rust/src/librustdoc/html/static/js/main.js

// Local js definitions:
/* global addClass, getSettingValue, hasClass, searchState, updateLocalStorage */
/* global onEach, onEachLazy, removeClass, getVar */

"use strict";

// The amount of time that the cursor must remain still over a hover target before
// revealing a tooltip.
//
// https://www.nngroup.com/articles/timing-exposing-content/
window.RUSTDOC_TOOLTIP_HOVER_MS = 300;
window.RUSTDOC_TOOLTIP_HOVER_EXIT_MS = 450;

// Given a basename (e.g. "storage") and an extension (e.g. ".js"), return a URL
// for a resource under the root-path, with the resource-suffix.
function resourcePath(basename, extension) {
    return getVar("root-path") + basename + getVar("resource-suffix") + extension;
}

function hideMain() {
    addClass(document.getElementById(MAIN_ID), "hidden");
}

function showMain() {
    removeClass(document.getElementById(MAIN_ID), "hidden");
}

function blurHandler(event, parentElem, hideCallback) {
    if (!parentElem.contains(document.activeElement) &&
        !parentElem.contains(event.relatedTarget)
    ) {
        hideCallback();
    }
}

window.rootPath = getVar("root-path");
window.currentCrate = getVar("current-crate");

function setMobileTopbar() {
    // FIXME: It would be nicer to generate this text content directly in HTML,
    // but with the current code it's hard to get the right information in the right place.
    const mobileTopbar = document.querySelector(".mobile-topbar");
    const locationTitle = document.querySelector(".sidebar h2.location");
    if (mobileTopbar) {
        const mobileTitle = document.createElement("h2");
        mobileTitle.className = "location";
        if (hasClass(document.querySelector(".rustdoc"), "crate")) {
            mobileTitle.innerText = `Crate ${window.currentCrate}`;
        } else if (locationTitle) {
            mobileTitle.innerHTML = locationTitle.innerHTML;
        }
        mobileTopbar.appendChild(mobileTitle);
    }
}

// Gets the human-readable string for the virtual-key code of the
// given KeyboardEvent, ev.
//
// This function is meant as a polyfill for KeyboardEvent#key,
// since it is not supported in IE 11 or Chrome for Android. We also test for
// KeyboardEvent#keyCode because the handleShortcut handler is
// also registered for the keydown event, because Blink doesn't fire
// keypress on hitting the Escape key.
//
// So I guess you could say things are getting pretty interoperable.
function getVirtualKey(ev) {
    if ("key" in ev && typeof ev.key !== "undefined") {
        return ev.key;
    }

    const c = ev.charCode || ev.keyCode;
    if (c === 27) {
        return "Escape";
    }
    return String.fromCharCode(c);
}

const MAIN_ID = "main-content";
const SETTINGS_BUTTON_ID = "settings-menu";
const ALTERNATIVE_DISPLAY_ID = "alternative-display";
const NOT_DISPLAYED_ID = "not-displayed";
const HELP_BUTTON_ID = "help-button";

function getSettingsButton() {
    return document.getElementById(SETTINGS_BUTTON_ID);
}

function getHelpButton() {
    return document.getElementById(HELP_BUTTON_ID);
}

// Returns the current URL without any query parameter or hash.
function getNakedUrl() {
    return window.location.href.split("?")[0].split("#")[0];
}

/**
 * This function inserts `newNode` after `referenceNode`. It doesn't work if `referenceNode`
 * doesn't have a parent node.
 *
 * @param {HTMLElement} newNode
 * @param {HTMLElement} referenceNode
 */
function insertAfter(newNode, referenceNode) {
    referenceNode.parentNode.insertBefore(newNode, referenceNode.nextSibling);
}

/**
 * This function creates a new `<section>` with the given `id` and `classes` if it doesn't already
 * exist.
 *
 * More information about this in `switchDisplayedElement` documentation.
 *
 * @param {string} id
 * @param {string} classes
 */
function getOrCreateSection(id, classes) {
    let el = document.getElementById(id);

    if (!el) {
        el = document.createElement("section");
        el.id = id;
        el.className = classes;
        insertAfter(el, document.getElementById(MAIN_ID));
    }
    return el;
}

/**
 * Returns the `<section>` element which contains the displayed element.
 *
 * @return {HTMLElement}
 */
function getAlternativeDisplayElem() {
    return getOrCreateSection(ALTERNATIVE_DISPLAY_ID, "content hidden");
}

/**
 * Returns the `<section>` element which contains the not-displayed elements.
 *
 * @return {HTMLElement}
 */
function getNotDisplayedElem() {
    return getOrCreateSection(NOT_DISPLAYED_ID, "hidden");
}

