Repeat writes the text once; cut 2.18.1

CHANGELOG.md

@@ -8,6 +8,17 @@ follows [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## Unreleased
 
+## 2.18.1 — 2026-10-13
+
+### Changed
+
+- **`Repeat` writes the text once instead of concatenating copies.** It builds the string in a few
+  block copies and the runs directly, so `MarkupText.Space.Repeat(1000000)` takes about 1 ms and 2 MB
+  instead of 18 ms and 18 MB. Padding, fills and blank lines in layouts go through it too. The
+  result is unchanged.
+
+## 2.18.0 — 2026-10-10
+
 ### Added
 
 - **More theme colours.** `ThemeRole` gains `Subtle` (text quieter than muted), `Link`, `Highlight` (a
@@ -18,17 +29,22 @@ follows [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 - **A page can theme the sixteen ANSI colours.** HTML writes a standard colour as
   `var(--ms-ansi-N, #hex)`, so a page that sets `--ms-ansi-0` to `--ms-ansi-15` gives `ansi()` colours
   its own scheme, and `--ms-ansi-bg-N` for backgrounds. A page that sets none shows the same colours as before.
-- **Text for a client without Unicode.** `AsciiFold` replaces each character an ASCII-only or
-  Latin-1 client cannot show with the nearest one it can (`·` to `*`, `—` to `-`, `é` to `e`, `?` for
-  the rest), keeping markup and, for the built-in stand-ins, each character's width. A game's own
-  stand-ins come first. `LayoutContext.Fold` folds the text inside every block before it is
-  measured, through the new `Block.MapText`, so tables stay aligned whatever the stand-ins' widths.
 
 ### Changed
 
 - **A base16 palette's tertiary colour is `base09` (orange),** not `base0C`, which info already used,
   so bullets and info text are no longer the same colour.
 
+## 2.17.0 — 2026-10-09
+
+### Added
+
+- **Text for a client without Unicode.** `AsciiFold` replaces each character an ASCII-only or
+  Latin-1 client cannot show with the nearest one it can (`·` to `*`, `—` to `-`, `é` to `e`, `?` for
+  the rest), keeping markup and, for the built-in stand-ins, each character's width. A game's own
+  stand-ins come first. `LayoutContext.Fold` folds the text inside every block before it is
+  measured, through the new `Block.MapText`, so tables stay aligned whatever the stand-ins' widths.
+
 ## 2.16.0 — 2026-10-09
 
 ### Added

MarkupString.Ansi/MarkupString.Ansi.csproj

@@ -12,7 +12,7 @@
          each time one goes out; drop it for a release that removes public API on purpose, and put
          it back straight after. -->
     <EnablePackageValidation>true</EnablePackageValidation>
-    <PackageValidationBaselineVersion>2.15.5</PackageValidationBaselineVersion>
+    <PackageValidationBaselineVersion>2.18.0</PackageValidationBaselineVersion>
     <Description>Terminal styling for MarkupString: colours (16, 256 and truecolor), text attributes and links, an ansi() code parser, and emitters that fold a run's layers into one SGR sequence, HTML span, Pueblo/MXP tag or BBCode tag.</Description>
   </PropertyGroup>
 

MarkupString.Html/MarkupString.Html.csproj

@@ -12,7 +12,7 @@
          each time one goes out; drop it for a release that removes public API on purpose, and put
          it back straight after. -->
     <EnablePackageValidation>true</EnablePackageValidation>
-    <PackageValidationBaselineVersion>2.15.5</PackageValidationBaselineVersion>
+    <PackageValidationBaselineVersion>2.18.0</PackageValidationBaselineVersion>
     <Description>Raw HTML tag markup for MarkupString — an anchor, a pre, a span — rendered as itself in the HTML, Pueblo and MXP formats and folded into terminal styling elsewhere, with checked construction and tag policies for untrusted input.</Description>
   </PropertyGroup>
 

MarkupString.Mxp/MarkupString.Mxp.csproj

@@ -12,7 +12,7 @@
          each time one goes out; drop it for a release that removes public API on purpose, and put
          it back straight after. -->
     <EnablePackageValidation>true</EnablePackageValidation>
-    <PackageValidationBaselineVersion>2.15.5</PackageValidationBaselineVersion>
+    <PackageValidationBaselineVersion>2.18.0</PackageValidationBaselineVersion>
     <Description>MXP for MarkupString: writes the shared vocabulary — sounds, music, pictures, panes, gauges, status, variables, link expiry, relocation, login prompts — as MXP tags, holding each to what the client said it supports.</Description>
   </PropertyGroup>
 

MarkupString.Pueblo/MarkupString.Pueblo.csproj

@@ -12,7 +12,7 @@
          each time one goes out; drop it for a release that removes public API on purpose, and put
          it back straight after. -->
     <EnablePackageValidation>true</EnablePackageValidation>
-    <PackageValidationBaselineVersion>2.15.5</PackageValidationBaselineVersion>
+    <PackageValidationBaselineVersion>2.18.0</PackageValidationBaselineVersion>
     <Description>Pueblo for MarkupString: writes the shared vocabulary — sounds, pictures, panes, clearing the screen, prefetching — in the Pueblo client's own HTML extensions.</Description>
   </PropertyGroup>
 

