/// <summary>
/// Parse a part (real or complex) from a complex number.
/// </summary>
/// <param name="token">Start Token.</param>
/// <param name="imaginary">Is set to <c>true</c> if the part identified itself as being imaginary.</param>
/// <param name="format">
/// An <see cref="IFormatProvider"/> that supplies culture-specific
/// formatting information.
/// </param>
/// <returns>Resulting part as double.</returns>
/// <exception cref="FormatException"/>
private static double ParsePart(ref LinkedListNode <string> token, out bool imaginary, IFormatProvider format)
{
imaginary = false;
if (token == null)
{
throw new FormatException();
}
// handle prefix modifiers
if (token.Value == "+")
{
token = token.Next;
if (token == null)
{
throw new FormatException();
}
}
var negative = false;
if (token.Value == "-")
{
negative = true;
token = token.Next;
if (token == null)
{
throw new FormatException();
}
}
// handle prefix imaginary symbol
if (String.Compare(token.Value, "i", StringComparison.OrdinalIgnoreCase) == 0 ||
String.Compare(token.Value, "j", StringComparison.OrdinalIgnoreCase) == 0)
{
imaginary = true;
token = token.Next;
if (token == null)
{
return(negative ? -1 : 1);
}
}
#if NETSTANDARD1_3
var value = GlobalizationHelper.ParseDouble(ref token);
#else
var value = GlobalizationHelper.ParseDouble(ref token, format.GetCultureInfo());
#endif
// handle suffix imaginary symbol
if (token != null && (String.Compare(token.Value, "i", StringComparison.OrdinalIgnoreCase) == 0 ||
String.Compare(token.Value, "j", StringComparison.OrdinalIgnoreCase) == 0))
{
if (imaginary)
{
// only one time allowed: either prefix or suffix, or neither.
throw new FormatException();
}
imaginary = true;
token = token.Next;
}
return(negative ? -value : value);
}
/// <summary>
/// Creates a complex number based on a string. The string can be in the
/// following formats (without the quotes): 'n', 'ni', 'n +/- ni',
/// 'ni +/- n', 'n,n', 'n,ni,' '(n,n)', or '(n,ni)', where n is a double.
/// </summary>
/// <returns>
/// A complex number containing the value specified by the given string.
/// </returns>
/// <param name="value">
/// the string to parse.
/// </param>
/// <param name="formatProvider">
/// An <see cref="IFormatProvider"/> that supplies culture-specific
/// formatting information.
/// </param>
public static Complex ToComplex(this string value, IFormatProvider formatProvider)
{
if (value == null)
{
throw new ArgumentNullException(nameof(value));
}
value = value.Trim();
if (value.Length == 0)
{
throw new FormatException();
}
// strip out parens
if (value.StartsWith("(", StringComparison.Ordinal))
{
if (!value.EndsWith(")", StringComparison.Ordinal))
{
throw new FormatException();
}
value = value.Substring(1, value.Length - 2).Trim();
}
// keywords
var numberFormatInfo = formatProvider.GetNumberFormatInfo();
var textInfo = formatProvider.GetTextInfo();
var keywords =
new[]
{
textInfo.ListSeparator, numberFormatInfo.NaNSymbol,
numberFormatInfo.NegativeInfinitySymbol, numberFormatInfo.PositiveInfinitySymbol,
"+", "-", "i", "j"
};
// lexing
var tokens = new LinkedList <string>();
GlobalizationHelper.Tokenize(tokens.AddFirst(value), keywords, 0);
var token = tokens.First;
// parse the left part
bool isLeftPartImaginary;
var leftPart = ParsePart(ref token, out isLeftPartImaginary, formatProvider);
if (token == null)
{
return(isLeftPartImaginary ? new Complex(0, leftPart) : new Complex(leftPart, 0));
}
// parse the right part
if (token.Value == textInfo.ListSeparator)
{
// format: real,imag
token = token.Next;
if (isLeftPartImaginary)
{
// left must not contain 'i', right doesn't matter.
throw new FormatException();
}
bool isRightPartImaginary;
var rightPart = ParsePart(ref token, out isRightPartImaginary, formatProvider);
return(new Complex(leftPart, rightPart));
}
else
{
// format: real + imag
bool isRightPartImaginary;
var rightPart = ParsePart(ref token, out isRightPartImaginary, formatProvider);
if (!(isLeftPartImaginary ^ isRightPartImaginary))
{
// either left or right part must contain 'i', but not both.
throw new FormatException();
}
return(isLeftPartImaginary ? new Complex(rightPart, leftPart) : new Complex(leftPart, rightPart));
}
}
