NAME

Text::Xslate - High performance template engine

VERSION

This document describes Text::Xslate version 0.1029.

SYNOPSIS

use Text::Xslate;
use FindBin qw($Bin);

my $tx = Text::Xslate->new(
    # the fillowing options are optional.
    path       => ['.'],
    cache_dir  => "$ENV{HOME}/.xslate_cache",
    cache      => 1,
);

my %vars = (
    title => 'A list of books',
    books => [
        { title => 'Islands in the stream' },
        { title => 'Programming Perl'      },
        { title => 'River out of Eden'     },
        { title => 'Beautiful code'        },
    ],
);

# for files
print $tx->render('hello.tx', \%vars);

# for strings
my $template = q{
    <h1><: $title :></h1>
    <ul>
    : for $books -> $book {
        <li><: $book.title :></li>
    : } # for
    </ul>
};

print $tx->render_string($template, \%vars);

# you can tell the engine that some strings are already escaped.
use Text::Xslate qw(escaped_string);

$vars{email} = escaped_string('gfx &lt;gfuji at cpan.org&gt;');
# or
$vars{email} = Text::Xslate::EscapedString->new(
    'gfx &lt;gfuji at cpan.org&gt;',
); # if you don't want to pollute your namespace.


# if you want Template-Toolkit syntx:
$tx = Text::Xslate->new(syntax => 'TTerse');
# ...

DESCRIPTION

Text::Xslate is a template engine tuned for persistent applications. This engine introduces the virtual machine paradigm. That is, templates are compiled into xslate intermediate code, and then executed by the xslate virtual machine.

The concept of Xslate is strongly influenced by Text::MicroTemplate and Template-Toolkit, 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.

This software is under development. Version 0.1xxx is a developing stage, which may include radical changes. Version 0.2xxx and more will be somewhat stable.

Features

High performance

Xslate has a virtual machine written in XS, which is highly optimized. According to benchmarks, Xslate is much faster than other template engines (Template-Toolkit, HTML::Template::Pro, Text::MicroTemplate, etc.).

There are benchmarks to compare template engines (see benchmark/ for details).

Here is a result of benchmark/others.pl to compare various template engines.

$ perl -Mblib benchmark/others.pl include 100
Perl/5.10.1 i686-linux
Text::Xslate/0.1025
Text::MicroTemplate/0.11
Template/2.22
Text::ClearSilver/0.10.5.4
HTML::Template::Pro/0.94
1..4
ok 1 - TT: Template-Toolkit
ok 2 - MT: Text::MicroTemplate
ok 3 - TCS: Text::ClearSilver
ok 4 - HT: HTML::Template::Pro
Benchmarks with 'include' (datasize=100)
         Rate     TT     MT    TCS     HT Xslate
TT      313/s     --   -55%   -88%   -89%   -97%
MT      697/s   123%     --   -72%   -75%   -93%
TCS    2512/s   702%   260%     --    -9%   -74%
HT     2759/s   781%   296%    10%     --   -71%
Xslate 9489/s  2931%  1261%   278%   244%     --

You can see Xslate is 3 times faster than HTML::Template::Pro and Text::ClearSilver, which are implemented in XS.

Template cascading

Xslate supports template cascading, which allows you to extend templates with block modifiers. It is like traditional template inclusion, but is more powerful.

This mechanism is also called as template inheritance.

Syntax alternation

The Xslate virtual machine and the parser/compiler are completely separated so that one can use alternative parsers.

For example, TTerse, a Template-Toolkit-like parser, is supported as a completely different syntax parser.

INTERFACE

Methods

Text::Xslate->new(%options) :XslateEngine

Creates a new xslate template engine.

Possible options are:

path => \@path // ['.']

Specifies the include paths.

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 creates no caches. It's 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 on productions.

function => \%functions

Specifies functions, which may be called as f($arg) or $arg | f.

You can also define methods with pseudo type names: scalar, array, and hash. For example:

my $tx = Text::Xslate->new(
    function => {
        'scalar::some_method' => sub { my($scalar)    = @_; ... },
        'array::some_method'  => sub { my($array_ref) = @_; ... },
        'hash::some_method'   => sub { my($hash_ref)  = @_; ... },
    },
);

module => [$module => ?\@import_args, ...]