/**
 * To nicely switch between displayed "extra" elements (such as search results or settings menu)
 * and to alternate between the displayed and not displayed elements, we hold them in two different
 * `<section>` elements. They work in pair: one holds the hidden elements while the other
 * contains the displayed element (there can be only one at the same time!). So basically, we switch
 * elements between the two `<section>` elements.
 *
 * @param {HTMLElement} elemToDisplay
 */
function switchDisplayedElement(elemToDisplay) {
    const el = getAlternativeDisplayElem();

    if (el.children.length > 0) {
        getNotDisplayedElem().appendChild(el.firstElementChild);
    }
    if (elemToDisplay === null) {
        addClass(el, "hidden");
        showMain();
        return;
    }
    el.appendChild(elemToDisplay);
    hideMain();
    removeClass(el, "hidden");
}

function browserSupportsHistoryApi() {
    return window.history && typeof window.history.pushState === "function";
}

function preLoadCss(cssUrl) {
    // https://developer.mozilla.org/en-US/docs/Web/HTML/Link_types/preload
    const link = document.createElement("link");
    link.href = cssUrl;
    link.rel = "preload";
    link.as = "style";
    document.getElementsByTagName("head")[0].appendChild(link);
}

(function() {
    const isHelpPage = window.location.pathname.endsWith("/help.html");

    function loadScript(url) {
        const script = document.createElement("script");
        script.src = url;
        document.head.append(script);
    }

    getSettingsButton().onclick = event => {
        if (event.ctrlKey || event.altKey || event.metaKey) {
            return;
        }
        window.hideAllModals(false);
        addClass(getSettingsButton(), "rotate");
        event.preventDefault();
        // Sending request for the CSS and the JS files at the same time so it will
        // hopefully be loaded when the JS will generate the settings content.
        loadScript(getVar("static-root-path") + getVar("settings-js"));
        // Pre-load all theme CSS files, so that switching feels seamless.
        //
        // When loading settings.html as a standalone page, the equivalent HTML is
        // generated in context.rs.
        setTimeout(() => {
            const themes = getVar("themes").split(",");
            for (const theme of themes) {
                // if there are no themes, do nothing
                // "".split(",") == [""]
                if (theme !== "") {
                    preLoadCss(getVar("root-path") + theme + ".css");
                }
            }
        }, 0);
    };

    window.searchState = {
        loadingText: "Loading search results...",
        input: document.getElementsByClassName("search-input")[0],
        outputElement: () => {
            let el = document.getElementById("search");
            if (!el) {
                el = document.createElement("section");
                el.id = "search";
                getNotDisplayedElem().appendChild(el);
            }
            return el;
        },
        title: document.title,
        titleBeforeSearch: document.title,
        timeout: null,
        // On the search screen, so you remain on the last tab you opened.
        //
        // 0 for "In Names"
        // 1 for "In Parameters"
        // 2 for "In Return Types"
        currentTab: 0,
        // tab and back preserves the element that was focused.
        focusedByTab: [null, null, null],
        clearInputTimeout: () => {
            if (searchState.timeout !== null) {
                clearTimeout(searchState.timeout);
                searchState.timeout = null;
            }
        },
        isDisplayed: () => searchState.outputElement().parentElement.id === ALTERNATIVE_DISPLAY_ID,
        // Sets the focus on the search bar at the top of the page
        focus: () => {
            searchState.input.focus();
        },
        // Removes the focus from the search bar.
        defocus: () => {
            searchState.input.blur();
        },
        showResults: search => {
            if (search === null || typeof search === "undefined") {
                search = searchState.outputElement();
            }
            switchDisplayedElement(search);
            searchState.mouseMovedAfterSearch = false;
            document.title = searchState.title;
        },
        removeQueryParameters: () => {
            // We change the document title.
            document.title = searchState.titleBeforeSearch;
            if (browserSupportsHistoryApi()) {
                history.replaceState(null, "", getNakedUrl() + window.location.hash);
            }
        },
        hideResults: () => {
            switchDisplayedElement(null);
            // We also remove the query parameter from the URL.
            searchState.removeQueryParameters();
        },
        getQueryStringParams: () => {
            const params = {};
            window.location.search.substring(1).split("&").
                map(s => {
                    // https://github.com/rust-lang/rust/issues/119219
                    const pair = s.split("=").map(x => x.replace(/\+/g, " "));
                    params[decodeURIComponent(pair[0])] =
                        typeof pair[1] === "undefined" ? null : decodeURIComponent(pair[1]);
                });
            return params;
        },
        setup: () => {
            const search_input = searchState.input;
            if (!searchState.input) {
                return;
            }
            let searchLoaded = false;
            function loadSearch() {
                if (!searchLoaded) {
                    searchLoaded = true;
                    loadScript(getVar("static-root-path") + getVar("search-js"));
                    loadScript(resourcePath("search-index", ".js"));
                }
            }

            search_input.addEventListener("focus", () => {
                search_input.origPlaceholder = search_input.placeholder;
                search_input.placeholder = "Type your search here.";
                loadSearch();
            });

