Fediversity/website/presentation/dom.nix

367 lines
12 KiB
Nix

/**
A strongly typed module system implementation of the Document Object Model (DOM)
Based on the WHATWG's HTML Living Standard https://html.spec.whatwg.org (CC-BY 4.0)
Inspired by https://github.com/knupfer/type-of-html by @knupfer (BSD-3-Clause)
Similar work from the OCaml ecosystem: https://github.com/ocsigen/tyxml
*/
{ lib, ... }:
let
inherit (lib) mkOption types;
# https://html.spec.whatwg.org/multipage/dom.html#content-models
# https://html.spec.whatwg.org/multipage/dom.html#kinds-of-content
content-categories = [
"none" # https://html.spec.whatwg.org/multipage/dom.html#the-nothing-content-model
"text" # https://html.spec.whatwg.org/multipage/dom.html#text-content
"metadata" # https://html.spec.whatwg.org/multipage/dom.html#metadata-content
"flow" # https://html.spec.whatwg.org/multipage/dom.html#flow-content
"sectioning" # https://html.spec.whatwg.org/multipage/dom.html#sectioning-content
"heading" # https://html.spec.whatwg.org/multipage/dom.html#heading-content
"phrasing" # https://html.spec.whatwg.org/multipage/dom.html#phrasing-content
"embedded" # https://html.spec.whatwg.org/multipage/dom.html#embedded-content-2
"interactive" # https://html.spec.whatwg.org/multipage/dom.html#interactive-content
"palpable" # https://html.spec.whatwg.org/multipage/dom.html#palpable-content
"scripting" # https://html.spec.whatwg.org/multipage/dom.html#script-supporting-elements
];
# base type for all DOM elements
element = { name, config, ... }: {
# TODO: add fields for upstream documentation references
# TODO: programmatically generate documentation
options = with lib; {
attrs = mkAttrs { };
categories = mkOption {
type = types.listOfUnique (types.enum content-categories);
};
__toString = mkOption {
internal = true;
type = with types; functionTo str;
};
};
};
# options with types for all the defined DOM elements
element-types = lib.mapAttrs
(name: value: mkOption { type = types.submodule value; })
elements;
# attrset of categories, where values are module options with the type of the
# elements that belong to these categories
categories = with lib;
genAttrs
content-categories
(category:
(mapAttrs (_: e: mkOption { type = types.submodule e; })
# HACK: don't evaluate the submodule types, just grab the config directly
(filterAttrs (_: e: elem category (e { name = "dummy"; }).config.categories) elements))
);
global-attrs = lib.mapAttrs (name: value: mkOption value) {
class = {
type = with types; listOf nonEmptyStr;
default = [ ];
};
hidden = {
type = types.bool;
default = false;
};
id = {
type = with types; nullOr nonEmptyStr;
default = null;
};
lang = {
# TODO: https://www.rfc-editor.org/rfc/rfc5646.html
type = with types; nullOr str;
default = null;
};
style = {
# TODO: CSS type ;..)
type = with types; nullOr str;
default = null;
};
title = {
type = with types; nullOr lines;
default = null;
};
# TODO: more global attributes
# https://html.spec.whatwg.org/#global-attributes
# https://html.spec.whatwg.org/#attr-aria-*
# https://html.spec.whatwg.org/multipage/microdata.html#encoding-microdata
};
attrs = lib.mapAttrs (name: value: mkOption value) {
href = {
# TODO: https://url.spec.whatwg.org/#valid-url-string
# ;..O
type = types.str;
};
target = {
# https://html.spec.whatwg.org/multipage/document-sequences.html#valid-navigable-target-name-or-keyword
type =
let
is-valid-target = s:
let
inherit (lib) match;
has-lt = s: match ".*<.*" s != null;
has-tab-or-newline = s: match ".*[\t\n].*" s != null;
has-valid-start = s: match "^[^_].*$" s != null;
in
has-valid-start s && !(has-lt s && has-tab-or-newline s);
in
with types; either
(enum [ "_blank" "_self" "_parent" "_top" ])
(types.addCheck str is-valid-target)
;
};
};
mkAttrs = attrs: with lib;
mkOption {
type = types.submodule {
options = global-attrs // attrs;
};
default = { };
};
print-attrs = with lib; attrs:
# TODO: figure out how let attributes know how to print themselves without polluting the interface
let
result = trim (join " "
(mapAttrsToList
# TODO: this needs to be smarter for boolean attributes
# where the value must be written out explicitly.
# probably the attribute itself should have its own `__toString`.
(name: value:
if isBool value then
if value then name else ""
# TODO: some attributes must be explicitly empty
else optionalString (toString value != "") ''${name}="${toString value}"''
)
attrs)
);
in
optionalString (stringLength result > 0) " " + result
;
print-element = name: attrs: content:
with lib;
lib.squash ''
<${name}${print-attrs attrs}>
${lib.indent " " content}
</${name}>
'';
elements = rec {
document = { ... }: {
imports = [ element ];
options = {
inherit (element-types) html;
};
config.categories = [ ];
config.__toString = self: ''
<!DOCTYPE HTML >
${self.html}
'';
};
html = { name, ... }: {
imports = [ element ];
options = {
inherit (element-types) head body;
};
config.categories = [ ];
config.__toString = self: print-element name self.attrs ''
${self.head}
${self.body}
'';
};
head = { name, ... }: {
imports = [ element ];
