private static void MoveToBreaker(ConditionContext context)
{
while (context.PeekCurrent.HasValue && !breakers.Contains(context.PeekCurrent))
{
context.MoveCurrent();
}
context.MoveCurrent();
}
public static Condition Parse(string condition)
{
var context = new ConditionContext(condition);
if (string.IsNullOrWhiteSpace(condition))
{
return(context.Condition);
}
Tokenise(context);
if (!context.Finished)
{
throw new InvalidConditionException(condition);
}
return(Stack(context.Values, condition));
}
private static void ProcessWord(ConditionContext context)
{
MoveToBreaker(context);
switch (context.CurrentWord)
{
case "or":
context.Push(new Or());
context.MoveToCurrent();
return;
case "and":
context.Push(new And());
context.MoveToCurrent();
return;
case "is":
context.MoveToCurrent();
if (context.PeekWord(" less than "))
{
context.MoveNext(11);
if (context.PeekWord("or equal "))
{
context.MoveNext(9);
context.Push(new LessThanEqual());
}
else
{
context.Push(new LessThan());
}
return;
}
else if (context.PeekWord(" greater than "))
{
context.MoveNext(14);
if (context.PeekWord("or equal "))
{
context.MoveNext(9);
context.Push(new GreaterThanEqual());
}
else
{
context.Push(new GreaterThan());
}
}
else if (context.PeekWord(" not "))
{
context.MoveNext(5);
context.Push(new NotEqual());
}
else
{
context.Push(new Equal());
}
return;
default:
if (context.CurrentWord.Trim().Length > 0)
{
context.Push(CorrectLiteral(context.CurrentWord.Trim()));
context.MoveToCurrent();
}
break;
}
}
public static void Tokenise(ConditionContext context)
{
while (!context.Finished)
{
while (context.NextChar.HasValue && context.NextChar == ' ')
{
context.MoveNext();
}
if (!context.NextChar.HasValue)
{
context.MoveNext();
break;
}
switch (context.NextChar)
{
case '(':
context.Push(new OpenGroup());
context.MoveNext();
continue;
case ')':
context.Push(new CloseGroup());
context.MoveNext();
continue;
case '=':
if (context.Peek.HasValue && context.Peek.Value == '=')
{
context.Push(new Equal());
context.MoveNext(2);
continue;
}
break;
case '!':
if (context.Peek.HasValue && context.Peek.Value == '=')
{
context.Push(new NotEqual());
context.MoveNext(2);
continue;
}
context.Push(new Not());
context.MoveNext();
continue;
case '<':
if (context.Peek.HasValue && context.Peek.Value == '=')
{
context.Push(new LessThanEqual());
context.MoveNext(2);
continue;
}
context.Push(new LessThan());
context.MoveNext();
continue;
case '>':
if (context.Peek.HasValue && context.Peek.Value == '=')
{
context.Push(new GreaterThanEqual());
context.MoveNext(2);
continue;
}
context.Push(new GreaterThan());
context.MoveNext();
continue;
case '&':
if (context.Peek == '&')
{
context.Push(new And());
context.MoveNext(2);
continue;
}
break;
case '|':
if (context.Peek == '|')
{
context.Push(new Or());
context.MoveNext(2);
continue;
}
break;
default:
ProcessWord(context);
break;
}
}
if (context.CurrentWord.Length > 0)
{
context.Push(CorrectLiteral(context.CurrentWord));
}
}