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DefaultInterpolatedStringHandler for .netstandard2.1
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DefaultInterpolatedStringHandler.cs
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
#nullable enable
using System.Buffers;
using System.Diagnostics;
using System.Globalization;
using System.Runtime.InteropServices;
namespace System.Runtime.CompilerServices
{
/// <summary>Provides a handler used by the language compiler to process interpolated strings into <see cref="string"/> instances.</summary>
[InterpolatedStringHandler]
public ref partial struct DefaultInterpolatedStringHandler
{
// Implementation note:
// As this type lives in CompilerServices and is only intended to be targeted by the compiler,
// public APIs eschew argument validation logic in a variety of places, e.g. allowing a null input
// when one isn't expected to produce a NullReferenceException rather than an ArgumentNullException.
/// <summary>Expected average length of formatted data used for an individual interpolation expression result.</summary>
/// <remarks>
/// This is inherited from string.Format, and could be changed based on further data.
/// string.Format actually uses `format.Length + args.Length * 8`, but format.Length
/// includes the format items themselves, e.g. "{0}", and since it's rare to have double-digit
/// numbers of items, we bump the 8 up to 11 to account for the three extra characters in "{d}",
/// since the compiler-provided base length won't include the equivalent character count.
/// </remarks>
private const int GuessedLengthPerHole = 11;
/// <summary>Minimum size array to rent from the pool.</summary>
/// <remarks>Same as stack-allocation size used today by string.Format.</remarks>
private const int MinimumArrayPoolLength = 256;
/// <summary>Optional provider to pass to IFormattable.ToString or ISpanFormattable.TryFormat calls.</summary>
private readonly IFormatProvider? _provider;
/// <summary>Array rented from the array pool and used to back <see cref="_chars"/>.</summary>
private char[]? _arrayToReturnToPool;
/// <summary>The span to write into.</summary>
private Span<char> _chars;
/// <summary>Position at which to write the next character.</summary>
private int _pos;
/// <summary>Whether <see cref="_provider"/> provides an ICustomFormatter.</summary>
/// <remarks>
/// Custom formatters are very rare. We want to support them, but it's ok if we make them more expensive
/// in order to make them as pay-for-play as possible. So, we avoid adding another reference type field
/// to reduce the size of the handler and to reduce required zero'ing, by only storing whether the provider
/// provides a formatter, rather than actually storing the formatter. This in turn means, if there is a
/// formatter, we pay for the extra interface call on each AppendFormatted that needs it.
/// </remarks>
private readonly bool _hasCustomFormatter;
/// <summary>Creates a handler used to translate an interpolated string into a <see cref="string"/>.</summary>
/// <param name="literalLength">The number of constant characters outside of interpolation expressions in the interpolated string.</param>
/// <param name="formattedCount">The number of interpolation expressions in the interpolated string.</param>
/// <remarks>This is intended to be called only by compiler-generated code. Arguments are not validated as they'd otherwise be for members intended to be used directly.</remarks>
public DefaultInterpolatedStringHandler(int literalLength, int formattedCount)
{
_provider = null;
_chars = _arrayToReturnToPool = ArrayPool<char>.Shared.Rent(GetDefaultLength(literalLength, formattedCount));
_pos = 0;
_hasCustomFormatter = false;
}
/// <summary>Creates a handler used to translate an interpolated string into a <see cref="string"/>.</summary>
/// <param name="literalLength">The number of constant characters outside of interpolation expressions in the interpolated string.</param>
/// <param name="formattedCount">The number of interpolation expressions in the interpolated string.</param>
/// <param name="provider">An object that supplies culture-specific formatting information.</param>
/// <remarks>This is intended to be called only by compiler-generated code. Arguments are not validated as they'd otherwise be for members intended to be used directly.</remarks>
public DefaultInterpolatedStringHandler(int literalLength, int formattedCount, IFormatProvider? provider)
{
_provider = provider;
_chars = _arrayToReturnToPool = ArrayPool<char>.Shared.Rent(GetDefaultLength(literalLength, formattedCount));
