C# uses string like that 'dd MMMM yyyy HH:mm' to define format the date and time should be displayed in.
Equivalent of that in momentjs is 'DD MMMM YYYY HH:mm'.
Is there some function that can covert one format definition into the other regardless of what (legal) combination of format specifiers source format contains?
Basically what I want is:
function toMomentJsFormatDefinition(cSharpFormatDefinition) {
// should convert all format strings described here https://msdn.microsoft.com/en-us/library/8kb3ddd4%28v=vs.110%29.aspx
}
console.log(toMomentJsFormatDefinition('dd MMMM yyyy HH:mm'));
// outputs DD MMMM YYYY HH:mm
Ideally toMomentJsFormatDefinition should be defined in some already written and fairly well tested library I'll just use in my project.
I had the same task and created the following utility function to convert a DateTime Format String from Dotnet to MomentJS format.
Usage:
string lDotNetFormat = "yyyy-MM-dd HH:mm";
string lMomentJSFormat = MomentJSHelpers.GenerateMomentJSFormatString(lDotNetFormat, fTolerant: true, fCulture: CultureInfo.InvariantCulture);
MessageBox.Show(lMomentJSFormat);
// Output: YYYY[-]MM[-]DD[ ]HH[:]mm
Code:
using System;
using System.Globalization;
using System.Text;
namespace XYZ
{
/// <summary>
/// Class with helper functions to work with MomentJS
/// </summary>
public static class MomentJSHelpers
{
/// <summary>
/// Exception that is throws when trying to convert a dotnet datetime format string
/// to a MomentJS format string and this fails because we have an element in the format string
/// that has no equivalent in MomentJS
/// </summary>
public class UnsupportedFormatException : Exception
{
public UnsupportedFormatException (string fMessage): base(fMessage)
{
}
}
/// <summary>
/// Translate a dotnet datetime format string to a MomentJS format string<br/>
// Restriction:<br/>
// Fractional Seconds Lowecase F and Uppercase F are difficult to translate to MomentJS, so closest
// translation used
/// </summary>
/// <param name="fText">The dotnet datetime format string to convert</param>
/// <param name="fTolerant">If true, some cases where there is not exact equivalent in MomentJs is
/// handled by generating a similar format instead of throwing a UnsupportedFormatException exception.</param>
/// <param name="fCulture">The Culture to use. If none, the current Culture is used</param>
/// <returns>A format string to be used in MomentJS</returns>
/// <exception cref="UnsupportedFormatException">Conversion fails because we have an element in the format string
/// that has no equivalent in MomentJS</exception>
/// <exception cref="FormatException">fText is no valid DateTime format string in dotnet</exception>
/// <exception cref="ArgumentNullException">fText is null</exception>
public static string GenerateMomentJSFormatString(string fText, bool fTolerant = true, CultureInfo fCulture = null)
{
fCulture = fCulture ?? CultureInfo.CurrentCulture;
string lResult;
if(fText == null)
{
throw new ArgumentNullException("fText");
}
if(fText.Length == 0)
{
lResult = "";
}
if (fText.Length == 1)
{
lResult = GenerateMomentJSFormatStringFromStandardFormat(fText, fTolerant, fCulture);
}
else
{
lResult = GenerateMomentJSFormatStringFromUserFormat(fText, fTolerant, fCulture);
}
return lResult;
}
/// <summary>
/// State of StateMachine while scanning Format DateTime string
/// </summary>
