//
// Summary:
// Will either:
// - toggle current case
// - change to upper case
// - change to lower case
// of the characters of a given string.
//
// Parameters:
// inputStr:
// The string whose characters' case should be changed.
//
// initialInputStringOffset:
// The offset of the first character of the given string.
//
// selectionSpan:
// The document span which (partially) contains the given string.
//
// operation:
// null - toggle current case
// true - change to upper case
// false - change to lower case
//
// Returns:
// The result string after chaning its character case according to the specified operation.
//
internal static string CharacterCaseSwitchingHelper(string inputStr, int initialInputStringOffset, DocumentSpan selectionSpan, bool?operation)
{
StringBuilder builder = new StringBuilder(inputStr.Length);
int offsetInRun = initialInputStringOffset;
foreach (char c in inputStr)
{
// check if the offset of the current string character is intersecting with the selection's current document span
// (a selection may consists of more than one document span)
if (selectionSpan.Contains(offsetInRun))
{
// if current character is intersecting with the document span -> execute the operation over that character
if (!operation.HasValue)
{
builder.Append(char.IsUpper(c) ? char.ToLower(c) : char.ToUpper(c));
}
else if (operation.Value)
{
builder.Append(char.ToUpper(c));
}
else
{
builder.Append(char.ToLower(c));
}
}
else
{
// if current character is not intersecting with the document span -> don't do anything
builder.Append(c);
}
offsetInRun++;
}
return(builder.ToString());
}
