YUI Loader as Django middleware

Author:: akaihola
Posted:: April 21, 2008
Language:: Python
Version:: .96
Score:: 3 (after 3 ratings)

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This server-side middleware implements some of the functionality in the Yahoo User Interface Loader component. YUI JavaScript and CSS modules requirements can be declared anywhere in the base, inherited or included templates, and the resulting, optimized <script> and <link rel="stylesheet"> tags are inserted at the specified position of the resulting page.

Requirements may be specified in multiple locations. This is useful when zero or more components are included in the HTML head section, and inherited and/or included templates require possibly overlapping sets of YUI components in the body across inherited and included templates. All tags are collected in the head section, and duplicate tags are automatically eliminated.

The middleware understands component dependencies and ensures that resources are loaded in the right order. It knows about built-in rollup files that ship with YUI. By automatically using rolled-up files, the number of HTTP requests is reduced.

The default syntax looks like HTML comments. Markup for the insertion point is replaced with <script> and <link> tags:

<!-- YUI_init -->

Component requirements are indicated, possibly in multiple locations, with the YUI_include markup. It is removed from the resulting page by the middleware. Example:

<!-- YUI_include fonts grids event dragdrop -->

Non-minified and compressed versions are requested, respectively, by:

<!-- YUI_version raw -->
<!-- YUI_version debug -->

Example:

<html><head>
<!-- YUI_init -->
<!-- YUI_include dom event -->
</head><body>
<!-- YUI_include element selector reset fonts base -->
</body></html>

Renders:

<html><head>
<link rel="stylesheet" type="text/css" href="http://yui.yahooapis.com/2.5.1/build/reset-fonts/reset-fonts.css" />
<link rel="stylesheet" type="text/css" href="http://yui.yahooapis.com/2.5.1/build/base/base-min.css" />
<script type="text/javascript" src="http://yui.yahooapis.com/2.5.1/build/yahoo-dom-event/yahoo-dom-event.js"></script>
<script type="text/javascript" src="http://yui.yahooapis.com/2.5.1/build/element/element-beta-min.js"></script>
<script type="text/javascript" src="http://yui.yahooapis.com/2.5.1/build/selector/selector-beta-min.js"></script>
</head><body>
</body></html>

The markup format can be customized with global Django settings. Example:

YUI_INCLUDE_PREFIX_RE = r'{!'
YUI_INCLUDE_SUFFIX_RE = r'!}'

would change markup to e.g. {! init !} and {! include dom event !}.

The base URL is customized with the YUI_INCLUDE_BASE setting, e.g.:

YUI_INCLUDE_BASE = 'http://localhost:8000/yui/build/'

To remove the XHTML trailing slash from the <link> tag, use:

YUI_INCLUDE_CSS_TAG = '<link rel="stylesheet" type="text/css" href="%s">'

See also the home page for this module.

---- middleware.py

import re

from django.conf import settings

from module_info_2_5_1 import MODULE_INFO
from components import Components


DEFAULT_BASE = 'http://yui.yahooapis.com/2.5.1/build/'
DEFAULT_JS_TAG = '<script type="text/javascript" src="%s"></script>'
DEFAULT_CSS_TAG = '<link rel="stylesheet" type="text/css" href="%s" />'

YUI_BASE = getattr(settings, 'YUI_INCLUDE_BASE', DEFAULT_BASE)
PREFIX_RE = getattr(settings, 'YUI_INCLUDE_PREFIX_RE', '<!-- *YUI_')
SUFFIX_RE = getattr(settings, 'YUI_INCLUDE_SUFFIX_RE', ' *-->')
TAGS = {'js': getattr(settings, 'YUI_INCLUDE_JS_TAG', DEFAULT_JS_TAG),
        'css': getattr(settings, 'YUI_INCLUDE_CSS_TAG', DEFAULT_CSS_TAG)}
VERSIONS = {'raw': '', '': '', 'min': '-min', 'debug': '-debug'}