_pos = 0;
_hasCustomFormatter = provider is not null && HasCustomFormatter(provider);
}
/// <summary>Creates a handler used to translate an interpolated string into a <see cref="string"/>.</summary>
/// <param name="literalLength">The number of constant characters outside of interpolation expressions in the interpolated string.</param>
/// <param name="formattedCount">The number of interpolation expressions in the interpolated string.</param>
/// <param name="provider">An object that supplies culture-specific formatting information.</param>
/// <param name="initialBuffer">A buffer temporarily transferred to the handler for use as part of its formatting. Contents may be overwritten.</param>
/// <remarks>This is intended to be called only by compiler-generated code. Arguments are not validated as they'd otherwise be for members intended to be used directly.</remarks>
public DefaultInterpolatedStringHandler(int literalLength, int formattedCount, IFormatProvider? provider, Span<char> initialBuffer)
{
_provider = provider;
_chars = initialBuffer;
_arrayToReturnToPool = null;
_pos = 0;
_hasCustomFormatter = provider is not null && HasCustomFormatter(provider);
}
/// <summary>Derives a default length with which to seed the handler.</summary>
/// <param name="literalLength">The number of constant characters outside of interpolation expressions in the interpolated string.</param>
/// <param name="formattedCount">The number of interpolation expressions in the interpolated string.</param>
[MethodImpl(MethodImplOptions.AggressiveInlining)] // becomes a constant when inputs are constant
internal static int GetDefaultLength(int literalLength, int formattedCount) =>
Math.Max(MinimumArrayPoolLength, literalLength + (formattedCount * GuessedLengthPerHole));
/// <summary>Gets the built <see cref="string"/>.</summary>
/// <returns>The built string.</returns>
public override string ToString() => new string(Text);
/// <summary>Gets the built <see cref="string"/> and clears the handler.</summary>
/// <returns>The built string.</returns>
/// <remarks>
/// This releases any resources used by the handler. The method should be invoked only
/// once and as the last thing performed on the handler. Subsequent use is erroneous, ill-defined,
/// and may destabilize the process, as may using any other copies of the handler after ToStringAndClear
/// is called on any one of them.
/// </remarks>
public string ToStringAndClear()
{
string result = new string(Text);
Clear();
return result;
}
/// <summary>Clears the handler, returning any rented array to the pool.</summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)] // used only on a few hot paths
internal void Clear()
{
char[]? toReturn = _arrayToReturnToPool;
this = default; // defensive clear
if (toReturn is not null)
{
ArrayPool<char>.Shared.Return(toReturn);
}
}
/// <summary>Gets a span of the written characters thus far.</summary>
internal ReadOnlySpan<char> Text => _chars.Slice(0, _pos);
/// <summary>Writes the specified string to the handler.</summary>
/// <param name="value">The string to write.</param>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public void AppendLiteral(string value)
{
if (value.AsSpan().TryCopyTo(_chars.Slice(_pos)))
{
_pos += value.Length;
}
else
{
GrowThenCopyString(value);
}
}
#region AppendFormatted
// Design note:
// The compiler requires a AppendFormatted overload for anything that might be within an interpolation expression;
// if it can't find an appropriate overload, for handlers in general it'll simply fail to compile.
// (For target-typing to string where it uses DefaultInterpolatedStringHandler implicitly, it'll instead fall back to
// its other mechanisms, e.g. using string.Format. This fallback has the benefit that if we miss a case,
// interpolated strings will still work, but it has the downside that a developer generally won't know
// if the fallback is happening and they're paying more.)
//
// At a minimum, then, we would need an overload that accepts:
// (object value, int alignment = 0, string? format = null)
// Such an overload would provide the same expressiveness as string.Format. However, this has several
// shortcomings:
// - Every value type in an interpolation expression would be boxed.
// - ReadOnlySpan<char> could not be used in interpolation expressions.
// - Every AppendFormatted call would have three arguments at the call site, bloating the IL further.
// - Every invocation would be more expensive, due to lack of specialization, every call needing to account
// for alignment and format, etc.
