internal ParserExpression(string scheme, string content, ParserExpression next = null)
{
if (string.IsNullOrWhiteSpace(scheme))
{
throw new ArgumentNullException(nameof(scheme));
}
_scheme = scheme.ToLowerInvariant().Trim();
_content = content?.Trim();
_next = next;
}
public static bool TryParse(string text, out ParserExpression result)
{
result = null;
if (string.IsNullOrWhiteSpace(text))
{
return(false);
}
using (var reader = new StringReader(text))
{
while (reader.Peek() > 0)
{
var isFailed = false;
var current = ParseCore(reader, _ => isFailed = true);
//如果解析失败则重置输出参数为空并返回假
if (isFailed)
{
result = null;
return(false);
}
if (current == null)
{
continue;
}
if (result == null)
{
result = current;
}
else
{
var item = result;
while (item.Next != null)
{
item = item.Next;
}
item.Next = current;
}
}
}
return(true);
}
public static ParserExpression Parse(string text)
{
if (string.IsNullOrWhiteSpace(text))
{
return(null);
}
ParserExpression result = null;
ParserExpression current = null;
using (var reader = new StringReader(text))
{
while (reader.Peek() > 0)
{
current = ParseCore(reader, message =>
{
throw new ParserException(message);
});
if (result == null)
{
result = current;
}
else //线性查找命令表达式的管道链，并更新其指向
{
var item = result;
while (item.Next != null)
{
item = item.Next;
}
item.Next = current;
}
}
}
return(result);
}
