# This Source Code Form is subject to the terms of the Mozilla Public # License, v. 2.0. If a copy of the MPL was not distributed with this # file, You can obtain one at http://mozilla.org/MPL/2.0/. # # This Source Code Form is "Incompatible With Secondary Licenses", as # defined by the Mozilla Public License, v. 2.0. package Bugzilla::Markdown; use 5.10.1; use strict; use warnings; use Bugzilla::Constants; use Bugzilla::Template; use Digest::MD5 qw(md5_hex); use parent qw(Text::MultiMarkdown); @Bugzilla::Markdown::EXPORT = qw(new); # Regex to match balanced [brackets]. See Friedl's # "Mastering Regular Expressions", 2nd Ed., pp. 328-331. our ($g_nested_brackets, $g_nested_parens); $g_nested_brackets = qr{ (?> # Atomic matching [^\[\]]+ # Anything other than brackets | \[ (??{ $g_nested_brackets }) # Recursive set of nested brackets \] )* }x; # Doesn't allow for whitespace, because we're using it to match URLs: $g_nested_parens = qr{ (?> # Atomic matching [^()\s]+ # Anything other than parens or whitespace | \( (??{ $g_nested_parens }) # Recursive set of nested brackets \) )* }x; our %g_escape_table; my @code_blocks; foreach my $char (split //, '\\`*_{}[]()>#+-.!~') { $g_escape_table{$char} = md5_hex($char); } $g_escape_table{'<'} = md5_hex('<'); sub new { my $invocant = shift; my $class = ref $invocant || $invocant; return $class->SUPER::new(tab_width => MARKDOWN_TAB_WIDTH, # Bugzilla uses HTML not XHTML empty_element_suffix => '>'); } sub markdown { my $self = shift; my $text = shift; my $user = Bugzilla->user; if ($user->settings->{use_markdown}->{is_enabled} && $user->setting('use_markdown') eq 'on') { return $self->SUPER::markdown($text, @_); } return Bugzilla::Template::quoteUrls($text); } sub _Markdown { my $self = shift; my $text = shift; $text = Bugzilla::Template::quoteUrls($text, undef, undef, undef, 1); return $self->SUPER::_Markdown($text, @_); } sub _RunSpanGamut { # These are all the transformations that occur *within* block-level # tags like paragraphs, headers, and list items. my ($self, $text) = @_; $text = $self->_DoCodeSpans($text); $text = $self->_EscapeSpecialCharsWithinTagAttributes($text); $text = $self->_EscapeSpecialChars($text); $text = $self->_DoAnchors($text); # Strikethroughs is Bugzilla's extension $text = $self->_DoStrikethroughs($text); $text = $self->_DoAutoLinks($text); $text = $self->_EncodeAmpsAndAngles($text); $text = $self->_DoItalicsAndBold($text); $text =~ s/\n/{empty_element_suffix}\n/g; return $text; } # We first replace all fenced code blocks with just their # surrounding backticks and an empty body to know where # they are exactly for later processing. The bodies of # blocks will be in an array. This measure is taken to not # interpret fenced code blocks contents as possible markdown # structures. The contents of the body will be processed after # processing markdown structures. sub _removeFencedCodeBlocks { my ($self, $text) = @_; $text =~ s{ ^ `{3,} [\s\t]* \n ( # $1 = the entire code block (?: .* \n+)+? ) `{3,} [\s\t]* $ }{ push @code_blocks, $1; "%%%FENCED_BLOCK%%%"; }egmx; return $text; } # Override to check for HTML-escaped <>" chars. sub _StripLinkDefinitions { my ($self, $text) = @_; $text = $self->_removeFencedCodeBlocks($text); # # Strips link definitions from text, stores the URLs and titles in # hash references. # my $less_than_tab = $self->{tab_width} - 1; # Link defs are in the form: ^[id]: url "optional title" while ($text =~ s{ ^[ ]{0,$less_than_tab}\[(.+)\]: # id = \$1 [ \t]* \n? # maybe *one* newline [ \t]* (?:<)?\2(?:>)? # url = \$2 [ \t]* \n? # maybe one newline [ \t]* (?: (?<=\s) # lookbehind for whitespace (?:"|\() (.+?) # title = \$3 (?:"|\)) [ \t]* )? # title is optional (?:\n+|\Z) }{}omx) { $self->{_urls}{lc $1} = $self->_EncodeAmpsAndAngles( $2 ); # Link IDs are case-insensitive if ($3) { $self->{_titles}{lc $1} = $3; $self->{_titles}{lc $1} =~ s/"/"/g; } } return $text; } # We need to look for HTML-escaped '<' and '>' (i.e. < and >). # We also remove Email linkification from the original implementation # as it is already done in Bugzilla's quoteUrls(). sub _DoAutoLinks { my ($self, $text) = @_; $text =~ s{(?:<|<)((?:https?|ftp):[^'">\s]+?)