//
// To address that, we could just have overloads for T and ReadOnlySpan<char>:
// (T)
// (T, int alignment)
// (T, string? format)
// (T, int alignment, string? format)
// (ReadOnlySpan<char>)
// (ReadOnlySpan<char>, int alignment)
// (ReadOnlySpan<char>, string? format)
// (ReadOnlySpan<char>, int alignment, string? format)
// but this also has shortcomings:
// - Some expressions that would have worked with an object overload will now force a fallback to string.Format
// (or fail to compile if the handler is used in places where the fallback isn't provided), because the compiler
// can't always target type to T, e.g. `b switch { true => 1, false => null }` where `b` is a bool can successfully
// be passed as an argument of type `object` but not of type `T`.
// - Reference types get no benefit from going through the generic code paths, and actually incur some overheads
// from doing so.
// - Nullable value types also pay a heavy price, in particular around interface checks that would generally evaporate
// at compile time for value types but don't (currently) if the Nullable<T> goes through the same code paths
// (see https://github.com/dotnet/runtime/issues/50915).
//
// We could try to take a more elaborate approach for DefaultInterpolatedStringHandler, since it is the most common handler
// and we want to minimize overheads both at runtime and in IL size, e.g. have a complete set of overloads for each of:
// (T, ...) where T : struct
// (T?, ...) where T : struct
// (object, ...)
// (ReadOnlySpan<char>, ...)
// (string, ...)
// but this also has shortcomings, most importantly:
// - If you have an unconstrained T that happens to be a value type, it'll now end up getting boxed to use the object overload.
// This also necessitates the T? overload, since nullable value types don't meet a T : struct constraint, so without those
// they'd all map to the object overloads as well.
// - Any reference type with an implicit cast to ROS<char> will fail to compile due to ambiguities between the overloads. string
// is one such type, hence needing dedicated overloads for it that can be bound to more tightly.
//
// A middle ground we've settled on, which is likely to be the right approach for most other handlers as well, would be the set:
// (T, ...) with no constraint
// (ReadOnlySpan<char>) and (ReadOnlySpan<char>, int)
// (object, int alignment = 0, string? format = null)
// (string) and (string, int)
// This would address most of the concerns, at the expense of:
// - Most reference types going through the generic code paths and so being a bit more expensive.
// - Nullable types being more expensive until https://github.com/dotnet/runtime/issues/50915 is addressed.
// We could choose to add a T? where T : struct set of overloads if necessary.
// Strings don't require their own overloads here, but as they're expected to be very common and as we can
// optimize them in several ways (can copy the contents directly, don't need to do any interface checks, don't
// need to pay the shared generic overheads, etc.) we can add overloads specifically to optimize for them.
//
// Hole values are formatted according to the following policy:
// 1. If an IFormatProvider was supplied and it provides an ICustomFormatter, use ICustomFormatter.Format (even if the value is null).
// 2. If the type implements ISpanFormattable, use ISpanFormattable.TryFormat.
// 3. If the type implements IFormattable, use IFormattable.ToString.
// 4. Otherwise, use object.ToString.
// This matches the behavior of string.Format, StringBuilder.AppendFormat, etc. The only overloads for which this doesn't
// apply is ReadOnlySpan<char>, which isn't supported by either string.Format nor StringBuilder.AppendFormat, but more
// importantly which can't be boxed to be passed to ICustomFormatter.Format.
#region AppendFormatted T
/// <summary>Writes the specified value to the handler.</summary>
/// <param name="value">The value to write.</param>
/// <typeparam name="T">The type of the value to write.</typeparam>
public void AppendFormatted<T>(T value)
{
AppendFormatted(value, null);
}
/// <summary>Writes the specified value to the handler.</summary>
/// <param name="value">The value to write.</param>
/// <param name="format">The format string.</param>
/// <typeparam name="T">The type of the value to write.</typeparam>
public void AppendFormatted<T>(T value, string? format)
{
// If there's a custom formatter, always use it.
