Optimize moveAnchor

- Also fix support for offset > 1.
danny0838 · Apr 21, 2024 · 59105a9 · 59105a9
1 parent 9c4779c
commit 59105a9
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Showing 2 changed files with 82 additions and 50 deletions.
diff --git a/sts/data/htmlpage.tpl.html b/sts/data/htmlpage.tpl.html
@@ -41,36 +41,52 @@
 .popup a:not([tabindex="0"])::before { content: attr(tabindex) "."; }
 </style>
 <script>
-function moveAnchor(anchor, offset, filter) {
-  const viewer = document.querySelector('#viewer');
-  const anchors = viewer.querySelectorAll('a');
-  const len = anchors.length;
-
-  // no anchor, it's impossible to move
-  if (len === 0) {
-    return false;
+function* walkThroughAnchors(anchor, direction) {
+  let a = anchor;
+  if (direction > 0) {
+    while (a = a.nextElementSibling) {
+      if (a === anchor) { return; }
+      yield a;
+    }
+    if (a = anchor.parentNode.firstElementChild) {
+      if (a === anchor) { return; }
+      yield a;
+      while (a = a.nextElementSibling) {
+        if (a === anchor) { return; }
+        yield a;
+      }
+    }
+    return;
   }
-
-  let idx = Array.prototype.indexOf.call(anchors, anchor);
-
-  if (idx === -1) {
-    throw new Error(`specified anchor is invalid`);
+  if (direction < 0) {
+    while (a = a.previousElementSibling) {
+      if (a === anchor) { return; }
+      yield a;
+    }
+    if (a = anchor.parentNode.lastElementChild) {
+      if (a === anchor) { return; }
+      yield a;
+      while (a = a.previousElementSibling) {
+        if (a === anchor) { return; }
+        yield a;
+      }
+    }
+    return;
   }
+}
 
-  let anchorNew;
-  while (true) {
-    idx += offset;
-    while (idx >= len) { idx -= len; }
-    while (idx < 0) { idx += len; }
-    anchorNew = anchors[idx];
-    if (anchorNew === anchor) {
-      return false;
-    }
-    if (typeof filter !== "function" || filter(anchorNew)) {
-      break;
+function moveAnchor(anchor, offset, filter) {
+  let i = Math.abs(offset);
+  for (const a of walkThroughAnchors(anchor, offset)) {
+    if (typeof filter !== "function" || filter(a)) {
+      if (i > 1) {
+        i--;
+        continue;
+      }
+      return a;
     }
   }
-  return anchorNew;
+  return null;
 }
 
 function moveCandidate(anchor, offset, filter) {

diff --git a/sts/data/htmlpage/index.js b/sts/data/htmlpage/index.js
@@ -1,33 +1,49 @@
-function moveAnchor(anchor, offset, filter) {
-  const viewer = document.querySelector('#viewer');
-  const anchors = viewer.querySelectorAll('a');
-  const len = anchors.length;
-
-  // no anchor, it's impossible to move
-  if (len === 0) {
-    return false;
+function* walkThroughAnchors(anchor, direction) {
+  let a = anchor;
+  if (direction > 0) {
+    while (a = a.nextElementSibling) {
+      if (a === anchor) { return; }
+      yield a;
+    }
+    if (a = anchor.parentNode.firstElementChild) {
+      if (a === anchor) { return; }
+      yield a;
+      while (a = a.nextElementSibling) {
+        if (a === anchor) { return; }
+        yield a;
+      }
+    }
+    return;
   }
-
-  let idx = Array.prototype.indexOf.call(anchors, anchor);
-
-  if (idx === -1) {
-    throw new Error(`specified anchor is invalid`);
+  if (direction < 0) {
+    while (a = a.previousElementSibling) {
+      if (a === anchor) { return; }
+      yield a;
+    }
+    if (a = anchor.parentNode.lastElementChild) {
+      if (a === anchor) { return; }
+      yield a;
+      while (a = a.previousElementSibling) {
+        if (a === anchor) { return; }
+        yield a;
+      }
+    }
+    return;
   }
+}
 
-  let anchorNew;
-  while (true) {
-    idx += offset;
-    while (idx >= len) { idx -= len; }
-    while (idx < 0) { idx += len; }
-    anchorNew = anchors[idx];
-    if (anchorNew === anchor) {
-      return false;
-    }
-    if (typeof filter !== "function" || filter(anchorNew)) {
-      break;
+function moveAnchor(anchor, offset, filter) {
+  let i = Math.abs(offset);
+  for (const a of walkThroughAnchors(anchor, offset)) {
+    if (typeof filter !== "function" || filter(a)) {
+      if (i > 1) {
+        i--;
+        continue;
+      }
+      return a;
     }
   }
-  return anchorNew;
+  return null;
 }
 
 function moveCandidate(anchor, offset, filter) {