rustdoc: redesign toolbar and disclosure widgets

This adds labels to the icons and moves them away from the search box.

These changes are made together, because they work together, but are based on
several complaints:

* The [+/-] thing are a Reddit-ism. They don't look like buttons, but look
  like syntax
  <https://rust-lang.zulipchat.com/#narrow/stream/266220-t-rustdoc/topic/More.20visual.20difference.20for.20the.20.2B.2F-.20.20Icons>,
  <https://github.com/rust-lang/rust/issues/59851>
  (some of these are laundry lists with more suggestions, but they all
  mention [+/-] looking wrong)

* The settings, help, and summary buttons are also too hard to recognize
  <https://lwn.net/Articles/987070/>,
  <https://github.com/rust-lang/rust/issues/90310>,
  <https://github.com/rust-lang/rust/issues/14475#issuecomment-274241997>,
  <https://internals.rust-lang.org/t/improve-rustdoc-design/12758>
  ("Not all functionality is self-explanatory, for example the [+] button in
  the top right corner, the theme picker or the settings button.")

The toggle-all and toggle-individual buttons both need done at once, since we
want them to look like they go together. This changes them from both being
[+/-] to both being arrows.

Settings and Help are also migrated, so that the whole group can benefit from
being described using actual words.

Additionally, the Help button is only shown on SERPs, not all the time.
This is done for two major reasons:

* Most of what's in there is search-related. The things that aren't are
  keyboard commands, and the search box tells you about that anyway.
  Pressing <kbd>?</kbd> will temporarily show the button and its popover.
* I'm trading it off by showing the help button, even on mobile.
  It's useful since you can use the search engine suggestions there.
* The three buttons were causing line wrapping on too many desktop layouts.

1 files changed, 65 insertions, 57 deletions

diff --git a/src/librustdoc/html/static/js/main.js b/src/librustdoc/html/static/js/main.js
index 858753a1917..53326f0fcad 100644
--- a/src/librustdoc/html/static/js/main.js
+++ b/src/librustdoc/html/static/js/main.js
@@ -22,14 +22,14 @@ function hideMain() {
 }
 
 function showMain() {
-    removeClass(document.getElementById(MAIN_ID), "hidden");
-}
-
-function blurHandler(event, parentElem, hideCallback) {
-    if (!parentElem.contains(document.activeElement) &&
-        !parentElem.contains(event.relatedTarget)
-    ) {
-        hideCallback();
+    const main = document.getElementById(MAIN_ID);
+    removeClass(main, "hidden");
+    const mainHeading = main.querySelector(".main-heading");
+    if (mainHeading && searchState.rustdocToolbar) {
+        if (searchState.rustdocToolbar.parentElement) {
+            searchState.rustdocToolbar.parentElement.removeChild(searchState.rustdocToolbar);
+        }
+        mainHeading.appendChild(searchState.rustdocToolbar);
     }
 }
 
@@ -167,6 +167,14 @@ function switchDisplayedElement(elemToDisplay) {
     el.appendChild(elemToDisplay);
     hideMain();
     removeClass(el, "hidden");
+
+    const mainHeading = elemToDisplay.querySelector(".main-heading");
+    if (mainHeading && searchState.rustdocToolbar) {
+        if (searchState.rustdocToolbar.parentElement) {
+            searchState.rustdocToolbar.parentElement.removeChild(searchState.rustdocToolbar);
+        }
+        mainHeading.appendChild(searchState.rustdocToolbar);
+    }
 }
 
 function browserSupportsHistoryApi() {
@@ -194,33 +202,36 @@ function preLoadCss(cssUrl) {
         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");
-                }
+    if (getSettingsButton()) {
+        getSettingsButton().onclick = event => {
+            if (event.ctrlKey || event.altKey || event.metaKey) {
+                return;
             }
-        }, 0);
-    };
+            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 = {
+        rustdocToolbar: document.querySelector("rustdoc-toolbar"),
         loadingText: "Loading search results...",
         input: document.getElementsByClassName("search-input")[0],
         outputElement: () => {
@@ -919,8 +930,7 @@ function preLoadCss(cssUrl) {
                 e.open = true;
             }
         });
-        innerToggle.title = "collapse all docs";
-        innerToggle.children[0].innerText = "\u2212"; // "\u2212" is "−" minus sign
+        innerToggle.children[0].innerText = "Summary";
     }
 
     function collapseAllDocs() {
@@ -934,8 +944,7 @@ function preLoadCss(cssUrl) {
                 e.open = false;
             }
         });
-        innerToggle.title = "expand all docs";
-        innerToggle.children[0].innerText = "+";
+        innerToggle.children[0].innerText = "Show all";
     }
 
     function toggleAllDocs() {
@@ -1328,7 +1337,13 @@ function preLoadCss(cssUrl) {
     }
 
     function helpBlurHandler(event) {
-        blurHandler(event, getHelpButton(), window.hidePopoverMenus);
+        if (!getHelpButton().contains(document.activeElement) &&
+            !getHelpButton().contains(event.relatedTarget) &&
+            !getSettingsButton().contains(document.activeElement) &&
+            !getSettingsButton().contains(event.relatedTarget)
+        ) {
+            window.hidePopoverMenus();
+        }
     }
 
     function buildHelpMenu() {
@@ -1431,9 +1446,13 @@ href="https://doc.rust-lang.org/${channel}/rustdoc/read-documentation/search.htm
      * Hide all the popover menus.
      */
     window.hidePopoverMenus = () => {
-        onEachLazy(document.querySelectorAll(".search-form .popover"), elem => {
+        onEachLazy(document.querySelectorAll("rustdoc-toolbar .popover"), elem => {
             elem.style.display = "none";
         });
+        const button = getHelpButton();
+        if (button) {
+            removeClass(button, "help-open");
+        }
     };
 
     /**
@@ -1458,7 +1477,9 @@ href="https://doc.rust-lang.org/${channel}/rustdoc/read-documentation/search.htm
     function showHelp() {
         // Prevent `blur` events from being dispatched as a result of closing
         // other modals.
-        getHelpButton().querySelector("a").focus();
+        const button = getHelpButton();
+        addClass(button, "help-open");
+        button.querySelector("a").focus();
         const menu = getHelpMenu(true);
         if (menu.style.display === "none") {
             window.hideAllModals();
@@ -1466,28 +1487,15 @@ href="https://doc.rust-lang.org/${channel}/rustdoc/read-documentation/search.htm
         }
     }
 
+    const helpLink = document.querySelector(`#${HELP_BUTTON_ID} > a`);
     if (isHelpPage) {
-        showHelp();
-        document.querySelector(`#${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 => {
+        buildHelpMenu();
+    } else if (helpLink) {
+        helpLink.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 ||
+            if (!helpLink.contains(helpLink) ||
                 event.ctrlKey ||
                 event.altKey ||
                 event.metaKey) {