            if (search_input.value !== "") {
                loadSearch();
            }

            const params = searchState.getQueryStringParams();
            if (params.search !== undefined) {
                searchState.setLoadingSearch();
                loadSearch();
            }
        },
        setLoadingSearch: () => {
            const search = searchState.outputElement();
            search.innerHTML = "<h3 class=\"search-loading\">" + searchState.loadingText + "</h3>";
            searchState.showResults(search);
        },
    };

    const toggleAllDocsId = "toggle-all-docs";
    let savedHash = "";

    function handleHashes(ev) {
        if (ev !== null && searchState.isDisplayed() && ev.newURL) {
            // This block occurs when clicking on an element in the navbar while
            // in a search.
            switchDisplayedElement(null);
            const hash = ev.newURL.slice(ev.newURL.indexOf("#") + 1);
            if (browserSupportsHistoryApi()) {
                // `window.location.search`` contains all the query parameters, not just `search`.
                history.replaceState(null, "",
                    getNakedUrl() + window.location.search + "#" + hash);
            }
            const elem = document.getElementById(hash);
            if (elem) {
                elem.scrollIntoView();
            }
        }
        // This part is used in case an element is not visible.
        const pageId = window.location.hash.replace(/^#/, "");
        if (savedHash !== pageId) {
            savedHash = pageId;
            if (pageId !== "") {
                expandSection(pageId);
            }
        }
        if (savedHash.startsWith("impl-")) {
            // impl-disambiguated links, used by the search engine
            // format: impl-X[-for-Y]/method.WHATEVER
            // turn this into method.WHATEVER[-NUMBER]
            const splitAt = savedHash.indexOf("/");
            if (splitAt !== -1) {
                const implId = savedHash.slice(0, splitAt);
                const assocId = savedHash.slice(splitAt + 1);
                const implElem = document.getElementById(implId);
                if (implElem && implElem.parentElement.tagName === "SUMMARY" &&
                    implElem.parentElement.parentElement.tagName === "DETAILS") {
                    onEachLazy(implElem.parentElement.parentElement.querySelectorAll(
                        `[id^="${assocId}"]`),
                        item => {
                            const numbered = /([^-]+)-([0-9]+)/.exec(item.id);
                            if (item.id === assocId || (numbered && numbered[1] === assocId)) {
                                openParentDetails(item);
                                item.scrollIntoView();
                                // Let the section expand itself before trying to highlight
                                setTimeout(() => {
                                    window.location.replace("#" + item.id);
                                }, 0);
                            }
                        }
                    );
                }
            }
        }
    }

    function onHashChange(ev) {
        // If we're in mobile mode, we should hide the sidebar in any case.
        hideSidebar();
        handleHashes(ev);
    }

    function openParentDetails(elem) {
        while (elem) {
            if (elem.tagName === "DETAILS") {
                elem.open = true;
            }
            elem = elem.parentNode;
        }
    }

    function expandSection(id) {
        openParentDetails(document.getElementById(id));
    }

    function handleEscape(ev) {
        searchState.clearInputTimeout();
        searchState.hideResults();
        ev.preventDefault();
        searchState.defocus();
        window.hideAllModals(true); // true = reset focus for tooltips
    }

    function handleShortcut(ev) {
        // Don't interfere with browser shortcuts
        const disableShortcuts = getSettingValue("disable-shortcuts") === "true";
        if (ev.ctrlKey || ev.altKey || ev.metaKey || disableShortcuts) {
            return;
        }

        if (document.activeElement.tagName === "INPUT" &&
            document.activeElement.type !== "checkbox" &&
            document.activeElement.type !== "radio") {
            switch (getVirtualKey(ev)) {
            case "Escape":
                handleEscape(ev);
                break;
            }
        } else {
            switch (getVirtualKey(ev)) {
            case "Escape":
                handleEscape(ev);
                break;

            case "s":
            case "S":
                ev.preventDefault();
                searchState.focus();
                break;

            case "+":
                ev.preventDefault();
                expandAllDocs();
                break;
            case "-":
                ev.preventDefault();
                collapseAllDocs();
                break;

            case "?":
                showHelp();
                break;

            default:
                break;
            }
        }
    }

    document.addEventListener("keypress", handleShortcut);
    document.addEventListener("keydown", handleShortcut);

    function addSidebarItems() {
        if (!window.SIDEBAR_ITEMS) {
            return;
        }
        const sidebar = document.getElementsByClassName("sidebar-elems")[0];