private enum State
{
None,
LowerD1,
LowerD2,
LowerD3,
LowerD4,
LowerF1,
LowerF2,
LowerF3,
LowerF4,
LowerF5,
LowerF6,
LowerF7,
CapitalF1,
CapitalF2,
CapitalF3,
CapitalF4,
CapitalF5,
CapitalF6,
CapitalF7,
LowerG,
LowerH1,
LowerH2,
CapitalH1,
CapitalH2,
CapitalK,
LowerM1,
LowerM2,
CapitalM1,
CapitalM2,
CapitalM3,
CapitalM4,
LowerS1,
LowerS2,
LowerT1,
LowerT2,
LowerY1,
LowerY2,
LowerY3,
LowerY4,
LowerY5,
LowerZ1,
LowerZ2,
LowerZ3,
InSingleQuoteLiteral,
InDoubleQuoteLiteral,
EscapeSequence
}
private static string GenerateMomentJSFormatStringFromUserFormat(string fText, bool fTolerant, CultureInfo fCulture)
{
StringBuilder lResult = new StringBuilder();
State lState = State.None;
StringBuilder lTokenBuffer = new StringBuilder();
var ChangeState = new Action<State>((State fNewState) =>
{
switch (lState)
{
case State.LowerD1:
lResult.Append("D");
break;
case State.LowerD2:
lResult.Append("DD");
break;
case State.LowerD3:
lResult.Append("ddd");
break;
case State.LowerD4:
lResult.Append("dddd");
break;
case State.LowerF1:
case State.CapitalF1:
lResult.Append("S");
break;
case State.LowerF2:
case State.CapitalF2:
lResult.Append("SS");
break;
case State.LowerF3:
case State.CapitalF3:
lResult.Append("SSS");
break;
case State.LowerF4:
case State.CapitalF4:
lResult.Append("SSSS");
break;
case State.LowerF5:
case State.CapitalF5:
lResult.Append("SSSSS");
break;
case State.LowerF6:
case State.CapitalF6:
lResult.Append("SSSSSS");
break;
case State.LowerF7:
case State.CapitalF7:
lResult.Append("SSSSSSS");
break;
case State.LowerG:
throw new UnsupportedFormatException("Era not supported in MomentJS");
case State.LowerH1:
lResult.Append("h");
break;
case State.LowerH2:
lResult.Append("hh");
break;
case State.CapitalH1:
lResult.Append("H");
break;
case State.CapitalH2:
lResult.Append("HH");
break;
case State.LowerM1:
lResult.Append("m");
break;
case State.LowerM2:
lResult.Append("mm");
break;
case State.CapitalM1:
lResult.Append("M");
break;
case State.CapitalM2:
lResult.Append("MM");
break;
case State.CapitalM3:
lResult.Append("MMM");
break;
case State.CapitalM4:
lResult.Append("MMMM");
break;
case State.LowerS1:
lResult.Append("s");
break;
case State.LowerS2:
lResult.Append("ss");
break;
case State.LowerT1:
if (fTolerant)
{
lResult.Append("A");
}
else
{
throw new UnsupportedFormatException("Single Letter AM/PM not supported in MomentJS");
}
break;
case State.LowerT2:
lResult.Append("A");
break;
case State.LowerY1:
if (fTolerant)
{
lResult.Append("YY");
}
else
{
throw new UnsupportedFormatException("Single Letter Year not supported in MomentJS");
}
break;
case State.LowerY2:
lResult.Append("YY");
break;
case State.LowerY3:
if (fTolerant)
{
lResult.Append("YYYY");
}
else
{
throw new UnsupportedFormatException("Three Letter Year not supported in MomentJS");
}
break;
case State.LowerY4:
lResult.Append("YYYY");
break;
case State.LowerY5:
if(fTolerant)
{
lResult.Append("Y");
}
else
{
throw new UnsupportedFormatException("Five or more Letter Year not supported in MomentJS");
}
break;
case State.LowerZ1:
case State.LowerZ2:
if (fTolerant)
{
lResult.Append("ZZ");
}
else
{
throw new UnsupportedFormatException("Hours offset not supported in MomentJS");
}
break;
case State.LowerZ3:
lResult.Append("Z");
break;
case State.InSingleQuoteLiteral:
case State.InDoubleQuoteLiteral:
case State.EscapeSequence:
foreach (var lCharacter in lTokenBuffer.ToString())
