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/**
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* Hachette storage manager
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*
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* Copyright (C) 2021 Wojtek Kosior
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* Redistribution terms are gathered in the `copyright' file.
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*/
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/*
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* IMPORTS_START
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* IMPORT raw_storage
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* IMPORT TYPE_NAME
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* IMPORT list_prefixes
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* IMPORT make_lock
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* IMPORT lock
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* IMPORT unlock
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* IMPORT make_once
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* IMPORT browser
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* IMPORT observables
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* IMPORTS_END
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*/
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var exports = {};
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/* A special case of persisted variable is one that contains list of items. */
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async function get_list_var(name)
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{
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let list = await raw_storage.get_var(name);
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return list === undefined ? [] : list;
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}
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/* We maintain in-memory copies of some stored lists. */
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async function list(prefix)
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{
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let name = TYPE_NAME[prefix] + "s"; /* Make plural. */
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let map = new Map();
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for (let item of await get_list_var(name))
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map.set(item, await raw_storage.get(prefix + item));
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return {map, prefix, name, observable: observables.make(),
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lock: make_lock()};
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}
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var list_by_prefix = {};
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async function init()
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{
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for (let prefix of list_prefixes)
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list_by_prefix[prefix] = await list(prefix);
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return exports;
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}
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/*
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* Facilitate listening to changes
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*/
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exports.add_change_listener = function (cb, prefixes=list_prefixes)
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{
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if (typeof(prefixes) === "string")
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prefixes = [prefixes];
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for (let prefix of prefixes)
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observables.subscribe(list_by_prefix[prefix].observable, cb);
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}
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exports.remove_change_listener = function (cb, prefixes=list_prefixes)
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{
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if (typeof(prefixes) === "string")
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prefixes = [prefixes];
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for (let prefix of prefixes)
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observables.unsubscribe(list_by_prefix[prefix].observable, cb);
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}
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/* Prepare some hepler functions to get elements of a list */
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function list_items_it(list, with_values=false)
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{
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return with_values ? list.map.entries() : list.map.keys();
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}
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function list_entries_it(list)
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{
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return list_items_it(list, true);
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}
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function list_items(list, with_values=false)
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{
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let array = [];
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for (let item of list_items_it(list, with_values))
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array.push(item);
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return array;
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}
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function list_entries(list)
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{
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return list_items(list, true);
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}
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/*
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* Below we make additional effort to update map of given kind of items
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* every time an item is added/removed to keep everything coherent.
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*/
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async function set_item(item, value, list)
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{
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await lock(list.lock);
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let result = await _set_item(...arguments);
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unlock(list.lock)
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return result;
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}
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async function _set_item(item, value, list)
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{
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const key = list.prefix + item;
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const old_val = list.map.get(item);
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const set_obj = {[key]: value};
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if (old_val === undefined) {
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const items = list_items(list);
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items.push(item);
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set_obj["_" + list.name] = items;
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}
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await raw_storage.set(set_obj);
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list.map.set(item, value);
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const change = {
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prefix : list.prefix,
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item,
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old_val,
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new_val : value
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};
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observables.broadcast(list.observable, change);
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return old_val;
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}
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// TODO: The actual idea to set value to undefined is good - this way we can
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// also set a new list of items in the same API call. But such key
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// is still stored in the storage. We need to somehow remove it later.
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// For that, we're going to have to store 1 more list of each kind.
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async function remove_item(item, list)
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{
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await lock(list.lock);
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let result = await _remove_item(...arguments);
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unlock(list.lock)
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return result;
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}
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async function _remove_item(item, list)
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{
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const old_val = list.map.get(item);
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if (old_val === undefined)
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return;
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const items = list_items(list);
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const index = items.indexOf(item);
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items.splice(index, 1);
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await raw_storage.set({
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[list.prefix + item]: undefined,
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["_" + list.name]: items
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});
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list.map.delete(item);
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const change = {
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prefix : list.prefix,
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item,
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old_val,
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new_val : undefined
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};
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observables.broadcast(list.observable, change);
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return old_val;
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}
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// TODO: same as above applies here
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async function replace_item(old_item, new_item, list, new_val=undefined)
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{
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await lock(list.lock);
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let result = await _replace_item(...arguments);
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unlock(list.lock)
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return result;
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}
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async function _replace_item(old_item, new_item, list, new_val=undefined)
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{
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const old_val = list.map.get(old_item);
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if (new_val === undefined) {
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if (old_val === undefined)
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return;
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new_val = old_val;
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} else if (new_val === old_val && new_item === old_item) {
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return old_val;
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}
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if (old_item === new_item || old_val === undefined) {
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await _set_item(new_item, new_val, list);
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return old_val;
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}
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const items = list_items(list);
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const index = items.indexOf(old_item);
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items[index] = new_item;
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await raw_storage.set({
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[list.prefix + old_item]: undefined,
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[list.prefix + new_item]: new_val,
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["_" + list.name]: items
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});
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list.map.delete(old_item);
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const change = {
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prefix : list.prefix,
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item : old_item,
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old_val,
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new_val : undefined
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};
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observables.broadcast(list.observable, change);
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list.map.set(new_item, new_val);
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change.item = new_item;
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change.old_val = undefined;
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change.new_val = new_val;
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observables.broadcast(list.observable, change);
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return old_val;
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}
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/*
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* For scripts, item name is chosen by user, data should be
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* an object containing:
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* - script's url and hash or
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* - script's text or
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* - all three
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*/
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/*
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* For bags, item name is chosen by user, data is an array of 2-element
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* arrays with type prefix and script/bag names.
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*/
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/*
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* For pages data argument is an object with properties `allow'
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* and `components'. Item name is url.
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*/
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exports.set = async function (prefix, item, data)
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{
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return set_item(item, data, list_by_prefix[prefix]);
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}
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exports.get = function (prefix, item)
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{
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return list_by_prefix[prefix].map.get(item);
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}
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exports.remove = async function (prefix, item)
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{
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return remove_item(item, list_by_prefix[prefix]);
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}
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exports.replace = async function (prefix, old_item, new_item,
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new_data=undefined)
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{
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return replace_item(old_item, new_item, list_by_prefix[prefix],
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new_data);
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}
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exports.get_all_names = function (prefix)
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{
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return list_items(list_by_prefix[prefix]);
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}
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exports.get_all_names_it = function (prefix)
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{
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return list_items_it(list_by_prefix[prefix]);
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}
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exports.get_all = function (prefix)
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{
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return list_entries(list_by_prefix[prefix]);
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}
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exports.get_all_it = function (prefix)
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{
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return list_entries_it(list_by_prefix[prefix]);
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}
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/* Finally, a quick way to wipe all the data. */
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// TODO: maybe delete items in such order that none of them ever references
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// an already-deleted one?
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exports.clear = async function ()
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{
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let lists = list_prefixes.map((p) => list_by_prefix[p]);
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for (let list of lists)
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await lock(list.lock);
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for (let list of lists) {
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let change = {
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prefix : list.prefix,
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new_val : undefined
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};
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for (let [item, val] of list_entries_it(list)) {
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change.item = item;
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change.old_val = val;
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observables.broadcast(list.observable, change);
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}
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list.map = new Map();
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}
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await browser.storage.local.clear();
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for (let list of lists)
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unlock(list.lock);
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}
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const get_storage = make_once(init);
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/*
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* EXPORTS_START
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* EXPORT get_storage
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* EXPORTS_END
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*/
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