Function regChange

external/.scrollLibs.js:5580–5653

(cm, from, to, lendiff)

  // lines are divided into visual lines. regLineChange (below)
  // registers single-line changes.
  function regChange(cm, from, to, lendiff) {
    if (from == null) {
      from = cm.doc.first
    }
    if (to == null) {
      to = cm.doc.first + cm.doc.size
    }
    if (!lendiff) {
      lendiff = 0
    }

    var display = cm.display
    if (lendiff && to < display.viewTo && (display.updateLineNumbers == null || display.updateLineNumbers > from)) {
      display.updateLineNumbers = from
    }

    cm.curOp.viewChanged = true

    if (from >= display.viewTo) {
      // Change after
      if (sawCollapsedSpans && visualLineNo(cm.doc, from) < display.viewTo) {
        resetView(cm)
      }
    } else if (to <= display.viewFrom) {
      // Change before
      if (sawCollapsedSpans && visualLineEndNo(cm.doc, to + lendiff) > display.viewFrom) {
        resetView(cm)
      } else {
        display.viewFrom += lendiff
        display.viewTo += lendiff
      }
    } else if (from <= display.viewFrom && to >= display.viewTo) {
      // Full overlap
      resetView(cm)
    } else if (from <= display.viewFrom) {
      // Top overlap
      var cut = viewCuttingPoint(cm, to, to + lendiff, 1)
      if (cut) {
        display.view = display.view.slice(cut.index)
        display.viewFrom = cut.lineN
        display.viewTo += lendiff
      } else {
        resetView(cm)
      }
    } else if (to >= display.viewTo) {
      // Bottom overlap
      var cut$1 = viewCuttingPoint(cm, from, from, -1)
      if (cut$1) {
        display.view = display.view.slice(0, cut$1.index)
        display.viewTo = cut$1.lineN
      } else {
        resetView(cm)
      }
    } else {
      // Gap in the middle
      var cutTop = viewCuttingPoint(cm, from, from, -1)
      var cutBot = viewCuttingPoint(cm, to, to + lendiff, 1)
      if (cutTop && cutBot) {