if (_hasCustomFormatter)
{
AppendCustomFormatter(value, format);
return;
}
// Check first for IFormattable, even though we'll prefer to use ISpanFormattable, as the latter
// requires the former. For value types, it won't matter as the type checks devolve into
// JIT-time constants. For reference types, they're more likely to implement IFormattable
// than they are to implement ISpanFormattable: if they don't implement either, we save an
// interface check over first checking for ISpanFormattable and then for IFormattable, and
// if it only implements IFormattable, we come out even: only if it implements both do we
// end up paying for an extra interface check.
string? s;
if (value is IFormattable formattable)
{
// If the value can format itself directly into our buffer, do so.
s = (formattable).ToString(format, _provider); // constrained call avoiding boxing for value types
}
else
{
s = value?.ToString();
}
if (s is not null)
{
AppendLiteral(s);
}
}
/// <summary>Writes the specified value to the handler.</summary>
/// <param name="value">The value to write.</param>
/// <param name="alignment">Minimum number of characters that should be written for this value. If the value is negative, it indicates left-aligned and the required minimum is the absolute value.</param>
/// <typeparam name="T">The type of the value to write.</typeparam>
public void AppendFormatted<T>(T value, int alignment)
{
int startingPos = _pos;
AppendFormatted(value);
if (alignment != 0)
{
AppendOrInsertAlignmentIfNeeded(startingPos, alignment);
}
}
/// <summary>Writes the specified value to the handler.</summary>
/// <param name="value">The value to write.</param>
/// <param name="format">The format string.</param>
/// <param name="alignment">Minimum number of characters that should be written for this value. If the value is negative, it indicates left-aligned and the required minimum is the absolute value.</param>
/// <typeparam name="T">The type of the value to write.</typeparam>
public void AppendFormatted<T>(T value, int alignment, string? format)
{
int startingPos = _pos;
AppendFormatted(value, format);
if (alignment != 0)
{
AppendOrInsertAlignmentIfNeeded(startingPos, alignment);
}
}
#endregion
#region AppendFormatted ReadOnlySpan<char>
/// <summary>Writes the specified character span to the handler.</summary>
/// <param name="value">The span to write.</param>
public void AppendFormatted( ReadOnlySpan<char> value)
{
// Fast path for when the value fits in the current buffer
if (value.TryCopyTo(_chars.Slice(_pos)))
{
_pos += value.Length;
}
else
{
GrowThenCopySpan(value);
}
}
/// <summary>Writes the specified string of chars to the handler.</summary>
/// <param name="value">The span to write.</param>
/// <param name="alignment">Minimum number of characters that should be written for this value. If the value is negative, it indicates left-aligned and the required minimum is the absolute value.</param>
/// <param name="format">The format string.</param>
public void AppendFormatted( ReadOnlySpan<char> value, int alignment = 0, string? format = null)
{
bool leftAlign = false;
if (alignment < 0)
{
leftAlign = true;
alignment = -alignment;
}
int paddingRequired = alignment - value.Length;
if (paddingRequired <= 0)
{
// The value is as large or larger than the required amount of padding,
// so just write the value.
AppendFormatted(value);
return;
}
// Write the value along with the appropriate padding.
EnsureCapacityForAdditionalChars(value.Length + paddingRequired);
if (leftAlign)
{
value.CopyTo(_chars.Slice(_pos));
_pos += value.Length;
_chars.Slice(_pos, paddingRequired).Fill(' ');
_pos += paddingRequired;
}
else
{
_chars.Slice(_pos, paddingRequired).Fill(' ');
_pos += paddingRequired;
value.CopyTo(_chars.Slice(_pos));
_pos += value.Length;
}
}
#endregion
#region AppendFormatted string
/// <summary>Writes the specified value to the handler.</summary>
/// <param name="value">The value to write.</param>
public void AppendFormatted(string? value)
{
// Fast-path for no custom formatter and a non-null string that fits in the current destination buffer.
if (!_hasCustomFormatter &&
value is not null &&
value.AsSpan().TryCopyTo(_chars.Slice(_pos)))
{
_pos += value.Length;
}
else
{
AppendFormattedSlow(value);
}
}
/// <summary>Writes the specified value to the handler.</summary>
/// <param name="value">The value to write.</param>
/// <remarks>
/// Slow path to handle a custom formatter, potentially null value,
/// or a string that doesn't fit in the current buffer.
