Add support for Microdata

See: https://html.spec.whatwg.org/multipage/microdata.html

Author: toastal

lib/html_f.ml

@@ -502,6 +502,18 @@ struct
 
   let a_aria name = space_sep_attrib ("aria-" ^ name)
 
+  (* Microdata *)
+
+  let a_itemid = uri_attrib "itemid"
+
+  let a_itemprop = string_attrib "itemprop"
+
+  let a_itemref = space_sep_attrib "itemref"
+
+  let a_itemscope = constant_attrib "itemscope"
+
+  let a_itemtype = uris_attrib "itemtype"
+
   type 'a elt = Xml.elt
 
   type ('a, 'b) nullary = ?a: (('a attrib) list) -> unit -> 'b elt

lib/html_sigs.mli

@@ -694,6 +694,24 @@ module type T = sig
       @see <https://www.w3.org/TR/wai-aria-1.1/#state_prop_def> List of WAI-ARIA attributes
   *)
 
+  (** {3 Microdata support} *)
+
+  (** {{: https://html.spec.whatwg.org/multipage/microdata.html} Microdata} is
+      a specification written by the W3C, defining a set of additional HTML
+      attributes that can be applied to elements to annotate content with
+      specific machine-readable labels using schemas.
+  *)
+
+  val a_itemid : Xml.uri wrap -> [> | `ItemID ] attrib
+
+  val a_itemprop : string wrap -> [> | `ItemProp ] attrib
+
+  val a_itemref : idrefs wrap -> [> | `ItemRef ] attrib
+
+  val a_itemscope : unit -> [> | `ItemScope ] attrib
+
+  val a_itemtype : Xml.uri list wrap -> [> | `ItemType ] attrib
+
   (** {2:elements Elements} *)
 
   val txt : string wrap -> [> | txt] elt

lib/html_types.mli

@@ -380,8 +380,19 @@ type aria =
     | `Aria
   ]
 
+(** {2 Microdata} *)
+
+type microdata =
+  [
+    | `ItemID
+    | `ItemProp
+    | `ItemRef
+    | `ItemScope
+    | `ItemType
+  ]
+
 (** Common attributes *)
-type common = [ | core | i18n | events | aria ]
+type common = [ | core | i18n | events | aria | microdata ]
 
 (** {1 Categories of HTML elements}