{
lResult.Append("[" + lCharacter + "]");
}
break;
}
lTokenBuffer.Clear();
lState = fNewState;
}); // End ChangeState
foreach (var character in fText)
{
if (lState == State.EscapeSequence)
{
lTokenBuffer.Append(character);
ChangeState(State.None);
}
else if (lState == State.InDoubleQuoteLiteral)
{
if (character == '\"')
{
ChangeState(State.None);
}
else
{
lTokenBuffer.Append(character);
}
}
else if (lState == State.InSingleQuoteLiteral)
{
if (character == '\'')
{
ChangeState(State.None);
}
else
{
lTokenBuffer.Append(character);
}
}
else
{
switch (character)
{
case 'd':
switch (lState)
{
case State.LowerD1:
lState = State.LowerD2;
break;
case State.LowerD2:
lState = State.LowerD3;
break;
case State.LowerD3:
lState = State.LowerD4;
break;
case State.LowerD4:
break;
default:
ChangeState(State.LowerD1);
break;
}
break;
case 'f':
switch (lState)
{
case State.LowerF1:
lState = State.LowerF2;
break;
case State.LowerF2:
lState = State.LowerF3;
break;
case State.LowerF3:
lState = State.LowerF4;
break;
case State.LowerF4:
lState = State.LowerF5;
break;
case State.LowerF5:
lState = State.LowerF6;
break;
case State.LowerF6:
lState = State.LowerF7;
break;
case State.LowerF7:
break;
default:
ChangeState(State.LowerF1);
break;
}
break;
case 'F':
switch (lState)
{
case State.CapitalF1:
lState = State.CapitalF2;
break;
case State.CapitalF2:
lState = State.CapitalF3;
break;
case State.CapitalF3:
lState = State.CapitalF4;
break;
case State.CapitalF4:
lState = State.CapitalF5;
break;
case State.CapitalF5:
lState = State.CapitalF6;
break;
case State.CapitalF6:
lState = State.CapitalF7;
break;
case State.CapitalF7:
break;
default:
ChangeState(State.CapitalF1);
break;
}
break;
case 'g':
switch (lState)
{
case State.LowerG:
break;
default:
ChangeState(State.LowerG);
break;
}
break;
case 'h':
switch (lState)
{
case State.LowerH1:
lState = State.LowerH2;
break;
case State.LowerH2:
break;
default:
ChangeState(State.LowerH1);
break;
}
break;
case 'H':
switch (lState)
{
case State.CapitalH1:
lState = State.CapitalH2;
break;
case State.CapitalH2:
break;
default:
ChangeState(State.CapitalH1);
break;
}
break;
case 'K':
ChangeState(State.None);
if (fTolerant)
{
lResult.Append("Z");
}
else
{
throw new UnsupportedFormatException("TimeZoneInformation not supported in MomentJS");
}
break;
case 'm':
switch (lState)
{
case State.LowerM1:
lState = State.LowerM2;
break;
case State.LowerM2:
break;
default:
ChangeState(State.LowerM1);
break;
}
break;
case 'M':
switch (lState)
{
case State.CapitalM1:
lState = State.CapitalM2;
break;
case State.CapitalM2:
lState = State.CapitalM3;
break;
case State.CapitalM3:
lState = State.CapitalM4;
break;
case State.CapitalM4:
break;
default:
ChangeState(State.CapitalM1);
break;
}
break;
case 's':
switch (lState)
{
case State.LowerS1:
lState = State.LowerS2;
break;
case State.LowerS2:
break;
default:
ChangeState(State.LowerS1);
break;
}
break;
case 't':
switch (lState)
{
case State.LowerT1:
lState = State.LowerT2;
break;
case State.LowerT2:
break;
default:
ChangeState(State.LowerT1);
break;
}
break;
case 'y':
switch (lState)
{
case State.LowerY1:
lState = State.LowerY2;
break;
case State.LowerY2:
lState = State.LowerY3;
break;
case State.LowerY3:
lState = State.LowerY4;
break;
case State.LowerY4:
lState = State.LowerY5;
break;
case State.LowerY5:
break;
default:
ChangeState(State.LowerY1);
break;
