Move global click handlers to per-element ones.

In rustdoc's main.js, we had an onclick handler for the whole document
that would dispatch to handlers for various elements. This change
attaches the handlers to the elements that trigger them, instead.
This simplfies the code and avoids reimplementing the browser's bubbling
functionality.

As part of this change, change from a class to an id for help button.

Move the handlers and associated code for highlighting source lines into
source-script.js (and factor out a shared regex).

8 files changed, 138 insertions, 128 deletions

diff --git a/src/librustdoc/html/layout.rs b/src/librustdoc/html/layout.rs
index 99e96fdcf1e..ec04c94dc11 100644
--- a/src/librustdoc/html/layout.rs
+++ b/src/librustdoc/html/layout.rs
@@ -105,7 +105,7 @@ crate fn render<T: Print, S: Print>(
                            placeholder=\"Click or press ‘S’ to search, ‘?’ for more options…\" \
                            type=\"search\">\
                 </div>\
-                <button type=\"button\" class=\"help-button\">?</button>
+                <button type=\"button\" id=\"help-button\">?</button>
                 <a id=\"settings-menu\" href=\"{root_path}settings.html\">\
                     <img src=\"{static_root_path}wheel{suffix}.svg\" \
                          width=\"18\" height=\"18\" \
diff --git a/src/librustdoc/html/markdown.rs b/src/librustdoc/html/markdown.rs
index c2b40ab34e2..00a91e07d65 100644
--- a/src/librustdoc/html/markdown.rs
+++ b/src/librustdoc/html/markdown.rs
@@ -1347,6 +1347,7 @@ fn init_id_map() -> FxHashMap<String, usize> {
     map.insert("theme-picker".to_owned(), 1);
     map.insert("theme-choices".to_owned(), 1);
     map.insert("settings-menu".to_owned(), 1);
+    map.insert("help-button".to_owned(), 1);
     map.insert("main".to_owned(), 1);
     map.insert("search".to_owned(), 1);
     map.insert("crate-search".to_owned(), 1);
diff --git a/src/librustdoc/html/static/main.js b/src/librustdoc/html/static/main.js
index dc65e14ab37..65f936819f5 100644
--- a/src/librustdoc/html/static/main.js
+++ b/src/librustdoc/html/static/main.js
@@ -381,56 +381,9 @@ function hideThemeButtonState() {
         }
     }
 
-    function highlightSourceLines(match, ev) {
-        if (typeof match === "undefined") {
-            // If we're in mobile mode, we should hide the sidebar in any case.
-            hideSidebar();
-            match = window.location.hash.match(/^#?(\d+)(?:-(\d+))?$/);
-        }
-        if (!match) {
-            return;
-        }
-        var from = parseInt(match[1], 10);
-        var to = from;
-        if (typeof match[2] !== "undefined") {
-            to = parseInt(match[2], 10);
-        }
-        if (to < from) {
-            var tmp = to;
-            to = from;
-            from = tmp;
-        }
-        var elem = document.getElementById(from);
-        if (!elem) {
-            return;
-        }
-        if (!ev) {
-            var x = document.getElementById(from);
-            if (x) {
-                x.scrollIntoView();
-            }
-        }
-        onEachLazy(document.getElementsByClassName("line-numbers"), function(e) {
-            onEachLazy(e.getElementsByTagName("span"), function(i_e) {
-                removeClass(i_e, "line-highlighted");
-            });
-        });
-        for (var i = from; i <= to; ++i) {
-            elem = document.getElementById(i);
-            if (!elem) {
-                break;
-            }
-            addClass(elem, "line-highlighted");
-        }
-    }
-
     function onHashChange(ev) {
         // If we're in mobile mode, we should hide the sidebar in any case.
         hideSidebar();
-        var match = window.location.hash.match(/^#?(\d+)(?:-(\d+))?$/);
-        if (match) {
-            return highlightSourceLines(match, ev);
-        }
         handleHashes(ev);
     }
 
