Function executeToggleCase

src/vim/operators.ts:222–253

(count: number, ctx: OperatorContext)

 * Execute toggle case (~ command).
 */
export function executeToggleCase(count: number, ctx: OperatorContext): void {
  const startOffset = ctx.cursor.offset

  if (startOffset >= ctx.text.length) return

  let newText = ctx.text
  let offset = startOffset
  let toggled = 0

  while (offset < newText.length && toggled < count) {
    const grapheme = firstGrapheme(newText.slice(offset))
    const graphemeLen = grapheme.length

    const toggledGrapheme =
      grapheme === grapheme.toUpperCase()
        ? grapheme.toLowerCase()
        : grapheme.toUpperCase()

    newText =
      newText.slice(0, offset) +
      toggledGrapheme +
      newText.slice(offset + graphemeLen)
    offset += toggledGrapheme.length
    toggled++
  }

  ctx.setText(newText)
  // Cursor moves to position after the last toggled character
  // At end of line, cursor can be at the "end" position
  ctx.setOffset(offset)
  ctx.recordChange({ type: 'toggleCase', count })
}

/**
 * Execute join lines (J command).