Text::Xslate(3pm) User Contributed Perl Documentation Text::Xslate(3pm)
NAME
Text::Xslate - Scalable template engine for Perl5
VERSION
This document describes Text::Xslate version v3.5.9.
SYNOPSIS
use Text::Xslate qw(mark_raw);
my $tx = Text::Xslate->new();
my %vars = (
title => 'A list of books',
books => [
{ title => 'Islands in the stream' },
{ title => 'Programming Perl' },
# ...
],
# mark HTML components as raw not to escape its HTML tags
gadget => mark_raw('<div class="gadget">...</div>'),
);
# for files
print $tx->render('hello.tx', \%vars);
# for strings (easy but slow)
my $template = q{
<h1><: $title :></h1>
<ul>
: for $books -> $book {
<li><: $book.title :></li>
: } # for
</ul>
};
print $tx->render_string($template, \%vars);
DESCRIPTION
Xslate is a template engine, tuned for persistent applications, safe as
an HTML generator, and with rich features.
There are a lot of template engines in CPAN, for example Template-
Toolkit, Text::MicroTemplate, HTML::Template, and so on, but all of
them have some weak points: a full-featured template engine may be
slow, while a fast template engine may be too simple to use. This is
why Xslate is developed, which is the best template engine for web
applications.
The concept of Xslate is strongly influenced by Text::MicroTemplate and
Template-Toolkit 2, but the central philosophy of Xslate is different
from them. That is, the philosophy is sandboxing that the template
logic should not have no access outside the template beyond your
permission.
Other remarkable features are as follows:
Features
High performance
This engine introduces the virtual machine paradigm. Templates are
compiled into intermediate code, and then executed by the virtual
machine, which is highly optimized for rendering templates. Thus,
Xslate is much faster than any other template engines.
The template roundup project by Sam Graham shows Text::Xslate got
amazingly high scores in instance_reuse condition (i.e. for persistent
applications).
The template roundup project
<http://illusori.co.uk/projects/Template-Roundup/>
Perl Template Roundup October 2010 Performance vs Variant Report:
instance_reuse
<http://illusori.co.uk/projects/Template-Roundup/201010/performance_vs_variant_by_feature_for_instance_reuse.html>
There are also benchmarks in benchmark/ directory in the Xslate
distribution.
Smart escaping for HTML metacharacters
Xslate employs the smart escaping strategy, where a template engine
escapes all the HTML metacharacters in template expressions unless
users mark values as raw. That is, the output is unlikely to prone to
XSS.
Template cascading
Xslate supports the template cascading, which allows you to extend
templates with block modifiers. It is like a traditional template
inclusion, but is more powerful.
This mechanism is also called as template inheritance.
Easiness to enhance
Xslate is ready to enhance. You can add functions and methods to the
template engine and even add a new syntax via extending the parser.
INTERFACE
Methods
Text::Xslate->new(%options)
Creates a new Xslate template engine with options. You can reuse this
instance for multiple calls to "render()".
Possible options are:
"path => \@path // ['.']"
Specifies the include paths, which may be directory names or
virtual paths, i.e. HASH references which contain "$file_name =>
$content" pairs.
Note that if you use taint mode ("-T"), you have to give absolute
paths to "path" and "cache_dir". Otherwise you'll get errors
because they depend on the current working directory which might
not be secure.
"cache => $level // 1"
Sets the cache level.
If "$level == 1" (default), Xslate caches compiled templates on the
disk, and checks the freshness of the original templates every
time.
If "$level >= 2", caches will be created but the freshness will not
be checked.
"$level == 0" uses no caches, which is provided for testing.
"cache_dir => $dir // "$ENV{HOME}/.xslate_cache""
Specifies the directory used for caches. If $ENV{HOME} doesn't
exist, "File::Spec->tmpdir" will be used.
You should specify this option for productions to avoid conflicts
of template names.
"function => \%functions"
Specifies a function map which contains name-coderef pairs. A
function "f" may be called as "f($arg)" or "$arg | f" in templates.
Note that these registered functions have to return a text string,
not a binary string unless you want to handle bytes in whole
templates. Make sure what you want to use returns either a text
string or a binary string.
