Add escape/unescape functions

Foundation/include/Poco/UTF8String.h

@@ -58,6 +58,20 @@ struct Foundation_API UTF8
 	static void removeBOM(std::string& str);
 		/// Remove the UTF-8 Byte Order Mark sequence (0xEF, 0xBB, 0xBF)
 		/// from the beginning of the string, if it's there.
+
+	static std::string escape(const std::string& s);
+		/// Escapes a string. Special characters like tab, backslash, ... are
+		/// escaped. Unicode characters are escaped to \uxxxx.
+
+	static std::string escape(const std::string::const_iterator& begin, const std::string::const_iterator& end);
+		/// Escapes a string. Special characters like tab, backslash, ... are
+		/// escaped. Unicode characters are escaped to \uxxxx.
+
+	static std::string unescape(const std::string& s);
+		/// Creates an UTF8 string from a string that contains escaped characters.
+
+	static std::string unescape(const std::string::const_iterator& begin, const std::string::const_iterator& end);
+		/// Creates an UTF8 string from a string that contains escaped characters.
 };
 
 

Foundation/src/UTF8String.cpp

@@ -19,6 +19,8 @@
 #include "Poco/TextIterator.h"
 #include "Poco/TextConverter.h"
 #include "Poco/UTF8Encoding.h"
+#include "Poco/NumberFormatter.h"
+#include "Poco/Ascii.h"
 #include <algorithm>
 
 
@@ -171,5 +173,202 @@ void UTF8::removeBOM(std::string& str)
 	}
 }
 
+std::string UTF8::escape(const std::string &s)
+{
+	return escape(s.begin(), s.end());
+}
+
+std::string UTF8::escape(const std::string::const_iterator& begin, const std::string::const_iterator& end)
+{
+	static Poco::UInt32 offsetsFromUTF8[6] = {
+		0x00000000UL, 0x00003080UL, 0x000E2080UL,
+		0x03C82080UL, 0xFA082080UL, 0x82082080UL
+	};
+
+	std::string result;
+
+	std::string::const_iterator it = begin;
+
+	while(it != end)
+	{
+		Poco::UInt32 ch = 0;
+		unsigned int sz = 0;
+
+		do
+		{
+			ch <<= 6;
+			ch += (unsigned char)*it++;
+			sz++;
+		}
+		while (it != end && (*it & 0xC0) == 0x80 && sz < 6);
+		ch -= offsetsFromUTF8[sz-1];
+
+		if (ch == '\n') result += "\\n";
+		else if (ch == '\t') result += "\\t";
+		else if (ch == '\r') result += "\\r";
+		else if (ch == '\b') result += "\\b";
+		else if (ch == '\f') result += "\\f";
+		else if (ch == '\v') result += "\\v";
+		else if (ch == '\a') result += "\\a";
+		else if (ch == '\\') result +=  "\\\\";
+		else if (ch == '\"') result +=  "\\\"";
+		else if (ch == '/') result +=  "\\/";
+		else if (ch == '\0') result += "\\u0000";
+		else if (ch < 32 || ch == 0x7f)
+		{
+			result += "\\u";
+			NumberFormatter::appendHex(result, (unsigned short) ch, 4);
+		}
+		else if (ch > 0xFFFF)
+		{
+			ch -= 0x10000;
+			result += "\\u";
+			NumberFormatter::appendHex(result, (unsigned short) (( ch >> 10 ) & 0x03ff ) + 0xd800, 4);
+			result += "\\u";
+			NumberFormatter::appendHex(result, (unsigned short) (ch & 0x03ff ) + 0xdc00, 4);
+		}
+		else if (ch >= 0x80 && ch <= 0xFFFF)
+		{
+			result += "\\u";
+			NumberFormatter::appendHex(result, (unsigned short) ch, 4);
+		}
+		else
+		{
+			result += (char) ch;
+		}
+	}
+	return result;
+}
+
+std::string UTF8::unescape(const std::string &s)
+{
+	return unescape(s.begin(), s.end());
+}
+
+std::string UTF8::unescape(const std::string::const_iterator& begin, const std::string::const_iterator& end)
+{
+	std::string result;
+
+	std::string::const_iterator it = begin;
+
+	while (it != end)
+	{
+		Poco::UInt32 ch = (Poco::UInt32) *it++;
+
+		if (ch == '\\')
+		{
+			if ( it == end )
+			{
+				//Invalid sequence!
+			}
+
+			if (*it == 'n')
+			{
+				ch = '\n';
+				it++;
+			}
+			else if (*it == 't')
+			{
+				ch = '\t';
+				it++;
+			}
+			else if (*it == 'r')
+			{
+				ch = '\r';
+				it++;
+			}
+			else if (*it == 'b')
+			{
+				ch = '\b';
+				it++;
+			}
+			else if (*it == 'f')
+			{
+				ch = '\f';
+				it++;
+			}
+			else if (*it == 'v')
+			{
+				ch = '\v';
+				it++;
+			}
+			else if (*it == 'a')
+			{
+				ch = '\a';
+				it++;
+			}
+			else if (*it == 'u')
+			{
+				char digs[5];
+				memset(digs, 0, 5);
+				unsigned int dno = 0;
+
+				it++;
+
+				while (it != end && Ascii::isHexDigit(*it) && dno < 4) digs[dno++] = *it++;
+				if (dno > 0)
+				{
+					ch = strtol(digs, NULL, 16);
+				}
+
+				if( ch >= 0xD800 && ch <= 0xDBFF )
+				{
+					if ( it == end || *it != '\\' )
+					{
+						//Invalid sequence!
+					}
+					else
+					{
+						it++;
+						if ( it == end || *it != 'u' )
+						{
+							//Invalid sequence!
+						}
+						else
+						{
+							it++;
+						}
+					}
+
+					// UTF-16 surrogate pair. Go fetch other half
+					memset(digs, 0, 5);
+					dno = 0;
+					while (it != end && Ascii::isHexDigit(*it) && dno < 4) digs[dno++] = *it++;
+					if (dno > 0)
+					{
+						Poco::UInt32 temp = strtol(digs, NULL, 16);
+						if( temp >= 0xDC00 && temp <= 0xDFFF )
+						{
+							ch = ( ( ( ch - 0xD800 ) << 10 ) | ( temp - 0xDC00 ) ) + 0x10000;
+						}
+					}
+				}
+			}
+			else if (*it == 'U')
+			{
+				char digs[9];
+				memset(digs, 0, 9);
+				unsigned int dno = 0;
+
+				it++;
+				while (it != end && Ascii::isHexDigit(*it) && dno < 8)
+				{
+					digs[dno++] = *it++;
+				}
+				if (dno > 0)
+				{
+					ch = strtol(digs, NULL, 16);
+				}
+			}
+		}
+
+		unsigned char utf8[4];
+		UTF8Encoding encoding;
+		int sz = encoding.convert(ch, utf8, 4);
+		result.append((char*) utf8, sz);
+	}
+
+	return result;
+}
 
 } // namespace Poco