Function leftButtonSelect

GUI/codemirror/lib/codemirror.js:2611–2744

(cm, e, start, type, addNew)

  // Normal selection, as opposed to text dragging.
  function leftButtonSelect(cm, e, start, type, addNew) {
    var display = cm.display, doc = cm.doc;
    e_preventDefault(e);

    var ourRange, ourIndex, startSel = doc.sel;
    if (addNew && !e.shiftKey) {
      ourIndex = doc.sel.contains(start);
      if (ourIndex > -1)
        ourRange = doc.sel.ranges[ourIndex];
      else
        ourRange = new Range(start, start);
    } else {
      ourRange = doc.sel.primary();
    }

    if (e.altKey) {
      type = "rect";
      if (!addNew) ourRange = new Range(start, start);
      start = posFromMouse(cm, e, true, true);
      ourIndex = -1;
    } else if (type == "double") {
      var word = findWordAt(doc, start);
      if (cm.display.shift || doc.extend)
        ourRange = extendRange(doc, ourRange, word.anchor, word.head);
      else
        ourRange = word;
    } else if (type == "triple") {
      var line = new Range(Pos(start.line, 0), clipPos(doc, Pos(start.line + 1, 0)));
      if (cm.display.shift || doc.extend)
        ourRange = extendRange(doc, ourRange, line.anchor, line.head);
      else
        ourRange = line;
    } else {
      ourRange = extendRange(doc, ourRange, start);
    }

    if (!addNew) {
      ourIndex = 0;
      setSelection(doc, new Selection([ourRange], 0), sel_mouse);
      startSel = doc.sel;
    } else if (ourIndex > -1) {
      replaceOneSelection(doc, ourIndex, ourRange, sel_mouse);
    } else {
      ourIndex = doc.sel.ranges.length;
      setSelection(doc, normalizeSelection(doc.sel.ranges.concat([ourRange]), ourIndex),
                   {scroll: false, origin: "*mouse"});
    }

    var lastPos = start;
    function extendTo(pos) {
      if (cmp(lastPos, pos) == 0) return;
      lastPos = pos;

      if (type == "rect") {
        var ranges = [], tabSize = cm.options.tabSize;
        var startCol = countColumn(getLine(doc, start.line).text, start.ch, tabSize);
        var posCol = countColumn(getLine(doc, pos.line).text, pos.ch, tabSize);
        var left = Math.min(startCol, posCol), right = Math.max(startCol, posCol);