Add SepWriterOptions.WriteHeader (#107)

Fixes #71

README.md

@@ -715,6 +715,13 @@ public Sep Sep { get; init; }
 /// May be `null` for default culture.
 /// </summary>
 public CultureInfo? CultureInfo { get; init; }
+/// <summary>
+/// Specifies whether to write a header row 
+/// before data rows. Requires all columns 
+/// to have a name. Otherwise, columns can be
+/// added by indexing alone.
+/// </summary>
+public bool WriteHeader { get; init; } = true;
 ```
 
 ## Limitations and Constraints
@@ -1754,6 +1761,7 @@ namespace nietras.SeparatedValues
  public SepWriterOptions(nietras.SeparatedValues.Sep sep) { }
  public System.Globalization.CultureInfo? CultureInfo { get; init; }
  public nietras.SeparatedValues.Sep Sep { get; init; }
+ public bool WriteHeader { get; init; }
  }
 }
 ```

src/Sep.Test/SepWriterTest.cs

@@ -226,6 +226,80 @@ public void SepWriterTest_Extensions_ToFile()
  File.Delete(fileName);
  }
 
+ [TestMethod]
+ public void SepWriterTest_WriteHeader_False()
+ {
+ using var writer = Sep.Writer(o => o with { WriteHeader = false }).ToText();
+ {
+ using var row = writer.NewRow();
+ row["A"].Set("1");
+ row[1].Format(2);
+ row[2].Set($"{2 * 17}");
+ }
+ {
+ using var row = writer.NewRow();
+ // Order of cols is not important after first row written
+ row[2].Set("65");
+ row[1].Format(3);
+ row["A"].Set($"{23,3}");
+ }
+ var expected =
+@"1;2;34
+ 23;3;65
+";
+ Assert.AreEqual(expected, writer.ToString());
+ }
+
+ [TestMethod]
+ public void SepWriterTest_WriteHeader_False_UnknownColName()
+ {
+ using var writer = Sep.Writer(o => o with { WriteHeader = false }).ToText();
+ {
+ using var row = writer.NewRow();
+ row["A"].Set("1");
+ row[1].Format(2);
+ row[2].Set($"{2 * 17}");
+ }
+ {
+ using var row = writer.NewRow();
+ row[2].Set("65");
+ row[1].Format(3);
+ row["A"].Set($"{23,3}");
+
+ var e = AssertThrowsException<KeyNotFoundException>(row,
+ r => { r["B"].Set("Test"); });
+ Assert.AreEqual("B", e.Message);
+ }
+ var expected =
+@"1;2;34
+ 23;3;65
+";
+ Assert.AreEqual(expected, writer.ToString());
+ }
+
+ [TestMethod]
+ public void SepWriterTest_WriteHeader_False_ColMissingInSecondRow()
+ {
+ using var writer = Sep.Writer(o => o with { WriteHeader = false }).ToText();
+ {
+ using var row1 = writer.NewRow();
+ row1[0].Set("A");
+ row1[1].Set("B");
+ }
+ {
+ var row2 = writer.NewRow();
+ row2[1].Set("Y");
+ var e = AssertThrowsException<InvalidOperationException>(row2,
+ r => { r.Dispose(); });
+ Assert.AreEqual("Not all expected columns have been set.", e.Message);
+ }
+ // Expected output should only be valid rows
+ var expected =
+@"A;B
+";
+ Assert.AreEqual(expected, writer.ToString());
+ }
+
  static SepWriter CreateWriter() =>
  Sep.New(';').Writer().ToText();
 

src/Sep/Internals/SepThrow.cs

@@ -84,7 +84,14 @@ internal static void InvalidOperationException_WriterDoesNotHaveActiveRow()
  internal static void InvalidOperationException_NotAllColsSet(List<ColImpl> cols, string[] colNamesHeader)
  {
  // TODO: Make detailed exception
- throw new InvalidOperationException($"Not all expected columns '{string.Join(",", colNamesHeader)}' have been set.");
+ if (colNamesHeader.Length == 0)
+ {
+ throw new InvalidOperationException($"Not all expected columns have been set.");
+ }
+ else
+ {
+ throw new InvalidOperationException($"Not all expected columns '{string.Join(",", colNamesHeader)}' have been set.");
+ }
  }
 
