@dobesv/parquets/lib/concatValueArrays.js

TypeScript implementation of the Parquet file format, based on parquet.js

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
/**
 * Merge the given arrays into one.  The resulting array will have the
 * same type as the first one.
 *
 * If only the first array is non-empty (or there is just one array)
 * it will be returned unmodified.
 *
 * @param arrays Arrays to merge
 */
function concatValueArrays(arrays) {
    if (arrays.length === 0) {
        return [];
    }
    const head = arrays[0];
    if (arrays.length === 1) {
        return head;
    }
    // If we're dealing with normal arrays, just use Array.prototype.concat
    if (Array.isArray(head)) {
        return Array.prototype.concat(...arrays);
    }
    // Now we must be dealing with primitive arrays
    // Calculate the total size of all the arrays combined
    const totalSize = arrays.reduce((a, b) => a + b.length, 0);
    // Are all the arrays after the first actually empty?  If so just return the first one
    if (totalSize === head.length) {
        return head;
    }
    const arrayType = head.constructor;
    const result = new arrayType(totalSize);
    let offset = 0;
    for (const array of arrays) {
        if (array.length) {
            result.set(array, offset);
            offset += array.length;
        }
    }
    return result;
}
exports.default = concatValueArrays;
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