For example, some methods of "Time::Piece" might return a binary
string which is encoded in UTF-8, so you'll want to decode their
values.
# under LANG=ja_JP.UTF-8 on MacOSX (Darwin 11.2.0)
use Time::Piece;
use Encode qw(decode);
sub ctime {
my $ctime = Time::Piece->new->strftime; # UTF-8 encoded bytes
return decode "UTF-8", $ctime;
}
my $tx = Text::Xslate->new(
function => {
ctime => \&ctime,
},
...,
);
Built-in functions are described in Text::Xslate::Manual::Builtin.
"module => [$module => ?\@import_args, ...]"
Imports functions from $module, which may be a function-based or
bridge module. Optional @import_args are passed to "import" as
"$module->import(@import_args)".
For example:
# for function-based modules
my $tx = Text::Xslate->new(
module => ['Digest::SHA1' => [qw(sha1_hex)]],
);
print $tx->render_string(
'<: sha1_hex($x).substr(0, 6) :>',
{ x => foo() },
); # => 0beec7
# for bridge modules
my $tx = Text::Xslate->new(
module => ['Text::Xslate::Bridge::Star'],
);
print $tx->render_string(
'<: $x.uc() :>',
{ x => 'foo' },
); # => 'FOO'
Because you can use function-based modules with the "module"
option, and also can invoke any object methods in templates, Xslate
doesn't require specific namespaces for plugins.
"html_builder_module => [$module => ?\@import_args, ...]"
Imports functions from $module, wrapping each function with
"html_builder()".
"input_layer => $perliolayers // ':utf8'"
Specifies PerlIO layers to open template files.
"verbose => $level // 1"
Specifies the verbose level.
If "$level == 0", all the possible errors will be ignored.
If "$level >= 1" (default), trivial errors (e.g. to print nil) will
be ignored, but severe errors (e.g. for a method to throw the
error) will be warned.
If "$level >= 2", all the possible errors will be warned.
"suffix => $ext // '.tx'"
Specify the template suffix, which is used for "cascade" and
"include" in Kolon.
Note that this is used for static name resolution. That is, the
compiler uses it but the runtime engine doesn't.
"syntax => $name // 'Kolon'"
Specifies the template syntax you want to use.
$name may be a short name (e.g. "Kolon"), or a fully qualified name
(e.g. "Text::Xslate::Syntax::Kolon").
This option is passed to the compiler directly.
"type => $type // 'html'"
Specifies the output content type. If $type is "html" or "xml",
smart escaping is applied to template expressions. That is, they
are interpolated via the "html_escape" filter. If $type is "text"
smart escaping is not applied so that it is suitable for plain
texts like e-mails.
$type may be html, xml (identical to "html"), and text.
This option is passed to the compiler directly.
"line_start => $token // $parser_defined_str"
Specify the token to start line code as a string, which "quotemeta"
will be applied to. If you give "undef", the line code style is
disabled.
This option is passed to the parser via the compiler.
"tag_start => $str // $parser_defined_str"
Specify the token to start inline code as a string, which
"quotemeta" will be applied to.
This option is passed to the parser via the compiler.
"tag_end => $str // $parser_defined_str"
Specify the token to end inline code as a string, which "quotemeta"
will be applied to.
This option is passed to the parser via the compiler.
"header => \@template_files"
Specify the header template files, which are inserted to the head
of each template.
This option is passed to the compiler.
"footer => \@template_files"
Specify the footer template files, which are inserted to the foot
of each template.
This option is passed to the compiler.
"warn_handler => \&cb"
Specify the callback &cb which is called on warnings.
"die_handler => \&cb"
Specify the callback &cb which is called on fatal errors.
"pre_process_handler => \&cb"
Specify the callback &cb which is called after templates are loaded
from the disk in order to pre-process template.
For example:
# Remove whitespace from templates
my $tx = Text::Xslate->new(
pre_process_handler => sub {
my $text = shift;
$text=~s/\s+//g;
return $text;
}
);
The first argument is the template text string, which can be both
text strings and "byte strings".
This filter is applied only to files, not a string template for
"render_string".
$tx->render($file, \%vars) :Str
Renders a template file with given variables, and returns the result.
\%vars is optional.
Note that $file may be cached according to the cache level.
