/// <summary>
/// If <paramref name="value"/> is <see langword="null"/> or empty, removes the entry with <paramref name="name"/> (if any).
/// Otherwise, removes existing entries with <paramref name="name"/> and inserts an new entry.
/// </summary>
// Insertion sort should be sufficient. Generally we do not have tens of extra environment variables.
public void InsertOrRemove(string name, string value)
{
EnvironmentVariableUtil.ValidateNameAndValue(name, value);
var(start, end) = SearchMatchingElements(_array.AsSpan(0, _count), name);
Debug.Assert(end >= start);
if (string.IsNullOrEmpty(value))
{
// Remove
if (start == end)
{
// _array does not have any element with the name. Do nothing.
}
else
{
// Remove the matching elements.
Array.Copy(_array, end, _array, start, _count - end);
_count -= end - start;
}
}
else
{
// Insert
if (start == end)
{
// _array does not have any element with the name. Insert the new element.
Array.Copy(_array, end, _array, end + 1, _count - end);
_array[start] = new(name, value);
_count++;
}
else if (end == start + 1)
{
// _array has exactly one element with the name. Just overwrite it.
_array[start] = new(name, value);
}
else
{
// _array has multiple elements with the name. Overwrite the first one and remove the rest.
_array[start] = new(name, value);
Array.Copy(_array, end, _array, start + 1, _count - end);
_count -= end - start - 1;
}
}
}
