Пример #1
0
        private static Token ParseString(Reader reader, char quote)
        {
            Debug.Assert(reader != null);

            //
            // TODO Support full string syntax!
            //
            // string    {string1}|{string2}
            // string1   \"([^\n\r\f\\"]|\\{nl}|{nonascii}|{escape})*\"
            // string2   \'([^\n\r\f\\']|\\{nl}|{nonascii}|{escape})*\'
            // nonascii  [^\0-\177]
            // escape    {unicode}|\\[^\n\r\f0-9a-f]
            // unicode   \\[0-9a-f]{1,6}(\r\n|[ \n\r\t\f])?
            //

            var strpos = reader.Position;
            reader.MarkFromNext(); // skipping quote

            char? ch;
            StringBuilder sb = null;
            
            while ((ch = reader.Read()) != quote)
            {
                if (ch == null)
                    throw new FormatException(string.Format("Unterminated string at position {0}.", strpos));
                
                if (ch == '\\')
                {
                    ch = reader.Read();

                    //
                    // NOTE: Only escaping of quote and backslash supported!
                    //
                    
                    if (ch != quote && ch != '\\')
                        throw new FormatException(string.Format("Invalid escape sequence at position {0} in a string at position {1}.", reader.Position, strpos));
                    
                    if (sb == null)
                        sb = new StringBuilder();
                    
                    sb.Append(reader.MarkedExceptLast());
                    reader.Mark();
                }
            }
            
            var text = reader.Marked();

            if (sb != null)
                text = sb.Append(text).ToString();

            return Token.String(text);
        }