这是我最初的尝试：
using System;
using System.Collections.Generic;
using System.Collections.Concurrent;
using System.Linq;
using System.IO;
using System.Xml;
using System.Xml.Linq;
using System.Text;
namespace XMLTest
{
public struct Segment
{
public Segment(long index, long length)
{
Index = index;
Length = length;
}
public long Index;
public long Length;
public override string ToString()
{
return string.Format("Segment({0}, {1})", Index, Length);
}
}
public static class GeneralSerializationExtensions
{
public static string Segment(this string buffer, Segment segment)
{
return buffer.Substring((int)segment.Index, (int)segment.Length);
}
public static byte[] Bytes(this Stream stream, int startIndex = 0, bool setBack = false)
{
var bytes = new byte[stream.Length];
if (stream.CanSeek && stream.CanRead)
{
var position = stream.Position;
stream.Seek(startIndex, SeekOrigin.Begin);
stream.Read(bytes, 0, (int)stream.Length);
if (setBack)
stream.Position = position;
}
return bytes;
}
}
class Program
{
static void Main(string[] args)
{
var stream = new MemoryStream();
var element = XElement.Parse(@"<root><group id=""0"" combiner=""or""><filter id=""1"" /><filter id=""2"" /></group></root>");
//var element = XElement.Parse("<a>i<b id='1' o='2' p=''/><b id='2'><c /></b><b id='3' /><b id='4' o='u'>2</b></a>");
var pie = new PathIndexedXElement(element);
foreach (var path in pie.Paths.OrderBy(p => p))
{
var s = pie.store[path];
var t = pie[path];
Console.WriteLine("> {2,-30} {0,-20} {1}", s, t, path);
}
}
}
public class PathIndexedXElement
{
internal string buffer;
internal ConcurrentDictionary<string, Segment> store;
public PathIndexedXElement(XElement element)
{
buffer = XmlPathSegmenter.StringBuffer(element);
store = element.PathSegments();
}
public IEnumerable<string> Paths
{
get { return store.Keys; }
}
public string this[string path]
{
get { return buffer.Segment(store[path]); }
}
public bool TryGetValue(string path, out string xelement)
{
Segment segment;
if (store.TryGetValue(path, out segment))
{
xelement = buffer.Segment(segment);
return true;
}
xelement = null;
return false;
}
}
public static class XmlPathSegmenter
{
public static XmlWriter CreateWriter(Stream stream)
{
var settings = new XmlWriterSettings() { Encoding = Encoding.UTF8, Indent = false, OmitXmlDeclaration = true, NewLineHandling = NewLineHandling.None };
return XmlWriter.Create(stream, settings);
}
public static MemoryStream MemoryBuffer(XElement element)
{
var stream = new MemoryStream();
var writer = CreateWriter(stream);
element.Save(writer);
writer.Flush();
stream.Position = 0;
return stream;
}
public static string StringBuffer(XElement element)
{
return Encoding.UTF8.GetString(MemoryBuffer(element).Bytes()).Substring(1);
}
public static ConcurrentDictionary<string, Segment> PathSegments(string xmlElement, ConcurrentDictionary<string, Segment> store = null)
{
return PathSegments(XElement.Parse(xmlElement), store);
}
public static ConcurrentDictionary<string, Segment> PathSegments(this XElement element, ConcurrentDictionary<string, Segment> store = null)
{
var stream = new MemoryStream();
var writer = CreateWriter(stream);
element.Save(writer);
writer.Flush();
stream.Position = 0;
return PathSegments(stream, store);
}
public static ConcurrentDictionary<string, Segment> PathSegments(Stream stream, ConcurrentDictionary<string, Segment> store = null)
{
if (store == null)
store = new ConcurrentDictionary<string, Segment>();
var stack = new ConcurrentStack<KeyValuePair<string, int>>();
PathSegments(stream, stack, store);
return store;
}
//
static void PathSegments(Stream stream, ConcurrentStack<KeyValuePair<string, int>> stack, ConcurrentDictionary<string, Segment> store)
{
var reader = XmlReader.Create(stream, new XmlReaderSettings() { });
var line = reader as IXmlLineInfo;
while (reader.Read())
{
KeyValuePair<string, int> ep;
ok:
if (reader.IsStartElement())
{
stack.TryPeek(out ep);
stack.Push(new KeyValuePair<string, int>(ep.Key + Path(reader), line.LinePosition - 2));
}
if (reader.IsEmptyElement)
{
var name = reader.LocalName;
var d = reader.Depth;
reader.Read();
if (stack.TryPop(out ep))
{
var length = line.LinePosition - 2 - ep.Value - (d > reader.Depth ? 1 : 0);
Console.WriteLine("/{3}|{0} : {1} -> {2}", name, ep.Value, length, line.LineNumber);
store.TryAdd(ep.Key, new Segment(ep.Value, length));
}
goto ok;
}
if (reader.NodeType == XmlNodeType.EndElement)
{
if (stack.TryPop(out ep))
{
var length = line.LinePosition + reader.LocalName.Length - ep.Value;
Console.WriteLine("|{3}|{0} : {1} -> {2}", reader.LocalName, ep.Value, length, line.LineNumber);
store.TryAdd(ep.Key, new Segment(ep.Value, length));
}
}
}
}
//
public static string Path(XmlReader element)
{
if (!(element.IsStartElement() || element.IsEmptyElement))
return null;
if (!element.HasAttributes)
return "/" + element.LocalName;
var id = element.GetAttribute("id");
return string.Format(id == null ? "/{0}" : "/{0}-{1}", element.LocalName, id);
}
}
}
输出：
/1|filter : 34 -> 17
/1|filter : 51 -> 17
|1|group : 6 -> 70
|1|root : 0 -> 83
> /root Segment(0, 83) <root><group id="0" combiner="or"><filter id="1" /><filter id="2" /></group></root>
> /root/group-0 Segment(6, 70) <group id="0" combiner="or"><filter id="1" /><filter id="2" /></group>
> /root/group-0/filter-1 Segment(34, 17) <filter id="1" />
> /root/group-0/filter-2 Segment(51, 17) <filter id="2" />
促成者发现了由 XmlReader 类显式实现的IXmlLineInfo 接口，这是一条很难找到的信息。
备注
现在有点预先保护 :) 在我收到所有关于 this question 的 cmets 之后：
- 集合的并发版本在此示例中不起作用。我知道并乐于使用它们：)
- 路径方案很容易推广，但这满足了我的所有需求。
- 我知道 id 通常用作文档范围内的唯一标识符，我很高兴在这种特殊情况下使用它们。
- 段可以很容易地扩展为具有另一个指向开始标记的结束 > 符号的长度属性，从而能够仅提取文档树中任何给定元素的属性，以便围绕任何其他元素进行 上下文重建目标元素。对于浅树，这应该为使用上下文信息访问目标元素提供了一个很好的常量因素。
- 我完全清楚所有可能或可能不值得尝试的事情：我还没有我的方案的任何数字。只是想开发一种方法并与人们分享。