allow parsing attributes without values

src/Hox/SelectorParser.fs

@@ -36,15 +36,24 @@ let private pClass: Parser<SelectorValue, unit> =
   >>= fun cls -> preturn(Class cls)
 
 let private pAttribute: Parser<SelectorValue, unit> =
-  let name = manyChars(letter <|> digit <|> pchar '-')
+  let name =
+    letter .>>. manyChars(letter <|> digit <|> pchar '-')
+    >>= fun (initial, rest) -> preturn $"{initial}{rest}"
+
   let eq = pchar '='
   let value = manySatisfy(fun ch -> ch <> ']')
 
-  pchar '[' >>. name .>> eq .>>. value
+  pchar '[' >>. name .>> opt eq .>>. opt value
   .>> unicodeSpaces
   .>> pchar ']'
   .>> unicodeSpaces
-  >>= fun (name, value) -> preturn(Attribute { name = name; value = value })
+  >>= fun (name, value) ->
+    preturn(
+      Attribute {
+        name = name
+        value = defaultArg value System.String.Empty
+      }
+    )
 
 let private pSelector: Parser<Element, unit> =
   unicodeSpaces >>. tagName .>> unicodeSpaces

tests/Hox.Tests/Parser.fs

@@ -249,3 +249,19 @@ let ``Attributes can have arbitrary content within '[' ']'``() =
             """~!@#$%^&*()_+QWERTYUIOP{}|ASDFGHJKL:"ZXCVBNM<>?1234567890-=qwertyuiop\asdfghjkl;'zxcvbnm,./"""),
     attributes
   )
+
+[<Fact>]
+let ``Can parse selector without value``() =
+  let expected = {
+    tag = "div"
+    attributes = LinkedList [ Attribute { name = "data-foo"; value = "" } ]
+    children = LinkedList []
+  }
+
+  let actual = Parsers.selector "div[data-foo]"
+  Assert.Equal(expected.tag, actual.tag)
+
+  match actual.attributes.First.Value with
+  | Attribute { name = "data-foo"; value = "" } -> ()
+  | _ ->
+    Assert.Fail("Expected an attribute with the name 'data-foo' and value ''")