¿Utiliza expresiones regulares al analizar HTML en Perl?

Do you use regular expressions when parsing HTML in Perl?

If you’re going to parse HTML, don’t use regular expressions, and instead look at Perl HTML-parsing modules (also see an older link ). The canonical modules for that are HTML-Parser, which has built-in support for handling many of the irregularities of HTML in the wild, and XML-LibXML’s HTML support. Those should generally not be used directly.

The subclassing approach that HTML::Parser offers is worth knowing as it is a general technique (used by other Perl modules as well). The idea behind it requires only a bit of understanding of OOP concepts. HTML::Parser is a class that provides a few methods that you will be using verbatim, such as parse (), parse_file () or parse_chunk ().

The HTML::Parser module provides powerful mechanisms for extracting content, tags and tag attributes from any html stream. The subclassing approach that HTML::Parser offers is worth knowing as it is a general technique (used by other Perl modules as well).

Objects of the HTML::Parser class will recognize markup and separate it from plain text (alias data content) in HTML documents. As different kinds of markup and text are recognized, the corresponding event handlers are invoked. HTML::Parser is not a generic SGML parser.

Now that you know what the regex essentially does, you also need to be able to parse a string using the previously described regex. Something important also remains to be said: The proposed regex does only return the last Key-Value pair, therefore we need to process the input string multiple times.

The first operator is a test and assignment operator. There are three regular expression operators within Perl. The forward slashes in each case act as delimiters for the regular expression (regex) that you are specifying. If you are comfortable with any other delimiter, then you can use in place of forward slash.

Perl makes it easy for you to extract parts of the string that match by using parentheses () around any data in the regular expression. For each set of capturing parentheses, Perl populates the matches into the special variables $1, $2, $3 and so on. Perl populates those special only when the matches succeed.