rapidxml对unicode的支持

　　为了提高duilib创建布局控件的效率，在LuaDui项目中使用rapidxml解析器替换了duilib库自带的xml解析器。

duilib使用unicode编译，所以rapidxml需要解析unicode xml字符串。

　　使用rapidxml解析unicode字符串很简单，只需在rapidxml的模板参数中设置为TCHAR即可，所以定义以下类型方便使用。

#include <rapidxml/rapidxml.hpp>
typedef rapidxml::xml_document<TCHAR> XmlDoc;
typedef rapidxml::xml_node<TCHAR> XmlNode;
typedef rapidxml::xml_attribute<TCHAR> XmlAttr;

　　在使用过程中发现了解析xml中的中文字符出现bug，解析如下xml会出现问题抛出异常。

<?xml version="1.0" encoding="UTF-8"?>
<Window caption="0,0,0,30" sizebox="5,5,5,5" mininfo="480,360" defaultfontcolor="#ff010000" width="600" height="480">
<Font name="微软雅黑" size="12" bold="false"/>
 
<VerticalLayout bkcolor="#ff019bd0" inset="1,1,1,1" bordersize="1" bordercolor="#FF010000">
    <HorizontalLayout height="30" inset="5,0,0,0">
	<Label name="标题" text="调试窗口" textcolor="#FFFFFFFF"></Label>
	<Control />
        <Button name="minbtn" width="40" height="22" text="最小化" bkcolor="#ff3fd536">
	　　<Event click="DebugUIEvent.minBtnClick" />
	</Button>
        <Button name="closebtn" width="47" height="22" text="关闭" bkcolor="#ffef2f4d">
	　　<Event click="DebugUIEvent.closeBtnClick" />
	</Button>
    </HorizontalLayout>
 
　　<VerticalLayout  bkcolor="#66ffffff">
 
　　</VerticalLayout>
</VerticalLayout>
</Window>

　　断点时发现在解析 text="最小化" 属性时出现问题，解析text值的时候把后面的内容全部当做text的属性值，无法再往下解析了。

最后终于找到了问题所在，rapidxml为提高解析效率，定义了如下的表：

        template<int Dummy>
        struct lookup_tables
        {
            static const unsigned char lookup_whitespace[256];              // Whitespace table
            static const unsigned char lookup_node_name[256];               // Node name table
            static const unsigned char lookup_text[256];                    // Text table
            static const unsigned char lookup_text_pure_no_ws[256];         // Text table
            static const unsigned char lookup_text_pure_with_ws[256];       // Text table
            static const unsigned char lookup_attribute_name[256];          // Attribute name table
            static const unsigned char lookup_attribute_data_1[256];        // Attribute data table with single quote
            static const unsigned char lookup_attribute_data_1_pure[256];   // Attribute data table with single quote
            static const unsigned char lookup_attribute_data_2[256];        // Attribute data table with double quotes
            static const unsigned char lookup_attribute_data_2_pure[256];   // Attribute data table with double quotes
            static const unsigned char lookup_digits[256];                  // Digits
            static const unsigned char lookup_upcase[256];                  // To uppercase conversion table for ASCII characters
        };

　　来识别xml中的标志符，在进行查找的时候直接通过数组直接找到使用了

如下操作：

internal::lookup_tables<0>::lookup_text_pure_no_ws[static_cast<unsigned char>(ch)];

但在unicode下static_cast<unsigned char>(ch)的ch是wchar占两个字节直接转换为unsigned char会出现判断出错问题。所以要在rapidxml中解析unicode需要修改rapidxml代码：

       // Detect whitespace character
        struct whitespace_pred
        {
            static unsigned char test(Ch ch)
            {
				if(ch<=255)
					return internal::lookup_tables<0>::lookup_whitespace[static_cast<unsigned char>(ch)];
				else
					return 0;
            }
        };
 
        // Detect node name character
        struct node_name_pred
        {
            static unsigned char test(Ch ch)
            {
				if(ch<=255)
					return internal::lookup_tables<0>::lookup_node_name[static_cast<unsigned char>(ch)];
				else
					return 1;
            }
        };
 
        // Detect attribute name character
        struct attribute_name_pred
        {
            static unsigned char test(Ch ch)
            {
				if(ch<=255)
					return internal::lookup_tables<0>::lookup_attribute_name[static_cast<unsigned char>(ch)];
				else
					return 1;
            }
        };
 
        // Detect text character (PCDATA)
        struct text_pred
        {
            static unsigned char test(Ch ch)
            {
				if(ch<=255)
					return internal::lookup_tables<0>::lookup_text[static_cast<unsigned char>(ch)];
				else
					return 1;
            }
        };
 
        // Detect text character (PCDATA) that does not require processing
        struct text_pure_no_ws_pred
        {
            static unsigned char test(Ch ch)
            {
				if(ch<=255)
					return internal::lookup_tables<0>::lookup_text_pure_no_ws[static_cast<unsigned char>(ch)];
				else
					return 1;
            }
        };
 
        // Detect text character (PCDATA) that does not require processing
        struct text_pure_with_ws_pred
        {
            static unsigned char test(Ch ch)
            {
				if(ch<=255)
					return internal::lookup_tables<0>::lookup_text_pure_with_ws[static_cast<unsigned char>(ch)];
				else
					return 1;
            }
        };
 
        // Detect attribute value character
        template<Ch Quote>
        struct attribute_value_pred
        {
            static unsigned char test(Ch ch)
            {
 
                if (Quote == Ch('\''))
					if(ch<=255)
						return internal::lookup_tables<0>::lookup_attribute_data_1[static_cast<unsigned char>(ch)];
					else
						return 1;
                if (Quote == Ch('\"'))
					if(ch<=255)
						return internal::lookup_tables<0>::lookup_attribute_data_2[static_cast<unsigned char>(ch)];
					else
						return 1;
                return 0;       // Should never be executed, to avoid warnings on Comeau
            }
        };
 
        // Detect attribute value character
        template<Ch Quote>
        struct attribute_value_pure_pred
        {
            static unsigned char test(Ch ch)
            {
                if (Quote == Ch('\''))
					if(ch<=255)
						return internal::lookup_tables<0>::lookup_attribute_data_1_pure[static_cast<unsigned char>(ch)];
					else
						return 1;
                if (Quote == Ch('\"'))
					if(ch<=255)
						return internal::lookup_tables<0>::lookup_attribute_data_2_pure[static_cast<unsigned char>(ch)];
					else
						return 1;
                return 0;       // Should never be executed, to avoid warnings on Comeau
            }
        };