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Template::Flute - Modern designer-friendly HTML templating Engine
Perl Perl6 HTML
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README

NAME
    Template::Flute - Modern designer-friendly HTML templating Engine

VERSION
    Version 0.0183

SYNOPSIS
        use Template::Flute;

        my ($cart, $flute, %values);

        $cart = [{...},{...}];
        $values{cost} = ...

        $flute = new Template::Flute(specification_file => 'cart.xml',
                               template_file => 'cart.html',
                               iterators => {cart => $cart},
                               values => \%values,
                               autodetect => {
                                              disable => [qw/Foo::Bar/],
                                             }
                               );

        print $flute->process();

DESCRIPTION
    Template::Flute enables you to completely separate web design and
    programming tasks for dynamic web applications.

    Templates are designed to be designer-friendly; there's no inline code
    or mini templating language for your designers to learn - instead,
    standard HTML and CSS classes are used, leading to HTML that can easily
    be understood and edited by WYSIWYG editors and hand-coding designers
    alike.

    An example is easier than a wordy description:

    Given the following template snippet:

        <div class="customer_name">Mr A Test</div>
        <div class="customer_email">someone@example.com</div>

    and the following specification:

       <specification name="example" description="Example">
            <value name="customer_name" />
            <value name="email" class="customer_email" />
        </specification>

    Processing the above as follows:

        $flute = Template::Flute->new(
            template_file      => 'template.html',
            specification_file => 'spec.xml',
        );
        $flute->set_values({
            customer_name => 'Bob McTest',
            email => 'bob@example.com',
        });;
        print $flute->process;

    The resulting output would be:

        <div class="customer_name">Bob McTest</div>
        <div class="email">bob@example.com</div>

    In other words, rather than including a templating language within your
    templates which your designers must master and which could interfere
    with previews in WYSWYG tools, CSS selectors in the template are tied to
    your data structures or objects by a specification provided by the
    programmer.

  Workflow
    The easiest way to use Template::Flute is to pass all necessary
    parameters to the constructor and call the process method to generate
    the HTML.

    You can also break it down in separate steps:

    1. Parse specification
        Parse specification based on your specification format (e.g with
        Template::Flute::Specification::XML or
        Template::Flute::Specification::Scoped.).

            $xml_spec = new Template::Flute::Specification::XML;
            $spec = $xml_spec->parse(q{<specification name="cart" description="Cart">
                 <list name="cart" class="cartitem" iterator="cart">
                 <param name="name" field="title"/>
                 <param name="quantity"/>
                 <param name="price"/>
                 </list>
                 <value name="cost"/>
                 </specification>});

    2. Parse template
        Parse template with Template::Flute::HTML object.

            $template = new Template::Flute::HTML;
            $template->parse(q{<html>
                <head>
                <title>Cart Example</title>
                </head>
                <body>
                <table class="cart">
                <tr class="cartheader">
                <th>Name</th>
                <th>Quantity</th>
                <th>Price</th>
                </tr>
                <tr class="cartitem">
                <td class="name">Sample Book</td>
                <td><input class="quantity" name="quantity" size="3" value="10"></td>
                <td class="price">$1</td>
                </tr>
                <tr class="cartheader"><th colspan="2"></th><th>Total</th>
                </tr>
                <tr>
                <td colspan="2"></td><td class="cost">$10</td>
                </tr>
                </table>
                </body></html>},
                $spec);

    3. Produce HTML output
            $flute = new Template::Flute(template => $template,
                                       iterators => {cart => $cart},
                                       values => {cost => '84.94'});
            $flute->process();

CONSTRUCTOR
  new
    Create a Template::Flute object with the following parameters:

    specification_file
        Specification file name.

    specification_parser
        Select specification parser. This can be either the full class name
        like MyApp::Specification::Parser or the last part for classes
        residing in the Template::Flute::Specification namespace.

    specification
        Specification object or specification as string.

    template_file
        HTML template file.

    template
        Template::Flute::HTML object or template as string.

    database
        Template::Flute::Database::Rose object.

    filters
        Hash reference of filter functions.

    i18n
        Template::Flute::I18N object.

    translate_attributes
        An arrayref of attribute names to translate. If the name has a dot,
        it is interpreted as tagname + attribute, so `placeholder'" will
        unconditionally translate all the placeholders, while
        `input.placeholder' only the placeholder found on the input tag.

