Buffer

Example: Usage

import { Buffer } from "@ende/io/buffer";
import { assertEquals } from "@ende/assert/equals";

const buf = new Buffer();
await buf.write(new TextEncoder().encode("Hello, "));
await buf.write(new TextEncoder().encode("world!"));

const data = new Uint8Array(13);
await buf.read(data);

assertEquals(new TextDecoder().decode(data), "Hello, world!");

constructor

new Buffer(ab?: ArrayBufferLike | ArrayLike<number>)

Constructs a new instance with the specified ArrayBuffer as its initial contents.

ab?: ArrayBufferLike | ArrayLike<number>

The ArrayBuffer to use as the initial contents of the buffer.

bytes

bytes(options: { copy: boolean } = [UNSUPPORTED]): Uint8Array

Returns a slice holding the unread portion of the buffer.

The slice is valid for use only until the next buffer modification (that is, only until the next call to a method like read(), write(), reset(), or truncate()). If options.copy is false the slice aliases the buffer content at least until the next buffer modification, so immediate changes to the slice will affect the result of future reads.

options: { copy: boolean } = [UNSUPPORTED]

The options for the slice.

Returns

A slice holding the unread portion of the buffer.

import { Buffer } from "@ende/io/buffer";
import { assertEquals } from "@ende/assert/equals";

const buf = new Buffer();
await buf.write(new TextEncoder().encode("Hello, world!"));

const slice = buf.bytes();
assertEquals(new TextDecoder().decode(slice), "Hello, world!");

empty

empty(): boolean

Returns whether the unread portion of the buffer is empty.

Returns

true if the unread portion of the buffer is empty, false otherwise.

import { Buffer } from "@ende/io/buffer";
import { assertEquals } from "@ende/assert/equals";

const buf = new Buffer();
assertEquals(buf.empty(), true);
await buf.write(new TextEncoder().encode("Hello, world!"));
assertEquals(buf.empty(), false);

length

get length(): number

A read only number of bytes of the unread portion of the buffer.

Returns

The number of bytes of the unread portion of the buffer.

import { Buffer } from "@ende/io/buffer";
import { assertEquals } from "@ende/assert/equals";

const buf = new Buffer();
await buf.write(new TextEncoder().encode("Hello, world!"));

assertEquals(buf.length, 13);

capacity

get capacity(): number

The read only capacity of the buffer's underlying byte slice, that is, the total space allocated for the buffer's data.

Returns

The capacity of the buffer.

import { Buffer } from "@ende/io/buffer";
import { assertEquals } from "@ende/assert/equals";

const buf = new Buffer();
assertEquals(buf.capacity, 0);
await buf.write(new TextEncoder().encode("Hello, world!"));
assertEquals(buf.capacity, 13);

truncate

truncate(n: number): void

Discards all but the first n unread bytes from the buffer but continues to use the same allocated storage. It throws if n is negative or greater than the length of the buffer.

n: number

The number of bytes to keep.

import { Buffer } from "@ende/io/buffer";
import { assertEquals } from "@ende/assert/equals";

const buf = new Buffer();
await buf.write(new TextEncoder().encode("Hello, world!"));
buf.truncate(6);
assertEquals(buf.length, 6);

reset

reset(): void

Resets the contents

import { Buffer } from "@ende/io/buffer";
import { assertEquals } from "@ende/assert/equals";

const buf = new Buffer();
await buf.write(new TextEncoder().encode("Hello, world!"));
buf.reset();
assertEquals(buf.length, 0);

readSync

readSync(p: Uint8Array): number | null

Reads the next p.length bytes from the buffer or until the buffer is drained. Returns the number of bytes read. If the buffer has no data to return, the return is EOF (null).

p: Uint8Array

The buffer to read data into.

Returns

The number of bytes read.

import { Buffer } from "@ende/io/buffer";
import { assertEquals } from "@ende/assert/equals";

const buf = new Buffer();
await buf.write(new TextEncoder().encode("Hello, world!"));

const data = new Uint8Array(5);
const res = await buf.read(data);

assertEquals(res, 5);
assertEquals(new TextDecoder().decode(data), "Hello");

read

read(p: Uint8Array): Promise<number | null>

Reads the next p.length bytes from the buffer or until the buffer is drained. Resolves to the number of bytes read. If the buffer has no data to return, resolves to EOF (null).

NOTE: This methods reads bytes synchronously; it's provided for compatibility with Reader interfaces.

p: Uint8Array

The buffer to read data into.

Returns

The number of bytes read.

import { Buffer } from "@ende/io/buffer";
import { assertEquals } from "@ende/assert/equals";

const buf = new Buffer();
await buf.write(new TextEncoder().encode("Hello, world!"));

const data = new Uint8Array(5);
const res = await buf.read(data);

assertEquals(res, 5);
assertEquals(new TextDecoder().decode(data), "Hello");

writeSync

writeSync(p: Uint8Array): number

Writes the given data to the buffer.

p: Uint8Array

The data to write to the buffer.

Returns

The number of bytes written.

import { Buffer } from "@ende/io/buffer";
import { assertEquals } from "@ende/assert/equals";

const buf = new Buffer();
const data = new TextEncoder().encode("Hello, world!");
buf.writeSync(data);

const slice = buf.bytes();
assertEquals(new TextDecoder().decode(slice), "Hello, world!");

write

write(p: Uint8Array): Promise<number>

Writes the given data to the buffer. Resolves to the number of bytes written.

p: Uint8Array

The data to write to the buffer.

Returns

The number of bytes written.

import { Buffer } from "@ende/io/buffer";
import { assertEquals } from "@ende/assert/equals";

const buf = new Buffer();
const data = new TextEncoder().encode("Hello, world!");
await buf.write(data);

const slice = buf.bytes();
assertEquals(new TextDecoder().decode(slice), "Hello, world!");

grow

grow(n: number): void

Grows the buffer's capacity, if necessary, to guarantee space for another n bytes. After .grow(n), at least n bytes can be written to the buffer without another allocation. If n is negative, .grow() will throw. If the buffer can't grow it will throw an error.

Based on Go Lang's Buffer.Grow.

n: number

The number of bytes to grow the buffer by.

import { Buffer } from "@ende/io/buffer";
import { assertEquals } from "@ende/assert/equals";

const buf = new Buffer();
buf.grow(10);
assertEquals(buf.capacity, 10);

readFrom

readFrom(r: Reader): Promise<number>

Reads data from r until EOF (null) and appends it to the buffer, growing the buffer as needed. It resolves to the number of bytes read. If the buffer becomes too large, .readFrom() will reject with an error.

Based on Go Lang's Buffer.ReadFrom.

r: Reader

The reader to read from.

Returns

The number of bytes read.

import { Buffer } from "@ende/io/buffer";
import { assertEquals } from "@ende/assert/equals";

const buf = new Buffer();
const r = new Buffer(new TextEncoder().encode("Hello, world!"));
const n = await buf.readFrom(r);

assertEquals(n, 13);

readFromSync

readFromSync(r: ReaderSync): number

Reads data from r until EOF (null) and appends it to the buffer, growing the buffer as needed. It returns the number of bytes read. If the buffer becomes too large, .readFromSync() will throw an error.

Based on Go Lang's Buffer.ReadFrom.

r: ReaderSync

The reader to read from.

Returns

The number of bytes read.

import { Buffer } from "@ende/io/buffer";
import { assertEquals } from "@ende/assert/equals";

const buf = new Buffer();
const r = new Buffer(new TextEncoder().encode("Hello, world!"));
const n = buf.readFromSync(r);

assertEquals(n, 13);