3 HTML Syntax Objects

0.45+9.1

Rhombus

3 HTML Syntax Objects🔗ℹ

An HTML syntax object encodes an HTML document as a human-readable shrubbery form represented by a Rhombus syntax object. The html.from_syntax function converts an HTML syntax object to a html.Document, and html.to_syntax goes in the other direction. HTML syntax objects can be produced from HTML directly with html.read_syntax, html.string_to_syntax, and html.bytes_to_syntax, and they can converted to XML directly with html.write_syntax, html.syntax_to_string, and html.syntax_to_bytes. HTML syntax objects are similar to XML syntax objects as supported by the xml library.

The html.syntax form is essentially an alias of '' (see #%quotes), but it checks that the result syntax object conforms to HTML syntax object constraints.

def my_doc:
  html.syntax:
    head:
      title:
        "Greeting"
    body:
      h1:
        "Hello, World!"
      div:
        ~class: "main"
        "Today is sometime after "
        $(to_string(date.Date.from_seconds(0, ~local: #false)))

> html.write_syntax(my_doc)
<head><title>Greeting</title></head
><body><h1>Hello, World!</h1
><div class="main">Today is sometime after 1970-01-01</div
></body
>

expression

html.syntax:

...

id:

...

...

keyword: value_string

content

element

string

content ...

(content, ...)

[content, ...]

other

Returns the same syntax object as 'content; ...', but with the constraint that the result conforms to the grammar of an HTML syntax object. Although not shown above in the grammar for element, an escape using $ can appear anywhere in the block after html.syntax, and it works the same as in 'content; ...' (see #%quotes). Conformance is checked on the result after substituting escapes.

An element corresponds to an html.Element. It always starts with an identifier, and it is followed by a block (possibly empty) for the element’s attributes and content. The attributes must appear first, where each attribute starts with a keyword and is followed by a block for the attribute’s value, together corresponding to html.Attribute.

Each content can be one the following:

element: Corresponds to a nested html.Element.
string: Used directly as string content.
content ..., (content, ...), or [content, ...]: Content can be spliced from multiple content forms with a group, within parentheses, or within square brackets. Note that this splicing accommodates @ forms, as in the example below.
other: Any value that is satisfies html.Content is allowed. For example, a html.Comment value can appear here. Constructing such objects will require a $ escape with Syntax.inject.

> html.write_syntax(
    html.syntax:
      a: "hello <name>"
  )
<a>hello <name></a>
> html.write_syntax(
    html.syntax:
      a: ("b", "c", [["d"], "e"])
  )
<a>bcde</a>
> html.write_syntax(
    html.syntax:
      a: @{say this: "hello <name>"}
  )
<a>say this: "hello <name>"</a>
> html.write_syntax(
    html.syntax:
      a: $(Syntax.inject(html.Comment(~data: "123")))
  )
<a></a>