        Additional dotted values compose conditions for attributes. E.g.
        `input.value.type.submit' means all the value attributes with
        attribute `type' set to `submit'.

        Defaults to `['input.value.type.submit', 'placeholder']'

    iterators
        Hash references of iterators.

    values
        Hash reference of values to be used by the process method.

    auto_iterators
        Builds iterators automatically from values.

    autodetect
        A configuration option. It should be an hashref with a key `disable'
        and a value with an arrayref with a list of classes for objects
        which should be considered plain hashrefs instead. Example:

          my $flute = Template::Flute->new(....
                                           autodetect => { disable => [qw/My::Object/] },
                                           ....
                                          );

        Doing so, if you pass a value holding a `My::Object' object, and you
        have a specification with something like this:

          <specification>
           <value name="name" field="object.method"/>
          </specification>

        The value will be `$object-'{method}>, not `$object-'$method>.

        The object is checked with `isa'.

        Classical example: `Dancer::Session::Abstract'.

    uri Base URI for your template. This adjusts the links in the HTML tags
        `a', `base', `img', `link' and `script'.

    email_cids
        This is meant to be used on HTML emails. When this is set to an hash
        reference (which should be empty), the hash will be populated with
        the following values:

          cid1 => { filename => 'foo.png' },
          cid2 => { filename => 'foo2.gif' },

        and in the body the images `src' attribute will be replaced with
        `cid:cid1'.

        The cid names are arbitrary and assigned by the template. The code
        should look at the reference values which were modified.

    cids
        Optional hashref with options for the CID replacement behaviour.

        By default, if the source looks like an HTTP/HTTPS URI, the image
        source is not altered and no CID is assigned.

        If you pass a `base_url' value in this hashref, the URI matching it
        will be converted to cids and the rest of the path will be added to
        the `email_cids' hashref.

        Example:

            my $cids = {};
            $flute = Template::Flute->new(template => $template,
                                          specification => $spec,
                                          email_cids => $cids,
                                          cids => {
                                                   base_url => 'http://example.com/'
                                                  });

        Say the template contains images with source
        `http://example.com/image.png', the `email_cids' hashref will
        contain a cid with `filename' "image.png".

METHODS
  process [HASHREF]
    Processes HTML template, manipulates the HTML tree based on the
    specification, values and iterators.

    Returns HTML output.

  process_template
    Processes HTML template and returns Template::Flute::HTML object.

  filter ELEMENT VALUE
    Runs the filter used by ELEMENT on VALUE and returns the result.

  value NAME
    Returns the value for NAME.

  set_values HASHREF
    Sets hash reference of values to be used by the process method. Same as
    passing the hash reference as values argument to the constructor.

  template
    Returns HTML template object, see Template::Flute::HTML for details.

  specification
    Returns specification object, see Template::Flute::Specification for
    details.

SPECIFICATION
    The specification ties the elements in the HTML template to the data
    (variables, lists, forms) which is added to the template.

    The default format for the specification is XML implemented by the
    Template::Flute::Specification::XML module. You can use the
    Config::Scoped format implemented by
    Template::Flute::Specification::Scoped module or write your own
    specification parser class.

  COMMON ATTRIBUTES
    Common attributes for specification elements are:

    name
        Name of element.

            <value name="dancefloor"/>

    class
        Class of corresponding elements in the HTML template.

            <value name="dancefloor" class="dancefloor-link"/>

        If this attribute is omitted, the value of the name attribute is
        used to relate to the class in the HTML template.

    id  Id of corresponding element in the HTML template. Overrides the
        class attribute for the specification element.