$tx->render_string($string, \%vars) :Str
Renders a template string with given variables, and returns the result.
\%vars is optional.
Note that $string is never cached, so this method should be avoided in
production environment. If you want in-memory templates, consider the
path option for HASH references which are cached as you expect:
my %vpath = (
'hello.tx' => 'Hello, <: $lang :> world!',
);
my $tx = Text::Xslate->new( path => \%vpath );
print $tx->render('hello.tx', { lang => 'Xslate' });
Note that $string must be a text string, not a binary string.
$tx->load_file($file) :Void
Loads $file into memory for following "render()". Compiles and saves
it as disk caches if needed.
Text::Xslate->current_engine :XslateEngine
Returns the current Xslate engine while executing. Otherwise returns
"undef". This method is significant when it is called by template
functions and methods.
Text::Xslate->current_vars :HashRef
Returns the current variable table, namely the second argument of
"render()" while executing. Otherwise returns "undef".
Text::Xslate->current_file :Str
Returns the current file name while executing. Otherwise returns
"undef". This method is significant when it is called by template
functions and methods.
Text::Xslate->current_line :Int
Returns the current line number while executing. Otherwise returns
"undef". This method is significant when it is called by template
functions and methods.
Text::Xslate->print(...) :Void
Adds the argument into the output buffer. This method is available on
executing.
$tx->validate($file) :Void
Checks whether the syntax of $file is valid or invalid as Xslate. If
it detects the invalid factor, this method throws the exception.
Exportable functions
"mark_raw($str :Str) :RawStr"
Marks $str as raw, so that the content of $str will be rendered as is,
so you have to escape these strings by yourself.
For example:
use Text::Xslate qw( mark_raw );
my $tx = Text::Xslate->new();
my $tmpl = 'Mailaddress: <: $email :>';
my %vars = (
email => mark_raw('Foo <foo at example.com>'),
);
print $tx->render_string($tmpl, \%email);
# => Mailaddress: Foo <foo@example.com>
This function is available in templates as the "mark_raw" filter,
although the use of it is strongly discouraged.
"unmark_raw($str :Str) :Str"
Clears the raw marker from $str, so that the content of $str will be
escaped before rendered.
This function is available in templates as the "unmark_raw" filter.
"html_escape($str :Str) :RawStr"
Escapes HTML meta characters in $str, and returns it as a raw string
(see above). If $str is already a raw string, it returns $str as is.
By default, this function will automatically be applied to all template
expressions.
This function is available in templates as the "html" filter, but
you're better off using "unmark_raw" to ensure that expressions are
html-escaped.
"uri_escape($str :Str) :Str"
Escapes URI unsafe characters in $str, and returns it.
This function is available in templates as the "uri" filter.
"html_builder { block } | \&function :CodeRef"
Wraps a block or &function with "mark_raw" so that the new subroutine
will return a raw string.
This function is used to tell the xslate engine that &function is an
HTML builder that returns HTML sources. For example:
sub some_html_builder {
my @args = @_;
my $html;
# build HTML ...
return $html;
}
my $tx = Text::Xslate->new(
function => {
some_html_builder => html_builder(\&some_html_builder),
},
);
See also Text::Xslate::Manual::Cookbook.
Command line interface
The xslate(1) command is provided as a CLI to the Text::Xslate module,
which is used to process directory trees or to evaluate one liners.
For example:
$ xslate -Dname=value -o dest_path src_path
$ xslate -e 'Hello, <: $ARGV[0] :> wolrd!' Xslate
$ xslate -s TTerse -e 'Hello, [% ARGV.0 %] world!' TTerse
See xslate(1) for details.
TEMPLATE SYNTAX
There are multiple template syntaxes available in Xslate.
Kolon
Kolon is the default syntax, using "<: ... :>" inline code and ":
..." line code, which is explained in Text::Xslate::Syntax::Kolon.
Metakolon
Metakolon is the same as Kolon except for using "[% ... %]" inline
code and "%% ..." line code, instead of "<: ... :>" and ": ...".
TTerse
TTerse is a syntax that is a subset of Template-Toolkit 2 (and
partially TT3), which is explained in Text::Xslate::Syntax::TTerse.
HTMLTemplate
There's HTML::Template compatible layers in CPAN.
