Function computePaths

dash/dash-renderer/src/actions/paths.js:25–68

(subTree, startingPath, oldPaths, events)

 */

export function computePaths(subTree, startingPath, oldPaths, events) {
    const {strs: oldStrs, objs: oldObjs} = oldPaths || {strs: {}, objs: {}};

    const diffHead = path => startingPath.some((v, i) => path[i] !== v);

    const spLen = startingPath.length;
    // if we're updating a subtree, clear out all of the existing items
    const strs = spLen ? filter(diffHead, oldStrs) : {};
    const objs = {};
    if (spLen) {
        forEachObjIndexed((oldValPaths, oldKeys) => {
            const newVals = filter(({path}) => diffHead(path), oldValPaths);
            if (newVals.length) {
                objs[oldKeys] = newVals;
            }
        }, oldObjs);
    }

    crawlLayout(subTree, (child, itempath) => {
        const id = path(['props', 'id'], child);
        if (id) {
            if (typeof id === 'object') {
                const keys = Object.keys(id).sort();
                const values = props(keys, id);
                const keyStr = keys.join(',');
                const paths = (objs[keyStr] = objs[keyStr] || []);
                const oldie = oldObjs[keyStr] || [];
                const item = {values, path: concat(startingPath, itempath)};
                const index = indexOf(item, oldie);
                if (index === -1) {
                    paths.push(item);
                } else {
                    objs[keyStr] = insert(index, item, paths);
                }
            } else {
                strs[id] = concat(startingPath, itempath);
            }
        }
    });

    // We include an event emitter here because it will be used along with
    // paths to determine when the app is ready for callbacks.
    return {strs, objs, events: events || oldPaths.events};
}

export function getPath(paths, id) {
    if (typeof id === 'object') {