        /**
         * Append to the sidebar a "block" of links - a heading along with a list (`<ul>`) of items.
         *
         * @param {string} shortty - A short type name, like "primitive", "mod", or "macro"
         * @param {string} id - The HTML id of the corresponding section on the module page.
         * @param {string} longty - A long, capitalized, plural name, like "Primitive Types",
         *                          "Modules", or "Macros".
         */
        function block(shortty, id, longty) {
            const filtered = window.SIDEBAR_ITEMS[shortty];
            if (!filtered) {
                return;
            }

            const modpath = hasClass(document.querySelector(".rustdoc"), "mod") ? "../" : "";

            const h3 = document.createElement("h3");
            h3.innerHTML = `<a href="${modpath}index.html#${id}">${longty}</a>`;
            const ul = document.createElement("ul");
            ul.className = "block " + shortty;

            for (const name of filtered) {
                let path;
                if (shortty === "mod") {
                    path = `${modpath}${name}/index.html`;
                } else {
                    path = `${modpath}${shortty}.${name}.html`;
                }
                let current_page = document.location.href.toString();
                if (current_page.endsWith("/")) {
                    current_page += "index.html";
                }
                const link = document.createElement("a");
                link.href = path;
                if (path === current_page) {
                    link.className = "current";
                }
                link.textContent = name;
                const li = document.createElement("li");
                li.appendChild(link);
                ul.appendChild(li);
            }
            sidebar.appendChild(h3);
            sidebar.appendChild(ul);
        }

        if (sidebar) {
            // keep this synchronized with ItemSection::ALL in html/render/mod.rs
            // Re-exports aren't shown here, because they don't have child pages
            //block("reexport", "reexports", "Re-exports");
            block("primitive", "primitives", "Primitive Types");
            block("mod", "modules", "Modules");
            block("macro", "macros", "Macros");
            block("struct", "structs", "Structs");
            block("enum", "enums", "Enums");
            block("constant", "constants", "Constants");
            block("static", "static", "Statics");
            block("trait", "traits", "Traits");
            block("fn", "functions", "Functions");
            block("type", "types", "Type Aliases");
            block("union", "unions", "Unions");
            // No point, because these items don't appear in modules
            //block("impl", "impls", "Implementations");
            //block("tymethod", "tymethods", "Type Methods");
            //block("method", "methods", "Methods");
            //block("structfield", "fields", "Fields");
            //block("variant", "variants", "Variants");
            //block("associatedtype", "associated-types", "Associated Types");
            //block("associatedconstant", "associated-consts", "Associated Constants");
            block("foreigntype", "foreign-types", "Foreign Types");
            block("keyword", "keywords", "Keywords");
            block("opaque", "opaque-types", "Opaque Types");
            block("attr", "attributes", "Attribute Macros");
            block("derive", "derives", "Derive Macros");
            block("traitalias", "trait-aliases", "Trait Aliases");
        }
    }

    // <https://github.com/search?q=repo%3Arust-lang%2Frust+[RUSTDOCIMPL]+trait.impl&type=code>
    window.register_implementors = imp => {
        const implementors = document.getElementById("implementors-list");
        const synthetic_implementors = document.getElementById("synthetic-implementors-list");
        const inlined_types = new Set();

        const TEXT_IDX = 0;
        const SYNTHETIC_IDX = 1;
        const TYPES_IDX = 2;

        if (synthetic_implementors) {
            // This `inlined_types` variable is used to avoid having the same implementation
            // showing up twice. For example "String" in the "Sync" doc page.
            //
            // By the way, this is only used by and useful for traits implemented automatically
            // (like "Send" and "Sync").
            onEachLazy(synthetic_implementors.getElementsByClassName("impl"), el => {
                const aliases = el.getAttribute("data-aliases");
                if (!aliases) {
                    return;
                }
                aliases.split(",").forEach(alias => {
                    inlined_types.add(alias);
                });
            });
        }

        let currentNbImpls = implementors.getElementsByClassName("impl").length;
        const traitName = document.querySelector(".main-heading h1 > .trait").textContent;
        const baseIdName = "impl-" + traitName + "-";
        const libs = Object.getOwnPropertyNames(imp);
        // We don't want to include impls from this JS file, when the HTML already has them.
        // The current crate should always be ignored. Other crates that should also be
        // ignored are included in the attribute `data-ignore-extern-crates`.
        const script = document
            .querySelector("script[data-ignore-extern-crates]");
        const ignoreExternCrates = new Set(
            (script ? script.getAttribute("data-ignore-extern-crates") : "").split(",")
        );
        for (const lib of libs) {
            if (lib === window.currentCrate || ignoreExternCrates.has(lib)) {
                continue;
            }
            const structs = imp[lib];

            struct_loop:
            for (const struct of structs) {
                const list = struct[SYNTHETIC_IDX] ? synthetic_implementors : implementors;

