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Rune extensions micro-optimizations (#3910)

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* Add benchmarks for potentially optimizable RuneExtensions

* Add new RuneExtensions.DecodeSurrogatePair benchmark implementation

Avoids intermediate heap array allocations which is especially nice when the rune is not surrogate pair because then array heap allocations are completely avoided.

* Enable nullable reference types in RuneExtensions

* Make RuneExtensions.MaxUnicodeCodePoint readonly

Makes sure no one can accidentally change the value. Ideally would be const value.

* Optimize RuneExtensions.DecodeSurrogatePair

* Remove duplicate Rune.GetUnicodeCategory call

* Add new RuneExtensions.IsSurrogatePair benchmark implementation

Avoids intermediate heap allocations by using stack allocated buffer.

* Optimize RuneExtensions.IsSurrogatePair

* Add RuneExtensions.GetEncodingLength tests

* Optimize RuneExtensions.GetEncodingLength

* Optimize RuneExtensions.Encode

* Print encoding name in benchmark results

* Rename variable to better match return description

* Add RuneExtensions.EncodeSurrogatePair benchmark

---------

Co-authored-by: Tig <tig@users.noreply.github.com>
This commit is contained in:
Tonttu
2025-02-25 18:42:32 +02:00
committed by GitHub
parent ff353fc57c
commit e24bd67658
10 changed files with 417 additions and 23 deletions
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79
Terminal.Gui/Text/RuneExtensions.cs
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@@ -1,4 +1,6 @@
using System.Globalization;
#nullable enable
using System.Globalization;
using Wcwidth;
namespace Terminal.Gui;
@@ -7,7 +9,7 @@ namespace Terminal.Gui;
public static class RuneExtensions
{
/// <summary>Maximum Unicode code point.</summary>
public static int MaxUnicodeCodePoint = 0x10FFFF;
public static readonly int MaxUnicodeCodePoint = 0x10FFFF;
/// <summary>Reports if the provided array of bytes can be encoded as UTF-8.</summary>
/// <param name="buffer">The byte array to probe.</param>
@@ -32,17 +34,25 @@ public static class RuneExtensions
/// <param name="rune">The rune to decode.</param>
/// <param name="chars">The chars if the rune is a surrogate pair. Null otherwise.</param>
/// <returns><see langword="true"/> if the rune is a valid surrogate pair; <see langword="false"/> otherwise.</returns>
public static bool DecodeSurrogatePair (this Rune rune, out char [] chars)
public static bool DecodeSurrogatePair (this Rune rune, out char []? chars)
{
if (rune.IsSurrogatePair ())
bool isSingleUtf16CodeUnit = rune.IsBmp;
if (isSingleUtf16CodeUnit)
{
chars = rune.ToString ().ToCharArray ();
chars = null;
return false;
}
const int maxCharsPerRune = 2;
Span<char> charBuffer = stackalloc char[maxCharsPerRune];
int charsWritten = rune.EncodeToUtf16 (charBuffer);
if (charsWritten >= 2 && char.IsSurrogatePair (charBuffer [0], charBuffer [1]))
{
chars = charBuffer [..charsWritten].ToArray ();
return true;
}
chars = null;
return false;
}
@@ -55,21 +65,24 @@ public static class RuneExtensions
/// <returns>he number of bytes written into the destination buffer.</returns>
public static int Encode (this Rune rune, byte [] dest, int start = 0, int count = -1)
{
byte [] bytes = Encoding.UTF8.GetBytes (rune.ToString ());
var length = 0;
const int maxUtf8BytesPerRune = 4;
Span<byte> bytes = stackalloc byte[maxUtf8BytesPerRune];
int writtenBytes = rune.EncodeToUtf8 (bytes);
for (var i = 0; i < (count == -1 ? bytes.Length : count); i++)
int bytesToCopy = count == -1
? writtenBytes
: Math.Min (count, writtenBytes);
int bytesWritten = 0;
for (int i = 0; i < bytesToCopy; i++)
{
if (bytes [i] == 0)
if (bytes [i] == '\0')
{
break;
}
dest [start + i] = bytes [i];
length++;
bytesWritten++;
}
return length;
return bytesWritten;
}
/// <summary>Attempts to encode (as UTF-16) a surrogate pair.</summary>
@@ -105,18 +118,26 @@ public static class RuneExtensions
/// <param name="rune">The rune to probe.</param>
/// <param name="encoding">The encoding used; the default is UTF8.</param>
/// <returns>The number of bytes required.</returns>
public static int GetEncodingLength (this Rune rune, Encoding encoding = null)
public static int GetEncodingLength (this Rune rune, Encoding? encoding = null)
{
encoding ??= Encoding.UTF8;
byte [] bytes = encoding.GetBytes (rune.ToString ().ToCharArray ());
var offset = 0;
if (bytes [^1] == 0)
const int maxCharsPerRune = 2;
// Get characters with UTF16 to keep that part independent of selected encoding.
Span<char> charBuffer = stackalloc char[maxCharsPerRune];
int charsWritten = rune.EncodeToUtf16(charBuffer);
Span<char> chars = charBuffer[..charsWritten];
int maxEncodedLength = encoding.GetMaxByteCount (charsWritten);
Span<byte> byteBuffer = stackalloc byte[maxEncodedLength];
int bytesEncoded = encoding.GetBytes (chars, byteBuffer);
ReadOnlySpan<byte> encodedBytes = byteBuffer[..bytesEncoded];
if (encodedBytes [^1] == '\0')
{
offset++;
return encodedBytes.Length - 1;
}
return bytes.Length - offset;
return encodedBytes.Length;
}
/// <summary>Returns <see langword="true"/> if the rune is a combining character.</summary>
@@ -127,7 +148,7 @@ public static class RuneExtensions
{
UnicodeCategory category = Rune.GetUnicodeCategory (rune);
return Rune.GetUnicodeCategory (rune) == UnicodeCategory.NonSpacingMark
return category == UnicodeCategory.NonSpacingMark
|| category == UnicodeCategory.SpacingCombiningMark
|| category == UnicodeCategory.EnclosingMark;
}
@@ -136,7 +157,19 @@ public static class RuneExtensions
/// <remarks>This is a Terminal.Gui extension method to <see cref="System.Text.Rune"/> to support TUI text manipulation.</remarks>
/// <param name="rune">The rune to probe.</param>
/// <returns><see langword="true"/> if the rune is a surrogate code point; <see langword="false"/> otherwise.</returns>
public static bool IsSurrogatePair (this Rune rune) { return char.IsSurrogatePair (rune.ToString (), 0); }
public static bool IsSurrogatePair (this Rune rune)
{
bool isSingleUtf16CodeUnit = rune.IsBmp;
if (isSingleUtf16CodeUnit)
{
return false;
}
const int maxCharsPerRune = 2;
Span<char> charBuffer = stackalloc char[maxCharsPerRune];
int charsWritten = rune.EncodeToUtf16 (charBuffer);
return charsWritten >= 2 && char.IsSurrogatePair (charBuffer [0], charBuffer [1]);
}
/// <summary>
/// Ensures the rune is not a control character and can be displayed by translating characters below 0x20 to