# `Statifier.Validator.Checks.Content`
[🔗](https://github.com/riddler/statifier-ex/blob/v2.0.0/lib/statifier/validator/checks/content.ex#L1)

Spec 5.6: a `<content>` element must not specify both an `expr`
attribute and inline content, whether that content is text or markup
(ADR-0041). Reports `{:content_expr_and_text, expr}` at the `<content>`
element's own `location` - same reason, same shape, regardless of which
form the content takes.

`lib/statifier/document/content.ex` makes `expr`, `text`, and `markup` all
nilable and all representable at once precisely so this check can report
the shape rather than lowering refusing to build it - the same division of
labour check 8 has with `<donedata>`.

**Whitespace-only text is not text.** `Statifier.Parser.DOM.text/1`
concatenates `<content>`'s direct text children verbatim and untrimmed, so
a pretty-printed `<content expr="x">\n  </content>` carries a `text` of
`"\n  "`. That is source formatting, not a payload, and firing on it
would reject documents the spec allows. `markup`, when present, is never
blank - it is nil unless `<content>` has at least one element child - so
no equivalent whitespace carve-out applies to it.

Two places today hold a `%Statifier.Document.Content{}`: a `<final>`'s
`<donedata><content>` (`Statifier.Document.Donedata`) and any state's
`<invoke><content>` (`Statifier.Document.Invoke`), so this check walks
both. `<send>` has a `<content>` child too
(`lib/statifier/document/send.ex:54`, `lib/statifier/compiler.ex:1113`),
but it is executable content living inside a block's `content` list
(`lib/statifier/document/send.ex:27-30`), not a state field this walk
already reaches - reaching it needs a block walk this check does not have.
That gap predates this change and stays open here; the rule itself is
unchanged regardless, since spec 5.6 states it on `<content>` rather than
on whichever parent holds it.

The `Content` alias below is `Statifier.Document.Content`, the document
node - not this module.

# `check`

```elixir
@spec check(
  document :: Statifier.Document.t(),
  context :: Statifier.Validator.Context.t()
) :: [
  Statifier.Validator.Error.t()
]
```

Walks every `<final>`'s `<donedata><content>` and every state's
`<invoke><content>` in the document and returns a `:content_expr_and_text`
error for each one that carries both an `expr` attribute and non-blank
inline text. Returns `[]` when no `<content>` element mixes the two forms.

---

*Consult [api-reference.md](api-reference.md) for complete listing*