                // The types list is only used for synthetic impls.
                // If this changes, `main.js` and `write_shared.rs` both need changed.
                if (struct[SYNTHETIC_IDX]) {
                    for (const struct_type of struct[TYPES_IDX]) {
                        if (inlined_types.has(struct_type)) {
                            continue struct_loop;
                        }
                        inlined_types.add(struct_type);
                    }
                }

                const code = document.createElement("h3");
                code.innerHTML = struct[TEXT_IDX];
                addClass(code, "code-header");

                onEachLazy(code.getElementsByTagName("a"), elem => {
                    const href = elem.getAttribute("href");

                    if (href && !href.startsWith("#") && !/^(?:[a-z+]+:)?\/\//.test(href)) {
                        elem.setAttribute("href", window.rootPath + href);
                    }
                });

                const currentId = baseIdName + currentNbImpls;
                const anchor = document.createElement("a");
                anchor.href = "#" + currentId;
                addClass(anchor, "anchor");

                const display = document.createElement("div");
                display.id = currentId;
                addClass(display, "impl");
                display.appendChild(anchor);
                display.appendChild(code);
                list.appendChild(display);
                currentNbImpls += 1;
            }
        }
    };
    if (window.pending_implementors) {
        window.register_implementors(window.pending_implementors);
    }

    /**
     * <https://github.com/search?q=repo%3Arust-lang%2Frust+[RUSTDOCIMPL]+type.impl&type=code>
     *
     * [RUSTDOCIMPL] type.impl
     *
     * This code inlines implementations into the type alias docs at runtime. It's done at
     * runtime because some crates have many type aliases and many methods, and we don't want
     * to generate *O*`(types*methods)` HTML text. The data inside is mostly HTML fragments,
     * wrapped in JSON.
     *
     * - It only includes docs generated for the current crate. This function accepts an
     *   object mapping crate names to the set of impls.
     *
     * - It filters down to the set of applicable impls. The Rust type checker is used to
     *   tag each HTML blob with the set of type aliases that can actually use it, so the
     *   JS only needs to consult the attached list of type aliases.
     *
     * - It renames the ID attributes, to avoid conflicting IDs in the resulting DOM.
     *
     * - It adds the necessary items to the sidebar. If it's an inherent impl, that means
     *   adding methods, associated types, and associated constants. If it's a trait impl,
     *   that means adding it to the trait impl sidebar list.
     *
     * - It adds the HTML block itself. If it's an inherent impl, it goes after the type
     *   alias's own inherent impls. If it's a trait impl, it goes in the Trait
     *   Implementations section.
     *
     * - After processing all of the impls, it sorts the sidebar items by name.
     *
     * @param {{[cratename: string]: Array<Array<string|0>>}} impl
     */
    window.register_type_impls = imp => {
        if (!imp || !imp[window.currentCrate]) {
            return;
        }
        window.pending_type_impls = null;
        const idMap = new Map();

        let implementations = document.getElementById("implementations-list");
        let trait_implementations = document.getElementById("trait-implementations-list");
        let trait_implementations_header = document.getElementById("trait-implementations");

        // We want to include the current type alias's impls, and no others.
        const script = document.querySelector("script[data-self-path]");
        const selfPath = script ? script.getAttribute("data-self-path") : null;

        // These sidebar blocks need filled in, too.
        const mainContent = document.querySelector("#main-content");
        const sidebarSection = document.querySelector(".sidebar section");
        let methods = document.querySelector(".sidebar .block.method");
        let associatedTypes = document.querySelector(".sidebar .block.associatedtype");
        let associatedConstants = document.querySelector(".sidebar .block.associatedconstant");
        let sidebarTraitList = document.querySelector(".sidebar .block.trait-implementation");

        for (const impList of imp[window.currentCrate]) {
            const types = impList.slice(2);
            const text = impList[0];
            const isTrait = impList[1] !== 0;
            const traitName = impList[1];
            if (types.indexOf(selfPath) === -1) {
                continue;
            }
            let outputList = isTrait ? trait_implementations : implementations;
            if (outputList === null) {
                const outputListName = isTrait ? "Trait Implementations" : "Implementations";
                const outputListId = isTrait ?
                    "trait-implementations-list" :
                    "implementations-list";
                const outputListHeaderId = isTrait ? "trait-implementations" : "implementations";
                const outputListHeader = document.createElement("h2");
                outputListHeader.id = outputListHeaderId;
                outputListHeader.innerText = outputListName;
                outputList = document.createElement("div");
                outputList.id = outputListId;
                if (isTrait) {
                    const link = document.createElement("a");
                    link.href = `#${outputListHeaderId}`;
                    link.innerText = "Trait Implementations";
                    const h = document.createElement("h3");
                    h.appendChild(link);
                    trait_implementations = outputList;
                    trait_implementations_header = outputListHeader;
                    sidebarSection.appendChild(h);
                    sidebarTraitList = document.createElement("ul");
                    sidebarTraitList.className = "block trait-implementation";
                    sidebarSection.appendChild(sidebarTraitList);
                    mainContent.appendChild(outputListHeader);
                    mainContent.appendChild(outputList);
                } else {
                    implementations = outputList;
                    if (trait_implementations) {
                        mainContent.insertBefore(outputListHeader, trait_implementations_header);
                        mainContent.insertBefore(outputList, trait_implementations_header);
                    } else {
                        const mainContent = document.querySelector("#main-content");
                        mainContent.appendChild(outputListHeader);
                        mainContent.appendChild(outputList);
                    }
                }
            }
            const template = document.createElement("template");
            template.innerHTML = text;

