Poor man's POWERFUL html templating system for python

htmltemplates.py

import sys


class Element:
    def __init__(self, name, **attributes):
        self.name = name
        self.attributes = attributes
        self.childs = []

    def setAttribute(self, key, val):
        self.attributes[key] = val

    def setAttributes(self, **kwargs):
        for key, val in kwargs.items():
            self.attributes[key] = val

    def appendChild(self, child):
        self.childs.append(child)

    def writeHTML(self, out=None):
        if out is None:
            out = sys.stdout
        out.write('<')
        out.write(self.name)
        for key, val in self.attributes.items():
            # TODO: escaping
            out.write(' %s="%s"' %(key, val))
        out.write('>\n')
        for child in self.childs:
            child.writeHTML(out)
        out.write('</')
        out.write(self.name)
        out.write('>\n')

    def __enter__(self):
        return NestingElements(self)

    def __exit__(self, *args):
        pass


class TextNode:
    def __init__(self, text):
        self.text = text
    def writeHTML(self, out):
        out.write(self.text
                    .replace('&', '&amp;')
                    .replace('<', '&lt;')
                    .replace('>', '&gt;')
                    .replace('"', '&quot;'))

    def nest(self, nesting):
        return nest(nesting, self)


class NestingElements:
    def __init__(self, root_elem):
        self.stack = [root_elem]

    def get_root_elem(self):
        assert len(self.stack) >= 1
        return self.stack[0]

    def get_current_elem(self):
        assert len(self.stack) >= 1
        return self.stack[-1]

    def setAttribute(self, key, val):
        self.get_current_elem().setAttribute(key, val)

    def setAttributes(self, **kwargs):
        self.get_current_elem().setAttributes(**kwargs)

    def nest(self, elem):
        return nest(self, elem)

    def nestNewElem(self, *args, **kwargs):
        return nest(self, Element(*args, **kwargs))

    def addText(self, text):
        self.get_current_elem().appendChild(TextNode(text))


class nest:
    def __init__(self, nesting, elem):
        self.nesting = nesting
        self.elem = elem

        self.nesting.stack[-1].appendChild(self.elem)

    def __enter__(self):
        self.nesting.stack.append(self.elem)

    def __exit__(self, *args):
        top = self.nesting.stack.pop()
        assert top is self.elem



# Code:
# with Element('div') as ctx:
#     with ctx.nestNewElem('ul'):
#         with ctx.nestNewElem('li', style='border: 1px'):
#             ctx.addText('Item 1')
#         with ctx.nestNewElem('li'):
#             ctx.addText('Item 2')
# ctx.get_root_elem().writeHTML()
#
# Output:
# <div>
# <ul>
# <li>
# Item 1</li>
# <li>
# Item 2</li>
# </ul>
# </div>


# test code...

class Person:
    def __init__(self, firstname, lastname):
        self.firstname = firstname
        self.lastname = lastname


def comma_separated(elems):
    out = []
    for i, elem in enumerate(elems):
        if i:
            out.append(TextNode(', '))
        out.append(elem)
    return out


def formatPerson(person):
    return TextNode('%s %s' %(person.firstname, person.lastname))


persons = [
    Person('Joe', 'Doe'),
    Person('Jane', 'Dane')
]


with Element('p') as ctx:
    for elem in comma_separated(formatPerson(p) for p in persons):
        ctx.nest(elem)


ctx.get_root_elem().writeHTML()