/// <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);
}
/// <summary>
/// 获取当前Token
/// </summary>
/// <returns>当前Token</returns>
private Token CurrentToken()
{
while (Char.IsWhiteSpace(currentChar))
{
NextChar();
}
TokenType type;
int tokenPos = currentPosition;
if (OperatorChar.Contains(currentChar))
{
type = TokenType.Operator;
string mark = currentChar.ToString();
// 处理双操作符
NextChar();
if (OperatorChar.Contains(currentChar))
{
mark = mark + currentChar.ToString();
if (OperatorWord.Contains(mark))
{
NextChar();
}
}
}
else if (Char.IsLetter(currentChar) || currentChar == MarkChar.Parameter || currentChar == MarkChar.Underline)
{
type = TokenType.Identifier;
do
{
NextChar();
} while (Char.IsLetterOrDigit(currentChar) || currentChar == MarkChar.Underline || currentChar == OperatorChar.Question);
}
else if (PackageValue.Contains(currentChar))
{
type = TokenType.PackageValue;
char mark = currentChar;
do
{
NextChar();
} while (currentChar != mark && currentPosition < sourceLength);
if (currentPosition == sourceLength)
{
throw new ArgumentException(string.Format("PackageValue not matched to paired {0}", mark));
}
NextChar();
}
else if (Char.IsDigit(currentChar))
{
type = TokenType.DigitValue;
do
{
NextChar();
} while (Char.IsDigit(currentChar));
// 数值尾标
if (DigitValue.Contains(currentChar))
{
NextChar();
}
else if (currentChar == MarkChar.Dot)
{
NextChar();
ValidateDigit();
do
{
NextChar();
} while (Char.IsDigit(currentChar));
// 指数
if (MarkChar.Exponent.Contains(currentChar))
{
NextChar();
if (currentChar == MarkChar.Positive || currentChar == MarkChar.Negative)
{
NextChar();
}
ValidateDigit();
while (Char.IsDigit(currentChar))
{
NextChar();
}
}
// 数值尾标
if (DigitValue.Contains(currentChar))
{
NextChar();
}
}
}
else if (currentChar == MarkChar.End)
{
type = TokenType.End;
}
else
{
throw new ArgumentException(string.Format("Unsupported Char {0}", currentChar));
}
var text = source.Substring(tokenPos, currentPosition - tokenPos);
return(new Token {
Type = type, Text = text, Index = tokenPos
});
}