@@ -585,78 +538,9 @@ function hideThemeButtonState() {
         }
     }
 
-    function findParentElement(elem, tagName) {
-        do {
-            if (elem && elem.tagName === tagName) {
-                return elem;
-            }
-            elem = elem.parentNode;
-        } while (elem);
-        return null;
-    }
-
     document.addEventListener("keypress", handleShortcut);
     document.addEventListener("keydown", handleShortcut);
 
-    var handleSourceHighlight = (function() {
-        var prev_line_id = 0;
-
-        var set_fragment = function(name) {
-            var x = window.scrollX,
-                y = window.scrollY;
-            if (searchState.browserSupportsHistoryApi()) {
-                history.replaceState(null, null, "#" + name);
-                highlightSourceLines();
-            } else {
-                location.replace("#" + name);
-            }
-            // Prevent jumps when selecting one or many lines
-            window.scrollTo(x, y);
-        };
-
-        return function(ev) {
-            var cur_line_id = parseInt(ev.target.id, 10);
-            ev.preventDefault();
-
-            if (ev.shiftKey && prev_line_id) {
-                // Swap selection if needed
-                if (prev_line_id > cur_line_id) {
-                    var tmp = prev_line_id;
-                    prev_line_id = cur_line_id;
-                    cur_line_id = tmp;
-                }
-
-                set_fragment(prev_line_id + "-" + cur_line_id);
-            } else {
-                prev_line_id = cur_line_id;
-
-                set_fragment(cur_line_id);
-            }
-        };
-    }());
-
-    document.addEventListener("click", function(ev) {
-        var helpElem = getHelpElement(false);
-        if (hasClass(ev.target, "help-button")) {
-            displayHelp(true, ev);
-        } else if (ev.target.tagName === "SPAN" && hasClass(ev.target.parentNode, "line-numbers")) {
-            handleSourceHighlight(ev);
-        } else if (helpElem && hasClass(helpElem, "hidden") === false) {
-            var is_inside_help_popup = ev.target !== helpElem && helpElem.contains(ev.target);
-            if (is_inside_help_popup === false) {
-                addClass(helpElem, "hidden");
-                removeClass(document.body, "blur");
-            }
-        } else {
-            // Making a collapsed element visible on onhashchange seems
-            // too late
-            var a = findParentElement(ev.target, "A");
-            if (a && a.hash) {
-                expandSection(a.hash.replace(/^#/, ""));
-            }
-        }
-    });
-
     (function() {
         var x = document.getElementsByClassName("version-selector");
         if (x.length > 0) {
@@ -1121,6 +1005,27 @@ function hideThemeButtonState() {
         });
     }());
 
+    function handleClick(id, f) {
+        var elem = document.getElementById(id);
+        if (elem) {
+            elem.addEventListener("click", f);
+        }
+    }
+    handleClick("help-button", function(ev) {
+        displayHelp(true, ev);
+    });
+
+    onEachLazy(document.getElementsByTagName("a"), function(el) {
+        // For clicks on internal links (<A> tags with a hash property), we expand the section we're
+        // jumping to *before* jumping there. We can't do this in onHashChange, because it changes
+        // the height of the document so we wind up scrolled to the wrong place.
+        if (el.hash) {
+            el.addEventListener("click", function() {
+                expandSection(el.hash.slice(1));
+            });
+        }
+    });
+
     onEachLazy(document.getElementsByClassName("notable-traits"), function(e) {
         e.onclick = function() {
             this.getElementsByClassName('notable-traits-tooltiptext')[0]
@@ -1165,6 +1070,13 @@ function hideThemeButtonState() {
         addClass(popup, "hidden");
         popup.id = "help";
 
