Function updateDoc

GUI/codemirror/lib/codemirror.js:5927–5970

(doc, change, markedSpans, estimateHeight)

  // Perform a change on the document data structure.
  function updateDoc(doc, change, markedSpans, estimateHeight) {
    function spansFor(n) {return markedSpans ? markedSpans[n] : null;}
    function update(line, text, spans) {
      updateLine(line, text, spans, estimateHeight);
      signalLater(line, "change", line, change);
    }

    var from = change.from, to = change.to, text = change.text;
    var firstLine = getLine(doc, from.line), lastLine = getLine(doc, to.line);
    var lastText = lst(text), lastSpans = spansFor(text.length - 1), nlines = to.line - from.line;

    // Adjust the line structure
    if (isWholeLineUpdate(doc, change)) {
      // This is a whole-line replace. Treated specially to make
      // sure line objects move the way they are supposed to.
      for (var i = 0, added = []; i < text.length - 1; ++i)
        added.push(new Line(text[i], spansFor(i), estimateHeight));
      update(lastLine, lastLine.text, lastSpans);
      if (nlines) doc.remove(from.line, nlines);
      if (added.length) doc.insert(from.line, added);
    } else if (firstLine == lastLine) {
      if (text.length == 1) {
        update(firstLine, firstLine.text.slice(0, from.ch) + lastText + firstLine.text.slice(to.ch), lastSpans);
      } else {
        for (var added = [], i = 1; i < text.length - 1; ++i)
          added.push(new Line(text[i], spansFor(i), estimateHeight));
        added.push(new Line(lastText + firstLine.text.slice(to.ch), lastSpans, estimateHeight));
        update(firstLine, firstLine.text.slice(0, from.ch) + text[0], spansFor(0));
        doc.insert(from.line + 1, added);
      }
    } else if (text.length == 1) {
      update(firstLine, firstLine.text.slice(0, from.ch) + text[0] + lastLine.text.slice(to.ch), spansFor(0));
      doc.remove(from.line + 1, nlines);
    } else {
      update(firstLine, firstLine.text.slice(0, from.ch) + text[0], spansFor(0));
      update(lastLine, lastText + lastLine.text.slice(to.ch), lastSpans);
      for (var i = 1, added = []; i < text.length - 1; ++i)
        added.push(new Line(text[i], spansFor(i), estimateHeight));
      if (nlines > 1) doc.remove(from.line + 1, nlines - 1);
      doc.insert(from.line + 1, added);
    }

    signalLater(doc, "change", doc, change);
  }

  // The document is represented as a BTree consisting of leaves, with
  // chunk of lines in them, and branches, with up to ten leaves or