byte-rw/dist/dataview/writer.js

Byte reader/writer for buffers and streams in typescript/javascript

import { copy, textEncoder } from "../utils/index.js";
export class DataViewByteWriter {
    get _bytesRemaining() {
        return this._dataview.byteLength - this._byteOffset;
    }
    get dataview() {
        return this._dataview;
    }
    set dataview(dataview) {
        this._dataview = dataview;
    }
    isComplete() {
        return this._isComplete || (this._isComplete = this.updateIsComplete());
    }
    constructor(dataview, littleEndian = true) {
        this.littleEndian = littleEndian;
        this._isComplete = false;
        this._byteOffset = 0;
        this._dataview = dataview;
    }
    updateIsComplete() {
        return this.tryEnsureAvailable(1) > 0;
    }
    complete() {
        this._isComplete = true;
    }
    /**
     * Attempts to ensure that a specified number of bytes are available in the
     * current dataview.
     *
     * @param bytes the number of bytes to request available in the current
     * dataview
     * @returns the number of bytes at least made available in the current
     * dataview, up to the requested number of bytes
     */
    tryEnsureAvailable(bytes) {
        if (this._isComplete)
            return 0;
        if (this._bytesRemaining < bytes)
            return this._bytesRemaining;
        else
            return bytes;
    }
    ensureAvailable(bytes) {
        const available = this.tryEnsureAvailable(bytes);
        if (available !== bytes)
            throw new Error(`Not all bytes could be available (${bytes} bytes requested, ${available} bytes available)`);
    }
    writeFloat32(value) {
        const bytes = 4;
        this.ensureAvailable(bytes);
        this._dataview.setFloat32(this._byteOffset, value, this.littleEndian);
        this._byteOffset += bytes;
    }
    writeFloat64(value) {
        const bytes = 8;
        this.ensureAvailable(bytes);
        this._dataview.setFloat64(this._byteOffset, value, this.littleEndian);
        this._byteOffset += bytes;
    }
    writeInt8(value) {
        const bytes = 1;
        this.ensureAvailable(bytes);
        this._dataview.setInt8(this._byteOffset, value);
        this._byteOffset += bytes;
    }
    writeInt16(value) {
        const bytes = 2;
        this.ensureAvailable(bytes);
        this._dataview.setInt16(this._byteOffset, value, this.littleEndian);
        this._byteOffset += bytes;
    }
    writeInt32(value) {
        const bytes = 4;
        this.ensureAvailable(bytes);
        this._dataview.setInt32(this._byteOffset, value, this.littleEndian);
        this._byteOffset += bytes;
    }
    writeUint8(value) {
        const bytes = 1;
        this.ensureAvailable(bytes);
        this._dataview.setUint8(this._byteOffset, value);
        this._byteOffset += bytes;
    }
    writeUint16(value) {
        const bytes = 2;
        this.ensureAvailable(bytes);
        this._dataview.setUint16(this._byteOffset, value, this.littleEndian);
        this._byteOffset += bytes;
    }
    writeUint32(value) {
        const bytes = 4;
        this.ensureAvailable(bytes);
        this._dataview.setUint32(this._byteOffset, value, this.littleEndian);
        this._byteOffset += bytes;
    }
    tryWriteBytes(view) {
        const bytes = view.byteLength;
        const write = this.tryEnsureAvailable(bytes);
        const dst = this._dataview.buffer;
        const src = view.buffer;
        const dstOffset = this._dataview.byteOffset + this._byteOffset;
        const srcOffset = view.byteOffset;
        copy({
            buffer: src,
            byteOffset: srcOffset,
            byteLength: write,
        }, {
            buffer: dst,
            byteOffset: dstOffset,
            byteLength: write,
        });
        this._byteOffset += write;
        return write;
    }
    writeBytes(view) {
        const written = this.tryWriteBytes(view);
        if (written !== view.byteLength)
            throw new Error(`Not all bytes could be written (${view.byteLength} bytes requested, ${written} bytes written)`);
    }
    writeString(value) {
        const encoded = textEncoder.encode(value);
        this.writeUint32(encoded.byteLength);
        this.writeBytes(encoded);
    }
}