Fix .NET framework xlsx reading bug.

Fix RowFieldCount for empty rows.

docs/ReleaseNotes.md

@@ -1,5 +1,9 @@
 # Sylvan.Data.Excel Release Notes
 
+_0.4.15_
+- Fix a bug that prevented .xlsx reader from working on .NET Framework versions.
+- Fix a bug where FieldRowCount would be incorrect on empty rows.
+
 _0.4.14_
 - Add `CompressionLevel` as a configuration option for ExcelDataWriter.
     Changes the default compression level to `Fastest`, which produces 

source/Sylvan.Data.Excel.Tests/ExcelDataReaderTests.cs

@@ -206,6 +206,27 @@ public void Gap()
 		Assert.False(edr.Read());
 	}
 
+	[Fact]
+	public void GapRowFieldCount()
+	{
+		var file = GetFile("Gap");
+		using var edr = ExcelDataReader.Create(file, noHeaders);
+		for (int i = 0; i < 41; i++)
+		{
+			Assert.True(edr.Read());
+
+			if (i % 10 == 0)
+			{
+				Assert.Equal(1, edr.RowFieldCount);
+			}
+			else
+			{
+				Assert.Equal(0, edr.RowFieldCount);
+			}
+		}
+		Assert.False(edr.Read());
+	}
+
 	[Fact]
 	public void MultiSheet()
 	{

source/Sylvan.Data.Excel.Tests/ExcelDataWriterTests.cs

@@ -22,7 +22,7 @@ protected override string GetFile(string name)
 		return string.Format(FileFormat, name);
 	}
 }
-
+#if NETCOREAPP1_0_OR_GREATER
 public class XlsbDataWriterTests : ExcelDataWriterTests
 {
 	const string FileFormat = "{0}.xlsb";
@@ -34,6 +34,7 @@ protected override string GetFile(string name)
 		return string.Format(FileFormat, name);
 	}
 }
+#endif
 
 public abstract class ExcelDataWriterTests
 {
@@ -434,7 +435,11 @@ public void GuidData()
 				i =>
 				{
 					var b = new byte[16];
-					Array.Fill(b, (byte)(i | i << 4));
+					for (int x = 0; x < b.Length; x++)
+					{
+						b[i] = (byte)(i | i << 4);
+
+					}
 					return new
 					{
 						Name = "Id " + i,
@@ -583,7 +588,7 @@ public override long GetChars(int ordinal, long dataOffset, char[] buffer, int b
 		var dat = col1[row];
 		var count = Math.Min(length, dat.Length - (int)dataOffset);
 
-		dat.AsSpan((int)dataOffset, count).CopyTo(buffer.AsSpan(bufferOffset));
+		Array.Copy(dat, dataOffset, buffer, bufferOffset, count);
 		return count;
 	}
 
@@ -696,4 +701,4 @@ public override bool NextResult()
 	}
 
 	#endregion
-}
+}

source/Sylvan.Data.Excel.Tests/ExternalDataTests.cs

@@ -18,7 +18,9 @@ public class ExternalDataTests
 	public ExternalDataTests(ITestOutputHelper o)
 	{
 		this.o = o;
+#if NETCOREAPP1_0_OR_GREATER
 		Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
+#endif
 	}
 
 	public static IEnumerable<object[]> GetInputs()

source/Sylvan.Data.Excel.Tests/Sylvan.Data.Excel.Tests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
 	<PropertyGroup>
-		<TargetFrameworks>net6.0</TargetFrameworks>
+		<TargetFrameworks>net6.0;net48</TargetFrameworks>
 		<RootNamespace>Sylvan.Data.Excel</RootNamespace>
 		<IsPackable>false</IsPackable>
 		<DisableImplicitNamespaceImports>true</DisableImplicitNamespaceImports>

source/Sylvan.Data.Excel/Sylvan.Data.Excel.csproj

@@ -3,7 +3,7 @@
 	<PropertyGroup>
 		<TargetFrameworks>net6.0;netstandard2.1;netstandard2.0</TargetFrameworks>
 		<LangVersion>latest</LangVersion>
-		<VersionPrefix>0.4.14</VersionPrefix>
+		<VersionPrefix>0.4.15</VersionPrefix>
 		<Description>A cross-platform .NET library for reading Excel data files.</Description>
 		<PackageTags>excel;xls;xlsx;xlsb;datareader</PackageTags>
 		<Nullable>enable</Nullable>

source/Sylvan.Data.Excel/Xlsb/XlsbWorkbookReader.cs

@@ -260,7 +260,11 @@ public override bool Read()
 		{
 			if (rowIndex <= parsedRowIndex)
 			{
-				if (curFieldCount >= 0)
+				if (rowIndex < parsedRowIndex)
+				{
+					this.rowFieldCount = 0;
+				}
+				else
 				{
 					this.rowFieldCount = curFieldCount;
 					this.curFieldCount = -1;
@@ -272,19 +276,26 @@ public override bool Read()
 			{
 				var c = ParseRowValues();
 				if (c < 0)
+				{
+					this.rowFieldCount = 0;
 					return false;
+				}
 				if (c == 0)
 				{
 					continue;
 				}
+				if (rowIndex < parsedRowIndex)
+				{
+					this.curFieldCount = c;
+					this.rowFieldCount = 0;
+					return true;
+				}
 				return true;
 			}
 		}
 		else
 		if (state == State.Initialized)
 		{
-			//this.rowFieldCount = this.curFieldCount;
-			//this.curFieldCount = 0;
 			// after initizialization, the first record would already be in the buffer
 			// if hasRows is true.
 			if (hasRows)