options = with lib; {
# https://html.spec.whatwg.org/multipage/semantics.html#the-head-element:concept-element-content-model
# XXX: this doesn't implement the iframe srcdoc semantics
# as those have questionable value and would complicate things a bit.
# it should be possible though, by passing a flag via module arguments.
inherit (element-types) title;
base = mkOption {
type = with types; nullOr (submodule base);
default = null;
};
# https://html.spec.whatwg.org/multipage/semantics.html#attr-meta-charset
meta.charset = mkOption {
# TODO: create programmatically from https://encoding.spec.whatwg.org/encodings.json
type = types.enum [
"utf-8"
];
default = "utf-8";
};
# https://developer.mozilla.org/en-US/docs/Web/HTML/Viewport_meta_tag#viewport_width_and_screen_width
# this should not exist and no one should ever have to think about it
meta.viewport = mkOption {
type = types.submodule ({ ... }: {
# TODO: figure out how to render only non-default values
options = {
width = mkOption {
type = with types; either
(ints.between 1 10000)
(enum [ "device-width" ]);
default = "device-width"; # not default by standard
};
height = mkOption {
type = with types; either
(ints.between 1 10000)
(enum [ "device-height" ]);
default = "device-height"; # not default by standard (but seems to work if you don't set it)
};
initial-scale = mkOption {
type = types.numbers.between 0.1 10;
default = 1;
};
minimum-scale = mkOption {
type = types.numbers.between 0.1 10;
# TODO: render only as many digits as needed
default = 0.1;
};
maximum-scale = mkOption {
type = types.numbers.between 0.1 10;
default = 10;
};
user-scalable = mkOption {
type = types.bool;
default = true;
};
interactive-widget = mkOption {
type = types.enum [
"resizes-visual"
"resizes-content"
"overlays-content"
];
default = "resizes-visual";
};
};
});
default = { };
};
meta.authors = mkOption {
type = with types; listOf str;
default = [ ];
};
meta.description = mkOption {
type = with types; nullOr str;
default = null;
};
link.canonical = mkOption {
type = with types; nullOr str;
default = null;
};
# TODO: figure out `meta` elements
# https://html.spec.whatwg.org/multipage/semantics.html#the-meta-element:concept-element-attributes
# https://html.spec.whatwg.org/multipage/semantics.html#other-metadata-names
};
config.categories = [ ];
config.__toString = self:
with lib;
print-element name self.attrs ''
${self.title}
${with lib; optionalString (!isNull self.base) self.base}
<meta charset="${self.meta.charset}" />
${/* https://html.spec.whatwg.org/multipage/semantics.html#attr-meta-http-equiv-x-ua-compatible */
""}<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="${join ", " (mapAttrsToList
(name: value: "${name}=${toString value}") self.meta.viewport)
}" />
${join "\n" (map
(author: ''<meta name="author" content="${author}" />'')
self.meta.authors)
}
'';
};
title = { name, ... }: {
imports = [ element ];
options.text = mkOption {
type = types.str;
};
config.categories = [ "metadata" ];
config.__toString = self: "<${name}${print-attrs self.attrs}>${self.text}</${name}>";
};
base = { name, ... }: {
imports = [ element ];
# TODO: "A base element must have either an href attribute, a target attribute, or both."
attrs = mkAttrs { inherit (attrs) href target; };
config.categories = [ "metadata" ];
};
link = { name, ... }: {
imports = [ element ];
options = mkAttrs
{
# TODO: more attributes
# https://html.spec.whatwg.org/multipage/semantics.html#the-link-element:concept-element-attributes
inherit (attrs) href;
} // {
# XXX: there are variants of `rel` for `link`, `a`/`area`, and `form`
rel = mkOption {
# https://html.spec.whatwg.org/multipage/semantics.html#attr-link-rel
type = with types; listOfUnique str (enum
# TODO: work out link types in detail, there are lots of additional constraints
# https://html.spec.whatwg.org/multipage/links.html#linkTypes
[
"alternate"
"dns-prefetch"
"expect"
"help"
"icon"
"license"
"manifest"
"modulepreload"
"next"
"pingback"
"preconnect"
"prefetch"
"preload"
"prev"
"privacy-policy"
"search"
"stylesheet"
"terms-of-service"
]
);
};
};
# TODO: figure out how to make body-ok `link` elements
# https://html.spec.whatwg.org/multipage/semantics.html#allowed-in-the-body
config.categories = [ "metadata" ];
config.__toString = self: "<name${print-attrs self.attrs} />";
};
body = { name, ... }: {
imports = [ element ];
options = {
content = mkOption {
type = with types;
# HACK: bail out for now
# TODO: find a reasonable cut-off for where to place raw content
either str (listOf (attrTag categories.flow));
};
};
config.categories = [ ];
config.__toString = self: with lib;
if isList self.content then join "\n" (toString self.content) else self.content;
};
};
in
elements