            onEachLazy(template.content.querySelectorAll("a"), elem => {
                const href = elem.getAttribute("href");

                if (href && !href.startsWith("#") && !/^(?:[a-z+]+:)?\/\//.test(href)) {
                    elem.setAttribute("href", window.rootPath + href);
                }
            });
            onEachLazy(template.content.querySelectorAll("[id]"), el => {
                let i = 0;
                if (idMap.has(el.id)) {
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             "Look for functions that accept or return \
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    function getHelpMenu(buildNeeded) {
        let menu = getHelpButton().querySelector(".popover");
        if (!menu && buildNeeded) {
            menu = buildHelpMenu();
        }
        return menu;
    }

    /**
     * Show the help popup menu.
     */
    function showHelp() {
        // Prevent `blur` events from being dispatched as a result of closing
        // other modals.
        getHelpButton().querySelector("a").focus();
        const menu = getHelpMenu(true);
        if (menu.style.display === "none") {
            window.hideAllModals();
            menu.style.display = "";
        }
    }

    if (isHelpPage) {
        showHelp();
        document.querySelector(`#${HELP_BUTTON_ID} > a`).addEventListener("click", event => {
            // Already on the help page, make help button a no-op.
            const target = event.target;
            if (target.tagName !== "A" ||
                target.parentElement.id !== HELP_BUTTON_ID ||
                event.ctrlKey ||
                event.altKey ||
                event.metaKey) {
                return;
            }
            event.preventDefault();
        });
    } else {
        document.querySelector(`#${HELP_BUTTON_ID} > a`).addEventListener("click", event => {
            // By default, have help button open docs in a popover.
            // If user clicks with a moderator, though, use default browser behavior,
            // probably opening in a new window or tab.
            const target = event.target;
            if (target.tagName !== "A" ||
                target.parentElement.id !== HELP_BUTTON_ID ||
                event.ctrlKey ||
                event.altKey ||
                event.metaKey) {
                return;
            }
            event.preventDefault();
            const menu = getHelpMenu(true);
            const shouldShowHelp = menu.style.display === "none";
            if (shouldShowHelp) {
                showHelp();
            } else {
                window.hidePopoverMenus();
            }
        });
    }

    setMobileTopbar();
    addSidebarItems();
    addSidebarCrates();
    onHashChange(null);
    window.addEventListener("hashchange", onHashChange);
    searchState.setup();
}());

// Hide, show, and resize the sidebar
//
// The body class and CSS variable are initially set up in storage.js,
// but in this file, we implement:
//
//   * the show sidebar button, which appears if the sidebar is hidden
//     and, by clicking on it, will bring it back
//   * the sidebar resize handle, which appears only on large viewports
//     with a [fine precision pointer] to allow the user to change
//     the size of the sidebar
//
// [fine precision pointer]: https://developer.mozilla.org/en-US/docs/Web/CSS/@media/pointer
(function() {
    // 100 is the size of the logo
    // don't let the sidebar get smaller than that, or it'll get squished
    const SIDEBAR_MIN = 100;
    // Don't let the sidebar get bigger than this
    const SIDEBAR_MAX = 500;
    // Don't let the body (including the gutter) get smaller than this
    //
    // WARNING: RUSTDOC_MOBILE_BREAKPOINT MEDIA QUERY
    // Acceptable values for BODY_MIN are constrained by the mobile breakpoint
    // (which is the minimum size of the whole page where the sidebar exists)
    // and the default sidebar width:
    //
    //     BODY_MIN <= RUSTDOC_MOBILE_BREAKPOINT - DEFAULT_SIDEBAR_WIDTH
    //
    // At the time of this writing, the DEFAULT_SIDEBAR_WIDTH on src pages is
    // 300px, and the RUSTDOC_MOBILE_BREAKPOINT is 700px, so BODY_MIN must be
    // at most 400px. Otherwise, it would start out at the default size, then
    // grabbing the resize handle would suddenly cause it to jank to
    // its contraint-generated maximum.
    const RUSTDOC_MOBILE_BREAKPOINT = 700;
    const BODY_MIN = 400;
    // At half-way past the minimum size, vanish the sidebar entirely
    const SIDEBAR_VANISH_THRESHOLD = SIDEBAR_MIN / 2;

    // Toolbar button to show the sidebar.
    //
    // On small, "mobile-sized" viewports, it's not persistent and it
    // can only be activated by going into Settings and hiding the nav bar.
    // On larger, "desktop-sized" viewports (though that includes many
    // tablets), it's fixed-position, appears in the left side margin,
    // and it can be activated by resizing the sidebar into nothing.
    const sidebarButton = document.getElementById("sidebar-button");
    if (sidebarButton) {
        sidebarButton.addEventListener("click", e => {
            removeClass(document.documentElement, "hide-sidebar");
            updateLocalStorage("hide-sidebar", "false");
            if (document.querySelector(".rustdoc.src")) {
                window.rustdocToggleSrcSidebar();
            }
            e.preventDefault();
        });
    }

