Fix: ts-morph incorrectly transforms nodes which begin with whitespace

[ofersadgat]

Fixes: #1591

Note that using .pos matches what typescript is doing as well:

function visitNodes2(nodes, visitor, test, start, count) {
  if (nodes === void 0) {
    return nodes;
  }
  const length2 = nodes.length;
  if (start === void 0 || start < 0) {
    start = 0;
  }
  if (count === void 0 || count > length2 - start) {
    count = length2 - start;
  }
  let hasTrailingComma;
  let pos = -1;
  let end = -1;
  if (start > 0 || count < length2) {
    hasTrailingComma = nodes.hasTrailingComma && start + count === length2;
  } else {
    pos = nodes.pos;
    end = nodes.end;
    hasTrailingComma = nodes.hasTrailingComma;
  }
  const updated = visitArrayWorker(nodes, visitor, test, start, count); 
  if (updated !== nodes) {
    const updatedArray = factory.createNodeArray(updated, hasTrailingComma);
    setTextRangePosEnd(updatedArray, pos, end);
    return updatedArray;
  }
  return nodes;
}

The line:
const updated = visitArrayWorker(nodes, visitor, test, start, count);
is calling visitArrayWorker which calls innerVisit which first calls the transform function followed by the handleTransformation function. So, on the way out typescript is using .pos as well.

[dsherret]

I'm not sure this is correct and it seems to cause some tests to fail.

[ofersadgat]

@dsherret Hi, I have done some more due diligence here. The code IS incorrect for a specific circumstance: JsxText. The reason for this is that getStart(true) includes comments but excludes leading whitespace. The problem, as you've mentioned elsewhere, is that leading whitespace is actually a part of a JsxText node. Therefore, excluding that when you're doing a transform is incorrect. This leads to the result of continually prepending whitespace to the transformed jsx node.

You run into a similar situation with replaceWithText(). This function similarly also doesnt include leading whitespace. This leads to the problem:

const text = node.getFullText();
node.replaceWithText(text);

this will also prepend whitespace which is counter intuitive. Also, afaict there isnt an api around this. So I have added an option into the replaceWithText api to allow replacing the full thing. If there is a prefered alternative change, lmk.