static bool IsHexNumber(TokenStringReader reader)
{
if (!reader.HasNext(3))
{
return(false);
}
int c = reader.PeekForward(2);
return(reader.PeekForward() == '0' && reader.PeekForward(1) == 'x' && ((c >= '0' && c <= '7') || (c >= 'A' && c <= 'F')));
}
static bool IsOctalNumber(TokenStringReader reader)
{
if (!reader.HasNext(3))
{
return(false);
}
int c = reader.PeekForward(2);
return(reader.PeekForward() == '0' && reader.PeekForward(1) == 'o' && (c >= '0' && c <= '7'));
}
static bool IsBinaryNumber(TokenStringReader reader)
{
if (!reader.HasNext(3))
{
return(false);
}
int c = reader.PeekForward(2);
return(reader.PeekForward() == '0' && reader.PeekForward(1) == 'b' && (c == '0' || c == '1'));
}
/****************************/
static bool IsNumber(TokenStringReader reader)
{
if (!reader.HasNext())
{
return(false);
}
int c = reader.PeekForward();
return(c >= 48 && c <= 57);
}
static bool IsIdentifier(TokenStringReader reader)
{
if (!reader.HasNext())
{
return(false);
}
int c = reader.PeekForward();
return(!(c >= 48 && c <= 57) && (c == '_' || (c >= 65 && c <= 90) || (c >= 97 && c <= 122)));
}
public Lexer(TokenStringReader stream)
{
reader = stream;
}
/// <summary>
/// Identify a token for its type.
/// </summary>
/// <param name="reader">The reader with the wanted state to use for checking.</param>
/// <returns>The token type and advancement value.</returns>
public static (TokenType, int) Identify(TokenStringReader reader)
{
TokenType type = TokenType.Unknown;
int advance = 1; // amount of characters to advance for a token, for value parsing; advance the needed chars to get to the actual value
if (IsBinaryNumber(reader))
{
type = TokenType.BinaryNumber; advance = 2;
}
else if (IsOctalNumber(reader))
{
type = TokenType.OctalNumber; advance = 2;
}
else if (IsHexNumber(reader))
{
type = TokenType.HexNumber; advance = 2;
}
else if (IsNumber(reader))
{
type = TokenType.Number; advance = 0;
}
else if (IsLeftParenthesis(reader))
{
type = TokenType.LeftParenthesis;
}
else if (IsRightParenthesis(reader))
{
type = TokenType.RightParenthesis;
}
else if (IsPowerOperator(reader))
{
type = TokenType.PowerOperator;
}
else if (IsMultiplicationOperator(reader))
{
type = TokenType.MultiplicationOperator;
}
else if (IsDivisionOperator(reader))
{
type = TokenType.DivisionOperator;
}
else if (IsModuloOperator(reader))
{
type = TokenType.ModuloOperator;
}
else if (IsAndOperator(reader))
{
type = TokenType.AndOperator;
}
else if (IsXorOperator(reader))
{
type = TokenType.XorOperator;
}
else if (IsShiftLeftOperator(reader))
{
type = TokenType.ShiftLeftOperator; advance = 2;
}
else if (IsShiftRightOperator(reader))
{
type = TokenType.ShiftRightOperator; advance = 2;
}
else if (IsMinusOperator(reader))
{
type = TokenType.MinusOperator;
}
else if (IsNegationOperator(reader))
{
type = TokenType.NegationOperator;
}
else if (IsPlussOperator(reader))
{
type = TokenType.PlussOperator;
}
else if (IsOrOperator(reader))
{
type = TokenType.OrOperator;
}
else if (IsParamSeparator(reader))
{
type = TokenType.ParamSeparator;
}
else if (IsAssignmentOperator(reader))
{
type = TokenType.AssignmentOperator;
}
else if (IsFactorialOperator(reader))
{
type = TokenType.FactorialOperator;
}
else if (IsIdentifier(reader))
{
type = TokenType.Identifier; advance = 0;
}
return(type, advance);
}
static bool IsFactorialOperator(TokenStringReader reader)
{
return(reader.HasNext() && reader.PeekForward() == '!');
}
static bool IsAssignmentOperator(TokenStringReader reader)
{
return(reader.HasNext() && reader.PeekForward() == '=');
}
static bool IsParamSeparator(TokenStringReader reader)
{
return(reader.HasNext() && reader.PeekForward() == ',');
}
static bool IsPlussOperator(TokenStringReader reader)
{
return(reader.HasNext() && reader.PeekForward() == '+');
}
static bool IsNegationOperator(TokenStringReader reader)
{
return(reader.HasNext() && reader.PeekForward() == '~');
}
static bool IsShiftRightOperator(TokenStringReader reader)
{
return(reader.HasNext(2) && reader.PeekForward() == '>' && reader.PeekForward(1) == '>');
}
static bool IsModuloOperator(TokenStringReader reader)
{
return(reader.HasNext() && reader.PeekForward() == '%');
}
static bool IsRightParenthesis(TokenStringReader reader)
{
return(reader.HasNext() && reader.PeekForward() == ')');
}