+        popup.addEventListener("click", function(ev) {
+            if (ev.target === popup) {
+                // Clicked the blurred zone outside the help popup; dismiss help.
+                displayHelp(false, ev);
+            }
+        });
+
         var book_info = document.createElement("span");
         book_info.innerHTML = "You can find more information in \
             <a href=\"https://doc.rust-lang.org/rustdoc/\">the rustdoc book</a>.";
@@ -1223,7 +1135,7 @@ function hideThemeButtonState() {
     }
 
     onHashChange(null);
-    window.onhashchange = onHashChange;
+    window.addEventListener("hashchange", onHashChange);
     searchState.setup();
 }());
 
diff --git a/src/librustdoc/html/static/rustdoc.css b/src/librustdoc/html/static/rustdoc.css
index aaa2525644f..6622756bcc3 100644
--- a/src/librustdoc/html/static/rustdoc.css
+++ b/src/librustdoc/html/static/rustdoc.css
@@ -1289,7 +1289,7 @@ h4 > .notable-traits {
 	outline: none;
 }
 
-#settings-menu, .help-button {
+#settings-menu, #help-button {
 	position: absolute;
 	top: 10px;
 }
@@ -1299,7 +1299,7 @@ h4 > .notable-traits {
 	outline: none;
 }
 
-#theme-picker, #settings-menu, .help-button, #copy-path {
+#theme-picker, #settings-menu, #help-button, #copy-path {
 	padding: 4px;
 	width: 27px;
 	height: 29px;
@@ -1308,7 +1308,7 @@ h4 > .notable-traits {
 	cursor: pointer;
 }
 
-.help-button {
+#help-button {
 	right: 30px;
 	font-family: "Fira Sans", Arial, sans-serif;
 	text-align: center;
@@ -1593,7 +1593,7 @@ h4 > .notable-traits {
 	}
 
 	/* We don't display the help button on mobile devices. */
-	.help-button {
+	#help-button {
 		display: none;
 	}
 	.search-container > div {
diff --git a/src/librustdoc/html/static/source-script.js b/src/librustdoc/html/static/source-script.js
index 42b54e4cc1e..a5aa2c5f678 100644
--- a/src/librustdoc/html/static/source-script.js
+++ b/src/librustdoc/html/static/source-script.js
@@ -3,6 +3,7 @@
 
 // Local js definitions:
 /* global addClass, getCurrentValue, hasClass, removeClass, updateLocalStorage */
+(function() {
 
 function getCurrentFilePath() {
     var parts = window.location.pathname.split("/");
@@ -150,3 +151,99 @@ function createSourceSidebar() {
         selected_elem.focus();
     }
 }
+
+var lineNumbersRegex = /^#?(\d+)(?:-(\d+))?$/;
+
+function highlightSourceLines(match, ev) {
+    if (typeof match === "undefined") {
+        match = window.location.hash.match(lineNumbersRegex);
+    }
+    if (!match) {
+        return;
+    }
+    var from = parseInt(match[1], 10);
+    var to = from;
+    if (typeof match[2] !== "undefined") {
+        to = parseInt(match[2], 10);
+    }
+    if (to < from) {
+        var tmp = to;
+        to = from;
+        from = tmp;
+    }
+    var elem = document.getElementById(from);
+    if (!elem) {
+        return;
+    }
+    if (!ev) {
+        var x = document.getElementById(from);
+        if (x) {
+            x.scrollIntoView();
+        }
+    }
+    onEachLazy(document.getElementsByClassName("line-numbers"), function(e) {
+        onEachLazy(e.getElementsByTagName("span"), function(i_e) {
+            removeClass(i_e, "line-highlighted");
+        });
+    });
+    for (var i = from; i <= to; ++i) {
+        elem = document.getElementById(i);
+        if (!elem) {
+            break;
+        }
+        addClass(elem, "line-highlighted");
+    }
+}
+
+var handleSourceHighlight = (function() {
+    var prev_line_id = 0;
+
+    var set_fragment = function(name) {
+        var x = window.scrollX,
+            y = window.scrollY;
+        if (searchState.browserSupportsHistoryApi()) {
+            history.replaceState(null, null, "#" + name);
+            highlightSourceLines();
+        } else {
+            location.replace("#" + name);
+        }
+        // Prevent jumps when selecting one or many lines
+        window.scrollTo(x, y);
+    };
+
+    return function(ev) {
+        var cur_line_id = parseInt(ev.target.id, 10);
+        ev.preventDefault();
+
+        if (ev.shiftKey && prev_line_id) {
+            // Swap selection if needed
+            if (prev_line_id > cur_line_id) {
+                var tmp = prev_line_id;
+                prev_line_id = cur_line_id;
+                cur_line_id = tmp;
+            }
+
+            set_fragment(prev_line_id + "-" + cur_line_id);
+        } else {
+            prev_line_id = cur_line_id;
+
+            set_fragment(cur_line_id);
+        }
+    };
+}());
+
+window.addEventListener("hashchange", function() {
+    var match = window.location.hash.match(lineNumbersRegex);
+    if (match) {
+        return highlightSourceLines(match, ev);
+    }
+});
+
+onEachLazy(document.getElementsByClassName("line-numbers"), function(el) {
+    el.addEventListener("click", handleSourceHighlight);
+});
+
+highlightSourceLines();
+
+window.createSourceSidebar = createSourceSidebar;
+})();
diff --git a/src/librustdoc/html/static/themes/ayu.css b/src/librustdoc/html/static/themes/ayu.css
index aafb7f6300e..08148fdcf95 100644
--- a/src/librustdoc/html/static/themes/ayu.css
+++ b/src/librustdoc/html/static/themes/ayu.css
@@ -503,7 +503,7 @@ kbd {
 	box-shadow-color: #c6cbd1;
 }
 