COMPONENTS = Components(MODULE_INFO)


class YUILoader:

    def __init__(self):
        self._components = set()
        self._rolled_up_components = {}
        self._rollup_counters = {}
        self.set_version('min')

    def set_version(self, version):
        self._version = VERSIONS[version]

    def add_component(self, new_component_name):
        if not self._has_component(new_component_name):
            self._add_requirements(new_component_name)
            self._count_in_rollups(new_component_name)
            rollup_name = self._get_satisfied_rollup(new_component_name)
            if rollup_name:
                self.add_component(rollup_name)
            else:
                self._components.add(new_component_name)
                self._roll_up_superseded(new_component_name)

    def render(self):
        return '\n'.join(self._render_component(component)
                         for component in self._sort_components())

    def _has_component(self, component_name):
        return component_name in self._components \
               or component_name in self._rolled_up_components

    def _get_satisfied_rollup(self, component_name):
        if self._version == '-min':
            for rollup_name in COMPONENTS.get_rollups(component_name):
                rollup_status = self._rollup_counters.get(rollup_name, set())
                if len(rollup_status) >= COMPONENTS[rollup_name].rollup:
                    return rollup_name

    def _count_in_rollups(self, component_name):
        for rollup_name in COMPONENTS.get_rollups(component_name):
            rolled_up = self._rollup_counters.setdefault(rollup_name, set())
            rolled_up.add(component_name)
        for superseded in COMPONENTS[component_name].supersedes:
            self._count_in_rollups(superseded)

    def _roll_up_superseded(self, component_name):
        for superseded in COMPONENTS[component_name].supersedes:
            self._rolled_up_components[superseded] = component_name
            if superseded in self._components:
                self._components.remove(superseded)

    def _add_requirements(self, component_name):
        for requirement in COMPONENTS[component_name].requires:
            self.add_component(requirement)

    def _render_component(self, component_name):
        component = COMPONENTS[component_name]
        path = component.path
        if component.type == 'js':
            if self._version != '-min' and path.endswith('-min.js'):
                path = path[:-7] + self._version + '.js'
        elif component.type == 'css':
            if self._version == '' and path.endswith('-min.css'):
                path = path[:-8] + '.css'
        return TAGS[component.type] % (YUI_BASE + path,)

    def _sort_components(self, component_names=None):
        if component_names is None:
            comps = self._components.copy()
        else:
            comps = component_names
        while comps:
            component_name = comps.pop()
            component = COMPONENTS[component_name]
            direct_deps = component.requires + component.after
            indirect_deps = [
                self._rolled_up_components[r] for r in direct_deps
                if r in self._rolled_up_components]
            all_deps = set(direct_deps).union(set(indirect_deps))
            deps_left = comps.intersection(all_deps)
            for r in self._sort_components(deps_left):
                yield r
                comps.remove(r)
            yield component_name


YUI_RE = re.compile(
    r'%s(include|version) +(.*?)%s' % (PREFIX_RE, SUFFIX_RE))
YUI_INIT_RE = re.compile(
    '%sinit%s' % (PREFIX_RE, SUFFIX_RE))

class YUIIncludeMiddleware(object):
    def process_response(self, request, response):
        components = set()
        node = YUILoader()
        def collect(match):
            cmd, data = match.groups()
            if cmd == 'include':
                components.update(data.split())
            elif cmd == 'version':
                node.set_version(data)
            else:
                return '<!-- UNKNOWN COMMAND YUI_%s -->' % cmd
            return ''
        content = YUI_RE.sub(collect, response.content)
        for component in components:
            node.add_component(component)
        content = YUI_INIT_RE.sub(node.render(), content, 1)
        response.content = YUI_INIT_RE.sub(
            '<!-- WARNING: MULTIPLE YUI_init STATEMENTS -->', content)
        return response


---- components.py

class ComponentAdapter:

    def __init__(self, components, name, data):
        self.components = components
        self.name = name
        self.data = data

    @property
    def supersedes(self):
        return self.data.get('supersedes', [])

    @property
    def requires(self):
        r = self.data.get('requires', [])

        if self.type != 'js' \
        or self.name == 'yahoo' \
        or 'yahoo' in self.supersedes \
        or 'yahoo' in r:
            return r
        else:
            return ['yahoo'] + r

    @property
    def after(self):
        if self.type == 'css':
            return self.data.get('after', [])
        elif self.type == 'js':
            return self.data.get('after', []) + \
                   self.components.get_css_components()