  [DoesNotReturn]

src/Sep/SepWriter.Row.cs

@@ -86,12 +86,12 @@ public void Dispose()
  internal ColImpl GetOrAddCol(int colIndex)
  {
  var cols = _cols;
- //if (colIndex == sbs.Count)
- //{
- // // TODO: Add without name if WriteHeader false
- //}
- var c = cols[colIndex];
- return c;
+ if (colIndex == cols.Count && !_writeHeader)
+ {
+ var col = new ColImpl(this, colIndex, string.Empty, SepStringBuilderPool.Take());
+  _cols.Add(col);
+ }
+ return cols[colIndex];
  }
 
  internal ColImpl GetOrAddCol(string colName)
@@ -109,7 +109,7 @@ internal ColImpl GetOrAddCol(string colName)
 
  if (!_colNameToCol.TryGetValue(colName, out var col))
  {
- if (!_headerWritten)
+ if (!_headerWrittenOrSkipped)
  {
  var colIndex = _colNameToCol.Count;
  col = new ColImpl(this, colIndex, colName, SepStringBuilderPool.Take());

src/Sep/SepWriter.cs

@@ -10,6 +10,7 @@ public partial class SepWriter : IDisposable
  const int DefaultCapacity = 16;
  readonly Sep _sep;
  readonly CultureInfo? _cultureInfo;
+ readonly bool _writeHeader;
  readonly TextWriter _writer;
  internal readonly List<(string ColName, int ColIndex)> _colNameCache = new(DefaultCapacity);
 
@@ -20,14 +21,15 @@ public partial class SepWriter : IDisposable
  internal string[] _colNamesHeader = Array.Empty<string>();
 
  internal readonly SepArrayPoolAccessIndexed _arrayPool = new();
- bool _headerWritten = false;
+ bool _headerWrittenOrSkipped = false;
  bool _newRowActive = false;
  int _cacheIndex = 0;
 
  public SepWriter(SepWriterOptions options, TextWriter writer)
  {
  _sep = options.Sep;
  _cultureInfo = options.CultureInfo;
+ _writeHeader = options.WriteHeader;
  _writer = writer;
  }
 
@@ -47,37 +49,43 @@ internal void EndRow(Row row)
  {
  if (!_newRowActive) { SepThrow.InvalidOperationException_WriterDoesNotHaveActiveRow(); }
 
- A.Assert(_colNameToCol.Count == _cols.Count);
+ A.Assert(!_writeHeader || _colNameToCol.Count == _cols.Count);
  var cols = _cols;
 
  // Header
- if (!_headerWritten)
+ if (!_headerWrittenOrSkipped)
  {
- A.Assert(_colNamesHeader.Length == 0);
- if (cols.Count != _colNamesHeader.Length)
+ if (_writeHeader)
  {
- _colNamesHeader = new string[cols.Count];
- }
- var notFirstHeader = false;
- for (var colIndex = 0; colIndex < cols.Count; ++colIndex)
- {
- var col = cols[colIndex];
- A.Assert(colIndex == col.Index);
-
- if (notFirstHeader)
+ A.Assert(_colNamesHeader.Length == 0);
+ if (cols.Count != _colNamesHeader.Length)
  {
- _writer.Write(_sep.Separator);
+ _colNamesHeader = new string[cols.Count];
+ }
+ var notFirstHeader = false;
+ for (var colIndex = 0; colIndex < cols.Count; ++colIndex)
+ {
+ var col = cols[colIndex];
+ A.Assert(colIndex == col.Index);
+
+ if (notFirstHeader)
+ {
+ _writer.Write(_sep.Separator);
+ }
+ var name = col.Name;
+ _writer.Write(name);
+ _colNamesHeader[colIndex] = name;
+ notFirstHeader = true;
  }
- var name = col.Name;
- _writer.Write(name);
- _colNamesHeader[colIndex] = name;
- notFirstHeader = true;
+ _writer.WriteLine();
  }
- _writer.WriteLine();
- _headerWritten = true;
+ _headerWrittenOrSkipped = true;
  }
  else
  {
+ // Note this prevents writing different number of cols (or less cols
+ // than previous row) in case of no header written. Revisit this if
+ // variable cols count is needed.
  for (var colIndex = 0; colIndex < cols.Count; ++colIndex)
  {
  var col = cols[colIndex];
@@ -86,7 +94,7 @@ internal void EndRow(Row row)
  SepThrow.InvalidOperationException_NotAllColsSet(cols, _colNamesHeader);
  }
  }
- A.Assert(cols.Count == _colNamesHeader.Length);
+ A.Assert(!_writeHeader || cols.Count == _colNamesHeader.Length);
  }
 
  // New Row

src/Sep/SepWriterOptions.cs

@@ -10,6 +10,7 @@ public SepWriterOptions(Sep sep)
  {
  Sep = sep;
  CultureInfo = SepDefaults.CultureInfo;
+ WriteHeader = true;
  }
 
  /// <summary>
@@ -21,4 +22,11 @@ public SepWriterOptions(Sep sep)
  /// May be `null` for default culture.
  /// </summary>
  public CultureInfo? CultureInfo { get; init; }
+ /// <summary>
+ /// Specifies whether to write a header row 
+ /// before data rows. Requires all columns 
+ /// to have a name. Otherwise, columns can be
+ /// added by indexing alone.
+ /// </summary>
+ public bool WriteHeader { get; init; } = true;
 }