           <value name="dancefloor" id="dancefloor-link"/>

    target
        HTML attribute to fill the value instead of replacing the body of
        the HTML element.

           <value name="dancefloor" class="dancefloor-link" target="href"/>

    joiner
        String placed between the text and the appended value. The joiner
        isn't added if the value is empty.

  ELEMENTS
    Possible elements in the specification are:

    container
        The first container is only shown in the output if the value
        `billing_address' is set:

          <container name="billing" value="billing_address" class="billingWrapper">
          </container>

        The second container is shown if the value `warnings' or the value
        `errors' is set:

          <container name="account_errors" value="warnings|errors" class="infobox">
          <value name="warnings"/>
          <value name="errors"/>
          </container>

    list
    separator
        Separator elements for list are added after any list item in the
        output with the exception of the last one.

        Example specification, HTML template and output:

          <specification>
          <list name="list" iterator="tokens">
          <param name="key"/>
          <separator name="sep"/>
          </list>
          </specification>

          <div class="list"><span class="key">KEY</span></div><span class="sep"> | </span>

          <div class="list"><span class="key">FOO</span></div><span class="sep"> | </span>
          <div class="list"><span class="key">BAR</span></div>

    param
        Param elements are replaced with the corresponding value from the
        list iterator.

        The following operations are supported for param elements:

        append
            Appends the param value to the text found in the HTML template.

        target
            The attribute to operate on. See below `target' for `value' for
            details.

        toggle
            When the `args' attribute is set to `tree', it doesn't
            interpolate anything and just shows corresponding HTML element
            if param value is set.

            With `target' attribute, it simply toggles the target attribute.

            Otherwise, if value is true, shows the HTML element and set its
            content to the value. If value is false, removes the HTML
            element.

            So, if your element has children elements, you probably want to
            use the `args="tree"' attribute (see below for an example).

        Other attributes for param elements are:

        filter
            Applies filter to param value.

        increment
            Uses value from increment instead of a value from the iterator.

                <param name="pos" increment="1">

    value
        Value elements are replaced with a single value present in the
        values hash passed to the constructor of this class or later set
        with the set_values method.

        The following operations are supported for value elements:

        append
            Appends the value to the text found in the HTML template.

        hook
            Insert HTML residing in value as subtree of the corresponding
            HTML element. HTML will be parsed with XML::Twig. See INSERT
            HTML for an example.

        toggle
            Only shows corresponding HTML element if value is set.

        Other attributes for value elements are:

        target
            Specify the attribute to operate on instead of the tag content.
            It can be a named attribute (e.g., `href'), the wildcard
            character(`*', meaning all the attributes found in the HTML
            template), or a comma separated list (e.g., `alt,title').

        filter
            Applies filter to value.

        include
            Processes the template file named in this attribute. This
            implies the hook operation. See INCLUDE FILES for more
            information.

    form
        Form elements are tied through specification to HTML forms.
        Attributes for form elements in addition to `class' and `id' are:

        link
            The link attribute can only have the value `name' and allows to
            base the relationship between form specification elements and
            HTML form tags on the name HTML attribute instead of `class',
            which is usually more convenient.

    input
    filter
    sort
    i18n
    skip
        This attribute (which can be provided to `param' or `value'
        specification elements) supports the following values:

        empty
            Do not replace the template string if the value or parameter is
            undefined, empty or just whitespace.

            E.g.

             <value name="cartline" skip="empty"/>
             <list name="items" iterator="items">
               <param name="category" skip="empty"/>
             </list>

    pattern
        You can define patterns in your specification to *interpolate* the
        strings instead of replacing them.

        A pattern is defined by the attributes `name' and `type' and its
        content. `type' can be only `string' or `regexp'.

        The interpolation happens if the `value' and `param' elements of the
        specification have an attribute `pattern' set with the pattern's
        name.