    @property
    def rollup(self):
        return self.data.get('rollup', 1)

    def __getattr__(self, attname):
        return self.data[attname]


class Components(dict):
    def __init__(self, components_dict):
        super(Components, self).__init__(components_dict)
        self.rollup_mapping = {}
        for component_name, data in components_dict.items():
            self.rollup_mapping.setdefault(component_name, set())
            if 'rollup' not in data:
                continue
            for rolled_up in data['supersedes']:
                self.rollup_mapping.setdefault(rolled_up, set()).add(
                    component_name)

    def __getitem__(self, component_name):
        data = super(Components, self).__getitem__(component_name)
        return ComponentAdapter(self, component_name, data)

    def get_rollups(self, component_name):
        return self.rollup_mapping[component_name]

    def get_all_rollups(self, component_name):
        rollups = self.get_rollups(component_name)
        for superseded in self[component_name].supersedes:
            rollups.update(self.get_all_rollups(superseded))
        return rollups

    def get_css_components(self):
        return [name for name, data in self.items()
                if data['type'] == 'css']


---- module_info_2_5_1.py

MODULE_INFO = {
    'animation': {'path': 'animation/animation-min.js',
                  'requires': ['dom', 'event'],
                  'type': 'js'},
    'autocomplete': {'optional': ['connection', 'animation'],
                     'path': 'autocomplete/autocomplete-min.js',
                     'requires': ['dom', 'event'],
                     'skinnable': True,
                     'type': 'js'},
    'base': {'after': ['reset', 'fonts', 'grids'],
             'path': 'base/base-min.css',
             'type': 'css'},
    'button': {'optional': ['menu'],
               'path': 'button/button-min.js',
               'requires': ['element'],
               'skinnable': True,
               'type': 'js'},
    'calendar': {'path': 'calendar/calendar-min.js',
                 'requires': ['event', 'dom'],
                 'skinnable': True,
                 'type': 'js'},
    'charts': {'path': 'charts/charts-experimental-min.js',
               'requires': ['element', 'json', 'datasource'],
               'type': 'js'},
    'colorpicker': {'optional': ['animation'],
                    'path': 'colorpicker/colorpicker-min.js',
                    'requires': ['slider', 'element'],
                    'skinnable': True,
                    'type': 'js'},
    'connection': {'path': 'connection/connection-min.js',
                   'requires': ['event'],
                   'type': 'js'},
    'container': {'optional': ['dragdrop', 'animation', 'connection'],
                  'path': 'container/container-min.js',
                  'requires': ['dom', 'event'],
                  'skinnable': True,
                  'supersedes': ['containercore'],
                  'type': 'js'},
    'containercore': {'path': 'container/container_core-min.js',
                      'pkg': 'container',
                      'requires': ['dom', 'event'],
                      'type': 'js'},
    'cookie': {'path': 'cookie/cookie-beta-min.js',
               'requires': ['yahoo'],
               'type': 'js'},
    'datasource': {'optional': ['connection'],
                   'path': 'datasource/datasource-beta-min.js',
                   'requires': ['event'],
                   'type': 'js'},
    'datatable': {'optional': ['calendar', 'dragdrop'],
                  'path': 'datatable/datatable-beta-min.js',
                  'requires': ['element', 'datasource'],
                  'skinnable': True,
                  'type': 'js'},
    'dom': {'path': 'dom/dom-min.js', 'requires': ['yahoo'], 'type': 'js'},
    'dragdrop': {'path': 'dragdrop/dragdrop-min.js',
                 'requires': ['dom', 'event'],
                 'type': 'js'},
    'editor': {'optional': ['animation', 'dragdrop'],
               'path': 'editor/editor-beta-min.js',
               'requires': ['menu', 'element', 'button'],
               'skinnable': True,
               'type': 'js'},
    'element': {'path': 'element/element-beta-min.js',
                'requires': ['dom', 'event'],
                'type': 'js'},
    'event': {'path': 'event/event-min.js',
              'requires': ['yahoo'],
              'type': 'js'},
    'fonts': {'path': 'fonts/fonts-min.css', 'type': 'css'},
    'get': {'path': 'get/get-min.js', 'requires': ['yahoo'], 'type': 'js'},
    'grids': {'optional': ['reset'],
              'path': 'grids/grids-min.css',
              'requires': ['fonts'],
              'type': 'css'},
    'history': {'path': 'history/history-min.js',
                'requires': ['event'],
                'type': 'js'},
    'imagecropper': {'path': 'imagecropper/imagecropper-beta-min.js',
                     'requires': ['dom',
                                  'event',
                                  'dragdrop',
                                  'element',
                                  'resize'],
                     'skinnable': True,
                     'type': 'js'},
    'imageloader': {'path': 'imageloader/imageloader-min.js',
                    'requires': ['event', 'dom'],
                    'type': 'js'},
    'json': {'path': 'json/json-min.js',
             'requires': ['yahoo'],
             'type': 'js'},
    'layout': {'optional': ['animation', 'dragdrop', 'resize', 'selector'],
               'path': 'layout/layout-beta-min.js',
               'requires': ['dom', 'event', 'element'],
               'skinnable': True,
               'type': 'js'},
    'logger': {'optional': ['dragdrop'],
               'path': 'logger/logger-min.js',
               'requires': ['event', 'dom'],
               'skinnable': True,
               'type': 'js'},
    'menu': {'path': 'menu/menu-min.js',
             'requires': ['containercore'],
             'skinnable': True,
             'type': 'js'},
    'profiler': {'path': 'profiler/profiler-beta-min.js',
                 'requires': ['yahoo'],
                 'type': 'js'},
    'profilerviewer': {'path': 'profilerviewer/profilerviewer-beta-min.js',



