Question

I’ve got a task in which I should capture specified text which cannot be between headline (of any size) and anchor html tags (<h*></h*> and <a></a>) nor inside tag as attribute.

For example I’ve got text:

<h1>TfL</h1>
<a href="tfl.gov.uk">Tfl</a>
TfL is official organization for keeping London moving.

Is it possible to match “TfL” only outside those tags using regular expressions?

Many thanks.

Peter.

Answer 1

I ended up with selecting nodes using HtmlAgilityPack.HtmlDocument.SelectNodes() and then checking the node in selection if it is excluded tag or not and has or has not such parent (recursively).

Public Const cAlphabet As String = "AÁÄBCČDĎEÉĚFGHIÍJKLĹĽMNŇOÓÔPQRŔŘSŠTŤUÚŮVWXYÝZŽ0123456789" ' Accepted chars '

Dim nodes As HtmlNodeCollection = nothing
Dim doc As HtmlDocument = New HtmlDocument()

' div encapsulation is used for text which is not between any tags. '
' iHtmlText is variable which holds html document in text form '
doc.LoadHtml(String.Format("<div>{0}</div>", If(iHtmlText, String.Empty))) 

' "FIND_THIS_TEXT" can be any text which you want to find '
' Node selecting is case insensitive due to translate feature of xpath '
nodes = doc.DocumentNode.SelectNodes(
        String.Format("//*[contains(translate(text(), '{0}', '{1}'), '{2}')]",
                      cAlphabet, cAlphabet.ToLower, "FIND_THIS_TEXT".ToLower))

For Each node As HtmlNode In nodes
   If (IsNotOrNestedInSpecifiedNode(node, "a", "h1", "h2", "h3", "h4", "h5", "h6")) Then
       ' do something with the node here '
   End If
Next

IsNotOrNestedInSpecifiedNode function used in code above:

Private Function IsNotOrNestedInSpecifiedNode(ByVal iNode As HtmlNode, ByVal ParamArray iExcludedHtmlTags() As String) As Boolean
        Dim ret As Boolean = False

        If (iNode.Name.IsIn(iExcludedHtmlTags)) Then
            ret = False
        ElseIf (iNode.ParentNode IsNot Nothing) Then
            ret = IsNotOrNestedInSpecifiedNode(iNode.ParentNode, iExcludedHtmlTags)
        Else
            ret = True
        End If

        Return ret
    End Function