univ-conv/lib/converters/HexConverter.js

The universal binary and text converter

import { AbstractConverter, _ } from "./AbstractConverter";
import { deleteStartLength, getStartEnd, hasNoStartLength, } from "./core";
import { newBuffer } from "./Environment";
import { getTextHelper } from "./StringUtil";
const BYTE_TO_HEX = [];
for (let n = 0; n <= 0xff; ++n) {
    const hexOctet = n.toString(16).padStart(2, "0");
    BYTE_TO_HEX.push(hexOctet);
}
const HEX_STRINGS = "0123456789abcdef";
const MAP_HEX = {
    0: 0,
    1: 1,
    2: 2,
    3: 3,
    4: 4,
    5: 5,
    6: 6,
    7: 7,
    8: 8,
    9: 9,
    a: 10,
    A: 10,
    b: 11,
    B: 11,
    c: 12,
    C: 12,
    d: 13,
    D: 13,
    e: 14,
    E: 14,
    f: 15,
    F: 15,
};
export class HexConverter extends AbstractConverter {
    constructor() {
        super(...arguments);
        this.type = "hex";
    }
    empty() {
        return "";
    }
    is(input, options) {
        return typeof input === "string" && options.inputStringType === "hex";
    }
    async _from(input, options) {
        if (typeof input === "string" && options.inputStringType === "hex") {
            if (hasNoStartLength(options)) {
                return input;
            }
            const { start, end } = await this._getStartEnd(input, options);
            return input.slice(start * 2, end ? end * 2 : undefined);
        }
        const u8 = await _().convert("uint8array", input, options);
        return (Array.from(u8)
            .map((b) => HEX_STRINGS[b >> 4] + HEX_STRINGS[b & 15])
            .join(""));
    }
    _getStartEnd(input, options) {
        return Promise.resolve(getStartEnd(options, input.length / 2));
    }
    _isEmpty(input) {
        return !input;
    }
    async _merge(chunks) {
        return Promise.resolve(chunks.join(""));
    }
    _size(input) {
        return Promise.resolve(input.length / 2);
    }
    async _toArrayBuffer(input, options) {
        const u8 = await this._toUint8Array(input, options);
        return u8.buffer.slice(u8.byteOffset, u8.byteOffset + u8.byteLength);
    }
    async _toBase64(input, options) {
        const u8 = await this._toUint8Array(input, options);
        return await _().convert("base64", u8, deleteStartLength(options));
    }
    async _toText(input, options) {
        const u8 = await this._toUint8Array(input, options);
        const textHelper = await getTextHelper();
        return await textHelper.bufferToText(u8, options);
    }
    async _toUint8Array(input, options) {
        const startEnd = await this._getStartEnd(input, options);
        let start = startEnd.start;
        const end = startEnd.end;
        const size = end - start;
        const u8 = newBuffer(size);
        for (; start < end; start++) {
            const ai = input[start * 2];
            const a = MAP_HEX[ai];
            const bi = input[start * 2 + 1];
            const b = MAP_HEX[bi];
            if (a == null || b == null) {
                break;
            }
            u8[start] = (a << 4) | b;
        }
        return u8;
    }
}
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