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package Dancer::Template::Implementation::ForkedTiny;
# ABSTRACT: Dancer own implementation of Template::Tiny
use 5.00503;
use strict;
no warnings;
# Evaluatable expression
my $EXPR = qr/ [a-z_][\w.]* /xs;
sub new {
my $self = bless { start_tag => '[%',
end_tag => '%]', @_[1..$#_] }, $_[0];
# Opening tag including whitespace chomping rules
my $LEFT = $self->{LEFT} = qr/
(?:
(?: (?:^|\n) [ \t]* )? \Q$self->{start_tag}\E\-
|
\Q$self->{start_tag}\E \+?
) \s*
/xs;
# Closing %] tag including whitespace chomping rules
my $RIGHT = $self->{RIGHT} = qr/
\s* (?:
\+? \Q$self->{end_tag}\E
|
\-\Q$self->{end_tag}\E (?: [ \t]* \n )?
)
/xs;
# Preparsing run for nesting tags
$self->{PREPARSE} = qr/
$LEFT ( IF | UNLESS | FOREACH ) \s+
(
(?: \S+ \s+ IN \s+ )?
\S+ )
$RIGHT
(?!
.*?
$LEFT (?: IF | UNLESS | FOREACH ) \b
)
( .*? )
(?:
$LEFT ELSE $RIGHT
(?!
.*?
$LEFT (?: IF | UNLESS | FOREACH ) \b
)
( .+? )
)?
$LEFT END $RIGHT
/xs;
$self->{CONDITION} = qr/
\Q$self->{start_tag}\E\s
( ([IUF])\d+ ) \s+
(?:
([a-z]\w*) \s+ IN \s+
)?
( $EXPR )
\s\Q$self->{end_tag}\E
( .*? )
(?:
\Q$self->{start_tag}\E\s \1 \s\Q$self->{end_tag}\E
( .+? )
)?
\Q$self->{start_tag}\E\s \1 \s\Q$self->{end_tag}\E
/xs;
$self;
}
# Copy and modify
sub preprocess {
my $self = shift;
my $text = shift;
$self->_preprocess(\$text);
return $text;
}
sub process {
my $self = shift;
my $copy = ${shift()};
my $stash = shift || {};
local $@ = '';
local $^W = 0;
# Preprocess to establish unique matching tag sets
$self->_preprocess( \$copy );
# Process down the nested tree of conditions
my $result = $self->_process( $stash, $copy );
if ( @_ ) {
${$_[0]} = $result;
} elsif ( defined wantarray ) {
require Carp;
Carp::carp('Returning of template results is deprecated in Template::Tiny 0.11');
return $result;
} else {
print $result;
}
}
######################################################################
# Support Methods
# The only reason this is a standalone is so we can
# do more in-depth testing.
sub _preprocess {
my $self = shift;
my $copy = shift;
# Preprocess to establish unique matching tag sets
my $id = 0;
1 while $$copy =~ s/
$self->{PREPARSE}
/
my $tag = substr($1, 0, 1) . ++$id;
"\[\% $tag $2 \%\]$3\[\% $tag \%\]"
. (defined($4) ? "$4\[\% $tag \%\]" : '');
/sex;
}
sub _process {
my ($self, $stash, $text) = @_;
$text =~ s/
$self->{CONDITION}
/
($2 eq 'F')
? $self->_foreach($stash, $3, $4, $5)
: eval {
$2 eq 'U'
xor
!! # Force boolification
$self->_expression($stash, $4)
}
? $self->_process($stash, $5)
: $self->_process($stash, $6)
/gsex;
# Resolve expressions
$text =~ s/
$self->{LEFT} ( $EXPR ) $self->{RIGHT}
/
eval {
$self->_expression($stash, $1)
. '' # Force stringification
}
/gsex;
# Trim the document
$text =~ s/^\s*(.+?)\s*\z/$1/s if $self->{TRIM};
return $text;
}
# Special handling for foreach
sub _foreach {
my ($self, $stash, $term, $expr, $text) = @_;
# Resolve the expression
my $list = $self->_expression($stash, $expr);
unless ( ref $list eq 'ARRAY' ) {
return '';
}
# Iterate
return join '', map {
$self->_process( { %$stash, $term => $_ }, $text )
} @$list;
}
# Evaluates a stash expression
sub _expression {
my $cursor = $_[1];
my @path = split /\./, $_[2];
foreach ( @path ) {
# Support for private keys
return undef if substr($_, 0, 1) eq '_';
# Split by data type
my $type = ref $cursor;
if ( $type eq 'ARRAY' ) {
return '' unless /^(?:0|[0-9]\d*)\z/;
$cursor = $cursor->[$_];
} elsif ( $type eq 'HASH' ) {
$cursor = $cursor->{$_};
} elsif ( $type ) {
$cursor = $cursor->$_();
} else {
return '';
}
}
# If the last expression is a CodeRef, execute it
ref($cursor) eq 'CODE'
and $cursor = $cursor->();
return $cursor;
}
1;
__END__
=pod
=head1 NAME
Dancer::Template::Implementation::ForkedTiny - Template Toolkit reimplemented in as little code as possible, forked from Template::Tiny
=head1 SYNOPSIS
my $template = Dancer::Template::Implementation::ForkedTiny->new(
TRIM => 1,
);
# Print the template results to STDOUT
$template->process( <<'END_TEMPLATE', { foo => 'World' } );
Hello [% foo %]!
