CODEWITHSUNDEEP
htmlxmlregexperl
daliaessam
daliaessam

Reputation: 1666

Find and replace xml tags in html string in Perl with regex

I need to find and replace xml tags inside html string which is not complete xml that's why I can not use xml parser to deal with it. So I need to manually find the xml tags and replace them with content inside these html strings.

Example of html string containing the xml tags:

some text<p>hello p</p>
<vars type="text" name="fname" age="64" style="<b>color='red'</b>
Class::SubClass->color" /> other text or html open tags like <p><table><tr>

So I need to find the xml "vars" tags with their variable number of optional attributes and replace them with contents.

Upvotes: 1

Views: 1333

Answers (2)

daliaessam
daliaessam

Reputation: 1666

Looking at some Perl parsers for XML and HTML like Mojo::DOM as pointed by Miller answer above and also looking at XML::TreePP, I found they are using regex to parse the entire contents, so I tried their regex and got good results just may need some optimizations.

Here is what I did:

my $text =<<'XHTML';
some text
<p>hello p</p>
<vars  type="text" name= "fname" single='single quoted' unqouted=noquotes hastags=" <b>color='red'</b> Class::SubClass->color"/>
other text or html open tags like
<vars type="text" name= "lname" single1='single quoted' unqouted1=noquotes hastags1=" <b>bgcolor='red'</b> Class::SubClass->bgcolor">
<table><tr>
<vars name="mname" />
XHTML

while ( $text =~ m{(<vars\s+([^\!\?\s<>](?:"[^"]*"|'[^']*'|[^"'<>\/])*)/?>)}sxgi ) {
    my $match = $1;
    my $args = $2;
    #print "[[$match]] \n{{$args}}\n\n";

    #parse name=value attributes, values may be double or single quoted or unquoted
    while ( $args =~ m/([^<>=\s\/]+|\/)(?:\s*=\s*(?:"([^"]*?)"|'([^']*?)'|([^>\s\/]*)))?\s*/sxgi ) {
        my $name = $1;
        #any better solution with regex above to just get $2
        my $value = $2? $2: ($3? $3 : $4);
        print "$name=$value\n";
    }
    print "\n";
}

and here is the output as expected:

type=text
name=fname
single=single quoted
unqouted=noquotes
hastags= <b>color='red'</b> Class::SubClass->color

type=text
name=lname
single1=single quoted
unqouted1=noquotes
hastags1= <b>bgcolor='red'</b> Class::SubClass->bgcolor

name=mname

of course the variable $match in the code has the entire match so I can replace it with my contents.

the second regex that matches the attributes needs optimizations, I am not satisfied with this line :

my $value = $2? $2: ($3? $3 : $4);

can the regex be modified to just get the attribute value in $2.

The regex as used in Mojo::Dom is

my $ATTR_RE = qr/
  ([^<>=\s\/]+|\/)   # Key
  (?:
    \s*=\s*
    (?:
      "([^"]*?)"     # Quotation marks
    |
      '([^']*?)'     # Apostrophes
    |
      ([^>\s\/]*)    # Unquoted
    )
  )?
  \s*
/x;
my $END_RE   = qr!^\s*/\s*(.+)!;
my $TOKEN_RE = qr/
  ([^<]+)?                                          # Text
  (?:
    <\?(.*?)\?>                                     # Processing Instruction
  |
    <!--(.*?)--\s*>                                 # Comment
  |
    <!\[CDATA\[(.*?)\]\]>                           # CDATA
  |
    <!DOCTYPE(
      \s+\w+
      (?:(?:\s+\w+)?(?:\s+(?:"[^"]*"|'[^']*'))+)?   # External ID
      (?:\s+\[.+?\])?                               # Int Subset
      \s*
    )>
  |
    <(
      \s*
      [^<>\s]+                                      # Tag
      \s*
      (?:$ATTR_RE)*                                 # Attributes
    )>
  |
    (<)                                             # Runaway "<"
  )??
/xis;

I just messed up with it to match if closing tag with or without slash > or />.

Upvotes: 0

Miller
Miller

Reputation: 35208

Do not use regular expressions for parsing HTML. Instead use an actual HTML Parser like Mojo::DOM. There's a nice 8 minute video about using this module at mojocast episode 5.

The following takes your html, and translates your special vars tag into some new text.

use strict;
use warnings;

use Mojo::DOM;

# Parse
my $dom = Mojo::DOM->new(do {local $/; <DATA>});

for my $var ($dom->find('vars')->each) {
    my $type = $var->{type};
    my $name = $var->{name};

    $var->replace("<b>name is $name</b> + <i>type is $type</i>");
}

print $dom;

__DATA__
<html>
<head>
<title>Always use a parser, not a regex</title>
</head>
<body>
some text<p>hello p</p>
<vars type="text" name="fname" age="64" style="<b>color='red'</b>
Class::SubClass->color" /> other text or html open tags like <p><table><tr><td></td></tr></table>

</body></html>

Outputs:

<html>
<head>
<title>Always use a parser, not a regex</title>
</head>
<body>
some text<p>hello p</p>
<b>name is fname</b> + <i>type is text</i> other text or html open tags like <p></p><table><tr><td></td></tr></table>

</body></html>

Upvotes: 2

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