Add SepReaderHeader.TryIndexOf (#146)

README.md

@@ -1687,6 +1687,7 @@ namespace nietras.SeparatedValues
         public void IndicesOf(System.ReadOnlySpan<string> colNames, System.Span<int> colIndices) { }
         public System.Collections.Generic.IReadOnlyList<string> NamesStartingWith(string prefix, System.StringComparison comparison = 4) { }
         public override string ToString() { }
+        public bool TryIndexOf(string colName, out int colIndex) { }
     }
     public readonly struct SepReaderOptions : System.IEquatable<nietras.SeparatedValues.SepReaderOptions>
     {

src/Sep.Test/SepReaderHeaderTest.cs

@@ -45,6 +45,13 @@ public void SepReaderHeaderTest_NotEmpty()
         AreEqual([0, 2], header.IndicesOf((ReadOnlySpan<string>)["A", "C"]));
         AreEqual([2, 0], header.IndicesOf((IReadOnlyList<string>)["C", "A"]));
 
+        var tryTrue = header.TryIndexOf("B", out var tryTrueIndex);
+        Assert.IsTrue(tryTrue);
+        Assert.AreEqual(1, tryTrueIndex);
+        var tryFalse = header.TryIndexOf("XX", out var tryFalseIndex);
+        Assert.IsFalse(tryFalse);
+        Assert.AreEqual(0, tryFalseIndex);
+
         var actualIndices = new int[2];
         header.IndicesOf((ReadOnlySpan<string>)["A", "C"], actualIndices);
         AreEqual([0, 2], actualIndices);

src/Sep/SepReaderHeader.cs

@@ -41,6 +41,8 @@ internal static SepReaderHeader Parse(Sep sep, string line, IEqualityComparer<st
 
     public int IndexOf(string colName) => _colNameToIndex[colName];
 
+    public bool TryIndexOf(string colName, out int colIndex) => _colNameToIndex.TryGetValue(colName, out colIndex);
+
     public IReadOnlyList<string> NamesStartingWith(string prefix, StringComparison comparison = StringComparison.Ordinal)
     {
         var colNames = new List<string>();