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phphtmldomxml-parsingpdflib

Locating a < symbol in HTML that isn't part of a tag

I'm trying to find a way to reliably locate and replace < and > symbols within an HTML/XML formatted string that do not belong to tags.

Basically I start with an HTML string and convert it into something usable by PDFLib, which uses a form of XML to describe documents to be written as PDF's. However if there is a < within in the content it sees it as the opening of a tag and throws a parse exception.

Example input:

<p>This is a test where 6 < 9</p>
<p>This is part of <strong>The same test</strong></p>
<p>This should also work 6<99999</p>

The text surrounding the < is not always numbers, it is user entered and could be anything such as Grade<C, Blue<Red<Green, Test < Test2.... just about anything really

Required output

This is a test where 6 <charref fontname=Helvetica encoding=unicode>&lt;<resetfont> 9\n
This is part of <fontname=Helvetica fontstyle=bold encoding=unicode>The same test<resetfont>\n
This should also work 6<charref fontname=Helvetica encoding=unicode>&lt;<resetfont>99999\n

I've tried a str_replace and preg_replace, but can't find a solution that will reliably leave the tags alone and replace just the < in context.

Parsing the DOM also seems to fail as the DOMDocument sees the < as an opening tag as well

Using htmlspecialchars on the string converts all the tags <> into &lt;&gt; as well which is no good.

Does anyone have any ideas?

Solution

  • Try using the answer from this question:

    how to repair malformed xml

    I tried to add this as as it stands, but StackOverflow requires me to add some description to the answer, or it automatically gets converted into a comment, which can't be accepted as an answer.