Proper MathML and SVG support

[Tamschi]

Describe the bug

Similarly to

lignin-html/src/lib.rs

Lines 516 to 588 in 471bb15

	#[derive(Logos, PartialEq)]
	enum ElementKind {
	/// See <https://html.spec.whatwg.org/multipage/syntax.html#void-elements>.
	#[regex("(?i)AREA")]
	#[regex("(?i)BASE")]
	#[regex("(?i)BR")]
	#[regex("(?i)COL")]
	#[regex("(?i)EMBED")]
	#[regex("(?i)HR")]
	#[regex("(?i)IMG")]
	#[regex("(?i)INPUT")]
	#[regex("(?i)LINK")]
	#[regex("(?i)META")]
	#[regex("(?i)PARAM")]
	#[regex("(?i)SOURCE")]
	#[regex("(?i)TRACK")]
	#[regex("(?i)WBR")]
	Void,
	/// See <https://html.spec.whatwg.org/multipage/syntax.html#the-template-element-2>.
	#[regex("(?i)TEMPLATE")]
	Template,
	/// See <https://html.spec.whatwg.org/multipage/syntax.html#raw-text-elements>.
	#[regex("(?i)SCRIPT")]
	#[regex("(?i)STYLE")]
	RawText,
	/// See <https://html.spec.whatwg.org/multipage/syntax.html#escapable-raw-text-elements>.
	/// See <https://html.spec.whatwg.org/multipage/syntax.html#element-restrictions> for special handling.
	#[regex("(?i)TEXTAREA")]
	EscapableRawTextTextarea,
	/// See <https://html.spec.whatwg.org/multipage/syntax.html#escapable-raw-text-elements>.
	#[regex("(?i)TITLE")]
	EscapableRawText,
	/// See <https://html.spec.whatwg.org/multipage/syntax.html#foreign-elements>.
	//TODO
	ForeignSelfClosing,
	/// See <https://html.spec.whatwg.org/multipage/syntax.html#foreign-elements>.
	//TODO
	ForeignNotSelfClosing,
	/// See <https://html.spec.whatwg.org/multipage/syntax.html#normal-elements>.
	/// See <https://html.spec.whatwg.org/multipage/syntax.html#element-restrictions> for special handling.
	NormalPre,
	/// See <https://html.spec.whatwg.org/multipage/syntax.html#normal-elements>,
	/// <https://html.spec.whatwg.org/multipage/syntax.html#syntax-tag-name>
	/// => <https://infra.spec.whatwg.org/#ascii-alphanumeric>
	/// => <https://infra.spec.whatwg.org/#ascii-digit> | <https://infra.spec.whatwg.org/#ascii-alpha>
	/// => <https://infra.spec.whatwg.org/#ascii-digit> | <https://infra.spec.whatwg.org/#ascii-upper-alpha> | <https://infra.spec.whatwg.org/#ascii-lower-alpha>.
	#[regex("[0-9A-Za-z]+")]
	Normal,
	/// See <https://html.spec.whatwg.org/multipage/custom-elements.html#valid-custom-element-name>,
	/// except that this variant occurs as continuation and may never occur first and anything [`Normal`](`ElementKind::Normal`) is exempted here.
	// I'm not sure if splitting it up like this is the fastest options, but it's the most readable.
	#[token(".")]
	#[token("_")]
	#[token("\u{00B7}")]
	#[regex("[\u{C0}-\u{D6}]")]
	#[regex("[\u{D8}-\u{F6}]")]
	#[regex("[\u{F8}-\u{37D}]")]
	#[regex("[\u{37F}-\u{1FFF}]")]
	#[regex("[\u{200C}-\u{200D}]")]
	#[regex("[\u{203F}-\u{2040}]")]
	#[regex("[\u{2070}-\u{218F}]")]
	#[regex("[\u{2C00}-\u{2FEF}]")]
	#[regex("[\u{3001}-\u{D7FF}]")]
	#[regex("[\u{F900}-\u{FDCF}]")]
	#[regex("[\u{FDF0}-\u{FFFD}]")]
	#[regex("[\u{10000}-\u{EFFFF}]")]
	PotentialCustomElementNameCharacter,
	/// To flag custom elements as valid, see above.
	#[token("-")]
	Dash,
	#[error]
	Invalid,
	}

, which categorises HTML element, MathML and SVG elements also have to be sorted and validated based on context.

There also needs to be a way to render documents and fragments that are not HTML, so a way to specify an initial context.

To Reproduce

Not specified.

Expected behavior

Correct handling of SVG and MathML according to their current specifications.

Screenshots

Not applicable.

Additional context

A breaking API change is explicitly okay here.