/// </remarks>
[MethodImpl(MethodImplOptions.NoInlining)]
private void AppendFormattedSlow(string? value)
{
if (_hasCustomFormatter)
{
AppendCustomFormatter(value, format: null);
}
else if (value is not null)
{
EnsureCapacityForAdditionalChars(value.Length);
value.AsSpan().CopyTo(_chars.Slice(_pos));
_pos += value.Length;
}
}
/// <summary>Writes the specified value to the handler.</summary>
/// <param name="value">The value to write.</param>
/// <param name="alignment">Minimum number of characters that should be written for this value. If the value is negative, it indicates left-aligned and the required minimum is the absolute value.</param>
/// <param name="format">The format string.</param>
public void AppendFormatted(string? value, int alignment = 0, string? format = null) =>
// Format is meaningless for strings and doesn't make sense for someone to specify. We have the overload
// simply to disambiguate between ROS<char> and object, just in case someone does specify a format, as
// string is implicitly convertible to both. Just delegate to the T-based implementation.
AppendFormatted<string?>(value, alignment, format);
#endregion
#region AppendFormatted object
/// <summary>Writes the specified value to the handler.</summary>
/// <param name="value">The value to write.</param>
/// <param name="alignment">Minimum number of characters that should be written for this value. If the value is negative, it indicates left-aligned and the required minimum is the absolute value.</param>
/// <param name="format">The format string.</param>
public void AppendFormatted(object? value, int alignment = 0, string? format = null) =>
// This overload is expected to be used rarely, only if either a) something strongly typed as object is
// formatted with both an alignment and a format, or b) the compiler is unable to target type to T. It
// exists purely to help make cases from (b) compile. Just delegate to the T-based implementation.
AppendFormatted<object?>(value, alignment, format);
#endregion
#endregion
/// <summary>Gets whether the provider provides a custom formatter.</summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)] // only used in a few hot path call sites
internal static bool HasCustomFormatter(IFormatProvider provider)
{
Debug.Assert(provider is not null);
Debug.Assert(provider is not CultureInfo || provider.GetFormat(typeof(ICustomFormatter)) is null, "Expected CultureInfo to not provide a custom formatter");
return
provider.GetType() != typeof(CultureInfo) && // optimization to avoid GetFormat in the majority case
provider.GetFormat(typeof(ICustomFormatter)) != null;
}
/// <summary>Formats the value using the custom formatter from the provider.</summary>
/// <param name="value">The value to write.</param>
/// <param name="format">The format string.</param>
/// <typeparam name="T">The type of the value to write.</typeparam>
[MethodImpl(MethodImplOptions.NoInlining)]
private void AppendCustomFormatter<T>(T value, string? format)
{
// This case is very rare, but we need to handle it prior to the other checks in case
// a provider was used that supplied an ICustomFormatter which wanted to intercept the particular value.
// We do the cast here rather than in the ctor, even though this could be executed multiple times per
// formatting, to make the cast pay for play.
