private ExpressionCompilationResult Compile()
{
_operations = null;
var result = new ExpressionCompilationResult {
Success = true
};
if (!string.IsNullOrEmpty(_statement))
{
try
{
var tokens = ExpressionLexer.Tokenize(_statement);
_operations = ExpressionParser.Parse(tokens);
}
catch (ExpressionTokenizeException exception)
{
result.Success = false;
result.Message = string.Format(_expressionTokenizeError, _statement, exception.Location, exception.Message);
}
catch (ExpressionParseException exception)
{
result.Success = false;
result.Message = string.Format(_expressionParseError, _statement, exception.Location, exception.Message);
}
}
return(result);
}
private static List <VariableToken> Parse(string variable)
{
var parsed = new List <VariableToken>();
var tokens = ExpressionLexer.Tokenize(variable);
var state = ExpressionTokenType.Identifier;
foreach (var token in tokens)
{
var text = variable.Substring(token.Start, token.End - token.Start);
if (!CheckState(state, token))
{
return(new List <VariableToken>());
}
switch (token.Type)
{
case ExpressionTokenType.Identifier:
{
parsed.Add(new VariableToken {
Type = state == ExpressionTokenType.Command ? VariableTokenType.Type : VariableTokenType.Name, Text = text
});
state = ExpressionTokenType.Operator;
break;
}
case ExpressionTokenType.Int:
{
parsed.Add(new VariableToken {
Type = VariableTokenType.Number, Text = text
});
state = ExpressionTokenType.EndLookup;
break;
}
case ExpressionTokenType.Operator:
{
if (text == Cast)
{
state = ExpressionTokenType.Command;
}
else if (text.Length == 1 && text[0] == Separator)
{
state = ExpressionTokenType.Identifier;
}
else
{
return(new List <VariableToken>());
}
break;
}
case ExpressionTokenType.StartLookup:
{
state = ExpressionTokenType.Int;
break;
}
case ExpressionTokenType.EndLookup:
{
state = ExpressionTokenType.Operator;
break;
}
default:
{
return(new List <VariableToken>());
}
}
}
return(state == ExpressionTokenType.Operator ? parsed : new List <VariableToken>());
}