@oniryk/xlsx/dist/shared-strings.js

A lightweight, efficient TypeScript library for generating single-sheet Excel XLSX files with support for large datasets

"use strict";
var __importDefault = (this && this.__importDefault) || function (mod) {
    return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
const crypto_1 = require("crypto");
const fs_1 = __importDefault(require("fs"));
const os_1 = __importDefault(require("os"));
const path_1 = __importDefault(require("path"));
const utils_1 = require("./utils");
/**
 * Manages shared strings in an Excel workbook
 * Handles deduplication and XML generation for the shared strings table
 * Used to optimize file size by storing repeated strings only once
 */
class SharedStrings {
    /**
     * Creates a new SharedStrings instance
     * Initializes a temporary file for XML generation
     */
    constructor() {
        /** Array of unique strings in the workbook */
        this.strings = [];
        /** Map of strings to their indices for quick lookup */
        this.stringIndexMap = new Map();
        this.file = path_1.default.join(os_1.default.tmpdir(), `xlsx-strings-${(0, crypto_1.randomUUID)()}.xml`);
    }
    /**
     * Adds a string to the shared strings table
     * If the string already exists, returns its index
     * If the string is new, adds it and returns the new index
     *
     * @param str - String to add to the shared strings table
     * @returns Index of the string in the shared strings table
     */
    add(str) {
        if (this.stringIndexMap.has(str)) {
            return this.stringIndexMap.get(str);
        }
        const index = this.strings.push(str) - 1;
        this.stringIndexMap.set(str, index);
        return index;
    }
    /**
     * Generates the shared strings XML file
     * Creates an XML file containing all unique strings in the workbook
     * Processes strings in chunks to manage memory usage
     *
     * @returns Promise that resolves to the path of the generated XML file
     */
    async generateSharedStringsXML() {
        const ws = fs_1.default.createWriteStream(this.file);
        const write = (0, utils_1.promiseWrite)(ws);
        await write(`<?xml version="1.0" encoding="UTF-8" standalone="yes"?>\n`, `<sst xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main"
            count="${this.strings.length}" uniqueCount="${this.strings.length}">`);
        const acc = [];
        for (const str of this.strings) {
            acc.push(`<si><t>${(0, utils_1.escapeXML)(str)}</t></si>`);
            if (acc.length % 5000 === 0) {
                await write(acc.join(''));
                acc.length = 0;
            }
        }
        await write(acc.join(''), '</sst>');
        await (0, utils_1.finishStream)(ws);
        return this.file;
    }
    /**
     * Gets the total number of unique strings in the table
     * @returns Number of unique strings
     */
    size() {
        return this.strings.length;
    }
    /**
     * Clears all strings and mappings from memory
     * Should be called when the shared strings table is no longer needed
     */
    destroy() {
        this.strings.length = 0;
        this.stringIndexMap.clear();
    }
}
exports.default = SharedStrings;