Debug.Assert(_hasCustomFormatter);
Debug.Assert(_provider != null);
ICustomFormatter? formatter = (ICustomFormatter?)_provider.GetFormat(typeof(ICustomFormatter));
Debug.Assert(formatter != null, "An incorrectly written provider said it implemented ICustomFormatter, and then didn't");
if (formatter is not null && formatter.Format(format, value, _provider) is string customFormatted)
{
AppendLiteral(customFormatted);
}
}
/// <summary>Handles adding any padding required for aligning a formatted value in an interpolation expression.</summary>
/// <param name="startingPos">The position at which the written value started.</param>
/// <param name="alignment">Non-zero minimum number of characters that should be written for this value. If the value is negative, it indicates left-aligned and the required minimum is the absolute value.</param>
private void AppendOrInsertAlignmentIfNeeded(int startingPos, int alignment)
{
Debug.Assert(startingPos >= 0 && startingPos <= _pos);
Debug.Assert(alignment != 0);
int charsWritten = _pos - startingPos;
bool leftAlign = false;
if (alignment < 0)
{
leftAlign = true;
alignment = -alignment;
}
int paddingNeeded = alignment - charsWritten;
if (paddingNeeded > 0)
{
EnsureCapacityForAdditionalChars(paddingNeeded);
if (leftAlign)
{
_chars.Slice(_pos, paddingNeeded).Fill(' ');
}
else
{
_chars.Slice(startingPos, charsWritten).CopyTo(_chars.Slice(startingPos + paddingNeeded));
_chars.Slice(startingPos, paddingNeeded).Fill(' ');
}
_pos += paddingNeeded;
}
}
/// <summary>Ensures <see cref="_chars"/> has the capacity to store <paramref name="additionalChars"/> beyond <see cref="_pos"/>.</summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private void EnsureCapacityForAdditionalChars(int additionalChars)
{
if (_chars.Length - _pos < additionalChars)
{
Grow(additionalChars);
}
}
/// <summary>Fallback for fast path in <see cref="AppendLiteral(string)"/> when there's not enough space in the destination.</summary>
/// <param name="value">The string to write.</param>
[MethodImpl(MethodImplOptions.NoInlining)]
private void GrowThenCopyString(string value)
{
Grow(value.Length);
value.AsSpan().CopyTo(_chars.Slice(_pos));
_pos += value.Length;
}
/// <summary>Fallback for <see cref="AppendFormatted(ReadOnlySpan{char})"/> for when not enough space exists in the current buffer.</summary>
/// <param name="value">The span to write.</param>
[MethodImpl(MethodImplOptions.NoInlining)]
private void GrowThenCopySpan( ReadOnlySpan<char> value)
{
Grow(value.Length);
value.CopyTo(_chars.Slice(_pos));
_pos += value.Length;
}
/// <summary>Grows <see cref="_chars"/> to have the capacity to store at least <paramref name="additionalChars"/> beyond <see cref="_pos"/>.</summary>
[MethodImpl(MethodImplOptions.NoInlining)] // keep consumers as streamlined as possible
private void Grow(int additionalChars)
{
// This method is called when the remaining space (_chars.Length - _pos) is
// insufficient to store a specific number of additional characters. Thus, we
// need to grow to at least that new total. GrowCore will handle growing by more
// than that if possible.
Debug.Assert(additionalChars > _chars.Length - _pos);
GrowCore((uint)_pos + (uint)additionalChars);
}
/// <summary>Grows the size of <see cref="_chars"/>.</summary>
[MethodImpl(MethodImplOptions.NoInlining)] // keep consumers as streamlined as possible
private void Grow()
{
// This method is called when the remaining space in _chars isn't sufficient to continue
// the operation. Thus, we need at least one character beyond _chars.Length. GrowCore
// will handle growing by more than that if possible.
GrowCore((uint)_chars.Length + 1);
}
/// <summary>Grow the size of <see cref="_chars"/> to at least the specified <paramref name="requiredMinCapacity"/>.</summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)] // but reuse this grow logic directly in both of the above grow routines
private void GrowCore(uint requiredMinCapacity)
{
// We want the max of how much space we actually required and doubling our capacity (without going beyond the max allowed length). We
// also want to avoid asking for small arrays, to reduce the number of times we need to grow, and since we're working with unsigned
// ints that could technically overflow if someone tried to, for example, append a huge string to a huge string, we also clamp to int.MaxValue.
// Even if the array creation fails in such a case, we may later fail in ToStringAndClear.
