Function clipToLen

static/js/codemirror/codemirror.js:2286–2291

(pos, linelen)

    return clipToLen(pos, getLine(doc, pos.line).text.length);
  }
  function clipToLen(pos, linelen) {
    var ch = pos.ch;
    if (ch == null || ch > linelen) return Pos(pos.line, linelen);
    else if (ch < 0) return Pos(pos.line, 0);
    else return pos;
  }
  function isLine(doc, l) {return l >= doc.first && l < doc.first + doc.size;}

  // If shift is held, this will move the selection anchor. Otherwise,