    // Pointer capture.
    //
    // Resizing is a single-pointer gesture. Any secondary pointer is ignored
    let currentPointerId = null;

    // "Desired" sidebar size.
    //
    // This is stashed here for window resizing. If the sidebar gets
    // shrunk to maintain BODY_MIN, and then the user grows the window again,
    // it gets the sidebar to restore its size.
    let desiredSidebarSize = null;

    // Sidebar resize debouncer.
    //
    // The sidebar itself is resized instantly, but the body HTML can be too
    // big for that, causing reflow jank. To reduce this, we queue up a separate
    // animation frame and throttle it.
    let pendingSidebarResizingFrame = false;

    // If this page has no sidebar at all, bail out.
    const resizer = document.querySelector(".sidebar-resizer");
    const sidebar = document.querySelector(".sidebar");
    if (!resizer || !sidebar) {
        return;
    }

    // src page and docs page use different variables, because the contents of
    // the sidebar are so different that it's reasonable to thing the user
    // would want them to have different sizes
    const isSrcPage = hasClass(document.body, "src");

    // Call this function to hide the sidebar when using the resize handle
    //
    // This function also nulls out the sidebar width CSS variable and setting,
    // causing it to return to its default. This does not happen if you do it
    // from settings.js, which uses a separate function. It's done here because
    // the minimum sidebar size is rather uncomfortable, and it must pass
    // through that size when using the shrink-to-nothing gesture.
    function hideSidebar() {
        if (isSrcPage) {
            window.rustdocCloseSourceSidebar();
            updateLocalStorage("src-sidebar-width", null);
            // [RUSTDOCIMPL] CSS variable fast path
            //
            // The sidebar width variable is attached to the <html> element by
            // storage.js, because the sidebar and resizer don't exist yet.
            // But the resize code, in `resize()`, sets the property on the
            // sidebar and resizer elements (which are the only elements that
            // use the variable) to avoid recalculating CSS on the entire
            // document on every frame.
            //
            // So, to clear it, we need to clear all three.
            document.documentElement.style.removeProperty("--src-sidebar-width");
            sidebar.style.removeProperty("--src-sidebar-width");
            resizer.style.removeProperty("--src-sidebar-width");
        } else {
            addClass(document.documentElement, "hide-sidebar");
            updateLocalStorage("hide-sidebar", "true");
            updateLocalStorage("desktop-sidebar-width", null);
            document.documentElement.style.removeProperty("--desktop-sidebar-width");
            sidebar.style.removeProperty("--desktop-sidebar-width");
            resizer.style.removeProperty("--desktop-sidebar-width");
        }
    }

    // Call this function to show the sidebar from the resize handle.
    // On docs pages, this can only happen if the user has grabbed the resize
    // handle, shrunk the sidebar down to nothing, and then pulls back into
    // the visible range without releasing it. You can, however, grab the
    // resize handle on a source page with the sidebar closed, because it
    // remains visible all the time on there.
    function showSidebar() {
        if (isSrcPage) {
            window.rustdocShowSourceSidebar();
        } else {
            removeClass(document.documentElement, "hide-sidebar");
            updateLocalStorage("hide-sidebar", "false");
        }
    }

    /**
     * Call this to set the correct CSS variable and setting.
     * This function doesn't enforce size constraints. Do that before calling it!
     *
     * @param {number} size - CSS px width of the sidebar.
     */
    function changeSidebarSize(size) {
        if (isSrcPage) {
            updateLocalStorage("src-sidebar-width", size);
            // [RUSTDOCIMPL] CSS variable fast path
            //
            // While this property is set on the HTML element at load time,
            // because the sidebar isn't actually loaded yet,
            // we scope this update to the sidebar to avoid hitting a slow
            // path in WebKit.
            sidebar.style.setProperty("--src-sidebar-width", size + "px");
            resizer.style.setProperty("--src-sidebar-width", size + "px");
        } else {
            updateLocalStorage("desktop-sidebar-width", size);
            sidebar.style.setProperty("--desktop-sidebar-width", size + "px");
            resizer.style.setProperty("--desktop-sidebar-width", size + "px");
        }
    }

    // Check if the sidebar is hidden. Since src pages and doc pages have
    // different settings, this function has to check that.
    function isSidebarHidden() {
        return isSrcPage ?
            !hasClass(document.documentElement, "src-sidebar-expanded") :
            hasClass(document.documentElement, "hide-sidebar");
    }

