Added Queued Pastes

site/queued-pastes/queue.mjs

@@ -0,0 +1,44 @@
+// Pure queue logic for the Queued Pastes tool. Kept free of DOM and
+// clipboard APIs so it can be unit tested under Node (see queue.test.mjs).
+
+// Returns the range of the first line, excluding its trailing newline.
+export function firstLineRange(text) {
+  const newline = text.indexOf('\n');
+  return { start: 0, end: newline === -1 ? text.length : newline };
+}
+
+// Returns the first line of text, without its trailing newline.
+export function currentLine(text) {
+  const { start, end } = firstLineRange(text);
+  return text.slice(start, end);
+}
+
+// Returns the text with the first line (and its trailing newline) removed.
+export function advance(text) {
+  const newline = text.indexOf('\n');
+  return newline === -1 ? '' : text.slice(newline + 1);
+}
+
+// Returns the text to copy for the first line, honoring the
+// include-new-line setting.
+export function copyText(text, includeNewline) {
+  const line = currentLine(text);
+  return includeNewline ? line + '\n' : line;
+}
+
+// Returns the clipboard contents adjusted for a toggled include-new-line
+// setting, or null if the clipboard does not currently hold the given line
+// (in which case it must be left untouched).
+export function adjustCopiedLine(clipboardText, line, includeNewline) {
+  const stripped = clipboardText.endsWith('\n') ? clipboardText.slice(0, -1) : clipboardText;
+  if (stripped !== line) {
+    return null;
+  }
+  return includeNewline ? line + '\n' : line;
+}
+
+// Removes trailing whitespace (spaces, tabs, newlines) from the end of the
+// text, so enabling the queue does not leave phantom trailing lines.
+export function trimTrailing(text) {
+  return text.replace(/\s+$/, '');
+}