uint newCapacity = Math.Max(requiredMinCapacity, Math.Min((uint)_chars.Length * 2, 100000));
int arraySize = (int)Math.Clamp(newCapacity, MinimumArrayPoolLength, int.MaxValue);
char[] newArray = ArrayPool<char>.Shared.Rent(arraySize);
_chars.Slice(0, _pos).CopyTo(newArray);
char[]? toReturn = _arrayToReturnToPool;
_chars = _arrayToReturnToPool = newArray;
if (toReturn is not null)
{
ArrayPool<char>.Shared.Return(toReturn);
}
}
}
}
Raw
DefaultInterpolatedStringHandler.NonGeneric.cs
namespace System.Runtime.CompilerServices
{
public ref partial struct DefaultInterpolatedStringHandler
{
public void AppendFormatted(float value)=> AppendFormatted(value, null);
public void AppendFormatted(int value)=> AppendFormatted(value, null);
public void AppendFormatted(double value)=> AppendFormatted(value, null);
public void AppendFormatted(decimal value)=> AppendFormatted(value, null);
public void AppendFormatted(long value)=> AppendFormatted(value, null);
public void AppendFormatted(int value, string? format)
{
// If there's a custom formatter, always use it.
if (_hasCustomFormatter)
{
AppendCustomFormatter(value, format);
return;
}
int charsWritten;
while (!value.TryFormat(_chars.Slice(_pos), out charsWritten, format, _provider)) // constrained call avoiding boxing for value types
{
Grow();
}
_pos += charsWritten;
}
public void AppendFormatted(double value, string? format)
{
// If there's a custom formatter, always use it.
if (_hasCustomFormatter)
{
AppendCustomFormatter(value, null);
return;
}
int charsWritten;
while (!value.TryFormat(_chars.Slice(_pos), out charsWritten, format, _provider)) // constrained call avoiding boxing for value types
{
Grow();
}
_pos += charsWritten;
}
public void AppendFormatted(decimal value, string? format)
{
// If there's a custom formatter, always use it.
if (_hasCustomFormatter)
{
AppendCustomFormatter(value, format);
return;
}
int charsWritten;
while (!value.TryFormat(_chars.Slice(_pos), out charsWritten, format, _provider)) // constrained call avoiding boxing for value types
{
Grow();
}
_pos += charsWritten;
}
public void AppendFormatted(long value, string? format)
{
// If there's a custom formatter, always use it.
if (_hasCustomFormatter)
{
AppendCustomFormatter(value, format);
return;
}
int charsWritten;
while (!value.TryFormat(_chars.Slice(_pos), out charsWritten, format, _provider)) // constrained call avoiding boxing for value types
{
Grow();
}
_pos += charsWritten;
}
}
}
Raw
InterpolatedStringHandlerArgumentAttribute.cs
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
namespace System.Runtime.CompilerServices
{
/// <summary>Indicates which arguments to a method involving an interpolated string handler should be passed to that handler.</summary>
[AttributeUsage(AttributeTargets.Parameter, AllowMultiple = false, Inherited = false)]
public sealed class InterpolatedStringHandlerArgumentAttribute : Attribute
{
/// <summary>Initializes a new instance of the <see cref="InterpolatedStringHandlerArgumentAttribute"/> class.</summary>
/// <param name="argument">The name of the argument that should be passed to the handler.</param>
/// <remarks>The empty string may be used as the name of the receiver in an instance method.</remarks>
public InterpolatedStringHandlerArgumentAttribute(string argument) => Arguments = new [] { argument };
/// <summary>Initializes a new instance of the <see cref="InterpolatedStringHandlerArgumentAttribute"/> class.</summary>
/// <param name="arguments">The names of the arguments that should be passed to the handler.</param>
/// <remarks>The empty string may be used as the name of the receiver in an instance method.</remarks>
public InterpolatedStringHandlerArgumentAttribute(params string[] arguments) => Arguments = arguments;
/// <summary>Gets the names of the arguments that should be passed to the handler.</summary>
/// <remarks>The empty string may be used as the name of the receiver in an instance method.</remarks>
public string[] Arguments { get; }
}
}
Raw
InterpolatedStringHandlerAttribute.cs
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
namespace System.Runtime.CompilerServices
{
/// <summary>Indicates the attributed type is to be used as an interpolated string handler.</summary>
[AttributeUsage(AttributeTargets.Class | AttributeTargets.Struct, AllowMultiple = false, Inherited = false)]
public sealed class InterpolatedStringHandlerAttribute : Attribute
{
/// <summary>Initializes the <see cref="InterpolatedStringHandlerAttribute"/>.</summary>
public InterpolatedStringHandlerAttribute() { }
}
}
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