Text::Xslate::Syntax::HTMLTemplate is a syntax for HTML::Template.
HTML::Template::Parser is a converter from HTML::Template to
Text::Xslate.
NOTES
There are common notes in Xslate.
Nil/undef handling
Note that nil (i.e. "undef" in Perl) handling is different from Perl's.
Basically it does nothing, but "verbose => 2" will produce warnings on
it.
to print
Prints nothing.
to access fields
Returns nil. That is, "nil.foo.bar.baz" produces nil.
to invoke methods
Returns nil. That is, "nil.foo().bar().baz()" produces nil.
to iterate
Dealt as an empty array.
equality
"$var == nil" returns true if and only if $var is nil.
DEPENDENCIES
Perl 5.8.1 or later.
If you have a C compiler, the XS backend will be used. Otherwise the
pure Perl backend will be used.
TODO
• Context controls. e.g. "<: [ $foo->bar @list ] :>".
• Augment modifiers.
• Default arguments and named arguments for macros.
• External macros.
Just idea: in the new macro concept, macros and external templates
will be the same in internals:
: macro foo($lang) { "Hello, " ~ $lang ~ " world!" }
: include foo { lang => 'Xslate' }
: # => 'Hello, Xslate world!'
: extern bar 'my/bar.tx'; # 'extern bar $file' is ok
: bar( value => 42 ); # calls an external template
: include bar { value => 42 } # ditto
• A "too-safe" HTML escaping filter which escape all the symbolic
characters
RESOURCES
PROJECT HOME: <https://github.com/xslate/>
REPOSITORY: <https://github.com/xslate/p5-Text-Xslate/>
BUGS
Please report issues at
<https://github.com/xslate/p5-Text-Xslate/issues>. Patches are always
welcome.
SEE ALSO
Documents:
Text::Xslate::Manual
Xslate template syntaxes:
Text::Xslate::Syntax::Kolon
Text::Xslate::Syntax::Metakolon
Text::Xslate::Syntax::TTerse
Xslate command:
xslate
Other template modules that Xslate has been influenced by:
Text::MicroTemplate
Text::MicroTemplate::Extended
Text::ClearSilver
Template (Template::Toolkit)
HTML::Template
HTML::Template::Pro
Template::Alloy
Template::Sandbox
Benchmarks:
Template::Benchmark
Papers:
<http://www.cs.usfca.edu/~parrt/papers/mvc.templates.pdf> - Enforcing
Strict Model-View Separation in Template Engines
ACKNOWLEDGEMENT
Thanks to lestrrat for the suggestion to the interface of "render()",
the contribution of Text::Xslate::Runner (was App::Xslate), and a lot
of suggestions.
Thanks to tokuhirom for the ideas, feature requests, encouragement, and
bug finding.
Thanks to gardejo for the proposal to the name template cascading.
Thanks to makamaka for the contribution of Text::Xslate::PP.
Thanks to jjn1056 to the concept of template overlay (now implemented
as "cascade with ...").
Thanks to typester for the various inspirations.
Thanks to clouder for the patch of adding "AND" and "OR" to TTerse.
Thanks to punytan for the documentation improvement.
Thanks to chiba for the bug reports and patches.
Thanks to turugina for the patch to fix Win32 problems
Thanks to Sam Graham for the bug reports.
Thanks to Mons Anderson for the bug reports and patches.
Thanks to hirose31 for the feature requests and bug reports.
Thanks to c9s for the contribution of the documents.
Thanks to shiba_yu36 for the bug reports.
Thanks to kane46taka for the bug reports.
Thanks to cho45 for the bug reports.
Thanks to shmorimo for the bug reports.
Thanks to ueda for the suggestions.
AUTHOR
Fuji, Goro (gfx) <gfuji@cpan.org>.
Makamaka Hannyaharamitu (makamaka) (Text::Xslate::PP)
Maki, Daisuke (lestrrat) (Text::Xslate::Runner)
LICENSE AND COPYRIGHT
Copyright (c) 2010-2013, Fuji, Goro (gfx). All rights reserved.
This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
perl v5.34.0 2022-02-06 Text::Xslate(3pm)
Generated by dwww version 1.14 on Fri Jan 24 09:41:11 CET 2025.