed32 readSFixed64 readString readSVarint readTag readVarint readVarint64 skip

Constructors

constructor

  • new PbfReader(buf?: ArrayBuffer | Uint8Array): PbfReader

  • Parameters

    • buf: ArrayBuffer | Uint8Array = ...

      an optional Uint8Array to use for reading. otherwise defaults to an empty Uint8Array for writing

    Returns PbfReader

Methods

destroy

  • destroy(): void

  • Destroys the PBF instance. You can still use the Pbf instance after calling this method. However, the buffer will be emptied.

    Returns void

readBoolean

  • readBoolean(): boolean

  • Returns boolean

    • parses the varint byte as a boolean expression

readBytes

  • readBytes(): Uint8Array

  • NOTE: bytes is preceeded by a varint dscribing the length of the bytes. The bytes themselves are presumed to be u8s and therefore don't need to be decoded

    Returns Uint8Array

    • the decoded byte array

readDouble

  • readDouble(): number

  • Read in a 64-bit float from the buffer. There are no compression advantages with this type of encoding.

    Returns number

    • 64-bit float

readFields

  • readFields<U>(readField: ReadFieldFunction<U>, input: U, end: number): U

  • If you know you are reading a message, but have already read the length of the message OR you're reading fields of the top level data, then this method is the alternative. It's often used by sub-classes So that it can be instationated prior to reading the message.

    Type Parameters

    • U

    Parameters

    • readField: ReadFieldFunction<U>

      user defined input function to parse the message fields

    • input: U

      The class to mutate given field data

    • end: number

      the end position of the message in the buffer

    Returns U

    • The class we mutated will be returned

    See

    readMessage.

    Ex.

    export class MapboxVectorLayer {
      constructor(pbf: Protobuf, end: number) {
        this.#pbf = pbf;
        pbf.readFields(this.#readLayer, this, end);
      }

      #readLayer(tag: number, layer: MapboxVectorLayer, pbf: Protobuf): void {
        if (tag === 15) layer.version = pbf.readVarint();
        else if (tag === 1) layer.name = pbf.readString();
        // ...
      }
    }

readFixed32

  • readFixed32(): number

  • Read in a 32-bit unsigned integer from the buffer. There are no compression advantages with this type of encoding.

    Returns number

    • 32-bit unsigned integer

readFixed64

  • readFixed64(): number

  • Read in a 64-bit unsigned integer from the buffer. There are no compression advantages with this type of encoding.

    Returns number

    • 64-bit unsigned integer

readFloat

  • readFloat(): number

  • Read in a 32-bit float from the buffer. There are no compression advantages with this type of encoding.

    Returns number

    • 32-bit float

readMessage

  • readMessage<U>(readField: ReadFieldFunction<U>, input: U): U

  • Reads a message from the buffer. Sometimes it's easier to manage sub structures so that the current method can build multiples of an entire structure/class. If you you are at the top level, or parsing the message inside a class, then

    Type Parameters

    • U

    Parameters

    • readField: ReadFieldFunction<U>

      user defined input function

    • input: U

      an instance of the class you are reading into

    Returns U

    • The class itself will be returned

    See

    readFields.

    Ex.

    class Test {
      a: number = 0;

      static read(tag: number, test: Test, pbf: Protobuf): void {
        if (tag === 1) test.a = pbf.readVarint();
        // ...
      }
    }

    const pbf = new Pbf(data);
    const t = new Test();
    pbf3.readTag();
    pbf3.readMessage(Test.read, t);

readPackedBoolean

  • readPackedBoolean(arr?: boolean[]): boolean[]

  • Parameters

    • arr: boolean[] = []

      the array to write to

    Returns boolean[]

    • the arr input with the decoded boolean values is also returned

readPackedDouble

  • readPackedDouble(arr?: number[]): number[]

  • Parameters

    • arr: number[] = []

      the array to write to

    Returns number[]

    • the arr input with the decoded doubles is also returned

readPackedFixed32

  • readPackedFixed32(arr?: number[]): number[]

  • Parameters

    • arr: number[] = []

      the array to write to

    Returns number[]

    • the arr input with the decoded unsigned integers is also returned

readPackedFixed64

  • readPackedFixed64(arr?: number[]): number[]

  • Parameters

    • arr: number[] = []

      the array to write to

    Returns number[]

    • the arr input with the decoded unsigned 64-bit integers is also returned

readPackedFloat

  • readPackedFloat(arr?: number[]): number[]

  • Parameters

    • arr: number[] = []

      the array to write to

    Returns number[]

    • the arr input with the decoded floats is also returned

readPackedSFixed32

  • readPackedSFixed32(arr?: number[]): number[]

  • Parameters

    • arr: number[] = []

      the array to write to

    Returns number[]

    • the arr input with the decoded signed integers is also returned

readPackedSFixed64

  • readPackedSFixed64(arr?: number[]): number[]

  • Parameters

    • arr: number[] = []

      the array to write to

    Returns number[]

    • the arr input with the decoded signed 64-bit integers is also returned

readPackedSVarint

  • readPackedSVarint(arr?: number[]): number[]

  • Parameters

    • arr: number[] = []

      the array to write to

    Returns number[]

    • the arr input with the decoded numbers is also returned

readPackedVarint

  • readPackedVarint(arr?: number[], isSigned?: boolean): number[]

  • Parameters

    • arr: number[] = []

      the array to write to

    • isSigned: boolean = false

      true if the numbers are signed

    Returns number[]

    • the arr input with the decoded numbers is also returned

readSFixed32

  • readSFixed32(): number

  • Read in a 32-bit signed integer from the buffer. There are no compression advantages with this type of encoding.

    Returns number

    • 32-bit signed integer

readSFixed64

  • readSFixed64(): number

  • Read in a 64-bit signed integer from the buffer. There are no compression advantages with this type of encoding.

    Returns number

    • 64-bit signed integer

readString

  • readString(): string

  • Returns string

    • the decoded string

readSVarint

  • readSVarint(): number

  • Returns number

    • the decoded number as a signed number

readTag

  • readTag(): Tag

  • Reads a tag from the buffer, pulls out the tag and type and returns it.

    Returns Tag

    • {tag: number, type: number}

readVarint

  • readVarint(isSigned?: boolean): number

  • Parameters

    • isSigned: boolean = false

      true if the number is signed

    Returns number

    • the decoded number

readVarint64

  • readVarint64(): number

  • Returns number

    • the decoded number

    See

    readVarint for better performance

skip

  • skip(val: number): void

  • Skip a value we are not interested in parsing

    Parameters

    • val: number

      the type to skip

    Returns void

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Protobuffer Reader
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