MarkupString.Tests/MarkupTextOperationsTests.cs

@@ -360,6 +360,47 @@ public async Task Repeat_ThreeTimes_RepeatsCorrectly()
 	public async Task Repeat_ZeroTimes_ReturnsEmpty()
 		=> await Assert.That(MarkupText.Plain("ab").Repeat(0).Length).IsEqualTo(0);
 
+	public static IEnumerable<Func<MarkupText>> RepeatUnits()
+	{
+		yield return () => MarkupText.Space;
+		yield return () => MarkupText.Plain("abc");
+		yield return () => MarkupText.Wrap(Red, "-");
+		yield return () => MarkupText.Wrap(Red, "ab");
+		yield return () => MarkupText.Concat([MarkupText.Wrap(Red, "a"), MarkupText.Plain("bc"), MarkupText.Wrap(Red, "d")]);
+		yield return () => MarkupText.Concat(MarkupText.Plain("x"), MarkupText.Wrap(Red, "y"));
+		yield return MarkupText.Bell;
+		yield return () => MarkupText.Concat(MarkupText.Plain("Hey"), MarkupText.Bell());
+	}
+
+	/// <summary>Repeat builds what concatenating the copies one by one builds, runs and all.</summary>
+	[Test]
+	[MethodDataSource(nameof(RepeatUnits))]
+	public async Task Repeat_MatchesConcatenatedCopies(MarkupText unit)
+	{
+		foreach (var count in new[] { 2, 3, 7, 64, 1001 })
+		{
+			var expected = MarkupText.Concat(Enumerable.Repeat(unit, count).ToArray().AsSpan());
+			var result = unit.Repeat(count);
+
+			await Assert.That(result.Text).IsEqualTo(expected.Text);
+			await Assert.That(result.Runs.SequenceEqual(expected.Runs)).IsTrue();
+		}
+	}
+
+	[Test]
+	public async Task Repeat_PlainText_AllocatesOnlyTheString()
+	{
+		const int count = 100_000;
+		GC.KeepAlive(MarkupText.Space.Repeat(count));
+
+		var before = GC.GetAllocatedBytesForCurrentThread();
+		GC.KeepAlive(MarkupText.Space.Repeat(count));
+		var allocated = GC.GetAllocatedBytesForCurrentThread() - before;
+
+		// Two bytes a character for the string, plus the MarkupText itself.
+		await Assert.That(allocated).IsBetween(2L * count, 2L * count + 512);
+	}
+
 	// Remove, Replace, Insert
 
 	[Test]

MarkupString/MarkupString.csproj

@@ -12,7 +12,7 @@
          each time one goes out; drop it for a release that removes public API on purpose, and put
          it back straight after. -->
     <EnablePackageValidation>true</EnablePackageValidation>
-    <PackageValidationBaselineVersion>2.15.5</PackageValidationBaselineVersion>
+    <PackageValidationBaselineVersion>2.18.0</PackageValidationBaselineVersion>
     <Description>Immutable styled text: a string plus layered markup runs, rendered to ANSI, HTML, Pueblo, MXP, BBCode or plain text through a registry of emitters, and round-tripped through JSON.</Description>
   </PropertyGroup>
 

MarkupString/MarkupText.Operations.cs

@@ -297,9 +297,28 @@ public MarkupText Repeat(int count)
 	{
 		if (count <= 0 || Length == 0) return Empty;
 		if (count == 1) return this;
-		var parts = new MarkupText[count];
-		Array.Fill(parts, this);
-		return Concat(parts.AsSpan());
+		var text = Length == 1
+			? new string(Text[0], count)
+			: string.Create(checked(Length * count), Text, static (span, unit) =>
+			{
+				// Each copy doubles what is written, so n copies take log n block copies.
+				unit.AsSpan().CopyTo(span);
+				for (var filled = unit.Length; filled < span.Length; filled *= 2)
+					span[..Math.Min(filled, span.Length - filled)].CopyTo(span[filled..]);
+			});
+		if (Runs.IsDefaultOrEmpty) return new MarkupText(text, ImmutableArray<Run>.Empty);
+		// One style over the whole text: the copies would coalesce into one run anyway. A point
+		// marks a single carrier, so its copies stay apart.
+		if (Runs is [{ Start: 0 } whole] && whole.Length == Length && !whole.Markups.Any(m => m is IPointMarkup))
+			return new MarkupText(text, [new Run(0, text.Length, whole.Markups)]);
+
+		var runs = ImmutableArray.CreateBuilder<Run>(Runs.Length * count);
+		for (var copy = 0; copy < count; copy++)
+		{
+			var offset = copy * Length;
+			foreach (var run in Runs) runs.Add(run with { Start = run.Start + offset });
+		}
+		return new MarkupText(text, runs.MoveToImmutable());
 	}
 
 	/// <summary>Removes <paramref name="length"/> code units from <paramref name="index"/>.</summary>