Deploying to gh-pages from @ 5ea95f8 🚀

ecmarkup.css

@@ -125,6 +125,7 @@ body.oldtoc {
 
 span[aria-hidden='true'] {
   font-size: 0;
+  white-space: pre;
 }
 
 a {
@@ -222,6 +223,10 @@ var.field {
   font: inherit;
   color: inherit;
 }
+/* suppress line break opportunities between `.` and `[[FieldName]]` */
+var.field::before {
+  content: '\2060'
+}
 
 var.referenced {
   color: inherit;

ecmarkup.js

@@ -1438,6 +1438,7 @@ const counterByDepth = [];
 function addStepNumberText(
   ol,
   depth = 0,
+  indent = '',
   special = [...ol.classList].some(c => c.startsWith('nested-')),
 ) {
   let counter = !special && counterByDepth[depth];
@@ -1461,16 +1462,19 @@ function addStepNumberText(
   let i = (Number(ol.getAttribute('start')) || 1) - 1;
   for (const li of ol.children) {
     const marker = document.createElement('span');
-    marker.textContent = `${i < cache.length ? cache[i] : getTextForIndex(i)}. `;
+    const markerText = i < cache.length ? cache[i] : getTextForIndex(i);
+    const extraIndent = ' '.repeat(markerText.length + 2);
+    marker.textContent = `${indent}${markerText}. `;
     marker.setAttribute('aria-hidden', 'true');
+    marker.setAttribute('class', 'list-marker');
     const attributesContainer = li.querySelector('.attributes-tag');
     if (attributesContainer == null) {
       li.prepend(marker);
     } else {
       attributesContainer.insertAdjacentElement('afterend', marker);
     }
     for (const sublist of li.querySelectorAll(':scope > ol')) {
-      addStepNumberText(sublist, depth + 1, special);
+      addStepNumberText(sublist, depth + 1, indent + extraIndent, special);
     }
     i++;
   }
@@ -1482,6 +1486,52 @@ document.addEventListener('DOMContentLoaded', () => {
   });
 });
 
+// Omit indendation when copying a single algorithm step.
+document.addEventListener('copy', evt => {
+  // Construct a DOM from the selection.
+  const doc = document.implementation.createHTMLDocument('');
+  const domRoot = doc.createElement('div');
+  const html = evt.clipboardData.getData('text/html');
+  if (html) {
+    domRoot.innerHTML = html;
+  } else {
+    const selection = getSelection();
+    const singleRange = selection?.rangeCount === 1 && selection.getRangeAt(0);
+    const container = singleRange?.commonAncestorContainer;
+    if (!container?.querySelector?.('.list-marker')) {
+      return;
+    }
+    domRoot.append(singleRange.cloneContents());
+  }
+
+  // Preserve the indentation if there is no hidden list marker, or if selection
+  // of more than one step is indicated by either multiple such markers or by
+  // visible text before the first one.
+  const listMarkers = domRoot.querySelectorAll('.list-marker');
+  if (listMarkers.length !== 1) {
+    return;
+  }
+  const treeWalker = document.createTreeWalker(domRoot, undefined, {
+    acceptNode(node) {
+      return node.nodeType === Node.TEXT_NODE || node === listMarkers[0]
+        ? NodeFilter.FILTER_ACCEPT
+        : NodeFilter.FILTER_SKIP;
+    },
+  });
+  while (treeWalker.nextNode()) {
+    const node = treeWalker.currentNode;
+    if (node.nodeType === Node.ELEMENT_NODE) break;
+    if (/\S/u.test(node.data)) return;
+  }
+
+  // Strip leading indentation from the plain text representation.
+  evt.clipboardData.setData('text/plain', domRoot.textContent.trimStart());
+  if (!html) {
+    evt.clipboardData.setData('text/html', domRoot.innerHTML);
+  }
+  evt.preventDefault();
+});
+
 'use strict';
 
 // Update superscripts to not suffer misinterpretation when copied and pasted as plain text.