frostice482/node-buffer-interface

A NodeJS library to deal with binary data, serialize from / deserialize to JS values, e.g. String, Number, BigInt, Boolean, Object, Array, etc.

Usage

// ESM
import BufInt from "node-buffer-interface";

// CJS
const BufInt = require("node-buffer-interface");

Methods

BufInt.serialize(value: unknown)

Serializes value into iterable chunks of Buffer

BufInt.serializeSync(value: unknown)

Serializes value into array of chunks of Buffer

BufInt.deserialize(buffer: Buffer | Uint8Array, offset: number)

Deserializes Buffer to value, returns deserialized value and new offset

Types

Some built-in types for BufInt are specified below.

Const

BufInt.Const(value: any)

Just a placeholder.

String

BufInt.String(sizeType: UINT, encoding: STRING)

Used to handle string interface. Adds extra few bytes at the beginning to store string length info.

Some known encodings can be used directly, e.g. BufInt.String.utf8_32be for UTF-8 encoding with uint32 size.

Buffer

BufInt.Buffer(sizeType: UINT)

Used to handle buffer interface. Adds extra few bytes at the beginning to store buffer length info.

Buffer with common sizes can be used directly, e.g. BufInt.Buffer.uint8 for buffer with uint8 size.

Number

BufInt.Number[NUMTYPE]

BigInt

BufInt.BigInt[TYPE]

Array

BufInt.Array(bufint: BufInt, sizeType: UINT)

Used to create array interface. Calls bufint method for every element in the array during serialize / deserialize. Adds extra few bytes at the beginning to store array length info.

Object

BufInt.Object(object: Record<string, BufInt>)

Used to create object interface. Objects should be ordered. Calls bufint method for every property during serialize / deserialize.

Enum

BufInt.Enum(values: Iterable<{ value: unknown, enumValue?: number }>, valueType: NUMTYPE)

Used to create enum interface. Auto-converts enumerables, like {ONE, TWO, THREE} to numbers {0, 1, 2}.

enumValue specifies number values to use in the buffer to the value. Defaults increments from minimum value. valueType specifies the number type to use in the buffer.

BufInt.Enum.fromArray can be used to use arrays as values instead, and the enumValue will be incremented from minimum.

Optional

BufInt.Optional(bufint: BufInt)

Used to create optional interface. Adds one extra byte to store value existence. 0 if undefined, 1 if exists.

BufInt.Optional.Nullable can be used to adds support for null values. Its value as number is 2.

BitFlags

BufInt.BitFlags(flags: ArrayLike<string | false>)

Used to create interface of an object of booleans. Uses one bit to store a boolean rather than a byte. A flag with false skips one bit. Can use up to 32 flags simultaneously.

For example, BitFlags(['a', 'b', false, 'c']) will get property a, b, and c from an object when serialize and uses 1 byte (3 bits) only rather than 3. If an object is {a: false, b: true, c: true}, then the byte will be 0b010100000.

BitField

BufInt.BitField(
    fields: ArrayLike<{
        key: string | false,
        bits: number
    }>, 
    bytes?: number
)

Used to create interface of an object of numbers. Each field / key can specify number of bits to use. Can use up to 32 bits simultaneously.

Consider following example:

BitField([
    { key: 'a', bits: 2 },
    { key: 'b', bits: 4 },
    { key: 'c', bits: 3 },
    { key: 'd', bits: 1 },
])

The byte representation will be AABBBBCC CD------

This interface will take property a, b, c, and d from an object when serialize and uses 2 bytes (10 bits) only rather than 4. If an object is {a: 2, b: 11, c: 5, d: 1}, then the byte will be 10101110 11000000.

Switch

BufInt.Switch(
    switchExpr: (value: unknown) => Cases
    cases: Iterable<{
        case: unknown;
        bufint: BufInt;
        enumValue?: number;
    }>,
    defaultCase: {
        bufint: BufInt;
        enumValue?: number;
    } | null | undefined,
    enumType: NUMTYPE
)

Used to create interface of switch case. Adds first few bytes to determine which case to use.

This allows multiple type of values to be used in a single bufint. The "switch" function expression determines which bufint to use depending on the case.

If any other value type is passed, it will check for default bufint provided. If the default bufint is not provided (null or undefined), it throws an error.

Same as enum, enumValue specifies number values to use in the buffer to the value. Defaults increments from minimum value. enumType specifies the number type to use in the buffer.