byte-rw/dist/dataview/reader.js

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

import { copy, textDecoder } from "../utils/index.js";
export class DataViewByteReader {
    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;
    }
    /**
     * 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._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)`);
    }
    /**
     * Gets the next Float32 value
     */
    readFloat32() {
        const bytes = 4;
        this.ensureAvailable(bytes);
        const value = this._dataview.getFloat32(this._byteOffset, this.littleEndian);
        this._byteOffset += bytes;
        return value;
    }
    /**
     * Gets the next Float64 value
     */
    readFloat64() {
        const bytes = 8;
        this.ensureAvailable(bytes);
        const value = this._dataview.getFloat64(this._byteOffset, this.littleEndian);
        this._byteOffset += bytes;
        return value;
    }
    /**
     * Gets the next Int8 value
     */
    readInt8() {
        const bytes = 1;
        this.ensureAvailable(bytes);
        const value = this._dataview.getInt8(this._byteOffset);
        this._byteOffset += bytes;
        return value;
    }
    /**
     * Gets the next Int16 value
     */
    readInt16() {
        const bytes = 2;
        this.ensureAvailable(bytes);
        const value = this._dataview.getInt16(this._byteOffset, this.littleEndian);
        this._byteOffset += bytes;
        return value;
    }
    /**
     * Gets the next Int32 value
     */
    readInt32() {
        const bytes = 4;
        this.ensureAvailable(bytes);
        const value = this._dataview.getInt32(this._byteOffset, this.littleEndian);
        this._byteOffset += bytes;
        return value;
    }
    /**
     * Gets the next Uint8 value
     */
    readUint8() {
        const bytes = 1;
        this.ensureAvailable(bytes);
        const value = this._dataview.getUint8(this._byteOffset);
        this._byteOffset += bytes;
        return value;
    }
    /**
     * Gets the next Uint16 value
     */
    readUint16() {
        const bytes = 2;
        this.ensureAvailable(bytes);
        const value = this._dataview.getUint16(this._byteOffset, this.littleEndian);
        this._byteOffset += bytes;
        return value;
    }
    /**
     * Gets the next Uint32 value
     */
    readUint32() {
        const bytes = 4;
        this.ensureAvailable(bytes);
        const value = this._dataview.getUint32(this._byteOffset, this.littleEndian);
        this._byteOffset += bytes;
        return value;
    }
    tryReadBytes(view) {
        const bytes = view.byteLength;
        const read = this.tryEnsureAvailable(bytes);
        const dst = view.buffer;
        const src = this._dataview.buffer;
        const dstOffset = view.byteOffset;
        const srcOffset = this._dataview.byteOffset + this._byteOffset;
        copy({
            buffer: src,
            byteOffset: srcOffset,
            byteLength: read,
        }, {
            buffer: dst,
            byteOffset: dstOffset,
            byteLength: read,
        });
        this._byteOffset += read;
        return read;
    }
    readBytes(view) {
        const read = this.tryReadBytes(view);
        if (read !== view.byteLength)
            throw new Error(`Not all bytes could be read (${view.byteLength} bytes request, ${read} bytes read)`);
    }
    readString() {
        const length = this.readUint32();
        this.ensureAvailable(length);
        const available = this._dataview.byteLength - this._byteOffset;
        console.assert(available >= length);
        const view = new DataView(this._dataview.buffer, this._dataview.byteOffset + this._byteOffset, length);
        this._byteOffset += length;
        return textDecoder.decode(view);
    }
}