/// <summary>
/// 读取表达式
/// </summary>
/// <param name="level">优先级别</param>
/// <returns>ReadResult</returns>
private ReadResult ReadExpression(int level = 0)
{
var exp = ReadFirstExpression();
int nextLevel = 0;
var next = spResult.PeekNext();
while (!exp.IsClosedWrap && (nextLevel = OperatorPriority.GetOperatorLevel(next.Text)) > level)
{
exp = ReadNextExpression(nextLevel, exp);
next = spResult.PeekNext();
}
return(exp);
}
/// <summary>
/// 读取第一个表达式
/// </summary>
/// <returns>ReadResult</returns>
private ReadResult ReadFirstExpression()
{
ReadResult result = ReadResult.Empty;
var token = spResult.Next();
// 只列出可以出现在最左边的
switch (token.Type)
{
case TokenType.Operator:
if (OperatorWord.UnaryExpressions.ContainsKey(token.Text))
{
result.Expression = OperatorWord.UnaryExpressions[token.Text](ReadExpression(OperatorPriority.GetOperatorLevel(token.Text)).Expression);
}
else if (token.Is(OperatorWord.LeftBracket))
{
result = ParseConvertType();
}
else if (token.Is(OperatorWord.Comma))
{
result = ReadExpression();
}
else
{
throw new ArgumentException(string.Format("Invalid Left Operator {0}", token.Text));
}
break;
case TokenType.Identifier:
result = ParseIdentifier(token);
break;
case TokenType.DigitValue:
result.Expression = Expression.Constant(DigitValue.Parse(token.Text), DigitValue.GetType(token.Text));
break;
case TokenType.PackageValue:
// 去掉首尾引号
if (token.Text.StartsWith(PackageValue.String))
{
result.Expression = Expression.Constant(token.Text.Substring(1, token.Text.Length - 2), PackageValue.All[PackageValue.String]);
}
else if (token.Text.StartsWith(PackageValue.Char))
{
result.Expression = Expression.Constant(token.Text[1], PackageValue.All[PackageValue.Char]);
}
break;
default:
throw new ArgumentException(string.Format("Unsupported TokenType {0}", token.Type));
}
return(result);
}
