Parse::BBCode - Module to turn BBCode into HTML or plain text
To parse a bbcode string, set up a parser with the default HTML defintions of Parse::BBCode::HTML:
use Parse::BBCode;
my $p = Parse::BBCode->new();
my $code = 'some [b]b code[/b]';
my $parsed = $p->render($code);
Or if you want to define your own tags:
my $p = Parse::BBCode->new({
tags => {
# load the default tags
Parse::BBCode::HTML->defaults,
# add/override tags
url => 'url:<a href="%{link}A">%{parse}s</a>',
i => '<i>%{parse}s</i>',
b => '<b>%{parse}s</b>',
noparse => '<pre>%{html}s</pre>',
code => sub {
my ($parser, $attr, $content, $attribute_fallback) = @_;
if ($attr eq 'perl') {
# use some syntax highlighter
$content = highlight_perl($content);
}
else {
$content = Parse::BBCode::escape_html($$content);
}
"<tt>$content</tt>"
},
test => 'this is klingon: %{klingon}s',
},
escapes => {
klingon => sub {
my ($parser, $tag, $text) = @_;
return translate_into_klingon($text);
},
},
}
);
my $code = 'some [b]b code[/b]';
my $parsed = $p->render($code);
Note: This module is still experimental, the syntax is subject to change. I'm open for any suggestions on how to improve the syntax. See "TODO" for what might change.
I wrote this module because HTML::BBCode is not extendable (or I didn't see how) and BBCode::Parser seemed good at the first glance but has some issues, for example it says that he following bbode
[code] foo [b] [/code]
is invalid, while I think you should be able to write unbalanced code in code tags. Also BBCode::Parser dies if you have invalid code or not-permitted tags, but in a forum you'd rather show a partly parsed text then an error message.
What I also wanted is an easy syntax to define own tags, ideally - for simple tags - as plain text, so you can put it in a configuration file. This allows forum admins to add tags easily. Some forums might want a tag for linking to perlmonks.org, other forums need other tags.
Another goal was to always output a result and don't die. I might add an option which lets the parser die with unbalanced code.
Constructor. Takes a hash reference with options as an argument.
my $parser = Parse::BBCode->new({
tags => {
url => ...,
i => ...,
},
escapes => {
link => ...,
},
close_open_tags => 1, # default 0
strict_attributes => 0, # default 0
);
See "ESCAPES"
If set to true (1), it will close open tags at the end or before block tags.
If set to true (1), tags with invalid attributes are left unparsed. If set to false (0), the attribute for this tags will be empty.
An invalid attribute:
[foo=bar far boo]...[/foo]
I might add an option to define your own attribute validation. Contact me if you'd like to have this.
Input: The text to parse
Returns: the rendered text
my $parsed = $parser->render($bbcode);
Input: The text to parse.
Returns: the parsed tree (a Parse::BBCode::Tag object)
my $tree = $parser->parse($bbcode);
Input: the parse tree
Returns: The rendered text
my $parsed = $parser->render_tree($tree);
$parser->forbid(qw/ img url /);
Disables the given tags.
$parser->permit(qw/ img url /);
Enables the given tags if they are in the tag definitions.
Utility to substitute
<>&"'
with their HTML entities.
my $escaped = Parse::BBCode::escape_html($text);
If the given bbcode is invalid (unbalanced or wrongly nested classes), currently Parse::BBCode::render() will either leave the invalid tags unparsed, or, if you set the option close_open_tags, try to add closing tags. If this happened error() will return the invalid tag(s), otherwise false. To get the corrected bbcode (if you set close_open_tags) you can get the tree and return the raw text from it:
if ($parser->error) {
my $tree = $parser->get_tree;
my $corrected = $tree->raw_text;
}
Here is an example of all the current definition possibilities:
my $p = Parse::BBCode->new({
tags => {
'' => sub {
my $e = Parse::BBCode::escape_html($_[2]);
$e =~ s/\r?\n|\r/<br>\n/g;
$e
},
i => '<i>%s</i>',
b => '<b>%{parse}s</b>',
size => '<font size="%a">%{parse}s</font>',
url => 'url:<a href="%{link}A">%{parse}s</a>',
wikipedia => 'url:<a href="http://wikipedia.../?search=%{uri}A">%{parse}s</a>',
noparse => '<pre>%{html}s</pre>',
quote => 'block:<blockquote>%s</blockquote>',
code => {
code => sub {
my ($parser, $attr, $content, $attribute_fallback) = @_;
if ($attr eq 'perl') {
# use some syntax highlighter
$content = highlight_perl($content);
}
else {
$content = Parse::BBCode::escape_html($$content);
}
"<tt>$content</tt>"
},
parse => 0,
class => 'block',
},
hr => {
class => 'block',
output => '<hr>',
single => 1,
},
},
}
);
The following list explains the above tag definitions:
This defines how plain text should be rendered:
'' => sub {
my $e = Parse::BBCode::escape_html($_[2]);
$e =~ s/\r?\n|\r/<br>\n/g;
$e
},
In the most cases, you would want HTML escaping like shown above. This is the default, so you can leave it out. Only if you want to render BBCode into plain text or something else, you need this option.
%s i => '<i>%s</i>'
[i] italic <html> [/i]
turns out as
<i> italic <html> </i>
So %s stands for the tag content. By default, it is parsed itself, so that you can nest tags.
%{parse}s b => '<b>%{parse}s</b>'
[b] bold <html> [/b]
turns out as
<b> bold <html> </b>
%{parse}s is the same as %s because 'parse' is the default.