        Given this HTML:

         <p class="cartline">There are 123 items in your shopping cart.</p>
         <ul>
           <li class="items">
             <span class="number">1</span>
             <span class="category">in category 123</span>
           </li>
         </ul>

        And this specification:

         <specification>
         <pattern name="pxt" type="string">123</pattern>
         <list name="items" iterator="items">
           <param name="number"/>
           <param name="category" pattern="pxt"/>
         </list>
         <value name="cartline" pattern="pxt"/>
         </specification>

        In this example, in the cartline and category classes' text, only
        the template text "123" will be replaced by the value, not the whole
        element content, yielding such output:

         <p class="cartline">There are 42 items in your shopping cart.</p>
         <ul>
          <li class="items">
           <span class="number">1</span>
           <span class="category">in category tofu</span>
          </li>
          <li class="items">
           <span class="number">2</span>
           <span class="category">in category pizza</span>
          </li>
         </ul>

SIMPLE OPERATORS
  append
    Appends the value to the text inside a HTML element or to an attribute
    if `target' has been specified. This can be used in `value' and `param'
    specification elements.

    The example shows how to add a HTML class to elements in a list:

    HTML:

        <ul class="nav-sub">
            <li class="category"><a href="" class="catname">Medicine</a></li>
        </ul>

    XML:

        <specification>
            <list name="category" iterator="categories">
                <param name="name" class="catname"/>
                <param name="catname" field="uri" target="href"/>
                <param name="css" class="catname" target="class" op="append" joiner=" "/>
            </list>
        </specification>

CONTAINERS
    Conditional processing like `IF' or `ELSE' is done with the help of
    containers.

  Display image only if present
    In this example we want to show an image only on a certain condition:

    HTML:

        <span class="banner-box">
            <img class="banner" src=""/>
        </span>

    XML:

        <container name="banner-box" value="banner">
            <value name="banner" target="src"/>
        </container>

    Source code:

        if ($organization eq 'Big One') {
            $values{banner} = 'banners/big_one.png';
        }

  Display link in a list only if present
    In this example we want so show a link only if an URL is available:

    HTML:

        <div class="linklist">
            <span class="name">Name</span>
            <div class="link">
                <a href="#" class="url">Goto ...</a>
            </div>
        </div>

    XML:

        <specification name="link">
            <list name="links" class="linklist" iterator="links">
                <param name="name"/>
                <param name="url" target="href"/>
                <container name="link" class="link" value="url"/>
            </list>
        </specification>

    Source code:

       @records = ({name => 'Link', url => 'http://localhost/'},
                   {name => 'No Link'},
                   {name => 'Another Link', url => 'http://localhost/'},
                  );

       $flute = Template::Flute->new(specification => $spec_xml,
                                     template => $template,
                                     iterators => {links => \@records});

       $output = $flute->process();

ITERATORS
    Template::Flute uses iterators to retrieve list elements and insert them
    into the document tree. This abstraction relieves us from worrying about
    where the data actually comes from. We basically just need an array of
    hash references and an iterator class with a next and a count method.
    For your convenience you can create an iterator from
    Template::Flute::Iterator class very easily.

  DROPDOWNS
    Iterators can be used for dropdowns (HTML <select> elements) as well.

    Template:

        <select class="color"></select>

    Specification:

        <value name="color" iterator="colors"/>

    Code:

        @colors = ({value => 'red', label => 'Red'},
                   {value => 'black', label => 'Black'});

        $flute = Template::Flute->new(template => $html,
                                  specification => $spec,
                                  iterators => {colors => \@colors},
                                  values => {color => 'black'},
                                 );

    HTML output:

          <select class="color">
          <option value="red">Red</option>
          <option value="black" selected="selected">Black</option>
          </select>

    Default value for dropdowns
    You can specify the dropdown item which is selected by default with the
    `iterator_default') attribute.

