ParseHttpDate.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / FX-1434 / FX-1434 / 1.0 / untmp / whidbey / REDBITS / ndp / fx / src / xsp / System / Web / Util / ParseHttpDate.cs / 1 / ParseHttpDate.cs
                        

                        
                            using System; 
using System.Globalization;


namespace System.Web.Util 
{
    internal static class HttpDate 
    { 
        static readonly int[] s_tensDigit = new int[10] { 0, 10, 20, 30, 40, 50, 60, 70, 80, 90 };
 
        /*++

            Converts a 2 character string to integer
 
            Arguments:
                s   String to convert 
 
            Returns:
                numeric equivalent, 0 on failure. 
        --*/
        static int atoi2(string s, int startIndex)
        {
            try { 
                int tens = s[0 + startIndex] - '0';
                int ones = s[1 + startIndex] - '0'; 
 
                return s_tensDigit[tens] + ones;
            } 
            catch {
                throw new FormatException(SR.GetString(SR.Atio2BadString, s, startIndex));
            }
        } 

        static readonly string[] s_days = new string [7] { 
            "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" 
        };
 
        static readonly string[] s_months = new string[12] {
            "Jan", "Feb", "Mar", "Apr",
            "May", "Jun", "Jul", "Aug",
            "Sep", "Oct", "Nov", "Dec" 
        };
 
        // Custom table for make_month() for mapping "Apr" to 4 
        static readonly sbyte[] s_monthIndexTable = new sbyte[64] {
           -1, (sbyte)'A',          2, 12, -1, -1,         -1,  8, // A to G 
           -1,         -1,         -1, -1,  7, -1, (sbyte)'N', -1, // H to O
            9,         -1, (sbyte)'R', -1, 10, -1,         11, -1, // P to W
           -1,          5,         -1, -1, -1, -1,         -1, -1, // X to Z
           -1, (sbyte)'A',          2, 12, -1, -1,         -1,  8, // a to g 
           -1,         -1,         -1, -1,  7, -1, (sbyte)'N', -1, // h to o
            9,         -1, (sbyte)'R', -1, 10, -1,         11, -1, // p to w 
           -1,          5,         -1, -1, -1, -1,         -1, -1  // x to z 
        };
 
        static int make_month(string s, int startIndex)
        {
            int i;
            sbyte monthIndex; 
            string monthString;
 
            // 
            // use the third character as the index
            // 

            i = ((int) s[2 + startIndex] - 0x40) & 0x3F;
            monthIndex = s_monthIndexTable[i];
 
            if ( monthIndex >= 13 ) {
 
                // 
                // ok, we need to look at the second character
                // 

                if ( monthIndex == (sbyte) 'N' ) {

                    // 
                    // we got an N which we need to resolve further
                    // 
 
                    //
                    // if s[1] is 'u' then Jun, if 'a' then Jan 
                    //


                    if ( s_monthIndexTable[(s[1 + startIndex]-0x40) & 0x3f] == (sbyte) 'A' ) { 
                        monthIndex = 1;
                    } else { 
                        monthIndex = 6; 
                    }
 
                } else if ( monthIndex == (sbyte) 'R' ) {

                    //
                    // if s[1] is 'a' then March, if 'p' then April 
                    //
 
                    if ( s_monthIndexTable[(s[1 + startIndex]-0x40) & 0x3f] == (sbyte) 'A' ) { 
                        monthIndex = 3;
                    } else { 
                        monthIndex = 4;
                    }
                } else {
                    throw new FormatException(SR.GetString(SR.MakeMonthBadString, s, startIndex)); 
                }
            } 
 

            monthString = s_months[monthIndex-1]; 

            if ( (s[0 + startIndex] == monthString[0]) &&
                 (s[1 + startIndex] == monthString[1]) &&
                 (s[2 + startIndex] == monthString[2]) ) { 

                return(monthIndex); 
 
            } else if ( ((Char.ToUpper(s[0 + startIndex], CultureInfo.InvariantCulture)) == monthString[0]) &&
                        ((Char.ToLower(s[1 + startIndex], CultureInfo.InvariantCulture)) == monthString[1]) && 
                        ((Char.ToLower(s[2 + startIndex], CultureInfo.InvariantCulture)) == monthString[2]) ) {

                return monthIndex;
            } 

            throw new FormatException(SR.GetString(SR.MakeMonthBadString, s, startIndex)); 
 
        } // make_month
 
        /*++

          Converts a string representation of a GMT time (three different
          varieties) to an NT representation of a file time. 

          We handle the following variations: 
 
            Sun, 06 Nov 1994 08:49:37 GMT   (RFC 822 updated by RFC 1123)
            Sunday, 06-Nov-94 08:49:37 GMT  (RFC 850) 
            Sun Nov 06 08:49:37 1994        (ANSI C's asctime() format

          Arguments:
            time                String representation of time field 

          Returns: 
            TRUE on success and FALSE on failure. 

          History: 

            Johnl       24-Jan-1995     Modified from WWW library

        --*/ 
        static internal DateTime UtcParse(string time)
        { 
            int         i; 
            int         year, month, day, hour, minute, second;
 
            if (time == null) {
                throw new ArgumentNullException("time");
            }
 
            if ((i = time.IndexOf(',')) != -1) {
 
                // 
                // Thursday, 10-Jun-93 01:29:59 GMT
                // or: Thu, 10 Jan 1993 01:29:59 GMT */ 
                //

                int length = time.Length - i;
                while (--length > 0 && time[++i] == ' ') ; 

                if (time[i+2] == '-' ) {      /* First format */ 
 
                    if (length < 18) {
                        throw new FormatException(SR.GetString(SR.UtilParseDateTimeBad, time)); 
                    }

                    day = atoi2(time, i);
                    month = make_month(time, i + 3); 
                    year = atoi2(time, i + 7);
                    if ( year < 50 ) { 
                        year += 2000; 
                    } else {
                        year += 1900; 
                    }

                    hour = atoi2(time, i + 10);
                    minute = atoi2(time, i + 13); 
                    second = atoi2(time, i +16);
 
                } else {                         /* Second format */ 

                    if (length < 20) { 
                        throw new FormatException(SR.GetString(SR.UtilParseDateTimeBad, time));
                    }

                    day = atoi2(time, i); 
                    month = make_month(time, i + 3);
                    year = atoi2(time, i + 7) * 100 + atoi2(time, i + 9); 
                    hour = atoi2(time, i + 12); 
                    minute = atoi2(time, i + 15);
                    second = atoi2(time, i + 18); 
                }
            } else {    /* Try the other format:  Wed Jun 09 01:29:59 1993 GMT */

                i = -1; 
                int length = time.Length + 1;
                while (--length > 0 && time[++i] == ' '); 
 
                if (length < 24) {
                    throw new FormatException(SR.GetString(SR.UtilParseDateTimeBad, time)); 
                }

                day = atoi2(time, i + 8);
                month = make_month(time, i + 4); 
                year = atoi2(time, i + 20) * 100 + atoi2(time, i + 22);
                hour = atoi2(time, i + 11); 
                minute = atoi2(time, i + 14); 
                second = atoi2(time, i + 17);
            } 

            return new DateTime(year, month, day, hour, minute, second);
        }
    } 
}

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