END_TEMPLATE
=head1 DESCRIPTION
B<Dancer::Template::Implementation::ForkedTiny> is a reimplementation of a subset of the functionality from
L<Template> Toolkit in as few lines of code as possible.
It is intended for use in light-usage, low-memory, or low-cpu templating
situations, where you may need to upgrade to the full feature set in the
future, or if you want the retain the familiarity of TT-style templates.
For the subset of functionality it implements, it has fully-compatible template
and stash API. All templates used with B<Dancer::Template::Implementation::ForkedTiny> should be able to be
transparently upgraded to full Template Toolkit.
Unlike Template Toolkit, B<Dancer::Template::Implementation::ForkedTiny> will process templates without a
compile phase (but despite this is still quicker, owing to heavy use of
the Perl regular expression engine.
=head2 SUPPORTED USAGE
By default, the C<[% %]> tag style is used. You can change the start tag and
end tag by specifying them at object creation :
my $template = Dancer::Template::Implementation::ForkedTiny->new(
start_tag => '<%',
end_tag => '%>,
);
In the rest of the documentation, C<[% %]> will be used, but it can be of
course your specified start / end tags.
Both the C<[%+ +%]> style explicit whitespace and the C<[%- -%]> style
explicit chomp B<are> support, although the C<[%+ +%]> version is unneeded
in practice as B<Dancer::Template::Implementation::ForkedTiny> does not support default-enabled C<PRE_CHOMP>
or C<POST_CHOMP>.
Variable expressions in the form C<[% foo.bar.baz %]> B<are> supported.
Appropriate simple behaviours for C<ARRAY> references, C<HASH> references and
objects are supported. "VMethods" such as [% array.length %] are B<not>
supported at this time.
If the resulting expression is a CodeRef, it'll be evaluated.
C<IF>, C<ELSE> and C<UNLESS> conditional blocks B<are> supported, but only with
simple C<[% foo.bar.baz %]> conditions.
Support for looping (or rather iteration) is available in simple
C<[% FOREACH item IN list %]> form B<is> supported. Other loop structures are
B<not> supported. Because support for arbitrary or infinite looping is not
available, B<Dancer::Template::Implementation::ForkedTiny> templates are not turing complete. This is
intentional.
All of the four supported control structures C<IF>/C<ELSE>/C<UNLESS>/C<FOREACH>
can be nested to arbitrary depth.
The treatment of C<_private> hash and method keys is compatible with
L<Template> Toolkit, returning null or false rather than the actual content
of the hash key or method.
Anything beyond the above is currently out of scope.
=head1 METHODS
=head2 new
my $template = Dancer::Template::Implementation::ForkedTiny->new(
TRIM => 1,
);
The C<new> constructor is provided for compatibility with Template Toolkit.
The only parameter it currently supports is C<TRIM> (which removes leading
and trailing whitespace from processed templates).
Additional parameters can be provided without error, but will be ignored.
=head2 process
# DEPRECATED: Return template results (emits a warning)
my $text = $template->process( \$input, $vars );
# Print template results to STDOUT
$template->process( \$input, $vars );
# Generate template results into a variable
my $output = '';
$template->process( \$input, $vars, \$output );
The C<process> method is called to process a template.
The first parameter is a reference to a text string containing the template
text. A reference to a hash may be passed as the second parameter containing
definitions of template variables.
If a third parameter is provided, it must be a scalar reference to be
populated with the output of the template.
For a limited amount of time, the old deprecated interface will continue to
be supported. If C<process> is called without a third parameter, and in
scalar or list contest, the template results will be returned to the caller.
If C<process> is called without a third parameter, and in void context, the
template results will be C<print()>ed to the currently selected file handle
(probably C<STDOUT>) for compatibility with L<Template>.
=head1 SUPPORT
Bugs should be reported via the CPAN bug tracker at
L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Template-Tiny>
For other issues, or commercial enhancement or support, contact the author.
=head1 AUTHOR
Adam Kennedy E<lt>adamk@cpan.orgE<gt>
Forked and improved by Damien Krotkine E<lt>dams@cpan.orgE<gt>
=head1 SEE ALSO
L<Config::Tiny>, L<CSS::Tiny>, L<YAML::Tiny>
=head1 COPYRIGHT
Copyright 2009 - 2011 Adam Kennedy.
Copyright 2012 Damien Krotkine.
This program is free software; you can redistribute
it and/or modify it under the same terms as Perl itself.
The full text of the license can be found in the
LICENSE file included with this module.
=cut
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