netcore/System.Private.CoreLib/shared/System/FormattableString.cs

   1 // Licensed to the .NET Foundation under one or more agreements.
   2 // The .NET Foundation licenses this file to you under the MIT license.
   3 // See the LICENSE file in the project root for more information.
   4
   5 /*============================================================
   6 **
   7 **
   8 **
   9 ** Purpose: implementation of the FormattableString
  10 ** class.
  11 **
  12 ===========================================================*/
  13
  14 namespace System
  15 {
  16     /// <summary>
  17     /// A composite format string along with the arguments to be formatted. An instance of this
  18     /// type may result from the use of the C# or VB language primitive "interpolated string".
  19     /// </summary>
  20     public abstract class FormattableString : IFormattable
  21     {
  22         /// <summary>
  23         /// The composite format string.
  24         /// </summary>
  25         public abstract string Format { get; }
  26
  27         /// <summary>
  28         /// Returns an object array that contains zero or more objects to format. Clients should not
  29         /// mutate the contents of the array.
  30         /// </summary>
  31         public abstract object?[] GetArguments();
  32
  33         /// <summary>
  34         /// The number of arguments to be formatted.
  35         /// </summary>
  36         public abstract int ArgumentCount { get; }
  37
  38         /// <summary>
  39         /// Returns one argument to be formatted from argument position <paramref name="index"/>.
  40         /// </summary>
  41         public abstract object? GetArgument(int index);
  42
  43         /// <summary>
  44         /// Format to a string using the given culture.
  45         /// </summary>
  46         public abstract string ToString(IFormatProvider? formatProvider);
  47
  48         string IFormattable.ToString(string? ignored, IFormatProvider? formatProvider)
  49         {
  50             return ToString(formatProvider);
  51         }
  52
  53         /// <summary>
  54         /// Format the given object in the invariant culture. This static method may be
  55         /// imported in C# by
  56         /// <code>
  57         /// using static System.FormattableString;
  58         /// </code>.
  59         /// Within the scope
  60         /// of that import directive an interpolated string may be formatted in the
  61         /// invariant culture by writing, for example,
  62         /// <code>
  63         /// Invariant($"{{ lat = {latitude}; lon = {longitude} }}")
  64         /// </code>
  65         /// </summary>
  66         public static string Invariant(FormattableString formattable)
  67         {
  68             if (formattable == null)
  69             {
  70                 throw new ArgumentNullException(nameof(formattable));
  71             }
  72
  73             return formattable.ToString(Globalization.CultureInfo.InvariantCulture);
  74         }
  75
  76         /// <summary>
  77         /// Format the given object in the current culture. This static method may be
  78         /// imported in C# by
  79         /// <code>
  80         /// using static System.FormattableString;
  81         /// </code>.
  82         /// Within the scope
  83         /// of that import directive an interpolated string may be formatted in the
  84         /// current culture by writing, for example,
  85         /// <code>
  86         /// CurrentCulture($"{{ lat = {latitude}; lon = {longitude} }}")
  87         /// </code>
  88         /// </summary>
  89         public static string CurrentCulture(FormattableString formattable)
  90         {
  91             if (formattable == null)
  92             {
  93                 throw new ArgumentNullException(nameof(formattable));
  94             }
  95
  96             return formattable.ToString(Globalization.CultureInfo.CurrentCulture);
  97         }
  98
  99         public override string ToString()
 100         {
 101             return ToString(Globalization.CultureInfo.CurrentCulture);
 102         }
 103     }
 104 }