RegEx for matching a special pattern in VB.net - regex

Question

I have code that extracts the text in different SGM files using the files Entity reference (&Ch1;). The code works great for this, but now it's expanded to need to get entity references for sectioned files with entity calls with this type of reference &Ch1-1; This can also grow to &Ch1-1-1;
I need to expand the code to accept these new entities so those files content can be added to the master file.
I believe the issue is the regular expression used so I changed it to
Dim rx = New Regex("&Ch(?<EntityNumber>\d+?[-\d+]?)?")
This doesn't create an error, but it also doesn't bring the file contents into the master document. I'm used to regular expressions but I've nevered used named capturing groups and found the explanations on the web a bit confusing.
Sub runProgram()
Dim DirFolder As String = txtDirectory.Text
Dim Directory As New IO.DirectoryInfo(DirFolder)
Dim allFiles As IO.FileInfo() = Directory.GetFiles("*.sgm")
Dim singleFile As IO.FileInfo
Dim Response As String
Dim Prefix As String
Dim newMasterFilePath As String
Dim masterFileName As String
Dim newMasterFileName As String
Dim startMark As String = "<!--#start#-->"
Dim stopMark As String = "<!--#stop#-->"
searchDir = txtDirectory.Text
Prefix = txtBxUnique.Text
For Each singleFile In allFiles
If File.Exists(singleFile.FullName) Then
Dim fileName = singleFile.FullName
Debug.Print("file name : " & fileName)
' A backup first
Dim backup As String = fileName & ".bak"
File.Copy(fileName, backup, True)
' Load lines from the source file in memory
Dim lines() As String = File.ReadAllLines(backup)
' Now re-create the source file and start writing lines inside a block
Dim insideBlock As Boolean = False
Using sw As StreamWriter = File.CreateText(backup)
For Each line As String In lines
If line = startMark Then
' start writing at the line below
insideBlock = True
ElseIf line = stopMark Then
' Stop writing
insideBlock = False
ElseIf insideBlock = True Then
' Write the current line in the block
sw.WriteLine(line)
End If
Next
End Using
End If
Next
masterFileName = Prefix & $"_Master_Document.sgm"
newMasterFileName = Prefix & $"_New_Master_Document.sgm"
newMasterFilePath = IO.Path.Combine(searchDir, newMasterFileName)
Dim existingMasterFilePath = IO.Path.Combine(searchDir, masterFileName)
'Read all text of the Master Document
'and create a StringBuilder from it.
'All replacements will be done on the
'StringBuilder as it is more efficient
'than using Strings directly
Dim strMasterDoc = File.ReadAllText(existingMasterFilePath)
Dim newMasterFileBuilder As New StringBuilder(strMasterDoc)
'Create a regex with a named capture group.
'The name is 'EntityNumber' and captures just the
'entity digits for use in building the file name
Dim rx = New Regex("&Ch(?<EntityNumber>\d+(-?\d*)*)?")
Dim rxMatches = rx.Matches(strMasterDoc)
For Each match As Match In rxMatches
Dim entity = match.ToString
'Build the file name using the captured digits from the entity in the master file
Dim entityFileName = Prefix & $"_Ch{match.Groups("EntityNumber")}.sgm.bak"
Dim entityFilePath = Path.Combine(searchDir, entityFileName)
'Check if the entity file exists and use its contents
'to replace the entity in the copy of the master file
'contained in the StringBuilder
If File.Exists(entityFilePath) Then
Dim entityFileContents As String = File.ReadAllText(entityFilePath)
newMasterFileBuilder.Replace(entity, entityFileContents)
End If
Next
'write the processed contents of the master file to a different file
File.WriteAllText(newMasterFilePath, newMasterFileBuilder.ToString)
Dim largeFilePath As String = newMasterFilePath
Dim lines1 = File.ReadLines(largeFilePath).ToList 'don't use ReadAllLines
Dim reg = New Regex("\<\!NOTATION.*$|\<\!ENTITY.*$", RegexOptions.IgnoreCase)
Dim entities = From line In lines1
Where reg.IsMatch(line)
Dim dictionary As New Dictionary(Of Integer, String)
Dim idx = -1
For Each s In entities
idx = lines1.IndexOf(s, idx + 1)
dictionary.Add(idx, s.Trim)
Next
Dim deletedItems = 0
For Each itm In dictionary
lines1.RemoveAt(itm.Key - deletedItems)
deletedItems += 1
Next
Dim uniqueDict = dictionary.GroupBy(Function(itm) itm.Value).
Select(Function(group) group.First()).
ToDictionary(Function(itm) itm.Key, Function(itm) itm.Value)
For Each s In uniqueDict.Values
lines1.Insert(1, s)
Next
Dim builtMaster As String = Prefix & "_FinalDeliverable.sgm"
Dim newBuiltMasterFilePath = IO.Path.Combine(searchDir, builtMaster)
Dim builtMasterDoc As String = newBuiltMasterFilePath
Using sw As New System.IO.StreamWriter(builtMasterDoc)
For Each line As String In lines1
sw.WriteLine(line)
Next
sw.Flush()
sw.Close()
End Using
'Delete the master document and new master document
If System.IO.File.Exists(existingMasterFilePath) = True Then
System.IO.File.Delete(existingMasterFilePath)
End If
If System.IO.File.Exists(newMasterFilePath) = True Then
System.IO.File.Delete(newMasterFilePath)
End If
For Each filename As String In IO.Directory.GetFiles(searchDir, "*.bak")
IO.File.Delete(filename)
Next
Response = MsgBox("File 'FinalDeliverable.sgm' has been created.", vbOKOnly, "SGM Status")
If Response = vbOK Then ' User chose Yes.
Close()
Else ' User chose No.
' Perform some action.
End If
End Sub
The results I'm expecting is for files with names Ch1-1.sgm content between and content will be added to a master file.
This does work for file entities that are &Ch1; it grabs Ch1.sgm content correctly.
Thank you for the help,
Maxine
Sample Code:
Master_Document.sgm
<!DOCTYPE DOC PUBLIC "-//USA-DOD//DTD 38784STD-BV7//EN"[
]>
&Ch1;
<body numcols="2">
&Ch2-1;
&Ch2-2;
&Ch2-3;
&Ch2-4;
&Ch2-5;
&Ch2-6;
&Ch2-7;
&Ch2-8;
&Ch2-9;
&Ch3;
</body></doc>
Sample SGM file
<?Pub /_gtinsert>
<body numcols="2">
<!--#start#-->
<chapter id="Chapter_4__Procedures">
<title>Procedures</title>
<section>
<title>Introduction</title>
<!--#stop#-->
<para0 verdate="7 Never 2012" verstatu
<title>Description</title>
<para>This chapterfor the following:

Answer 1

It turns out the problem is that &Ch(?<EntityNumber>\d+?[-\d+]?)? matched &Ch and then one or more, but as few as possible, digits (with \d+?) and then an optional single -, digit or + symbol. That is, after &Ch, only 1 digit was matched (as there is always a digit in your cases) and then a - was matched if it followed, and then matching stopped.
Use
Dim rx = New Regex("&Ch(?<EntityNumber>\d+(?:-\d+)*);")
See the regex demo and the regex graph: