@adguard/agtree/dist/deserializer/filterlist-deserializer.js

Tool set for working with adblock filter lists

/*
 * AGTree v3.4.3 (build date: Thu, 11 Dec 2025 13:43:19 GMT)
 * (c) 2025 Adguard Software Ltd.
 * Released under the MIT license
 * https://github.com/AdguardTeam/tsurlfilter/tree/master/packages/agtree#readme
 */
import { NULL } from '../utils/constants.js';
import { BaseDeserializer } from './base-deserializer.js';
import { RuleDeserializer } from './rule-deserializer.js';
import { FilterListNodeMarshallingMap } from '../marshalling-utils/filter-list-common.js';
import { BinaryTypeMarshallingMap } from '../marshalling-utils/misc/binary-type-common.js';

/**
 * Deserializer for filter lists.
 * Converts binary data into filter list nodes.
 */
class FilterListDeserializer extends BaseDeserializer {
    /**
     * Deserializes a filter list node from binary format.
     *
     * @param buffer ByteBuffer for reading binary data.
     * @param node Destination node.
     */
    static deserialize(buffer, node) {
        buffer.assertUint8(BinaryTypeMarshallingMap.FilterListNode);
        node.type = 'FilterList';
        let prop = buffer.readUint8();
        while (prop !== NULL) {
            switch (prop) {
                case FilterListNodeMarshallingMap.Children:
                    node.children = new Array(buffer.readUint32());
                    for (let i = 0; i < node.children.length; i += 1) {
                        RuleDeserializer.deserialize(buffer, node.children[i] = {});
                    }
                    break;
                case FilterListNodeMarshallingMap.Start:
                    node.start = buffer.readUint32();
                    break;
                case FilterListNodeMarshallingMap.End:
                    node.end = buffer.readUint32();
                    break;
                default:
                    throw new Error(`Invalid property: ${prop}.`);
            }
            prop = buffer.readUint8();
        }
    }
    /**
     * Helper method to jump to the children of the filter list node.
     *
     * Filter lists serialized in binary format are structured as follows:
     * - `FilterListNode` filter list node indicator (1 byte)
     * - Properties:
     *      - `Children` (1 byte) - children count, followed by children nodes
     *      - `Start` (1 byte) - start offset, if present, followed by the value
     *      - `End` (1 byte) - end offset, if present, followed by the value
     *      - `NULL` (1 byte) - closing indicator
     *
     * This method skips indicators, reads the children count and returns it.
     * This way the buffer is positioned at the beginning of the children nodes.
     *
     * @param buffer Reference to the input byte buffer.
     * @returns Number of children nodes.
     */
    static jumpToChildren(buffer) {
        buffer.assertUint8(BinaryTypeMarshallingMap.FilterListNode); // filter list indicator
        let prop = buffer.readUint8();
        while (prop) {
            switch (prop) {
                case FilterListNodeMarshallingMap.Children:
                    return buffer.readUint32();
                case FilterListNodeMarshallingMap.Start:
                case FilterListNodeMarshallingMap.End:
                    buffer.readUint32(); // ignore value
                    break;
                default:
                    throw new Error(`Invalid property: ${prop}.`);
            }
            prop = buffer.readUint8();
        }
        return 0;
    }
}

export { FilterListDeserializer };