}
break;
case 'z':
switch (lState)
{
case State.LowerZ1:
lState = State.LowerZ2;
break;
case State.LowerZ2:
lState = State.LowerZ3;
break;
case State.LowerZ3:
break;
default:
ChangeState(State.LowerZ1);
break;
}
break;
case ':':
ChangeState(State.None);
lResult.Append("[" + fCulture.DateTimeFormat.TimeSeparator + "]");
break;
case '/':
ChangeState(State.None);
lResult.Append("[" + fCulture.DateTimeFormat.DateSeparator + "]");
break;
case '\"':
ChangeState(State.InDoubleQuoteLiteral);
break;
case '\'':
ChangeState(State.InSingleQuoteLiteral);
break;
case '%':
ChangeState(State.None);
break;
case '\\':
ChangeState(State.EscapeSequence);
break;
default:
ChangeState(State.None);
lResult.Append("[" + character + "]");
break;
}
}
}
if (lState == State.EscapeSequence || lState == State.InDoubleQuoteLiteral || lState == State.InSingleQuoteLiteral)
{
throw new FormatException("Invalid Format String");
}
ChangeState(State.None);
return lResult.ToString();
}
private static string GenerateMomentJSFormatStringFromStandardFormat(string fText, bool fTolerant, CultureInfo fCulture)
{
string result;
switch (fText)
{
case "d":
result = GenerateMomentJSFormatStringFromUserFormat(fCulture.DateTimeFormat.ShortDatePattern, fTolerant, fCulture);
break;
case "D":
result = GenerateMomentJSFormatStringFromUserFormat(fCulture.DateTimeFormat.LongDatePattern, fTolerant, fCulture);
break;
case "f":
result = GenerateMomentJSFormatStringFromUserFormat(fCulture.DateTimeFormat.LongDatePattern + " " + fCulture.DateTimeFormat.ShortTimePattern, fTolerant, fCulture);
break;
case "F":
result = GenerateMomentJSFormatStringFromUserFormat(fCulture.DateTimeFormat.FullDateTimePattern, fTolerant, fCulture);
break;
case "g":
result = GenerateMomentJSFormatStringFromUserFormat(fCulture.DateTimeFormat.ShortDatePattern + " " + fCulture.DateTimeFormat.ShortTimePattern, fTolerant, fCulture);
break;
case "G":
result = GenerateMomentJSFormatStringFromUserFormat(fCulture.DateTimeFormat.ShortDatePattern + " " + fCulture.DateTimeFormat.LongTimePattern, fTolerant, fCulture);
break;
case "M":
case "m":
result = GenerateMomentJSFormatStringFromUserFormat(fCulture.DateTimeFormat.MonthDayPattern, fTolerant, fCulture);
break;
case "O":
case "o":
result = GenerateMomentJSFormatStringFromUserFormat("yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'fffffffK", fTolerant, fCulture);
break;
case "R":
case "r":
throw new UnsupportedFormatException("RFC 1123 not supported in MomentJS");
case "s":
result = GenerateMomentJSFormatStringFromUserFormat(fCulture.DateTimeFormat.SortableDateTimePattern, fTolerant, fCulture);
break;
case "t":
result = GenerateMomentJSFormatStringFromUserFormat(fCulture.DateTimeFormat.ShortTimePattern, fTolerant, fCulture);
break;
case "T":
result = GenerateMomentJSFormatStringFromUserFormat(fCulture.DateTimeFormat.LongTimePattern, fTolerant, fCulture);
break;
case "u":
throw new UnsupportedFormatException("Universal Sortable Format not supported in MomentJS");
case "U":
throw new UnsupportedFormatException("Universal Fulll Format not supported in MomentJS");
case "Y":
case "y":
result = GenerateMomentJSFormatStringFromUserFormat(fCulture.DateTimeFormat.YearMonthPattern, fTolerant, fCulture);
break;
default:
throw new FormatException("Unknown Standard DateTime Format");
}
return result;
}
}
}
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