Add IParsable/ISpanParsable to Rune

src/libraries/System.Private.CoreLib/src/System/Text/Rune.cs

@@ -32,6 +32,8 @@ namespace System.Text
 #pragma warning disable SA1001 // Commas should be spaced correctly
         , ISpanFormattable
         , IUtf8SpanFormattable
+        , IParsable<Rune>
+        , ISpanParsable<Rune>
         , IUtf8SpanParsable<Rune>
 #pragma warning restore SA1001
 #endif
@@ -996,6 +998,54 @@ static Rune IUtf8SpanParsable<Rune>.Parse(ReadOnlySpan<byte> utf8Text, System.IF
             return result;
         }
 
+        /// <inheritdoc cref="IParsable{TSelf}.Parse(string, IFormatProvider?)" />
+        static Rune IParsable<Rune>.Parse(string s, IFormatProvider? provider)
+        {
+            ArgumentNullException.ThrowIfNull(s);
+
+            if (DecodeFromUtf16(s, out Rune result, out int charsConsumed) != OperationStatus.Done || charsConsumed != s.Length)
+            {
+                ThrowHelper.ThrowFormatInvalidString();
+            }
+
+            return result;
+        }
+
+        /// <inheritdoc cref="IParsable{TSelf}.TryParse(string?, IFormatProvider?, out TSelf)" />
+        static bool IParsable<Rune>.TryParse([NotNullWhen(true)] string? s, IFormatProvider? provider, out Rune result)
+        {
+            if (DecodeFromUtf16(s, out result, out int charsConsumed) != OperationStatus.Done || charsConsumed != s!.Length)
+            {
+                result = ReplacementChar;
+                return false;
+            }
+
+            return true;
+        }
+
+        /// <inheritdoc cref="ISpanParsable{TSelf}.Parse(ReadOnlySpan{char}, IFormatProvider?)" />
+        static Rune ISpanParsable<Rune>.Parse(ReadOnlySpan<char> s, IFormatProvider? provider)
+        {
+            if (DecodeFromUtf16(s, out Rune result, out int charsConsumed) != OperationStatus.Done || charsConsumed != s.Length)
+            {
+                ThrowHelper.ThrowFormatInvalidString();
+            }
+
+            return result;
+        }
+
+        /// <inheritdoc cref="ISpanParsable{TSelf}.TryParse(ReadOnlySpan{char}, IFormatProvider?, out TSelf)" />
+        static bool ISpanParsable<Rune>.TryParse(ReadOnlySpan<char> s, IFormatProvider? provider, out Rune result)
+        {
+            if (DecodeFromUtf16(s, out result, out int charsConsumed) != OperationStatus.Done || charsConsumed != s.Length)
+            {
+                result = ReplacementChar;
+                return false;
+            }
+
+            return true;
+        }
+
         string IFormattable.ToString(string? format, IFormatProvider? formatProvider) => ToString();
 #endif
 

src/libraries/System.Runtime/ref/System.Runtime.cs

@@ -16046,7 +16046,7 @@ public enum NormalizationForm
         [System.Runtime.Versioning.UnsupportedOSPlatformAttribute("browser")]
         FormKD = 6,
     }
-    public readonly partial struct Rune : System.IComparable, System.IComparable<System.Text.Rune>, System.IEquatable<System.Text.Rune>, System.IFormattable, System.ISpanFormattable, System.IUtf8SpanFormattable, System.IUtf8SpanParsable<System.Text.Rune>
+    public readonly partial struct Rune : System.IComparable, System.IComparable<System.Text.Rune>, System.IEquatable<System.Text.Rune>, System.IFormattable, System.IParsable<System.Text.Rune>, System.ISpanFormattable, System.ISpanParsable<System.Text.Rune>, System.IUtf8SpanFormattable, System.IUtf8SpanParsable<System.Text.Rune>
     {
         private readonly int _dummyPrimitive;
         public Rune(char ch) { throw null; }
@@ -16101,7 +16101,11 @@ public enum NormalizationForm
         public static bool operator <=(System.Text.Rune left, System.Text.Rune right) { throw null; }
         int System.IComparable.CompareTo(object? obj) { throw null; }
         string System.IFormattable.ToString(string? format, System.IFormatProvider? formatProvider) { throw null; }
+        static System.Text.Rune System.IParsable<System.Text.Rune>.Parse(string s, System.IFormatProvider? provider) { throw null; }
+        static bool System.IParsable<System.Text.Rune>.TryParse([System.Diagnostics.CodeAnalysis.NotNullWhenAttribute(true)] string? s, System.IFormatProvider? provider, out System.Text.Rune result) { throw null; }
         bool System.ISpanFormattable.TryFormat(System.Span<char> destination, out int charsWritten, System.ReadOnlySpan<char> format, System.IFormatProvider? provider) { throw null; }
+        static System.Text.Rune System.ISpanParsable<System.Text.Rune>.Parse(System.ReadOnlySpan<char> s, System.IFormatProvider? provider) { throw null; }
+        static bool System.ISpanParsable<System.Text.Rune>.TryParse(System.ReadOnlySpan<char> s, System.IFormatProvider? provider, out System.Text.Rune result) { throw null; }
         bool System.IUtf8SpanFormattable.TryFormat(System.Span<byte> utf8Destination, out int bytesWritten, System.ReadOnlySpan<char> format, System.IFormatProvider? provider) { throw null; }
         static System.Text.Rune System.IUtf8SpanParsable<System.Text.Rune>.Parse(System.ReadOnlySpan<byte> utf8Text, System.IFormatProvider? provider) { throw null; }
         static bool System.IUtf8SpanParsable<System.Text.Rune>.TryParse(System.ReadOnlySpan<byte> utf8Text, System.IFormatProvider? provider, out System.Text.Rune result) { throw null; }

