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PrettyMarkupFormatter loses NoBreakSpaces/  at the beginning or end of the content

See original GitHub issue

Bug Report

AngleSharp 0.14.0

Description

Tidying an HTML document removes NoBreakSpaces ( nbsp ) characters from the output if they are located at the beginning or the end of a line (or even unique)

Steps to Reproduce

Given the following example :

        static void Main(string[] args)
        {
            var documentStr = "<html><head></head><body><p>&nbsp;</p></body></html>";
            var parser = new HtmlParser();
            
            var document = parser.ParseDocument(documentStr);
            var sw = new StringWriter();

            document.ToHtml(sw, new PrettyMarkupFormatter());

            Console.WriteLine(sw.ToString());
            Console.ReadLine();
        }

Expected behavior:

<html>
        <head></head>
        <body>
                <p>&nbsp;</p>
        </body>
</html>

Actual behavior:

<html>
        <head></head>
        <body>
                <p></p>
        </body>
</html>

Environment details: Windows 10, .Net Framework 4.6.1

Possible Solution

To me (i’m no expert), in PrettyMarkupFormatter.Text, you’re using TrimEnd() and TrimStart(), which will remove any space characters, inclusing 0xa0 (representing ).

I think they should be kept, as removing those can break the display (

and

are different in HTML/CSS and browsers render them differently if they are empty).

This should at least be configurable through an option somewhere (it actually broke the display of my HTML document by removing those).

Issue Analytics

State:
Created 3 years ago
Comments:6 (3 by maintainers)

Top GitHub Comments

2reactions

Tetedeienchcommented, Apr 15, 2020

Alright !

As for potential options, i’d personally include one as “DontEmptyTags” or something along those lines.

Going further in discussing whether it is a good idea or not is definitely out of my league, so if that’s the expected behaviour, i’d still describe it somewhere, and close this issue.

Thanks !

1reaction

TopCoder02commented, Mar 3, 2023

@Tetedeiench I had the same issue, this is what I did for a workaround. Essentially, there are two ways a Non-Breaking Space can be represented, one is an ASCII character that represents it but looks like a normal space, the other is the way you described.

@FlorianRappl I think an option like this can be added to the formatter to handle the scenario @Tetedeiench describe and you can use the code below, or something similar to accomplish it.

Three years late, but I’m sure this will help others who have the same issue.

Private Function MakePrettyHTML(ByVal vHTMLString As String) As String
     Dim PrettyParser As New AngleSharp.Html.Parser.HtmlParser
     vHTMLString = Regex.Replace(vHTMLString, "(?<=>) (?=[ \r\n\t<\/])", "~NBS~", RegexOptions.IgnoreCase Or RegexOptions.IgnorePatternWhitespace)
     vHTMLString = Regex.Replace(vHTMLString, "(?<=>)&nbsp; (?=[ \r\n\t<\/])", "~NBS2~", RegexOptions.IgnoreCase Or RegexOptions.IgnorePatternWhitespace)
     Dim oDocument = PrettyParser.ParseDocument(vHTMLString)
     Dim sw = New StringWriter()
     oDocument.ToHtml(sw, New PrettyMarkupFormatter())
     Dim oPrettyHTML As String = sw.ToString()
     oPrettyHTML = oPrettyHTML.Replace("~NBS~", " ")
     oPrettyHTML = oPrettyHTML.Replace("~NBS2~", "&nbsp;")
 End Function