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pyhtml.py
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pyhtml.py
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# -*- coding: utf-8 -*-
"""
PyHTML
======
Simple HTML generator for Python.
Usage:
Lets create a tag.
>>> t = div()
>>> t
div()
Tags can be rendered by converting to string.
>>> str(t)
'<div></div>'
Printing an object automatically calls str() with that object.
I will keep printing tags in this tutorial for clarity.
>>> print(div())
<div></div>
Parantheses can be omitted if the tag has no content.
>>> print(div)
<div></div>
Some tags are self closing.
>>> print(hr)
<hr/>
You can put some content into the tag.
>>> print(div('content'))
<div>
content
</div>
You can set attributes of the tag.
>>> print(div(lang='tr', id='content', class_="bar", data_value="foo"))
<div class="bar" data-value="foo" id="content" lang="tr"></div>
Or both:
>>> print(div(lang='tr')('content'))
<div lang="tr">
content
</div>
Content can be anything which can be converted to string.
If content is a callable, it will be called with a one argument
that is the context you pass to render() as keyword arguments.
>>> greet = lambda ctx: 'Hello %s' % ctx.get('user', 'guest')
>>> greeting = div(greet)
>>> print(greeting)
<div>
Hello guest
</div>
>>> print(greeting.render(user='Cenk'))
<div>
Hello Cenk
</div>
You can give list of items as content.
>>> print(div(nav(), greet, hr))
<div>
<nav></nav>
Hello guest
<hr/>
</div>
You can give give a callable returning a list as content.
>>> items = lambda ctx: [li('a'), li('b')]
>>> print(ul(items))
<ul>
<li>
a
</li>
<li>
b
</li>
</ul>
You can give give a generator as content.
>>> def items(ctx):
... for i in range(3):
... yield li(i)
>>> print(ul(items))
<ul>
<li>
0
</li>
<li>
1
</li>
<li>
2
</li>
</ul>
You can nest tags.
>>> print(div(div(p('a paragraph'))))
<div>
<div>
<p>
a paragraph
</p>
</div>
</div>
Some tags have sensible defaults.
>>> print(form())
<form method="POST"></form>
>>> print(html())
<!DOCTYPE html>
<html></html>
Full example:
>>> print(html(
... head(
... title('Awesome website'),
... script(src="http://path.to/script.js")
... ),
... body(
... header(
... img(src='/path/to/logo.png'),
... ),
... div(
... 'Content here'
... ),
... footer(
... hr,
... 'Copyright 2012'
... )
... )
... ))
<!DOCTYPE html>
<html>
<head>
<title>
Awesome website
</title>
<script src="http://path.to/script.js" type="text/javascript"></script>
</head>
<body>
<header>
<img src="/path/to/logo.png"/>
</header>
<div>
Content here
</div>
<footer>
<hr/>
Copyright 2012
</footer>
</body>
</html>
"""
from __future__ import print_function
import io
import sys
from copy import deepcopy
from types import GeneratorType
import lib.comm as comm
if sys.version_info[0] >= 3:
from typing import Dict, List # noqa
__version__ = '1.3.1'
# The list will be extended by register_all function.
__all__ = 'Tag Block Safe Var SelfClosingTag html script style form'.split()
tags = 'head body title div p h1 h2 h3 h4 h5 h6 u b i s a em strong span '\
'font del_ ins ul ol li dd dt dl article section nav aside header '\
'footer audio video deo_video object_ embed param fieldset legend button '\
'label select datalist option table thead tbody tr th td caption '\
'blockquote cite q abbr acronym address'
self_closing_tags = 'meta link br hr input_ img'
whitespace_sensitive_tags = 'code samp pre var kbd dfn source textarea'
INDENT = 2
def _escape(text):
r = (
('&', '&'),
('<', '<'),
('>', '>'),
('"', '"'),
("'", '''), )
for k, v in r:
text = text.replace(k, v)
return text
class TagMeta(type):
"""Type of the Tag. (type(Tag) == TagMeta)
"""
def __str__(cls):
"""Renders as empty tag."""
if cls.self_closing:
return '<%s/>' % cls.__name__
else:
return '<%s></%s>' % (cls.__name__, cls.__name__)
def __repr__(cls):
return cls.__name__
class Tag(comm.with_metaclass(TagMeta, object)): # type: ignore
safe = False # do not escape while rendering
self_closing = False
whitespace_sensitive = False
default_attributes = {} # type: Dict[str, str]
doctype = None # type: str
def __init__(self, *children, **attributes):
_safe = attributes.pop('_safe', None)
if _safe is not None:
self.safe = _safe
# Only children or attributes may be set at a time.
assert ((bool(children) ^ bool(attributes)) or (not children and not attributes))
if self.self_closing and children:
raise Exception("Self closing tag can't have children")
self.children = children
self.blocks = {} # type: Dict[str, List[Block]]
self._set_blocks(children)
self.attributes = self.default_attributes.copy()
self.attributes.update(attributes)
def __call__(self, *children, **options):
if self.self_closing:
raise Exception("Self closing tag can't have children")
_safe = options.pop('_safe', None)
if _safe is not None:
self.safe = _safe
self.children = children
self._set_blocks(children)
return self
def __repr__(self):
if self.attributes and not self.children:
return "%s(%s)" % (self.name, self._repr_attributes())
elif self.children and not self.attributes:
return "%s(%s)" % (self.name, self._repr_children())
elif self.attributes and self.children:
return "%s(%s)(%s)" % (self.name, self._repr_attributes(), self._repr_children())
else:
return "%s()" % self.name
def _repr_attributes(self):
return ', '.join("%s=%r" % (key, value) for key, value in self.attributes.items)
def _repr_children(self):
return ', '.join(repr(child) for child in self.children)
def __str__(self):
return self.render()
@property
def name(self):
return self.__class__.__name__
def copy(self):
return deepcopy(self)
def render(self, _out=None, _indent=0, **context):
if _out is None:
_out = io.StringIO('')
# Write doctype
if self.doctype:
_out.write(' ' * _indent)
_out.write(self.doctype)
_out.write('\n')
# Indent opening tag
_out.write(' ' * _indent)
# Open tag
_out.write('<%s' % self.name)
self._write_attributes(_out, context)
if self.self_closing:
_out.write('/>')
else:
# Close opening tag
_out.write('>')
if self.children:
# Newline after opening tag
if not self.whitespace_sensitive:
_out.write('\n')
# Write content
self._write_list(self.children, _out, context,
_indent + INDENT)
if not self.whitespace_sensitive:
# Newline after content
_out.write('\n')
# Indent closing tag
_out.write(' ' * _indent)
# Write closing tag
_out.write('</%s>' % self.name)
return _out.getvalue()
def _write_list(self, l, out, context, indent=0):
for i, child in enumerate(l):
# Write newline between items
if i != 0 and not self.whitespace_sensitive:
out.write('\n')
self._write_item(child, out, context, indent)
def _write_item(self, item, out, context, indent):
if isinstance(item, Tag):
item.render(out, indent, **context)
elif isinstance(item, TagMeta):
self._write_as_string(item, out, indent, escape=False)
elif callable(item):
rv = item(context)
self._write_item(rv, out, context, indent)
elif isinstance(item, (GeneratorType, list, tuple)):
self._write_list(item, out, context, indent)
else:
self._write_as_string(item, out, indent)
def _write_as_string(self, s, out, indent, escape=True):
if isinstance(s, str) and not isinstance(out, io.StringIO):
s = s
elif s is None:
s = ''
elif not isinstance(s, str):
s = str(s)
if escape and not self.safe:
s = _escape(s)
# Write content
if not self.whitespace_sensitive:
lines = s.splitlines(True)
for line in lines:
out.write(' ' * indent)
out.write(line)
else:
out.write(s)
def _write_attributes(self, out, context):
for key, value in sorted(self.attributes.items()):
# Some attribute names such as "class" conflict
# with reserved keywords in Python. These must
# be postfixed with underscore by user.
if key.endswith('_'):
key = key.rstrip('_')
# Dash is preffered to underscore in attribute names.
key = key.replace('_', '-')
if callable(value):
value = value(context)
if isinstance(value, str) and not isinstance(
out, io.StringIO):
value = value
if not isinstance(value, str):
value = str(value)
value = _escape(value)
out.write(' %s="%s"' % (key, value))
def __setitem__(self, block_name, *children):
for block in self.blocks[block_name]:
block(*children)
self._set_blocks(children, block_name=block_name)
def _set_blocks(self, children, block_name=None):
for child in children:
if isinstance(child, Block):
if child.block_name == block_name:
self.blocks[child.block_name] = [child]
elif child.block_name not in self.blocks:
self.blocks[child.block_name] = []
self.blocks[child.block_name].append(child)
elif isinstance(child, Tag):
for blocks in child.blocks.values():
self._set_blocks(blocks, block_name=block_name)
class Block(Tag):
"""List of renderable items."""
def __init__(self, name):
super(Block, self).__init__()
self.block_name = name
self.children = ()
def __repr__(self):
if not self.children:
return 'Block(%r)' % self.block_name
else:
return 'Block(%r)(%s)' % (self.block_name, self._repr_children())
def render(self, _out=None, _indent=0, **context):
if _out is None:
_out = io.StringIO('')
self._write_list(self.children, _out, context, _indent)
return _out.getvalue()
class Safe(Block):
"""Helper for wrapping content that do not need escaping."""
safe = True
def __init__(self, *children, **options):
super(Safe, self).__init__(None)
super(Safe, self).__call__(*children, **options)
def Var(var, default=None):
"""Helper function for printing a variable from context."""
return lambda ctx: ctx.get(var, default)
class SelfClosingTag(Tag):
self_closing = True
class WhitespaceSensitiveTag(Tag):
whitespace_sensitive = True
class html(Tag):
doctype = '<!DOCTYPE html>'
class script(Tag):
safe = True
default_attributes = {'type': 'text/javascript'}
class style(Tag):
default_attributes = {'type': 'text/css'}
class form(Tag):
default_attributes = {'method': 'POST'}
_M = sys.modules[__name__]
def register_all(tags, parent):
for tag in tags.split():
__all__.append(tag)
setattr(_M, tag, type(tag, (parent, ), {'name': tag.rstrip('_').replace('_', '-')}))
register_all(tags, Tag)
register_all(self_closing_tags, SelfClosingTag)
register_all(whitespace_sensitive_tags, WhitespaceSensitiveTag)
if __name__ == "__main__":
import doctest
doctest.testmod(extraglobs={'print_function': print_function}) # type: ignore