1 files changed, 106 insertions, 0 deletions
diff --git a/src/librustdoc/html/static/js/scrape-examples.js b/src/librustdoc/html/static/js/scrape-examples.js
new file mode 100644
index 000000000..fd7a14497
--- /dev/null
+++ b/src/librustdoc/html/static/js/scrape-examples.js
@@ -0,0 +1,106 @@
+/* global addClass, hasClass, removeClass, onEachLazy */
+
+"use strict";
+
+(function() {
+    // Number of lines shown when code viewer is not expanded
+    const MAX_LINES = 10;
+
+    // Scroll code block to the given code location
+    function scrollToLoc(elt, loc) {
+        const lines = elt.querySelector(".line-numbers");
+        let scrollOffset;
+
+        // If the block is greater than the size of the viewer,
+        // then scroll to the top of the block. Otherwise scroll
+        // to the middle of the block.
+        if (loc[1] - loc[0] > MAX_LINES) {
+            const line = Math.max(0, loc[0] - 1);
+            scrollOffset = lines.children[line].offsetTop;
+        } else {
+            const wrapper = elt.querySelector(".code-wrapper");
+            const halfHeight = wrapper.offsetHeight / 2;
+            const offsetMid = (lines.children[loc[0]].offsetTop
+                             + lines.children[loc[1]].offsetTop) / 2;
+            scrollOffset = offsetMid - halfHeight;
+        }
+
+        lines.scrollTo(0, scrollOffset);
+        elt.querySelector(".rust").scrollTo(0, scrollOffset);
+    }
+
+    function updateScrapedExample(example) {
+        const locs = JSON.parse(example.attributes.getNamedItem("data-locs").textContent);
+        let locIndex = 0;
+        const highlights = Array.prototype.slice.call(example.querySelectorAll(".highlight"));
+        const link = example.querySelector(".scraped-example-title a");
+
+        if (locs.length > 1) {
+            // Toggle through list of examples in a given file
+            const onChangeLoc = changeIndex => {
+                removeClass(highlights[locIndex], "focus");
+                changeIndex();
+                scrollToLoc(example, locs[locIndex][0]);
+                addClass(highlights[locIndex], "focus");
+
+                const url = locs[locIndex][1];
+                const title = locs[locIndex][2];
+
+                link.href = url;
+                link.innerHTML = title;
+            };
+
+            example.querySelector(".prev")
+                .addEventListener("click", () => {
+                    onChangeLoc(() => {
+                        locIndex = (locIndex - 1 + locs.length) % locs.length;
+                    });
+                });
+
+            example.querySelector("next")
+                .addEventListener("click", () => {
+                    onChangeLoc(() => {
+                        locIndex = (locIndex + 1) % locs.length;
+                    });
+                });
+        }
+
+        const expandButton = example.querySelector(".expand");
+        if (expandButton) {
+            expandButton.addEventListener("click", () => {
+                if (hasClass(example, "expanded")) {
+                    removeClass(example, "expanded");
+                    scrollToLoc(example, locs[0][0]);
+                } else {
+                    addClass(example, "expanded");
+                }
+            });
+        }
+
+        // Start with the first example in view
+        scrollToLoc(example, locs[0][0]);
+    }
+
+    const firstExamples = document.querySelectorAll(".scraped-example-list > .scraped-example");
+    onEachLazy(firstExamples, updateScrapedExample);
+    onEachLazy(document.querySelectorAll(".more-examples-toggle"), toggle => {
+        // Allow users to click the left border of the <details> section to close it,
+        // since the section can be large and finding the [+] button is annoying.
+        onEachLazy(toggle.querySelectorAll(".toggle-line, .hide-more"), button => {
+            button.addEventListener("click", () => {
+                toggle.open = false;
+            });
+        });
+
+        const moreExamples = toggle.querySelectorAll(".scraped-example");
+        toggle.querySelector("summary").addEventListener("click", () => {
+            // Wrapping in setTimeout ensures the update happens after the elements are actually
+            // visible. This is necessary since updateScrapedExample calls scrollToLoc which
+            // depends on offsetHeight, a property that requires an element to be visible to
+            // compute correctly.
+            setTimeout(() => {
+                onEachLazy(moreExamples, updateScrapedExample);
+            });
+        }, {once: true});
+    });
+})();