%a size => '<font size="%a">%{parse}s</font>'
[size=7] some big text [/size]
turns out as
<font size="7"> some big text </font>
So %a stands for the tag attribute. By default it will be HTML escaped.
%A, %{link}A url => 'url:<a href="%{link}a">%{parse}s</a>'
the first thing you can see is the url: at the beginning - this defines the url tag as a tag with the class 'url', and urls must not be nested. So this class definition is mainly there to prevent generating wrong HTML. if you nest url tags only the outer one will be parsed.
another thing you can see is how to apply a special escape. The attribute defined with %{link}a is checked for a valid URL. javascript: will be filtered.
[url=/foo.html]a link[/url]
turns out as
<a href="/foo.html">a link</a>
Note that a tag like
[url]http://some.link.example[/url]
will turn out as
<a href="">http://some.link.example</a>
In the cases where the attribute should be the same as the content you should use %A instead of %a which takes the content as the attribute as a fallback. You probably need this in all url-like tags:
url => 'url:<a href="%{link}A">%{parse}s</a>',
%{uri}AYou might want to define your own urls, e.g. for wikipedia references:
wikipedia => 'url:<a href="http://wikipedia/?search=%{uri}A">%{parse}s</a>',
%{uri}A will uri-encode the searched term:
[wikipedia]Harold & Maude[/wikipedia]
[wikipedia="Harold & Maude"]a movie[/wikipedia]
turns out as
<a href="http://wikipedia/?search=Harold+%26+Maude">Harold & Maude</a>
<a href="http://wikipedia/?search=Harold+%26+Maude">a movie</a>
Sometimes you need to display verbatim bbcode. The simplest form would be a noparse tag:
noparse => '<pre>%{html}s</pre>'
[noparse] [some]unbalanced[/foo] [/noparse]
With this definition the output would be
<pre> [some]unbalanced[/foo] </pre>
So inside a noparse tag you can write (almost) any invalid bbcode. The only exception is the noparse tag itself:
[noparse] [some]unbalanced[/foo] [/noparse] [b]really bold[/b] [/noparse]
Output:
[some]unbalanced[/foo] <b>really bold</b> [/noparse]
Because the noparse tag ends at the first closing tag, even if you have an additional opening noparse tag inside.
The %{html}s defines that the content should be HTML escaped. If you don't want any escaping you can't say %s because the default is 'parse'. In this case you have to write %{noescape}.
quote => 'block:<blockquote>%s</blockquote>',
To force valid html you can add classes to tags. The default class is 'inline'. To declare it as a block add 'block:" to the start of the string. Block tags inside of inline tags will either close the outer tag(s) or leave the outer tag(s) unparsed, depending on the option close_open_tags.
All these definitions might not be enough if you want to define your own code, for example to add a syntax highlighter.
Here's an example:
code => {
code => sub {
my ($parser, $attr, $content, $attribute_fallback) = @_;
if ($attr eq 'perl') {
# use some syntax highlighter
$content = highlight_perl($$content);
}
else {
$content = Parse::BBCode::escape_html($$content);
}
"<tt>$content</tt>"
},
parse => 0,
class => 'block',
},
So instead of a string you define a hash reference with a 'code' key and a sub reference. The other key is parse which is 0 by default. If it is 0 the content in the tag won't be parsed, just as in the noparse tag above. If it is set to 1 you will get the rendered content as an argument to the subroutine.
The first argument to the subroutine is the Parse::BBCode object itself. The second argument is the attribute, the third the tag content as a scalar reference and the fourth argument is the attribute fallback which is set to the content if the attribute is empty. The fourth argument is just for convenience.
Sometimes you might want single tags like for a horizontal line:
hr => {
class => 'block',
output => '<hr>',
single => 1,
},
The hr-Tag is a block tag (should not be inside inline tags), and it has no closing tag (option single)
[hr]
Output:
<hr>
my $p = Parse::BBCode->new({
...
escapes => {
link => sub {
},
},
});
You can define or override escapes. Default escapes are html, uri, link, email, htmlcolor, num. An escape functions as a validator and filter. For example, the 'link' escape looks if it got a valid URI (starting with / or \w+://) and html-escapes it. It returns the empty string if the input is invalid.
See "default_escapes" in Parse::BBCode::HTML for the detailed list of escapes.
There is a Parse::BBCode::Markdown module which is only roughly tested.
The main syntax is likely to stay, only the API for callbacks might change. At the moment it is not possible to add callbacks to the parsing process, only for the rendering phase. It is also not possible to declare your own attribute syntax, for example
[quote=nickname date]
Attributes always have to look like:
[tag=main_attribute other=foo]...
[tag="main_attribute" other="foo"]...
In a forum you might want to prefix links and images with a redirect script so that the actual referrer will be hidden from the target url. This is extremely helpful if you are using session-ids in your urls. I plan to add an option for url tags which lets you define the redirect-script url.
perl >= 5.6.1, Class::Accessor::Fast, URI::Escape
BBCode::Parser, HTML::BBCode, HTML::BBReverse
See examples/compare.html for a feature comparison of the modules and feel free to report mistakes.
See examples/bench.pl for a benchmark of the modules.
Please report bugs at http://rt.cpan.org/NoAuth/Bugs.html?Dist=Parse-BBCode
Tina Mueller
Thanks to Moritz Lenz for his suggestions about the implementation and the test cases.
Viacheslav Tikhanovskii
Sascha Kiefer
Copyright (C) 2008 by Tina Mueller
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.6.1 or, at your option, any later version of Perl 5 you may have available.