(?:>|>)}{$1}gi; return $text; } # The main reasons for overriding this method are # resolving URL conflicts with Bugzilla's quoteUrls() # and also changing '"' to '"' in regular expressions wherever needed. sub _DoAnchors { # # Turn Markdown link shortcuts into tags. # my ($self, $text) = @_; # We revert linkifications of non-email links and only # those links whose URL and title are the same because # this way we can be sure that link is generated by quoteUrls() $text =~ s@\1@$1@xmg; # # First, handle reference-style links: [link text] [id] # $text =~ s{ ( # wrap whole match in $1 \[ ($g_nested_brackets) # link text = $2 \] [ ]? # one optional space (?:\n[ ]*)? # one optional newline followed by spaces \[ (.*?) # id = $3 \] ) }{ my $whole_match = $1; my $link_text = $2; my $link_id = lc $3; if ($link_id eq "") { $link_id = lc $link_text; # for shortcut links like [this][]. } $link_id =~ s{[ ]*\n}{ }g; # turn embedded newlines into spaces $self->_GenerateAnchor($whole_match, $link_text, $link_id); }xsge; # # Next, inline-style links: [link text](url "optional title") # $text =~ s{ ( # wrap whole match in $1 \[ ($g_nested_brackets) # link text = $2 \] \( # literal paren [ \t]* ($g_nested_parens) # href = $3 [ \t]* ( # $4 ("|') # quote char = $5 (.*?) # Title = $6 \5 # matching quote [ \t]* # ignore any spaces/tabs between closing quote and ) )? # title is optional \) ) }{ my $result; my $whole_match = $1; my $link_text = $2; my $url = $3; my $title = $6; # Remove Bugzilla quoteUrls() linkification if ($url =~ /^a href="/ && $url =~ m|]+>//; $url =~ s@_GenerateAnchor($whole_match, $link_text, undef, $url, $title); }xsge; # # Handle reference-style shortcuts: [link text] # These must come last in case you've also got [link test][1] # or [link test](/foo) # $text =~ s{ ( # wrap whole match in $1 \[ ([^\[\]]+) # link text = $2; can't contain '[' or ']' \] ) }{ my $result; my $whole_match = $1; my $link_text = $2; (my $link_id = lc $2) =~ s{[ ]*\n}{ }g; # lower-case and turn embedded newlines into spaces $self->_GenerateAnchor($whole_match, $link_text, $link_id); }xsge; # Last, handle "naked" references # Caveat, does not handle ;http://amazon.com my $safe_url_regexp = Bugzilla::Template::SAFE_URL_REGEXP(); $text =~ s{ ( (^|(?])) # negative lookbehind, including ';' in '<' ( # wrap url in $3 (?:https?|ftp):[^'">\s]+\w ) ) }{ my $whole_match = $3; my $url = $whole_match; $self->_GenerateAnchor($whole_match, $url, undef, $url, undef); }xsge; return $text; } # The purpose of overriding this function is to add support # for a Github Flavored Markdown (GFM) feature called 'Multiple # underscores in words'. The standard markdown specification # specifies the underscore for making the text emphasized/bold. # However, some variable names in programming languages contain underscores # and we do not want a part of those variables to look emphasized/bold. # Instead, we render them as the way they originally are. sub _DoItalicsAndBold { my ($self, $text) = @_; # Handle at beginning of lines: $text =~ s{ (^__ (?=\S) (.+?[*_]*) (?<=\S) __ (?!\S)) } { my $result = _has_multiple_underscores($2) ? $1 : "$2"; $result; }gsxe; $text =~ s{ ^\*\* (?=\S) (.+?[*_]*) (?<=\S) \*\* }{$1}gsx; $text =~ s{ (^_ (?=\S) (.+?) (?<=\S) _ (?!\S)) } { my $result = _has_multiple_underscores($2) ? $1 : "$2"; $result; }gsxe; $text =~ s{ ^\* (?=\S) (.+?) (?<=\S) \* }{$1}gsx; # must go first: $text =~ s{ ( (?<=\W) __ (?=\S) (.+?[*_]*) (?<=\S) __ (?!\S) ) } { my $result = _has_multiple_underscores($2) ? $1 : "$2"; $result; }gsxe; $text =~ s{ (?<=\W) \*\* (?=\S) (.+?[*_]*) (?<=\S) \*\* }{$1}gsx; $text =~ s{ ( (?<=\W) _ (?=\S) (.+?) (?<=\S) _ (?!\S) ) } { my $result = _has_multiple_underscores($2) ? $1 : "$2"; $result; }gsxe; $text =~ s{ (?<=\W) \* (?=\S) (.+?) (?<=\S) \* }{$1}gsx; # And now, a second pass to catch nested strong and emphasis special cases $text =~ s{ ( (?<=\W) __ (?=\S) (.+?[*_]*) (?<=\S) __ (\S*) ) } { my $result = _has_multiple_underscores($3) ? $1 : "$2$3"; $result; }gsxe; $text =~ s{ (?<=\W) \*\* (?=\S) (.+?[*_]*) (?<=\S) \*\* }{$1}gsx; $text =~ s{ ( (?<=\W) _ (?=\S) (.+?) (?<=\S) _ (\S*) ) } { my $result = _has_multiple_underscores($3) ? $1 : "$2$3"; $result; }gsxe; $text =~ s{ (?<=\W) \* (?=\S) (.+?) (?