@openxmldev/linq-to-xml/src/transformations/descendants.js

LINQ to XML for TypeScript

/**
 * @author Thomas Barnekow
 * @license MIT
 */
import { XElement, XNode } from '../internal.js';
/**
 * Returns a function that, for the elements of the source sequence passed to
 * that function, returns the concatenated sequences of descendants of such
 * elements in document order.
 *
 * If a name is provided, the resulting sequence contains only those ancestors
 * having a matching name.
 *
 * @typeParam T The type of the elements contained in the source sequence.
 * @param name The optional name used to filter the sequence of descendants.
 * @returns A function that will return a flat sequence of descendants in
 * document order.
 */
export function descendants(name) {
    return function (source) {
        return name !== null
            ? getManyDescendants(source, name !== null && name !== void 0 ? name : null, false)
            : XElement.emptySequence;
    };
}
/**
 * Returns a function that, for the elements of the source sequence passed to
 * that function, returns the concatenated sequences of descendants of such
 * elements, including the elements themselves, in document order.
 *
 * If a name is provided, the resulting sequence contains only those elements
 * and descendants having a matching name.
 *
 * @param name The optional name used to filter the sequence of descendants
 * and elements.
 * @returns A function that will return a flat sequence of ancestors, including
 * the elements, in document order.
 */
export function descendantsAndSelf(name) {
    return function (source) {
        return name !== null
            ? getManyDescendants(source, name !== null && name !== void 0 ? name : null, true)
            : XElement.emptySequence;
    };
}
function* getManyDescendants(source, name, self) {
    for (const root of source) {
        if (root) {
            if (self && root instanceof XElement) {
                if (name === null || root.name === name)
                    yield root;
            }
            let n = root;
            let c = root;
            // eslint-disable-next-line no-constant-condition
            while (true) {
                if (c !== null && c._content instanceof XNode) {
                    n = c._content._next;
                }
                else {
                    while (n !== null && n !== root && n === n._parent._content) {
                        n = n._parent;
                    }
                    if (n === null || n === root)
                        break;
                    n = n._next;
                }
                const e = n instanceof XElement ? n : null;
                if (e !== null && (name === null || e._name === name)) {
                    yield e;
                }
                c = e;
            }
        }
    }
}
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