GetChars(Encoding,byte[],StringBuilder) helper

- encode ReadOnlySpan<byte> without allocs into StringBuilder
+ tests

src/Peachpie.Runtime/Utilities/EncodingExtensions.cs

@@ -0,0 +1,73 @@
+using System;
+using System.Buffers;
+using System.Collections.Generic;
+using System.Linq;
+using System.Runtime.InteropServices;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Pchp.Core.Utilities
+{
+ public static class EncodingExtensions
+ {
+ const int MaxBytesAtOnce = 1 * 1024 * 1024; // 1M
+
+ /// <summary>
+ /// Encodes byte array using <paramref name="encoding"/> into given <paramref name="builder"/>.
+ /// </summary>
+ /// <returns>Number of characters encoded.</returns>
+ public static int GetChars(this Encoding encoding, ReadOnlySpan<byte> bytes, StringBuilder builder)
+ {
+ ArgumentNullException.ThrowIfNull(encoding, nameof(encoding));
+ ArgumentNullException.ThrowIfNull(builder, nameof(builder));
+
+ if (bytes.IsEmpty)
+ {
+ return 0;
+ }
+
+ if (bytes.Length <= MaxBytesAtOnce)
+ {
+
+ var maxCharCount = encoding.GetCharCount(bytes);
+
+ var span = ArrayPool<char>.Shared.Rent(maxCharCount);
+ var chars = encoding.GetChars(bytes, span.AsSpan());
+
+ //
+ builder.Append(span.AsSpan(0, chars));
+
+ //
+ ArrayPool<char>.Shared.Return(span);
+
+ return chars;
+ }
+
+ //
+
+ var decoder = encoding.GetDecoder(); // we need to encode in chunks, preserve state between chunks
+ int charsCount = 0;
+
+ while (bytes.Length > 0)
+ {
+ var segment = bytes.Slice(0, Math.Min(MaxBytesAtOnce, bytes.Length));
+
+ bytes = bytes.Slice(segment.Length);
+
+ var maxCharCount = decoder.GetCharCount(segment, flush: bytes.IsEmpty);
+ var span = ArrayPool<char>.Shared.Rent(maxCharCount);
+ var chars = decoder.GetChars(segment, span.AsSpan(), flush: bytes.IsEmpty);
+
+ //
+ builder.Append(span.AsSpan(0, chars));
+ charsCount += chars;
+
+ //
+ ArrayPool<char>.Shared.Return(span);
+ }
+
+ //
+ return charsCount;
+ }
+ }
+}

src/Tests/Peachpie.Runtime.Tests/UtilitiesTests.cs

@@ -1,9 +1,10 @@
-using System;
+using System;
 using System.Text;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using Pchp.Core;
 using Pchp.Core.Collections;
 using Pchp.Core.Text;
+using Pchp.Core.Utilities;
 
 namespace Peachpie.Runtime.Tests
 {
@@ -63,5 +64,33 @@ public void ValueListToBytesTest()
 
  Assert.AreEqual(Encoding.UTF8.GetString(list.ToArray()), "hello");
  }
+
+ [DataTestMethod]
+ [DataRow("")]
+ [DataRow("lorem ipsum")]
+ [DataRow("顧客は非常に重要です、顧客は顧客に続きます")]
+ public void GetCharsTest(string input)
+ {
+ string value = input;
+
+ for (int multiplier = 0; multiplier < 10; multiplier++)
+ {
+ var encoding = Encoding.UTF8;
+ var bytes = encoding.GetBytes(value);
+
+ var builder = new StringBuilder();
+ var count = Pchp.Core.Utilities.EncodingExtensions.GetChars(encoding, bytes, builder);
+
+ Assert.AreEqual(value.Length, count, "Length don't match");
+ Assert.AreEqual(value, builder.ToString(), "String don't match");
+
+ // add ~1M chars
+ for (int i = 0; i < 1_000_000 / (input.Length + 1); i++)
+ {
+ builder.Append(input);
+ }
+ value = builder.ToString();
+ }
+ }
  }
 }