    Template:

        <select class="color"></select>

    Specification:

        <value name="color" iterator="colors" iterator_default="black"/>

    Code:

        @colors = ({value => 'red', label => 'Red'},
                   {value => 'black', label => 'Black'});

        $flute = Template::Flute->new(template => $html,
                                  specification => $spec,
                                  iterators => {colors => \@colors},
                                 );

    HTML output:

          <select class="color">
          <option value="red">Red</option>
          <option value="black" selected="selected">Black</option>
          </select>

    Custom iterators for dropdowns
    By default, the iterator for a dropdown is an arrayref of hashrefs with
    two hardcoded keys: `value' and (optionally) `label'. You can override
    this behaviour in the specification with `iterator_value_key' and
    `iterator_name_key' to use your own hashref's keys from the iterator,
    instead of `value' and `label'.

    Specification:

      <specification>
        <value name="color" iterator="colors"
               iterator_value_key="code" iterator_name_key="name"/>
      </specification>

    Template:

      <html>
       <select class="color">
       <option value="example">Example</option>
       </select>
      </html>

    Code:

      @colors = ({code => 'red', name => 'Red'},
                 {code => 'black', name => 'Black'},
                );
  
      $flute = Template::Flute->new(template => $html,
                                    specification => $spec,
                                    iterators => {colors => \@colors},
                                    values => { color => 'black' },
                                   );
  
      $out = $flute->process();

    Output:

      <html>
       <head></head>
       <body>
        <select class="color">
         <option value="red">Red</option>
         <option selected="selected" value="black">Black</option>
        </select>
       </body>
      </html>

    Limit lists
    Sometimes you may wish to limit the number or iterations through you
    list.

    Specification:

        <specification>
            <list name="images" iterator="images" limit="1">
                <param name="image" target="src" field="image_url" />
            </list>
        </specification>

    Template:

        <div class="images">
            <img class="image" src="/images/bottle.jpg" />
        </div>

    Code:

        $images = [
            { image_url => '/images/bottle1.jpg' },
            { image_url => '/images/bottle2.jpg' },
            { image_url => '/images/bottle3.jpg' },
        ];

        $flute = Template::Flute->new(
            template      => $html,
            specification => $spec,
            values        => { images => $images },
        );

        $out = $flute->process;

    Output:

        <html><head></head><body>
            <div class="images">
                <img class="image" src="/images/bottle1.jpg" />
            </div>
        </body></html>

LISTS
    Lists can be accessed after parsing the specification and the HTML
    template through the HTML template object:

        $flute->template->lists();

        $flute->template->list('cart');

    Only lists present in the specification and the HTML template can be
    addressed in this way.

    See Template::Flute::List for details about lists.

OBJECTS AND STRUCTURES
    You can pass objects and hashrefs as values. To access a key or an
    accessor, you have to use a dotted notation with `field'. An example for
    both hashrefs and objects follows.

    Specification:

      <specification>
       <value name="object" field="myobject.method" />
       <value name="struct" field="mystruct.key" />
      </specification>

    HTML:

      <html>
        <body>
          <span class="object">Welcome back!</span>
          <span class="struct">Another one</span>
        </body>
      </html>

    Code:

      package My::Object;
      sub new {
          my $class = shift;
          bless {}, $class;
      }
      sub method {
          return "Hello from the method";
      }
      package main;
      my $flute = Template::Flute->new(
          specification => $spec,
          template => $html,
          values => {
              myobject => My::Object->new,
              mystruct => { key => "Hello from hash" },
             }
         );

    `process' will return:

      <html>
        <head></head>
        <body>
          <span class="object">Hello from the method</span>
          <span class="struct">Hello from hash</span>
        </body>
      </html>

    Sometimes you need to treat an object like an hashref. How to do that is
    explained under the `autodetect' option for the constructor.

FORMS
    Forms can be accessed after parsing the specification and the HTML
    template through the HTML template object:

        $flute->template->forms();

        $flute->template->form('edit_content');

    Only forms present in the specification and the HTML template can be
    addressed in this way.

    See Template::Flute::Form for details about forms.

