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// storage.js is loaded in the `<head>` of all rustdoc pages and doesn't
// use `async` or `defer`. That means it blocks further parsing and rendering
// of the page: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/script.
// This makes it the correct place to act on settings that affect the display of
// the page, so we don't see major layout changes during the load of the page.
"use strict";
const darkThemes = ["dark", "ayu"];
window.currentTheme = document.getElementById("themeStyle");
const settingsDataset = (function() {
const settingsElement = document.getElementById("default-settings");
return settingsElement && settingsElement.dataset ? settingsElement.dataset : null;
})();
function getSettingValue(settingName) {
const current = getCurrentValue(settingName);
if (current === null && settingsDataset !== null) {
// See the comment for `default_settings.into_iter()` etc. in
// `Options::from_matches` in `librustdoc/config.rs`.
const def = settingsDataset[settingName.replace(/-/g,"_")];
if (def !== undefined) {
return def;
}
}
return current;
}
const localStoredTheme = getSettingValue("theme");
// eslint-disable-next-line no-unused-vars
function hasClass(elem, className) {
return elem && elem.classList && elem.classList.contains(className);
}
function addClass(elem, className) {
if (elem && elem.classList) {
elem.classList.add(className);
}
}
// eslint-disable-next-line no-unused-vars
function removeClass(elem, className) {
if (elem && elem.classList) {
elem.classList.remove(className);
}
}
/**
* Run a callback for every element of an Array.
* @param {Array<?>} arr - The array to iterate over
* @param {function(?)} func - The callback
* @param {boolean} [reversed] - Whether to iterate in reverse
*/
function onEach(arr, func, reversed) {
if (arr && arr.length > 0) {
if (reversed) {
for (let i = arr.length - 1; i >= 0; --i) {
if (func(arr[i])) {
return true;
}
}
} else {
for (const elem of arr) {
if (func(elem)) {
return true;
}
}
}
}
return false;
}
/**
* Turn an HTMLCollection or a NodeList into an Array, then run a callback
* for every element. This is useful because iterating over an HTMLCollection
* or a "live" NodeList while modifying it can be very slow.
* https://developer.mozilla.org/en-US/docs/Web/API/HTMLCollection
* https://developer.mozilla.org/en-US/docs/Web/API/NodeList
* @param {NodeList<?>|HTMLCollection<?>} lazyArray - An array to iterate over
* @param {function(?)} func - The callback
* @param {boolean} [reversed] - Whether to iterate in reverse
*/
// eslint-disable-next-line no-unused-vars
function onEachLazy(lazyArray, func, reversed) {
return onEach(
Array.prototype.slice.call(lazyArray),
func,
reversed);
}
function updateLocalStorage(name, value) {
try {
window.localStorage.setItem("rustdoc-" + name, value);
} catch (e) {
// localStorage is not accessible, do nothing
}
}
function getCurrentValue(name) {
try {
return window.localStorage.getItem("rustdoc-" + name);
} catch (e) {
return null;
}
}
// Get a value from the rustdoc-vars div, which is used to convey data from
// Rust to the JS. If there is no such element, return null.
const getVar = (function getVar(name) {
const el = document.getElementById("rustdoc-vars");
return el ? el.attributes["data-" + name].value : null;
});
function switchTheme(newThemeName, saveTheme) {
// If this new value comes from a system setting or from the previously
// saved theme, no need to save it.
if (saveTheme) {
updateLocalStorage("theme", newThemeName);
}
let newHref;
if (newThemeName === "light" || newThemeName === "dark" || newThemeName === "ayu") {
newHref = getVar("static-root-path") + getVar("theme-" + newThemeName + "-css");
} else {
newHref = getVar("root-path") + newThemeName + getVar("resource-suffix") + ".css";
}
if (!window.currentTheme) {
document.write(`<link rel="stylesheet" id="themeStyle" href="${newHref}">`);
window.currentTheme = document.getElementById("themeStyle");
} else if (newHref !== window.currentTheme.href) {
window.currentTheme.href = newHref;
}
}
const updateTheme = (function() {
// only listen to (prefers-color-scheme: dark) because light is the default
const mql = window.matchMedia("(prefers-color-scheme: dark)");
/**
* Update the current theme to match whatever the current combination of
* * the preference for using the system theme
* (if this is the case, the value of preferred-light-theme, if the
* system theme is light, otherwise if dark, the value of
* preferred-dark-theme.)
* * the preferred theme
* … dictates that it should be.
*/
function updateTheme() {
// maybe the user has disabled the setting in the meantime!
if (getSettingValue("use-system-theme") !== "false") {
const lightTheme = getSettingValue("preferred-light-theme") || "light";
const darkTheme = getSettingValue("preferred-dark-theme") || "dark";
updateLocalStorage("use-system-theme", "true");
// use light theme if user prefers it, or has no preference
switchTheme(mql.matches ? darkTheme : lightTheme, true);
// note: we save the theme so that it doesn't suddenly change when
// the user disables "use-system-theme" and reloads the page or
// navigates to another page
} else {
switchTheme(getSettingValue("theme"), false);
}
}
mql.addEventListener("change", updateTheme);
return updateTheme;
})();
if (getSettingValue("use-system-theme") !== "false" && window.matchMedia) {
// update the preferred dark theme if the user is already using a dark theme
// See https://github.com/rust-lang/rust/pull/77809#issuecomment-707875732
if (getSettingValue("use-system-theme") === null
&& getSettingValue("preferred-dark-theme") === null
&& darkThemes.indexOf(localStoredTheme) >= 0) {
updateLocalStorage("preferred-dark-theme", localStoredTheme);
}
}
updateTheme();
if (getSettingValue("source-sidebar-show") === "true") {
// At this point in page load, `document.body` is not available yet.
// Set a class on the `<html>` element instead.
addClass(document.documentElement, "source-sidebar-expanded");
}
// If we navigate away (for example to a settings page), and then use the back or
// forward button to get back to a page, the theme may have changed in the meantime.
// But scripts may not be re-loaded in such a case due to the bfcache
// (https://web.dev/bfcache/). The "pageshow" event triggers on such navigations.
// Use that opportunity to update the theme.
// We use a setTimeout with a 0 timeout here to put the change on the event queue.
// For some reason, if we try to change the theme while the `pageshow` event is
// running, it sometimes fails to take effect. The problem manifests on Chrome,
// specifically when talking to a remote website with no caching.
window.addEventListener("pageshow", ev => {
if (ev.persisted) {
setTimeout(updateTheme, 0);
}
});
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