XmlReaderEx (Improved Version 2)

gistfile1.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;
using System.Text.RegularExpressions;
using System.Reflection.Emit;
using System.Runtime.CompilerServices;
using System.Security;

namespace PServiceBus.Serializer.Xml {
    public unsafe sealed class XmlReaderEx {

        private int _index;
        private string _elementName, _attributeTypeValue, _xml;
        private bool _isEndElement;
        const string TypeStr = "Type", Quote = "\"";
        const char SpaceStr = ' ', GreaterStr = '>', LessStr = '<', BackSlash = '/', Null = '\0';

        public XmlReaderEx(string xml) {
            _xml = xml;
        }

        public string ElementName { get { return _elementName; } }
        public string TypeAttribute { get { return _attributeTypeValue; } }
        public bool IsEndElement { get { return _isEndElement; } }


        public string GetValue() {
            if (_isEndElement) return string.Empty;
            var count = 1;
            fixed (char* p = _xml) {
                char* chrs = p + _index;
                if (*chrs == Null) return string.Empty;
                var current = Null;
                do {
                    current = *(++chrs);
                    _index++;
                    if (current == LessStr) break;
                    count++;
                } while (true);
                var str = new string(Null, count);
                fixed (char* cp = str)
                    memcpy(cp, chrs - count, count);
                return str;
            }
        }

        public bool Read(){
            char current = Null;
            bool hasValue = false, hasTypeAttribute = false;
            string elementName = null;
            int count = 0;
            fixed (char* p = _xml) {
                char* chrs = p + _index;
                if (*chrs == Null) return false;
                _attributeTypeValue = null;
                _isEndElement = false;
                do {
                    current = *(++chrs);
                    count++;
                    _index++;
                    if (current == GreaterStr) {
                        _index++;
                        ++chrs;
                        break;
                    }
                    if (current == SpaceStr && elementName == null) {
                        var size = count - 1;
                        elementName = new string(Null, size);
                        fixed (char* cp = elementName)
                            memcpy(cp, chrs - size, size);
                        count = 0;
                        hasTypeAttribute = true;
                        continue;
                    }
                } while (true);
                if (hasValue = (count > 0 && *(chrs - count) != Null)) {
                    var text = GetString(chrs, count);
                    if (hasTypeAttribute) {
                        var index = text.IndexOf(Quote, StringComparison.Ordinal) + 1;
                        var endIndex = text.LastIndexOf(Quote, StringComparison.Ordinal);
                        _attributeTypeValue = text.Substring(index, endIndex - index);
                    } else if (elementName == null)
                        elementName = text;
                    if (elementName[0] == BackSlash) {
                        _isEndElement = true;
                        elementName = elementName.Substring(1);
                    }
                }
            }
            _elementName = elementName;
            return hasValue;
        }

        private unsafe static string GetString(char* chrs, int count) {
            var size = count - 1;
            var str = new string(Null, size);
            fixed (char* cp = str)
                memcpy(cp, chrs - count, size);
            return str;
        }

        private static unsafe void memcpy(char* dmem, char* smem, int charCount) {
            if ((((int)dmem) & 2) != 0) {
                dmem[0] = smem[0];
                dmem++;
                smem++;
                charCount--;
            }
            while (charCount >= 8) {
                *((int*)dmem) = *((int*)smem);
                *((int*)(dmem + 2)) = *((int*)(smem + 2));
                *((int*)(dmem + 4)) = *((int*)(smem + 4));
                *((int*)(dmem + 6)) = *((int*)(smem + 6));
                dmem += 8;
                smem += 8;
                charCount -= 8;
            }
            if ((charCount & 4) != 0) {
                *((int*)dmem) = *((int*)smem);
                *((int*)(dmem + 2)) = *((int*)(smem + 2));
                dmem += 4;
                smem += 4;
            }
            if ((charCount & 2) != 0) {
                *((int*)dmem) = *((int*)smem);
                dmem += 2;
                smem += 2;
            }
            if ((charCount & 1) != 0) {
                dmem[0] = smem[0];
            }
        }

        public void MoveToEndElement(string name) {
            do {
                if (_elementName == name && _isEndElement) return;
            } while (Read());
        }
    }
}