FILTERS
    Filters are used to change the display of value and param elements in
    the resulting HTML output:

        <value name="billing_address" filter="eol"/>

        <param name="price" filter="currency"/>

    The following filters are included:

    upper
        Uppercase filter, see Template::Flute::Filter::Upper.

    strip
        Strips whitespace at the beginning at the end, see
        Template::Flute::Filter::Strip.

    eol Filter preserving line breaks, see Template::Flute::Filter::Eol.

    nobreak_single
        Filter replacing missing text with no-break space, see
        Template::Flute::Filter::NobreakSingle.

    currency
        Currency filter, see Template::Flute::Filter::Currency. Requires
        Number::Format module.

    date
        Date filter, see Template::Flute::Filter::Date. Requires DateTime
        and DateTime::Format::ISO8601 modules.

    country_name
        Country name filter, see Template::Flute::Filter::CountryName.
        Requires Locales module.

    language_name
        Language name filter, see Template::Flute::Filter::LanguageName.
        Requires Locales module.

    json_var
        JSON to Javascript variable filter, see
        Template::Flute::Filter::JsonVar. Requires JSON module.

    lower_dash
        Replaces spaces with dashes (-) and makes lowercase. see
        Template::Flute::Filter::LowerDash.

    Filter classes are loaded at runtime for efficiency and to keep the
    number of dependencies for Template::Flute as small as possible.

    See above for prerequisites needed by the included filter classes.

  Chained Filters
    Filters can also be chained:

        <value name="note" filter="upper eol"/>

    Example template:

        <div class="note">
            This is a note.
        </div>

    With the following value:

        Update now!
        Avoid security hazards!

    The HTML output would look like:

        <div class="note">
        UPDATE NOW!<br />
        AVOID SECURITY HAZARDS!
        </div>

INSERT HTML AND INCLUDE FILES
  INSERT HTML
    HTML can be generated in the code or retrieved from a database and
    inserted into the template through the `hook' operation:

        <value name="description" op="hook"/>

    The result replaces the inner HTML of the following `div' tag:

        <div class="description">
            Sample content
        </div>

  INCLUDE FILES
    Files, especially components for web pages can be processed and included
    through value elements with the include attribute:

        <value name="sidebar" include="component.html"/>

    The result replaces the inner HTML of the following `div' tag:

        <div class="sidebar">
            Sample content
        </div>

AUTHOR
    Stefan Hornburg (Racke), <racke@linuxia.de>

BUGS
    Please report any bugs or feature requests at
    https://github.com/racke/Template-Flute/issues.

SUPPORT
    You can find documentation for this module with the perldoc command.

        perldoc Template::Flute

    You can also look for information at:

    * AnnoCPAN: Annotated CPAN documentation
        http://annocpan.org/dist/Template-Flute

    * CPAN Ratings
        http://cpanratings.perl.org/d/Template-Flute

    * Search CPAN
        http://search.cpan.org/dist/Template-Flute/

ACKNOWLEDGEMENTS
    Thanks to Peter Mottram (GH #81, #87).

    Thanks to William Carr (GH #86, #91).

    Thanks to David Precious (bigpresh) for writing a much clearer
    introduction for Template::Flute.

    Thanks to Grega Pompe for proper implementation of nested lists and a
    documentation fix.

    Thanks to Jeff Boes for spotting a typo in the documentation of the
    Template::Flute::Filter::JsonVar class.

    Thanks to Ton Verhagen for being a big supporter of my projects in all
    aspects.

    Thanks to Sam Batschelet (GH #14, #93).

    Thanks to Terrence Brannon for spotting a documentation mix-up.

HISTORY
    Template::Flute was initially named Template::Zoom. I renamed the module
    because of a request from Matt S. Trout, author of the HTML::Zoom
    module.

LICENSE AND COPYRIGHT
    Copyright 2010-2014 Stefan Hornburg (Racke) <racke@linuxia.de>.

    This program is free software; you can redistribute it and/or modify it
    under the terms of either: the GNU General Public License as published
    by the Free Software Foundation; or the Artistic License.

    See http://dev.perl.org/licenses/ for more information.

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