CIS 687 XmlTranslator for Project 1 & 2

XmlTranslator.h

#ifndef XMLENCODER_H
#define XMLENCODER_H

#include <string>

// the translator class of XmlReader / XmlWriter
class XmlEncoder {

  // escape markup
	static std::string encodeAttr(std::string str) {
		std::string buffer;
		buffer.reserve(str.length());
		for(size_t pos = 0; pos < str.length(); pos++) {
			switch(str[pos]) {  // escape the five XML built-in markups
			case '&':	buffer.append("&amp;");	break;
			case '\"':	buffer.append("&quot;");	break;
			case '\'':	buffer.append("&apos;");	break;
			case '<':	buffer.append("&lt;");	break;
			case '>':	buffer.append("&gt;");	break;
			default:	buffer.append(1,str[pos]);	break;
			}
		}
		return buffer.c_str();
	}

	// unescape markup
	static std::string decodeAttr(std::string str) {
		std::string buffer;
		buffer.reserve(str.length());
		for(size_t pos = 0, specialTokLength=0; pos < str.length(); pos++) {
			buffer.append(1, str[pos]);	// append first
			if (str[pos]=='&')
				specialTokLength=1;	// always count from the latest ampersand
			else if (specialTokLength>0 && str[pos]==';') {
				size_t specialTokPos = pos - (specialTokLength++);
				std::string specialTok = str.substr(specialTokPos, specialTokLength);
				char chr='\0';	// empty char by default
				if (specialTok=="&amp;") chr='&';
				else if (specialTok=="&quot;") chr='"';
				else if (specialTok=="&apos;") chr='\'';
				else if (specialTok=="&lt;") chr='<';
				else if (specialTok=="&gt;") chr='>';
				if (chr!='\0')
					buffer.replace(buffer.length()-specialTokLength, specialTokLength, 1, chr);
				specialTokLength=0;	// reset
			}
		}
		return buffer.c_str();
	}

	// encode text is pretty simple, a lazy way is just to add the CDATA
	// not used by current project, but I am gonna implement it anyway
	static std::string encodeText(std::string str) {
		std::string buffer("<![CDATA[");
		buffer.reserve(str.length());
		for (size_t pos=0; pos<str.length();pos++) {
			buffer.append(1,str[pos]);
			if (str[pos]=='>' && buffer.substr(buffer.length()-3)=="]]>")
				buffer.replace(buffer.length()-3,3,"]]><![CDATA[]]]]><![CDATA[>");	// a tricky way to replace ]]>
		}
		buffer.append("]]>");
		return buffer.c_str();
	}

	// decode test, simply by deleting all <!CDATA[ and ]]> markup
	static std::string decodeText(std::string str) {
		std::string buffer;
		buffer.reserve(str.length());
		for (size_t pos=0; pos<str.length();pos++) {
			buffer.append(1,str[pos]);
			if (str[pos]=='[' && buffer.substr(buffer.length()-9)=="<![CDATA[")
				buffer.erase(buffer.length()-9);
			else if (str[pos]=='>' && buffer.substr(buffer.length()-3)=="]]>")
				buffer.erase(buffer.length()-3);
		}
		return buffer.c_str();
	}
};

#endif