Imports functions from $module. @import_args is optional.

For example:

my $tx = Text::Xslate->new(
    module => ['Data::Dumper'], # use Data::Dumper
);
print $tx->render_string(
    '<: Dumper($x) :>',
    { x => [42] },
);
# => $VAR = [42]

You can use function based modules with the module option, and also can invoke object methods in templates. Thus, Xslate doesn't require the namespaces for plugins.

input_layer => $perliolayers // ':utf8'

Specifies PerlIO layers for reading templates.

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).

escape => $mode // 'html'

Specifies the escape mode, which is automatically applied to template expressions.

Possible escape modes are html and none.

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 template cascading.

$tx->render($file, \%vars) :Str

Renders a template file with variables, and returns the result. \%vars can be omitted.

Note that $file may be cached according to the cache level.

$tx->render_string($string, \%vars) :Str

Renders a template string with variables, and returns the result. \%vars can be omitted.

Note that $string is never cached so that this method is suitable for testing.

$tx->load_file($file) :Void

Loads $file for following render($file, \%vars). Compiles and saves it as caches if needed.

This method can be used for pre-compiling template files.

Exportable functions

`escaped_string($str :Str) -> EscapedString`

Marks $str as escaped. Escaped strings will not be escaped by the template engine, so you have to escape these strings by yourself.

For example:

my $tx   = Text::Xslate->new();
my $tmpl = 'Mailaddress: <: $email :>';
my %vars = (
    email => 'Foo &lt;foo@example.com&gt;',
);
print $tx->render_string($tmpl, \%email);
# => Mailaddress: Foo &lt;foo@example.com&gt;

This function is available in templates as the raw filter:

<: $var | raw :>

`html_escape($str :Str) -> EscapedString`

Escapes html special characters in $str, and returns an escaped string (see above).

Although you need not call it explicitly, this function is available in templates as the html filter:

<: $var | html :>

Application

xslate(1) is provided as an interface to the Text::Xslate module, which is used to process directory trees or evaluate one liners. For example:

$ xslate -D name=value -o dest_path src_path

$ xslate -e 'Hello, <: $ARGV[0] :> wolrd!' Xslate
$ xslate -s TTerse -e 'Hello, [% ARGV.0 %] world!' TTerse

See xslate for details.

TEMPLATE SYNTAX

There are several syntaxes you can use:

Kolon: Kolon is the default syntax, using <: ... :> tags and : ... line code, which is explained in Text::Xslate::Syntax::Kolon.
Metakolon: Metakolon is the same as Kolon except for using [% ... %] tags 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.

NOTES

There are common notes in the Xslate virtual machine.

Nil handling

Note that nil handling is different from Perl's. Basically it does nothing, but verbose => 2 will produce warnings for 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.

Automatic semicolon insertion

The Xslate tokenizer automatically inserts semicolons at the end of the line codes. Currently this mechanism is not so smart, which could cause problems:

For example, the following Kolon template causes syntax errors.

: my $foo = {
:    bar => 42,
: };

It must be:

<: my $foo = {
     bar => 42,
   };
-:>

This limitation should be resolved in a future.

DEPENDENCIES

Perl 5.8.1 or later.

If you have a C compiler, the XS backend will be used. Otherwise the pure Perl backend is used.

BUGS

All complex software has bugs lurking in it, and this module is no exception. If you find a bug please either email me, or add the bug to cpan-RT. Patches are welcome :)

ACKNOWLEDGEMENT

Thanks to lestrrat for the suggestion to the interface of render() and the contribution of App::Xslate.

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 jjn1056 to the concept of template overlay (now implemented as cascade with ...).

Thanks to makamaka for the contribution of Text::Xslate::PP.

AUTHOR

Fuji, Goro (gfx) <gfuji(at)cpan.org>

Makamaka Hannyaharamitu (makamaka)

Maki, Daisuke (lestrrat)

LICENSE AND COPYRIGHT

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

To install Text::Xslate, copy and paste the appropriate command in to your terminal.

cpanm

cpanm Text::Xslate

CPAN shell

perl -MCPAN -e shell
install Text::Xslate

For more information on module installation, please visit the detailed CPAN module installation guide.

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