hyde/hyde/template.py

# -*- coding: utf-8 -*-
# pylint: disable-msg=W0104,E0602,W0613,R0201
"""
Abstract classes and utilities for template engines
"""
from hyde.exceptions import HydeException
from hyde.util import getLoggerWithNullHandler

import abc

class HtmlWrap(object):
    """
    A wrapper class for raw html.

    Provides pyquery interface if available.
    Otherwise raw html access.
    """

    def __init__(self, html):
        super(HtmlWrap, self).__init__()
        self.raw = html
        try:
            from pyquery import PyQuery
        except:
            PyQuery = False
        if PyQuery:
            self.q = PyQuery(html)

    def __unicode__(self):
        return self.raw

    def __call__(self, selector=None):
        if not self.q:
            return self.raw
        return self.q(selector).html()

class Template(object):
    """
    Interface for hyde template engines. To use a different template engine,
    the following interface must be implemented.
    """

    __metaclass__ = abc.ABCMeta

    def __init__(self, sitepath):
        self.sitepath = sitepath
        self.logger = getLoggerWithNullHandler(self.__class__.__name__)

    @abc.abstractmethod
    def configure(self, site, engine):

        """
        The site object should contain a config attribute. The config object
        is a simple YAML object with required settings. The template
        implementations are responsible for transforming this object to match
        the `settings` required for the template engines.

        The engine is an informal protocol to provide access to some
        hyde internals.

        The preprocessor attribute must contain the function that trigger the
        hyde plugins to preprocess the template after load.

        A context_for_path attribute must contain the function that returns
        the context object that is populated with the appropriate variables
        for the given path.
        """
        return

    def clear_caches(self):
        """
        Clear all caches to prepare for regeneration
        """
        return

    def get_dependencies(self, text):
        """
        Finds the dependencies based on the included
        files.
        """
        return None

    @abc.abstractmethod
    def render_resource(self, resource, context):
        """
        This function must load the file represented by the resource
        object and return the rendered text.
        """
        return ''

    @abc.abstractmethod
    def render(self, text, context):
        """
        Given the text, and the context, this function must return the
        rendered string.
        """

        return ''

    @abc.abstractproperty
    def exception_class(self):
        return HydeException

    @abc.abstractproperty
    def patterns(self):
        """
        Patterns for matching selected template statements.
        """
        return {}

    @abc.abstractmethod
    def get_include_statement(self, path_to_include):
        """
        Returns an include statement for the current template,
        given the path to include.
        """
        return '{%% include \'%s\' %%}' % path_to_include

    @abc.abstractmethod
    def get_extends_statement(self, path_to_extend):
        """
        Returns an extends statement for the current template,
        given the path to extend.
        """
        return '{%% extends \'%s\' %%}' % path_to_extend

    @abc.abstractmethod
    def get_open_tag(self, tag, params):
        """
        Returns an open tag statement.
        """
        return '{%% %s %s %%}' % (tag, params)

    @abc.abstractmethod
    def get_close_tag(self, tag, params):
        """
        Returns an open tag statement.
        """
        return '{%% end%s %%}' % tag

    @abc.abstractmethod
    def get_content_url_statement(self, url):
        """
        Returns the content url statement.
        """
        return '/' + url

    @abc.abstractmethod
    def get_media_url_statement(self, url):
        """
        Returns the media url statement.
        """
        return '/media/' + url

    @staticmethod
    def find_template(site):
        """
        Reads the configuration to find the appropriate template.
        """
        # TODO: Find the appropriate template environment
        from hyde.ext.templates.jinja import Jinja2Template
        template = Jinja2Template(site.sitepath)
        return template