// parse
private string Parse()
{
foreach (string token in Tokens)
{
if (IsNumber(token))
{
Stack.Push(new Number(token));
}
else if (token == "X")
{
Stack.Push(new Number(token));
}
else if (IsUnary(token))
{
Stack.Push(UnaryExpr.Create(Stack, token));
}
else
{
Stack.Push(BinExpr.Create(Stack, token));
}
}
StringBuilder sb = new StringBuilder();
Stack.Pop().Write(sb);
return(sb.ToString());
}
public Filter BuildFilter()
{
if (tokens.Count == 0)
{
return(new True());
}
if (tokens.Count == 1)
{
if (tokens[0] is Expression)
{
return((tokens[0] as Expression).BuildFilter());
}
else if (tokens[0] is TokenVal)
{
return(Checker.Create((tokens[0] as TokenVal).Val));
}
throw new FormatException($"语法错误'{tokens[0]}'");
}
if (tokens[1] is TokenLogical)
{
List <Tuple <LogicalOperator, Filter> > list = new List <Tuple <LogicalOperator, Filter> >();
LogicalOperator op = LogicalOperator.And;
for (int i = 0; i < tokens.Count; i++)
{
list.Add(new Tuple <LogicalOperator, Filter>(op, (tokens[i] as Expression).BuildFilter()));
i++;
if (i < tokens.Count)
{
op = (tokens[i] as TokenLogical).Operator;
}
}
return(new Logic(list));
}
if (tokens[1] is TokenCompare)
{
if (tokens.Count < 3)
{
throw new FormatException($"表达式不完整！");
}
if (tokens.Count > 3)
{
throw new FormatException($"语法错误'{tokens[3]}'");
}
return(Checker.Create((tokens[0] as TokenVal).Val, (tokens[1] as TokenCompare).Operator, (tokens[2] as TokenVal).Val));
}
if (tokens[0] is TokenUnary)
{
if (tokens.Count == 2 && tokens[1] is Expression)
{
return(UnaryExpr.Create((tokens[0] as TokenUnary).Operator, (tokens[1] as Expression).BuildFilter()));
}
if (tokens.Count == 3 && tokens[1] is TokenVal && tokens[2] is Expression)
{
return(UnaryExpr.Create((tokens[0] as TokenUnary).Operator, (tokens[2] as Expression).BuildFilter(), (tokens[1] as TokenVal).Val));
}
throw new FormatException($"错误的用法'{tokens[0]}'");
}
throw new FormatException($"语法错误'{tokens[0]}'");
}