source/Sylvan.Data.Excel/Xlsx/SheetNameTable.cs

@@ -7,7 +7,8 @@ namespace Sylvan.Data.Excel.Xlsx;
 // these name tables avoid having to compute hashes on the
 // most common element names, and ensures that the strings
 // map the the const string so that equality will be ref
-// equality to the const values in our code.
+// equality to the const values in our code. NOTE: cannot use
+// ReferenceEquals however, because this doesn't apply in NET4.8
 sealed class SheetNameTable : NameTable
 {
 	public override string Add(char[] key, int start, int len)

source/Sylvan.Data.Excel/Xlsx/XlsxWorkbookReader.cs

@@ -36,11 +36,11 @@ sealed class XlsxWorkbookReader : ExcelDataReader
 
 	int rowIndex;
 	int parsedRowIndex = -1;
+	// the number of fields in the parsedRowIndex.
 	int curFieldCount = -1;
 
 	public override ExcelWorkbookType WorkbookType => ExcelWorkbookType.ExcelXml;
 
-
 	const string DefaultWorkbookPartName = "xl/workbook.xml";
 
 	public XlsxWorkbookReader(Stream iStream, ExcelDataReaderOptions opts) : base(iStream, opts)
@@ -320,7 +320,7 @@ bool NextRow()
 			}
 			else
 			{
-				this.parsedRowIndex++;
+				this.parsedRowIndex = -1;
 			}
 			reader.MoveToElement();
 			return true;
@@ -377,7 +377,11 @@ public override bool Read()
 		{
 			if (rowIndex <= parsedRowIndex)
 			{
-				if (curFieldCount >= 0)
+				if (rowIndex < parsedRowIndex)
+				{
+					this.rowFieldCount = 0;
+				} 
+				else
 				{
 					this.rowFieldCount = curFieldCount;
 					this.curFieldCount = -1;
@@ -389,8 +393,15 @@ public override bool Read()
 				var c = ParseRowValues();
 				if (c == 0)
 				{
+					// handles trailing empty rows.
 					continue;
 				}
+				if (rowIndex < parsedRowIndex)
+				{
+					this.curFieldCount = c;
+					this.rowFieldCount = 0;
+					return true;
+				}				
 				return true;
 			}
 		}
@@ -439,7 +450,7 @@ int ParseRowValues()
 			while (reader.MoveToNextAttribute())
 			{
 				var n = reader.Name;
-				if (ReferenceEquals(n, "r"))
+				if (n == "r")
 				{
 					len = reader.ReadValueChunk(valueBuffer, 0, valueBuffer.Length);
 					if (CellPosition.TryParse(valueBuffer.AsSpan().ToParsable(0, len), out var pos))
@@ -448,13 +459,13 @@ int ParseRowValues()
 					}
 				}
 				else
-				if (ReferenceEquals(n, "t"))
+				if (n == "t")
 				{
 					len = reader.ReadValueChunk(valueBuffer, 0, valueBuffer.Length);
 					type = GetCellType(valueBuffer, len);
 				}
 				else
-				if (ReferenceEquals(n, "s"))
+				if (n == "s")
 				{
 					len = reader.ReadValueChunk(valueBuffer, 0, valueBuffer.Length);
 					if (!TryParse(valueBuffer.AsSpan().ToParsable(0, len), out xfIdx))
@@ -679,7 +690,7 @@ static bool ReadToFollowing(XmlReader reader, string localName)
 	{
 		while (reader.Read())
 		{
-			if (reader.NodeType == XmlNodeType.Element && ReferenceEquals(localName, reader.LocalName))
+			if (reader.NodeType == XmlNodeType.Element && localName == reader.LocalName)
 			{
 				return true;
 			}
@@ -692,7 +703,7 @@ static bool ReadToNextSibling(XmlReader reader, string localName)
 		while (SkipSubtree(reader))
 		{
 			XmlNodeType nodeType = reader.NodeType;
-			if (nodeType == XmlNodeType.Element && ReferenceEquals(localName, reader.LocalName))
+			if (nodeType == XmlNodeType.Element && localName == reader.LocalName)
 			{
 				return true;
 			}
@@ -721,7 +732,7 @@ static bool ReadToDescendant(XmlReader reader, string localName)
 		}
 		while (reader.Read() && reader.Depth > num)
 		{
-			if (reader.NodeType == XmlNodeType.Element && ReferenceEquals(localName, reader.LocalName))
+			if (reader.NodeType == XmlNodeType.Element && localName == reader.LocalName)
 			{
 				return true;
 			}
@@ -813,7 +824,7 @@ void LoadSharedStrings(ZipArchiveEntry? entry)
 
 		while (reader.Read())
 		{
-			if (reader.NodeType == XmlNodeType.Element && ReferenceEquals(reader.LocalName, "si"))
+			if (reader.NodeType == XmlNodeType.Element && reader.LocalName == "si")
 			{
 				var str = ReadString(reader);
 				sstList.Add(str);