src/libraries/System.Runtime/tests/System.Runtime.Tests/System/Text/RuneTests.cs

@@ -199,6 +199,30 @@ public static void DecodeFromUtf16(char[] data, OperationStatus expectedOperatio
             Assert.Equal(expectedOperationStatus, Rune.DecodeFromUtf16(data, out Rune actualRune, out int actualCharsConsumed));
             Assert.Equal(expectedRuneValue, actualRune.Value);
             Assert.Equal(expectedCharsConsumed, actualCharsConsumed);
+
+            string s = new string(data);
+
+            // Parse / TryParse succeed iff the entire input decodes to a single scalar.
+            if (expectedOperationStatus == OperationStatus.Done && expectedCharsConsumed == data.Length)
+            {
+                Assert.Equal(expectedRuneValue, ParsableHelper<Rune>.Parse(s, null).Value);
+                Assert.True(ParsableHelper<Rune>.TryParse(s, null, out Rune parsedFromString));
+                Assert.Equal(expectedRuneValue, parsedFromString.Value);
+
+                Assert.Equal(expectedRuneValue, SpanParsableHelper<Rune>.Parse(data, null).Value);
+                Assert.True(SpanParsableHelper<Rune>.TryParse(data, null, out Rune parsedFromSpan));
+                Assert.Equal(expectedRuneValue, parsedFromSpan.Value);
+            }
+            else
+            {
+                Assert.Throws<FormatException>(() => ParsableHelper<Rune>.Parse(s, null));
+                Assert.False(ParsableHelper<Rune>.TryParse(s, null, out Rune parsedFromString));
+                Assert.Equal(Rune.ReplacementChar, parsedFromString);
+
+                Assert.Throws<FormatException>(() => SpanParsableHelper<Rune>.Parse(data, null));
+                Assert.False(SpanParsableHelper<Rune>.TryParse(data, null, out Rune parsedFromSpan));
+                Assert.Equal(Rune.ReplacementChar, parsedFromSpan);
+            }
         }
 
         [Theory]
@@ -247,47 +271,27 @@ public static void DecodeFromUtf8(byte[] data, OperationStatus expectedOperation
             Assert.Equal(expectedOperationStatus, Rune.DecodeFromUtf8(data, out Rune actualRune, out int actualBytesConsumed));
             Assert.Equal(expectedRuneValue, actualRune.Value);
             Assert.Equal(expectedBytesConsumed, actualBytesConsumed);
-        }
 
-        [Theory]
-        [InlineData(new byte[] { 0x30 }, 0x0030)] // ASCII byte
-        [InlineData(new byte[] { 0xC3, 0x90 }, 0x00D0)] // [ C3 90 ] is U+00D0 LATIN CAPITAL LETTER ETH
-        [InlineData(new byte[] { 0xE2, 0x88, 0xB4 }, 0x2234)] // [ E2 88 B4 ] is U+2234 THEREFORE
-        [InlineData(new byte[] { 0xF0, 0x9F, 0x98, 0xB2 }, 0x1F632)] // [ F0 9F 98 B2 ] is U+1F632 ASTONISHED FACE
-        public static void ParseUtf8(byte[] data, int expectedRuneValue)
-        {
-            Assert.Equal(expectedRuneValue, Utf8SpanParsableHelper<Rune>.Parse(data, null).Value);
-            Assert.True(Utf8SpanParsableHelper<Rune>.TryParse(data, null, out Rune actualRune));
-            Assert.Equal(expectedRuneValue, actualRune.Value);
+            // Parse / TryParse succeed iff the entire input decodes to a single scalar.
+            if (expectedOperationStatus == OperationStatus.Done && expectedBytesConsumed == data.Length)
+            {
+                Assert.Equal(expectedRuneValue, Utf8SpanParsableHelper<Rune>.Parse(data, null).Value);
+                Assert.True(Utf8SpanParsableHelper<Rune>.TryParse(data, null, out Rune parsedFromUtf8));
+                Assert.Equal(expectedRuneValue, parsedFromUtf8.Value);
+            }
+            else
+            {
+                Assert.Throws<FormatException>(() => Utf8SpanParsableHelper<Rune>.Parse(data, null));
+                Assert.False(Utf8SpanParsableHelper<Rune>.TryParse(data, null, out Rune parsedFromUtf8));
+                Assert.Equal(Rune.ReplacementChar, parsedFromUtf8);
+            }
         }
 