-#theme-picker, #settings-menu, .help-button, #copy-path {
+#theme-picker, #settings-menu, #help-button, #copy-path {
 	border-color: #5c6773;
 	background-color: #0f1419;
 	color: #fff;
@@ -515,7 +515,7 @@ kbd {
 
 #theme-picker:hover, #theme-picker:focus,
 #settings-menu:hover, #settings-menu:focus,
-.help-button:hover, .help-button:focus,
+#help-button:hover, #help-button:focus,
 #copy-path:hover, #copy-path:focus {
 	border-color: #e0e0e0;
 }
diff --git a/src/librustdoc/html/static/themes/dark.css b/src/librustdoc/html/static/themes/dark.css
index 715605d7b37..8ee51d39c92 100644
--- a/src/librustdoc/html/static/themes/dark.css
+++ b/src/librustdoc/html/static/themes/dark.css
@@ -393,7 +393,7 @@ kbd {
 	box-shadow-color: #c6cbd1;
 }
 
-#theme-picker, #settings-menu, .help-button, #copy-path {
+#theme-picker, #settings-menu, #help-button, #copy-path {
 	border-color: #e0e0e0;
 	background: #f0f0f0;
 	color: #000;
@@ -401,7 +401,7 @@ kbd {
 
 #theme-picker:hover, #theme-picker:focus,
 #settings-menu:hover, #settings-menu:focus,
-.help-button:hover, .help-button:focus,
+#help-button:hover, #help-button:focus,
 #copy-path:hover, #copy-path:focus {
 	border-color: #ffb900;
 }
diff --git a/src/librustdoc/html/static/themes/light.css b/src/librustdoc/html/static/themes/light.css
index 60ed8898793..e0efcfe2249 100644
--- a/src/librustdoc/html/static/themes/light.css
+++ b/src/librustdoc/html/static/themes/light.css
@@ -385,14 +385,14 @@ kbd {
 	box-shadow-color: #c6cbd1;
 }
 
-#theme-picker, #settings-menu, .help-button, #copy-path {
+#theme-picker, #settings-menu, #help-button, #copy-path {
 	border-color: #e0e0e0;
 	background-color: #fff;
 }
 
 #theme-picker:hover, #theme-picker:focus,
 #settings-menu:hover, #settings-menu:focus,
-.help-button:hover, .help-button:focus,
+#help-button:hover, #help-button:focus,
 #copy-path:hover, #copy-path:focus {
 	border-color: #717171;
 }