    // Respond to the resize handle event.
    // This function enforces size constraints, and implements the
    // shrink-to-nothing gesture based on thresholds defined above.
    function resize(e) {
        if (currentPointerId === null || currentPointerId !== e.pointerId) {
            return;
        }
        e.preventDefault();
        const pos = e.clientX - 3;
        if (pos < SIDEBAR_VANISH_THRESHOLD) {
            hideSidebar();
        } else if (pos >= SIDEBAR_MIN) {
            if (isSidebarHidden()) {
                showSidebar();
            }
            // don't let the sidebar get wider than SIDEBAR_MAX, or the body narrower
            // than BODY_MIN
            const constrainedPos = Math.min(pos, window.innerWidth - BODY_MIN, SIDEBAR_MAX);
            changeSidebarSize(constrainedPos);
            desiredSidebarSize = constrainedPos;
            if (pendingSidebarResizingFrame !== false) {
                clearTimeout(pendingSidebarResizingFrame);
            }
            pendingSidebarResizingFrame = setTimeout(() => {
                if (currentPointerId === null || pendingSidebarResizingFrame === false) {
                    return;
                }
                pendingSidebarResizingFrame = false;
                document.documentElement.style.setProperty(
                    "--resizing-sidebar-width",
                    desiredSidebarSize + "px"
                );
            }, 100);
        }
    }
    // Respond to the window resize event.
    window.addEventListener("resize", () => {
        if (window.innerWidth < RUSTDOC_MOBILE_BREAKPOINT) {
            return;
        }
        stopResize();
        if (desiredSidebarSize >= (window.innerWidth - BODY_MIN)) {
            changeSidebarSize(window.innerWidth - BODY_MIN);
        } else if (desiredSidebarSize !== null && desiredSidebarSize > SIDEBAR_MIN) {
            changeSidebarSize(desiredSidebarSize);
        }
    });
    function stopResize(e) {
        if (currentPointerId === null) {
            return;
        }
        if (e) {
            e.preventDefault();
        }
        desiredSidebarSize = sidebar.getBoundingClientRect().width;
        removeClass(resizer, "active");
        window.removeEventListener("pointermove", resize, false);
        window.removeEventListener("pointerup", stopResize, false);
        removeClass(document.documentElement, "sidebar-resizing");
        document.documentElement.style.removeProperty( "--resizing-sidebar-width");
        if (resizer.releasePointerCapture) {
            resizer.releasePointerCapture(currentPointerId);
            currentPointerId = null;
        }
    }
    function initResize(e) {
        if (currentPointerId !== null || e.altKey || e.ctrlKey || e.metaKey || e.button !== 0) {
            return;
        }
        if (resizer.setPointerCapture) {
            resizer.setPointerCapture(e.pointerId);
            if (!resizer.hasPointerCapture(e.pointerId)) {
                // unable to capture pointer; something else has it
                // on iOS, this usually means you long-clicked a link instead
                resizer.releasePointerCapture(e.pointerId);
                return;
            }
            currentPointerId = e.pointerId;
        }
        window.hideAllModals(false);
        e.preventDefault();
        window.addEventListener("pointermove", resize, false);
        window.addEventListener("pointercancel", stopResize, false);
        window.addEventListener("pointerup", stopResize, false);
        addClass(resizer, "active");
        addClass(document.documentElement, "sidebar-resizing");
        const pos = e.clientX - sidebar.offsetLeft - 3;
        document.documentElement.style.setProperty( "--resizing-sidebar-width", pos + "px");
        desiredSidebarSize = null;
    }
    resizer.addEventListener("pointerdown", initResize, false);
}());

// This section handles the copy button that appears next to the path breadcrumbs
(function() {
    let reset_button_timeout = null;

    const but = document.getElementById("copy-path");
    if (!but) {
        return;
    }
    but.onclick = () => {
        const parent = but.parentElement;
        const path = [];

        onEach(parent.childNodes, child => {
            if (child.tagName === "A") {
                path.push(child.textContent);
            }
        });

        const el = document.createElement("textarea");
        el.value = path.join("::");
        el.setAttribute("readonly", "");
        // To not make it appear on the screen.
        el.style.position = "absolute";
        el.style.left = "-9999px";

        document.body.appendChild(el);
        el.select();
        document.execCommand("copy");
        document.body.removeChild(el);

        // There is always one children, but multiple childNodes.
        but.children[0].style.display = "none";

        let tmp;
        if (but.childNodes.length < 2) {
            tmp = document.createTextNode("✓");
            but.appendChild(tmp);
        } else {
            onEachLazy(but.childNodes, e => {
                if (e.nodeType === Node.TEXT_NODE) {
                    tmp = e;
                    return true;
                }
            });
            tmp.textContent = "✓";
        }

        if (reset_button_timeout !== null) {
            window.clearTimeout(reset_button_timeout);
        }

        function reset_button() {
            tmp.textContent = "";
            reset_button_timeout = null;
            but.children[0].style.display = "";
        }

        reset_button_timeout = window.setTimeout(reset_button, 1000);
    };
}());