-        [Theory]
-        [InlineData(new byte[0])] // empty buffer
-        [InlineData(new byte[] { 0x30, 0x40, 0x50 })] // Multiple ASCII bytes
-        [InlineData(new byte[] { 0x80 })] // standalone continuation byte
-        [InlineData(new byte[] { 0x80, 0x80, 0x80 })] // standalone continuation byte
-        [InlineData(new byte[] { 0xC1 })] // C1 is never a valid UTF-8 byte
-        [InlineData(new byte[] { 0xF5 })] // F5 is never a valid UTF-8 byte
-        [InlineData(new byte[] { 0xC2 })] // C2 is a valid byte; expecting it to be followed by a continuation byte
-        [InlineData(new byte[] { 0xED })] // ED is a valid byte; expecting it to be followed by a continuation byte
-        [InlineData(new byte[] { 0xF4 })] // F4 is a valid byte; expecting it to be followed by a continuation byte
-        [InlineData(new byte[] { 0xC2, 0xC2 })] // C2 not followed by continuation byte
-        [InlineData(new byte[] { 0xC1, 0xBF })] // [ C1 BF ] is overlong 2-byte sequence, all overlong sequences have maximal invalid subsequence length 1
-        [InlineData(new byte[] { 0xE0, 0x9F })] // [ E0 9F ] is overlong 3-byte sequence, all overlong sequences have maximal invalid subsequence length 1
-        [InlineData(new byte[] { 0xE0, 0xA0 })] // [ E0 A0 ] is valid 2-byte start of 3-byte sequence
-        [InlineData(new byte[] { 0xED, 0x9F })] // [ ED 9F ] is valid 2-byte start of 3-byte sequence
-        [InlineData(new byte[] { 0xED, 0xBF })] // [ ED BF ] would place us in UTF-16 surrogate range, all surrogate sequences have maximal invalid subsequence length 1
-        [InlineData(new byte[] { 0xEE, 0x80 })] // [ EE 80 ] is valid 2-byte start of 3-byte sequence
-        [InlineData(new byte[] { 0xF0, 0x8F })] // [ F0 8F ] is overlong 4-byte sequence, all overlong sequences have maximal invalid subsequence length 1
-        [InlineData(new byte[] { 0xF0, 0x90 })] // [ F0 90 ] is valid 2-byte start of 4-byte sequence
-        [InlineData(new byte[] { 0xF4, 0x90 })] // [ F4 90 ] would place us beyond U+10FFFF, all such sequences have maximal invalid subsequence length 1
-        [InlineData(new byte[] { 0xE2, 0x88, 0xC0 })] // [ E2 88 ] followed by non-continuation byte, maximal invalid subsequence length 2
-        [InlineData(new byte[] { 0xF0, 0x9F, 0x98 })] // [ F0 9F 98 ] is valid 3-byte start of 4-byte sequence
-        [InlineData(new byte[] { 0xF0, 0x9F, 0x98, 0x20 })] // [ F0 9F 98 ] followed by non-continuation byte, maximal invalid subsequence length 3
-        public static void ParseUtf8_Invalid(byte[] data)
-        {
-            Assert.Throws<FormatException>(() => Utf8SpanParsableHelper<Rune>.Parse(data, null));
-            Assert.False(Utf8SpanParsableHelper<Rune>.TryParse(data, null, out Rune actualRune));
+        [Fact]
+        public static void Parse_String_Null()
+        {
+            Assert.Throws<ArgumentNullException>(() => ParsableHelper<Rune>.Parse(null, null));
+            Assert.False(ParsableHelper<Rune>.TryParse(null, null, out Rune actualRune));
             Assert.Equal(Rune.ReplacementChar, actualRune);
         }