Add ZStringWriter

src/ZString/ZStringWriter.cs

@@ -0,0 +1,206 @@
+using System;
+using System.Globalization;
+using System.IO;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Cysharp.Text
+{
+    /// <summary>
+    /// A <see cref="TextWriter"/> implementation that is backed with <see cref="Utf16ValueStringBuilder"/>.
+    /// </summary>
+    /// <remarks>
+    /// It's important to make sure the writer is always properly disposed.
+    /// </remarks>
+    public sealed class ZStringWriter : TextWriter
+    {
+        private Utf16ValueStringBuilder sb;
+        private bool isOpen;
+        private UnicodeEncoding encoding;
+
+        /// <summary>
+        /// Creates a new instance using <see cref="CultureInfo.CurrentCulture"/> as format provider.
+        /// </summary>
+        public ZStringWriter() : this(CultureInfo.CurrentCulture)
+        {
+        }
+
+        /// <summary>
+        /// Creates a new instance with given format provider.
+        /// </summary>
+        public ZStringWriter(IFormatProvider formatProvider) : base(formatProvider)
+        {
+            sb = ZString.CreateStringBuilder();
+            isOpen = true;
+        }
+
+        /// <summary>
+        /// Disposes this instance, operations are no longer allowed.
+        /// </summary>
+        public override void Close()
+        {
+            Dispose(true);
+        }
+
+        protected override void Dispose(bool disposing)
+        {
+            sb.Dispose();
+            isOpen = false;
+            base.Dispose(disposing);
+        }
+
+        public override Encoding Encoding => encoding = encoding ?? new UnicodeEncoding(false, false);
+
+        public override void Write(char value)
+        {
+            AssertNotDisposed();
+
+            sb.Append(value);
+        }
+
+        public override void Write(char[] buffer, int index, int count)
+        {
+            if (buffer == null)
+            {
+                throw new ArgumentNullException(nameof(buffer));
+            }
+            if (index < 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(index));
+            }
+            if (count < 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(count));
+            }
+            if (buffer.Length - index < count)
+            {
+                throw new ArgumentException();
+            }
+            AssertNotDisposed();
+
+            sb.Append(buffer.AsSpan(index, count));
+        }
+
+        public override void Write(string value)
+        {
+            AssertNotDisposed();
+
+            if (value != null)
+            {
+                sb.Append(value);
+            }
+        }
+
+        public override Task WriteAsync(char value)
+        {
+            Write(value);
+            return Task.CompletedTask;
+        }
+
+        public override Task WriteAsync(string value)
+        {
+            Write(value);
+            return Task.CompletedTask;
+        }
+
+        public override Task WriteAsync(char[] buffer, int index, int count)
+        {
+            Write(buffer, index, count);
+            return Task.CompletedTask;
+        }
+
+        public override Task WriteLineAsync(char value)
+        {
+            WriteLine(value);
+            return Task.CompletedTask;
+        }
+
+        public override Task WriteLineAsync(string value)
+        {
+            WriteLine(value);
+            return Task.CompletedTask;
+        }
+
+        public override Task WriteLineAsync(char[] buffer, int index, int count)
+        {
+            WriteLine(buffer, index, count);
+            return Task.CompletedTask;
+        }
+
+        public override void Write(bool value)
+        {
+            sb.Append(value);
+        }
+
+        public override void Write(decimal value)
+        {
+            sb.Append(value);
+        }
+
+        /// <summary>
+        /// No-op.
+        /// </summary>
+        public override Task FlushAsync()
+        {
+            return Task.CompletedTask;
+        }
+
+        /// <summary>
+        /// Materializes the current state from underlying string builder.
+        /// </summary>
+        public override string ToString()
+        {
+            return sb.ToString();
+        }
+
+#if !NETSTANDARD2_0
+        /// <inheritdoc />
+        public override void Write(ReadOnlySpan<char> buffer)
+        {
+            AssertNotDisposed();
+
+            sb.Append(buffer);
+        }
+
+        /// <inheritdoc />
+        public override void WriteLine(ReadOnlySpan<char> buffer)
+        {
+            AssertNotDisposed();
+
+            sb.Append(buffer);
+            WriteLine();
+        }
+
+        public override Task WriteAsync(ReadOnlyMemory<char> buffer, CancellationToken cancellationToken = default)
+        {
+            if (cancellationToken.IsCancellationRequested)
+            {
+                return Task.FromCanceled(cancellationToken);
+            }
+
+            Write(buffer.Span);
+            return Task.CompletedTask;
+        }
+
+        public override Task WriteLineAsync(ReadOnlyMemory<char> buffer, CancellationToken cancellationToken = default)
+        {
+            if (cancellationToken.IsCancellationRequested)
+            {
+                return Task.FromCanceled(cancellationToken);
+            }
+
+            WriteLine(buffer.Span);
+            return Task.CompletedTask;
+        }
+#endif
+
+        private void AssertNotDisposed()
+        {
+            if (!isOpen)
+            {
+                throw new ObjectDisposedException(nameof(sb));
+            }
+        }
+    }
+}

tests/ZString.Tests/ZStringWriterTest.cs

@@ -0,0 +1,37 @@
+using System;
+using Cysharp.Text;
+using Xunit;
+
+namespace ZStringTests
+{
+    public class ZStringWriterTest
+    {
+        [Fact]
+        public void DoubleDisposeTest()
+        {
+            var sb = new ZStringWriter();
+            sb.Dispose();
+            sb.Dispose(); // call more than once
+        }
+
+        [Fact]
+        public void BasicWrites()
+        {
+            using (var writer = new ZStringWriter())
+            {
+                writer.Write("text1".AsSpan());
+                writer.Write("text2");
+                writer.Write('c');
+                writer.Write(true);
+                writer.Write(123);
+                writer.Write(456f);
+                writer.Write(789d);
+                writer.Write("end".AsMemory());
+                writer.WriteLine();
+
+                var expected = "text1text2cTrue123456789end" + Environment.NewLine;
+                Assert.Equal(expected, writer.ToString());
+            }
+        }
+    }
+}