/// <summary>
/// Creates a <see cref="string"/> from a C string.
/// </summary>
/// <param name="ptr">The pointer to read from.</param>
/// <param name="option">The string trim options.</param>
/// <returns>
/// A managed string that holds a copy of the C string.
/// </returns>
internal static unsafe string FromCString(byte *ptr, StringTrimOption option)
{
if (!TryGetCStringLength(ptr, out int length))
{
return(null);
}
return(FromCString(ptr, length, option));
}
/// <summary>
/// Creates a <see cref="string"/> from a Pascal string.
/// </summary>
/// <param name="pascalString">The pascal string to convert.</param>
/// <returns>
/// A managed string that holds a copy of the Pascal string.
/// If <paramref name="pascalString"/> is null, the method returns null.
/// </returns>
internal static unsafe string FromPascalString(byte *pascalString, StringTrimOption option)
{
if (pascalString == null)
{
return(null);
}
TrimmedStringOffsets trimmed = GetTrimmedStringOffsets(pascalString, 1, pascalString[0], option);
if (trimmed.IsEmptyString)
{
return(string.Empty);
}
else
{
return(new string((sbyte *)pascalString, trimmed.startIndex, trimmed.length, Windows1252Encoding));
}
}
/// <summary>
/// Creates a <see cref="string"/> from a C string that is UTF-16LE encoded.
/// </summary>
/// <param name="ptr">The pointer to read from.</param>
/// <param name="length">The length of the string.</param>
/// <param name="option">The string trim options.</param>
/// <returns>
/// A managed string that holds a copy of the C string.
/// </returns>
internal static unsafe string FromCStringUni(char *ptr, int length, StringTrimOption option)
{
if (ptr == null)
{
return(null);
}
TrimmedStringOffsets stringOffsets = GetTrimmedStringOffsets(ptr, 0, length, option);
if (stringOffsets.IsEmptyString)
{
return(string.Empty);
}
else
{
return(new string(ptr, stringOffsets.startIndex, stringOffsets.length));
}
}
/// <summary>
/// Creates a <see cref="string"/> from a C string.
/// </summary>
/// <param name="ptr">The pointer to read from.</param>
/// <param name="length">The length of the string.</param>
/// <param name="option">The string trim options.</param>
/// <returns>
/// A managed string that holds a copy of the C string.
/// </returns>
internal static unsafe string FromCString(byte *ptr, int length, StringTrimOption option)
{
if (ptr == null)
{
return(null);
}
TrimmedStringOffsets stringOffsets = GetTrimmedStringOffsets(ptr, 0, length, option);
if (stringOffsets.IsEmptyString)
{
return(string.Empty);
}
else
{
return(new string((sbyte *)ptr, stringOffsets.startIndex, stringOffsets.length, Windows1252Encoding));
}
}
private static bool IsTrimmedValue(char value, StringTrimOption option)
{
switch (option)
{
case StringTrimOption.None:
return(false);
case StringTrimOption.NullTerminator:
return(value == '\0');
case StringTrimOption.WhiteSpace:
return(char.IsWhiteSpace(value));
case StringTrimOption.WhiteSpaceAndNullTerminator:
return(value == '\0' || char.IsWhiteSpace(value));
default:
throw new InvalidEnumArgumentException(nameof(option), (int)option, typeof(StringTrimOption));
}
}
private static bool IsTrimmedValue(byte value, StringTrimOption option)
{
switch (option)
{
case StringTrimOption.None:
return(false);
case StringTrimOption.NullTerminator:
return(value == 0);
case StringTrimOption.WhiteSpace:
return(IsWhiteSpaceWindows1252(value));
case StringTrimOption.WhiteSpaceAndNullTerminator:
return(value == 0 || IsWhiteSpaceWindows1252(value));
default:
throw new InvalidEnumArgumentException(nameof(option), (int)option, typeof(StringTrimOption));
}
}
private static unsafe TrimmedStringOffsets GetTrimmedStringOffsets(char *ptr, int startIndex, int length, StringTrimOption option)
{
if (length == 0 || option == StringTrimOption.None)
{
return(new TrimmedStringOffsets(startIndex, length));
}
int start = startIndex;
int end = length;
// The search at the start of the string can be skipped if we not trimming white space.
if (option == StringTrimOption.WhiteSpaceAndNullTerminator || option == StringTrimOption.WhiteSpace)
{
while (start < length)
{
if (!IsTrimmedValue(ptr[start], option))
{
break;
}
start++;
}
}
while (end >= start)
{
if (!IsTrimmedValue(ptr[end], option))
{
break;
}
end--;
}
return(new TrimmedStringOffsets(start, end - start + 1));
}
