protected virtual string ReadIdent()
{
var sb = new StringBuilder();
char ch = _reader.NextChar;
sb.Append(ch);
ch = _reader.Next();
while (CommandStream.IsAlpha(ch) || CommandStream.IsDigit(ch))
{
sb.Append(ch);
ch = _reader.Next();
}
return(sb.ToString());
}
protected virtual bool IsIdentStart(char ch)
{
return(CommandStream.IsAlpha(ch));
}
public ExpressionParser(CommandStream reader) : base(reader)
{
}
protected virtual void ScanNextToken()
{
char ch = _reader.NextChar;
if (IsToken("||", false, false))
{
_state._detailToken = ETokenType.XOrSy;
return;
}
if (IsToken("<<", false, false))
{
_state._detailToken = ETokenType.BitShiftLeftSy;
return;
}
if (IsToken(">>", false, false))
{
_state._detailToken = ETokenType.BitShiftRightSy;
return;
}
if (IsToken("==", false, false))
{
_state._detailToken = ETokenType.EqualSy;
return;
}
if (IsToken("!=", false, false))
{
_state._detailToken = ETokenType.UnEqualSy;
return;
}
if (IsToken(">=", false, false))
{
_state._detailToken = ETokenType.GreaterEqualSy;
return;
}
if (IsToken("<=", false, false))
{
_state._detailToken = ETokenType.LessEqualSy;
return;
}
if (ch == LeftParenthesis)
{
_state._detailToken = ETokenType.LeftParenthesisSy;
_reader.Next();
return;
}
if (ch == RightParenthesis)
{
_state._detailToken = ETokenType.RightParenthesisSy;
_reader.Next();
return;
}
switch (ch)
{
case '>':
_state._detailToken = ETokenType.GreaterSy;
_reader.Next();
return;
case '<':
_state._detailToken = ETokenType.LessSy;
_reader.Next();
return;
case '&':
_state._detailToken = ETokenType.AndSy;
_reader.Next();
return;
case '|':
_state._detailToken = ETokenType.OrSy;
_reader.Next();
return;
case '-':
_state._detailToken = ETokenType.MinusSy;
_reader.Next();
return;
case '+':
_state._detailToken = ETokenType.PlusSy;
_reader.Next();
return;
case '*':
_state._detailToken = ETokenType.MultiplySy;
_reader.Next();
return;
case '/':
_state._detailToken = ETokenType.DivideSy;
_reader.Next();
return;
case '%':
_state._detailToken = ETokenType.ModuloSy;
_reader.Next();
return;
case '^':
_state._detailToken = ETokenType.PowSy;
_reader.Next();
return;
case '!':
_state._detailToken = ETokenType.FactorialSy;
_reader.Next();
return;
case '=':
_state._detailToken = ETokenType.AssignSy;
_reader.Next();
return;
}
// check for a value
if (CommandStream.IsNumber(ch))
{
_state._detailToken = ETokenType.FloatSy;
_state._number = _reader.GetDouble(out bool istFloatingPoint);
return;
}
// check for variables or functions
if (IsIdentStart(ch))
{
var start = ReadIdent();
ch = _reader.SkipSpaces();
// check if this is a variable or a function.
// a function has a parenthesis '(' open after the name
if (ch == LeftParenthesis)
{
switch (start.ToUpper())
{
case "ABS":
_state._detailToken = ETokenType.AbsSy;
return;
case "EXP":
_state._detailToken = ETokenType.ExpSy;
return;
case "SIGN":
_state._detailToken = ETokenType.SignSy;
return;
case "SQRT":
_state._detailToken = ETokenType.SqrtSy;
return;
case "LOG":
_state._detailToken = ETokenType.LogSy;
return;
case "LOG10":
_state._detailToken = ETokenType.Log10Sy;
return;
case "SIN":
_state._detailToken = ETokenType.SinSy;
return;
case "COS":
_state._detailToken = ETokenType.CosSy;
return;
case "TAN":
_state._detailToken = ETokenType.TanSy;
return;
case "ASIN":
_state._detailToken = ETokenType.AsinSy;
return;
case "ACOS":
_state._detailToken = ETokenType.AcosSy;
return;
case "ATAN":
_state._detailToken = ETokenType.AtanSy;
return;
case "FACTORIAL":
_state._detailToken = ETokenType.FactorialFncSy;
return;
case "FIX":
_state._detailToken = ETokenType.FixSy;
return;
case "FUP":
_state._detailToken = ETokenType.FupSy;
return;
case "ROUND":
_state._detailToken = ETokenType.RoundSy;
return;
default:
Error(MESSAGE_EXPR_UNKNOWN_FUNCTION);
return;
}
}
else
{
_state._detailToken = ETokenType.VariableSy;
_state._variableOK = EvalVariable(start, ref _state._number);
}
return;
}
// something unknown is found, wrong characters -> a syntax error
_state._detailToken = ETokenType.UnknownSy;
Error(MESSAGE_EXPR_SYNTAX_ERROR);
}