                       'requires': ['profiler', 'yuiloader', 'element'],
                       'skinnable': True,
                       'type': 'js'},
    'reset': {'path': 'reset/reset-min.css', 'type': 'css'},
    'reset-fonts': {'path': 'reset-fonts/reset-fonts.css',
                    'rollup': 2,
                    'supersedes': ['reset', 'fonts'],
                    'type': 'css'},
    'reset-fonts-grids': {'path': 'reset-fonts-grids/reset-fonts-grids.css',
                          'rollup': 4,
                          'supersedes': ['reset',
                                         'fonts',
                                         'grids',
                                         'reset-fonts'],
                          'type': 'css'},
    'resize': {'optional': ['animation'],
               'path': 'resize/resize-beta-min.js',
               'requires': ['dom', 'event', 'dragdrop', 'element'],
               'skinnable': True,
               'type': 'js'},
    'selector': {'path': 'selector/selector-beta-min.js',
                 'requires': ['yahoo', 'dom'],
                 'type': 'js'},
    'simpleeditor': {'optional': ['containercore',
                                  'menu',
                                  'button',
                                  'animation',
                                  'dragdrop'],
                     'path': 'editor/simpleeditor-beta-min.js',
                     'pkg': 'editor',
                     'requires': ['element'],
                     'skinnable': True,
                     'type': 'js'},
    'slider': {'optional': ['animation'],
               'path': 'slider/slider-min.js',
               'requires': ['dragdrop'],
               'type': 'js'},
    'tabview': {'optional': ['connection'],
                'path': 'tabview/tabview-min.js',
                'requires': ['element'],
                'skinnable': True,
                'type': 'js'},
    'treeview': {'path': 'treeview/treeview-min.js',
                 'requires': ['event'],
                 'skinnable': True,
                 'type': 'js'},
    'uploader': {'path': 'uploader/uploader-experimental.js',
                 'requires': ['yahoo', 'element'],
                 'type': 'js'},
    'utilities': {'path': 'utilities/utilities.js',
                  'rollup': 8,
                  'supersedes': ['yahoo',
                                 'event',
                                 'dragdrop',
                                 'animation',
                                 'dom',
                                 'connection',
                                 'element',
                                 'yahoo-dom-event',
                                 'get',
                                 'yuiloader',
                                 'yuiloader-dom-event'],
                  'type': 'js'},
    'yahoo': {'path': 'yahoo/yahoo-min.js', 'type': 'js'},
    'yahoo-dom-event': {'path': 'yahoo-dom-event/yahoo-dom-event.js',
                        'rollup': 3,
                        'supersedes': ['yahoo', 'event', 'dom'],
                        'type': 'js'},
    'yuiloader': {'path': 'yuiloader/yuiloader-beta-min.js',
                  'supersedes': ['yahoo', 'get'],
                  'type': 'js'},
    'yuiloader-dom-event': {'path': 'yuiloader-dom-event/yuiloader-dom-event.js',
                            'rollup': 5,
                            'supersedes': ['yahoo',
                                           'dom',
                                           'event',
                                           'get',
                                           'yuiloader',
                                           'yahoo-dom-event'],
                            'type': 'js'},
    'yuitest': {'path': 'yuitest/yuitest-min.js',
                'requires': ['logger'],
                'skinnable': True,
                'type': 'js'}}

Comments

shadfc (on August 29, 2008):

This is really cool, but it doesnt seem to include any of the css dependencies on some of the controls such as autocomplete and calendar.

Hopefully someone can retool it to do this and updated it to YUI 2.5.2

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YUI Loader as Django middleware

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