start implementing new Image stuff, tie in RenderMachine into the new Image class, assoicated config stuff
"""
Generating HTML tags
"""
from cgi import escape
import itertools as _itertools
class IRenderable (object) :
"""
Something that's renderable as the contents of a HTML tag
"""
def render_raw_lines (self, indent=u'\t') :
"""
Render the indented lines for tag and contents, without newlines
"""
abstract
class Tag (IRenderable) :
"""
A HTML tag, with attributes and contents, which can a mixture of data and other renderables(tags).
Provides various kinds of rendering output
"""
@staticmethod
def process_contents (contents) :
"""
Postprocess contents iterable to return new list.
Items that are None will be omitted from the return value.
>>> Tag.process_contents([])
[]
>>> Tag.process_contents([None])
[]
>>> Tag.process_contents([u'foo'])
[u'foo']
"""
return [c for c in contents if c is not None]
@staticmethod
def process_attrs (attrs) :
"""
Postprocess attributes.
Key-value pairs where the value is None will be ommitted, and any trailing underscores in the key omitted.
TODO: only remove one underscore
>>> Tag.process_attrs(dict())
{}
>>> Tag.process_attrs(dict(foo='bar'))
{'foo': 'bar'}
>>> Tag.process_attrs(dict(class_='bar', frob=None))
{'class': 'bar'}
"""
return dict((k.rstrip('_'), v) for k, v in attrs.iteritems() if v is not None)
def __init__ (self, name, *contents, **attrs) :
"""
Construct tag with given name/attributes or contents.
The filtering rules desribed in process_contents/process_attrs apply.
>>> Tag('foo')
Tag('foo')
>>> Tag('foo', 'quux')
Tag('foo', 'quux')
>>> Tag('foo', 'quux', bar=5)
Tag('foo', 'quux', bar=5)
>>> Tag('foo', class_='ten')
Tag('foo', class='ten')
"""
self.name = name
# store filtered/processed versions
self.contents = self.process_contents(contents)
self.attrs = self.process_attrs(attrs)
def __call__ (self, *contents, **attrs) :
"""
Return a new Tag with this tag's attributes and contents, as well as the given attributes/contents.
The filtering rules desribed in process_contents/process_attrs apply.
>>> Tag('foo')('bar')
Tag('foo', 'bar')
>>> Tag('a', href='index.html')("Home")
Tag('a', 'Home', href='index.html')
>>> Tag('bar', None)(5, foo=None, class_='bar')
Tag('bar', 5, class='bar')
>>> Tag('a')('b')('c')(asdf=5)
Tag('a', 'b', 'c', asdf=5)
>>> t1 = Tag('a'); t2 = t1('b'); t1
Tag('a')
"""
# merge attrs/contents
# XXX: new_attrs is not an iterator...
new_attrs = dict(_itertools.chain(self.attrs.iteritems(), attrs.iteritems()))
new_contents = _itertools.chain(self.contents, contents)
# build new tag
return Tag(self.name, *new_contents, **new_attrs)
@staticmethod
def format_attr (name, value) :
"""
Format a single HTML tag attribute
>>> Tag.format_attr('name', 'value')
u'name="value"'
>>> Tag.format_attr('this', '<a"b>')
u'this="<a"b>"'
>>> Tag.format_attr('xx', 1337)
u'xx="1337"'
"""
return u'%s="%s"' % (name, escape(unicode(value), True))
def render_attrs (self) :
"""
Return the HTML attributes string
>>> Tag('x', foo=5, bar='<').render_attrs()
u'foo="5" bar="<"'
"""
return " ".join(self.format_attr(n, v) for n, v in self.attrs.iteritems())
def render_contents (self, **render_opts) :
"""
Render the contents of the tag as a series of indented lines, with given render_lines options for subtags
>>> list(Tag('x', 5).render_contents())
[u'5']
>>> list(Tag('x', 'line1', 'line2').render_contents())
[u'line1', u'line2']
>>> list(Tag('x', 'a', Tag('b', 'bb'), 'c').render_contents())
[u'a', u'<b>', u'\\tbb', u'</b>', u'c']
"""
for content in self.contents :
if isinstance(content, IRenderable) :
# sub-tags
for line in content.render_raw_lines(**render_opts) :
yield line
else :
# escape raw values
yield escape(unicode(content))
def render_raw_lines (self, indent=u'\t') :
"""
Render the tag and indented content
>>> list(Tag('xx', 'yy', zz='foo').render_raw_lines(indent=' '))
[u'<xx zz="foo">', u' yy', u'</xx>']
"""
# render attr string, including preceding space
attrs_stuff = (" " + self.render_attrs()) if self.attrs else ""
if self.contents :
# tag with content
yield u"<%s%s>" % (self.name, attrs_stuff)
for line in self.render_contents(indent=indent) :
yield indent + line
yield u"</%s>" % (self.name, )
else :
# singleton tag
yield u"<%s%s />" % (self.name, attrs_stuff)
def render_lines (self, indent=u'\t', newline=u'\n') :
"""
Render full output lines with given newlines
>>> list(Tag('xx', 'yy').render_lines())
[u'<xx>\\n', u'\\tyy\\n', u'</xx>\\n']
"""
for line in self.render_raw_lines(indent) :
yield line + newline
def render_unicode (self, **render_opts) :
"""
Render full tag as a single unicode string
>>> Tag('xx', 'yy').render_unicode()
u'<xx>\\n\\tyy\\n</xx>\\n'
"""
return "".join(self.render_lines(**render_opts))
def render_str (self, charset='ascii', **render_opts) :
"""
Render full tag as an encoded string
>>> Tag('xx', 'yy').render_str()
'<xx>\\n\\tyy\\n</xx>\\n'
"""
return self.render_unicode(**render_opts).encode(charset)
def render_out (self, stream, charset, **render_opts) :
"""
Render output into the given stream, encoding using the given charset
>>> from StringIO import StringIO; buf = StringIO(); Tag('xx', 'yy').render_out(buf, 'ascii'); buf.getvalue()
'<xx>\\n\\tyy\\n</xx>\\n'
"""
for line in self.render_lines(**render_opts) :
stream.write(line.encode(charset))
# default output
__str__ = render_str
__unicode__ = render_unicode
# default .render method
render = render_unicode
def __repr__ (self) :
return 'Tag(%s)' % ', '.join(
[
repr(self.name)
] + [
repr(c) for c in self.contents
] + [
'%s=%r' % (name, value) for name, value in self.attrs.iteritems()
]
)
class Text (IRenderable) :
"""
Raw HTML text
"""
def __init__ (self, line) :
"""
Initialize to render as the given lines
"""
self.lines = [line]
def render_raw_lines (self, indent=u'\t') :
return self.lines
class TagFactory (object) :
"""
Build Tags with names give as attribute names
"""
def __getattr__ (self, name) :
"""
Get a Tag object with the given name, but no contents
>>> TagFactory().a(href='bar')('quux')
Tag('a', 'quux', href='bar')
"""
return Tag(name)
# pretty names
tag = Tag
tags = TagFactory()
raw = Text
# testing
if __name__ == '__main__' :
import doctest
doctest.testmod()