<=\S) \* }{$1}gsx; return $text; } sub _DoStrikethroughs { my ($self, $text) = @_; $text =~ s{ ^ ~~ (?=\S) ([^~]+?) (?<=\S) ~~ (?!~) }{$1}gsx; $text =~ s{ (?<=_|[^~\w]) ~~ (?=\S) ([^~]+?) (?<=\S) ~~ (?!~) }{$1}gsx; return $text; } # The original _DoCodeSpans() uses the 's' modifier in its regex # which prevents _DoCodeBlocks() to match GFM fenced code blocks. # We copy the code from the original implementation and remove the # 's' modifier from it. sub _DoCodeSpans { my ($self, $text) = @_; $text =~ s@ (?_EncodeCode($c); "$c"; @egx; return $text; } # Override to add GFM Fenced Code Blocks sub _DoCodeBlocks { my ($self, $text) = @_; # First, do the standard code blocks to avoid generating nested code blocks # if the block is both indented and is surrounded by backticks. $text = $self->SUPER::_DoCodeBlocks($text); $text =~ s{ ^ %%%FENCED_BLOCK%%% }{ my $codeblock = shift @code_blocks; my $result; $codeblock = $self->_EncodeCode($codeblock); $codeblock = $self->_Detab($codeblock); $codeblock =~ s/\n\z//; # remove the trailing newline $result = "\n\n
" . $codeblock . "
\n\n"; $result; }egmx; return $text; } sub _DoBlockQuotes { my ($self, $text) = @_; $text =~ s{ ( # Wrap whole match in $1 (?: ^[ \t]*>[ \t]? # '>' at the start of a line .+\n # rest of the first line (?:.+\n)* # subsequent consecutive lines \n* # blanks )+ ) }{ my $bq = $1; $bq =~ s/^[ \t]*>[ \t]?//gm; # trim one level of quoting $bq =~ s/^[ \t]+$//mg; # trim whitespace-only lines $bq = $self->_removeFencedCodeBlocks($bq); $bq = $self->_RunBlockGamut($bq, {wrap_in_p_tags => 1}); # recurse $bq =~ s/^/ /mg; # These leading spaces screw with
 content, so we need to fix that:
            $bq =~ s{(\s*
.+?
)}{ my $pre = $1; $pre =~ s/^ //mg; $pre; }egs; "
\n$bq\n
\n\n"; }egmx; return $text; } sub _EncodeCode { my ($self, $text) = @_; # We need to unescape the escaped HTML characters in code blocks. # These are the reverse of the escapings done in Bugzilla::Util::html_quote() $text =~ s/<//g; $text =~ s/"/"/g; $text =~ s/@/@/g; # '&' substitution must be the last one, otherwise a literal like '>' # will turn to '>' because '&' is already changed to '&' in Bugzilla::Util::html_quote(). # In other words, html_quote() will change '>' to '&gt;' and then we will # change '&gt' -> '>' -> '>' if we write this substitution as the first one. $text =~ s/&/&/g; $text =~ s{ \1 }{$1}xmgi; $text = $self->SUPER::_EncodeCode($text); $text =~ s/~/$g_escape_table{'~'}/go; # Encode '<' to prevent URLs from getting linkified in code spans $text =~ s/</$g_escape_table{'<'}/go; return $text; } sub _EncodeBackslashEscapes { my ($self, $text) = @_; $text = $self->SUPER::_EncodeBackslashEscapes($text); $text =~ s/\\~/$g_escape_table{'~'}/go; return $text; } sub _UnescapeSpecialChars { my ($self, $text) = @_; $text = $self->SUPER::_UnescapeSpecialChars($text); $text =~ s/$g_escape_table{'~'}/~/go; $text =~ s/$g_escape_table{'<'}/</go; return $text; } # Check if the passed string is of the form multiple_underscores_in_a_word. # To check that, we first need to make sure that the string does not contain # any white-space. Then, if the string is composed of non-space chunks which # are bound together with underscores, the string has the desired form. sub _has_multiple_underscores { my $string = shift; return 0 unless defined($string) && length($string); return 0 if $string =~ /[\t\s]+/; return 1 if scalar (split /_/, $string) > 1; return 0; } 1; __END__ =head1 NAME Bugzilla::Markdown - Generates HTML output from structured plain-text input. =head1 SYNOPSIS use Bugzilla::Markdown; my $markdown = Bugzilla::Markdown->new(); print $markdown->markdown($text); =head1 DESCRIPTION Bugzilla::Markdown implements a Markdown engine that produces an HTML-based output from a given plain-text input. The majority of the implementation is done by C CPAN module. It also applies the linkifications done in L to the input resulting in an output which is a combination of both Markdown structures and those defined by Bugzilla itself. =head2 Accessors =over =item C C Produces an HTML-based output string based on the structures and format defined in the given plain-text input. =over =item B =over =item C C A plain-text string which includes Markdown structures. =back =back =back