kageurufu/dom.py

## dom.py
import html

from markupsafe import Markup


class InvalidVoidTag(Exception):
    pass


VOID_TAGS = {
    "area",
    "base",
    "br",
    "col",
    "embed",
    "hr",
    "img",
    "input",
    "link",
    "meta",
    "param",
    "source",
    "track",
    "wbr",
}


def dom(tag: str, *children) -> str:
    """
    >>> dom('html')
    Markup('<html></html>')

    >>> dom('html', ('head', ), ('body', ))
    Markup('<html><head></head><body></body></html>')

    >>> dom("script", 'var value = "this is a test script, we should not strip anything but </script>"')
    Markup('<script>var value = "this is a test script, we should not strip anything but <\\\\/script>"</script>')

    >>> dom("style", ".test-class { background-color: gray; }")
    Markup('<style>.test-class { background-color: gray; }</style>')

    >>> dom("body", {"class": "test-class"})
    Markup('<body class="test-class"></body>')

    >>> dom("p", "and we even prevent basic <script>xss</script> and <b>tag injection")
    Markup('<p>and we even prevent basic &lt;script&gt;xss&lt;/script&gt; and &lt;b&gt;tag injection</p>')

    >>> dom('img', ('test',))
    Traceback (most recent call last):
      ...
    e.InvalidVoidTag: Void tag img may not have child elements...

    >>> dom( \
            "html", \
            ( \
                "head", \
                ("script", 'var value = "this is a test script, we should not strip anything but </script>"'), \
                ("style", ".test-class { background-color: gray; }"), \
            ), \
            ( \
                "body", \
                {"class": "test-class"}, \
                ( \
                    "div", \
                    ("h1", "Heading"), \
                    ( \
                        "article", \
                        ("p", "some content goes here!"), \
                        ("p", "some more content here"), \
                        ( \
                            "p", \
                            "and we even prevent basic <script>xss</script> and <b>tag injection", \
                            ("img", {"src": "https://avatars1.githubusercontent.com/u/259751"}), \
                        ), \
                    ), \
                ), \
            ), \
        )
    Markup('<html><head><script>var value = "this is a test script, we should not strip anything but <\\\\/script>"</script><style>.test-class { background-color: gray; }</style></head><body class="test-class"><div><h1>Heading</h1><article><p>some content goes here!</p><p>some more content here</p><p>and we even prevent basic &lt;script&gt;xss&lt;/script&gt; and &lt;b&gt;tag injection<img src="https://avatars1.githubusercontent.com/u/259751"></p></article></div></body></html>')
    """
    html_attrs = []

    if children and isinstance(children[0], dict):
        attrs, *children = children

        for k, v in attrs.items():
            if v in (True, False):
                html_attrs.append(f" {k}")
            else:
                html_attrs.append(f' {k}="{html.escape(v)}"')

    open_tag = Markup(f"<{tag}{''.join(html_attrs)}>")
    end_tag = Markup(f"</{tag}>")

    if tag in VOID_TAGS:
        if children:
            raise InvalidVoidTag(
                f"Void tag {tag} may not have child elements\n"
                f"See https://www.w3.org/TR/html5/syntax.html#start-tags for more details"
            )

        return open_tag

    return (
        open_tag
        + Markup("").join(
            dom(*c)  # render sub-tuples to dom
            if isinstance(c, tuple)
            else Markup(c.replace("</script>", "<\\/script>"))  # don't escape script or style bodies
            if tag == "script"
            else Markup(c.replace("</style>", "<\\/style>"))
            if tag == "style"
            else c  # Use plaintext to make markupsafe escape it
            for c in children
        )
        + end_tag
    )
	import html

	from markupsafe import Markup


	class InvalidVoidTag(Exception):
	pass


	VOID_TAGS = {
	"area",
	"base",
	"br",
	"col",
	"embed",
	"hr",
	"img",
	"input",
	"link",
	"meta",
	"param",
	"source",
	"track",
	"wbr",
	}


	def dom(tag: str, *children) -> str:
	"""
	>>> dom('html')
	Markup('<html></html>')

	>>> dom('html', ('head', ), ('body', ))
	Markup('<html><head></head><body></body></html>')

	>>> dom("script", 'var value = "this is a test script, we should not strip anything but </script>"')
	Markup('<script>var value = "this is a test script, we should not strip anything but <\\\\/script>"</script>')

	>>> dom("style", ".test-class { background-color: gray; }")
	Markup('<style>.test-class { background-color: gray; }</style>')

	>>> dom("body", {"class": "test-class"})
	Markup('<body class="test-class"></body>')

	>>> dom("p", "and we even prevent basic <script>xss</script> and <b>tag injection")
	Markup('<p>and we even prevent basic <script>xss</script> and <b>tag injection</p>')

	>>> dom('img', ('test',))
	Traceback (most recent call last):
	...
	e.InvalidVoidTag: Void tag img may not have child elements...

	>>> dom( \
	"html", \
	( \
	"head", \
	("script", 'var value = "this is a test script, we should not strip anything but </script>"'), \
	("style", ".test-class { background-color: gray; }"), \
	), \
	( \
	"body", \
	{"class": "test-class"}, \
	( \
	"div", \
	("h1", "Heading"), \
	( \
	"article", \
	("p", "some content goes here!"), \
	("p", "some more content here"), \
	( \
	"p", \
	"and we even prevent basic <script>xss</script> and <b>tag injection", \
	("img", {"src": "https://avatars1.githubusercontent.com/u/259751"}), \
	), \
	), \
	), \
	), \
	)
	Markup('<html><head><script>var value = "this is a test script, we should not strip anything but <\\\\/script>"</script><style>.test-class { background-color: gray; }</style></head><body class="test-class"><div><h1>Heading</h1><article><p>some content goes here!</p><p>some more content here</p><p>and we even prevent basic <script>xss</script> and <b>tag injection<img src="https://avatars1.githubusercontent.com/u/259751"></p></article></div></body></html>')
	"""
	html_attrs = []

	if children and isinstance(children[0], dict):
	attrs, *children = children

	for k, v in attrs.items():
	if v in (True, False):
	html_attrs.append(f" {k}")
	else:
	html_attrs.append(f' {k}="{html.escape(v)}"')

	open_tag = Markup(f"<{tag}{''.join(html_attrs)}>")
	end_tag = Markup(f"</{tag}>")

	if tag in VOID_TAGS:
	if children:
	raise InvalidVoidTag(
	f"Void tag {tag} may not have child elements\n"
	f"See https://www.w3.org/TR/html5/syntax.html#start-tags for more details"
	)

	return open_tag

	return (
	open_tag
	+ Markup("").join(
	dom(*c) # render sub-tuples to dom
	if isinstance(c, tuple)
	else Markup(c.replace("</script>", "<\\/script>")) # don't escape script or style bodies
	if tag == "script"
	else Markup(c.replace("</style>", "<\\/style>"))
	if tag == "style"
	else c # Use plaintext to make markupsafe escape it
	for c in children
	)
	+ end_tag
	)