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fediversity.eu/presentation/dom.nix

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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
*/
{ config, lib, ... }:
let
cfg = config;
inherit (lib) mkOption types;
inherit (types) submodule;
# 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 = { ... }: {
# TODO: add fields for upstream documentation references
# TODO: programmatically generate documentation
options = with lib; {
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 = 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 = submodule e; })
# HACK: don't evaluate the submodule types, just grab the config directly
# TODO: we may want to do this properly and loop `categories` through the top-level `config`
(filterAttrs (_: e: elem category (e { name = "dummy"; config = { }; }).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 "^[^_].*$" s != null;
in
has-valid-start s && !(has-lt s && has-tab-or-newline s);
in
with types; either
(enum [ "_blank" "_self" "_parent" "_top" ])
(types.addCheck str is-valid-target)
;
};
};
mkAttrs = attrs: with lib;
mkOption {
type = submodule {
options = global-attrs // attrs;
};
default = { };
};
print-attrs = with lib; attrs:
# TODO: figure out how let attributes know how to print themselves without polluting the interface
let
result = trim (join " "
(mapAttrsToList
# TODO: this needs to be smarter for boolean attributes
# where the value must be written out explicitly.
# probably the attribute itself should have its own `__toString`.
(name: value:
if isBool value then
if value then name else ""
# TODO: some attributes must be explicitly empty
else optionalString (toString value != "") ''${name}="${toString value}"''
)
attrs)
);
in
if attrs == null then throw "wat" else
optionalString (stringLength result > 0) " " + result
;
print-element = name: attrs: content:
with lib;
# TODO: be smarter about content to save some space and repetition at the call sites
squash (trim ''
<${name}${print-attrs attrs}>
${lib.indent " " content}
</${name}>
'');
toString-unwrap = e:
with lib;
if isAttrs e
then toString (head (attrValues e))
else if isList e
then toString (map toString-unwrap e)
else e;
elements = rec {
document = { ... }: {
imports = [ element ];
options = {
inherit (element-types) html;
attrs = mkAttrs { };
};
config.categories = [ ];
config.__toString = self: ''
<!DOCTYPE HTML >
${self.html}
'';
};
html = { name, ... }: {
imports = [ element ];
options = {
attrs = mkAttrs { };
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; {
attrs = mkAttrs { };
# 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 = 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.attrs = mkAttrs { };
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."
options = global-attrs // { inherit (attrs) href target; };
config.categories = [ "metadata" ];
config.__toString = self: "<base${print-attrs self}>";
};
link = { name, ... }: {
imports = [ element ];
options = global-attrs // {
# TODO: more attributes
# https://html.spec.whatwg.org/multipage/semantics.html#the-link-element:concept-element-attributes
inherit (attrs) href;
# XXX: there are variants of `rel` for `link`, `a`/`area`, and `form`
rel = mkOption {
# https://html.spec.whatwg.org/multipage/semantics.html#attr-link-rel
type = with types; listOfUnique str (enum
# TODO: work out link types in detail, there are lots of additional constraints
# https://html.spec.whatwg.org/multipage/links.html#linkTypes
[
"alternate"
"dns-prefetch"
"expect"
"help"
"icon"
"license"
"manifest"
"modulepreload"
"next"
"pingback"
"preconnect"
"prefetch"
"preload"
"prev"
"privacy-policy"
"search"
"stylesheet"
"terms-of-service"
]
);
};
};
# TODO: figure out how to make body-ok `link` elements
# https://html.spec.whatwg.org/multipage/semantics.html#allowed-in-the-body
config.categories = [ "metadata" ];
config.__toString = self: "<link${print-attrs self}>";
};
body = { config, name, ... }: {
imports = [ element ];
options = {
attrs = mkAttrs { };
content = mkOption {
type = with types;
let
# Type check that ensures spec-compliant section hierarchy
# https://html.spec.whatwg.org/multipage/sections.html#headings-and-outlines-2:concept-heading-7
with-section-constraints = baseType: baseType // {
merge = loc: defs:
with lib;
let
find-and-attach = def:
let
process-with-depth = depth: content:
map
(x:
if isAttrs x && x ? section
then x // {
section = x.section // {
heading-level = depth;
content = process-with-depth (depth + 1) (x.section.content or [ ]);
};
}
else x
)
content;
find-with-depth = depth: content:
let
sections = map (v: { inherit (def) file; value = v; depth = depth; })
(filter (x: isAttrs x && x ? section) content);
subsections = concatMap
(x:
if isAttrs x && x ? section && x.section ? content
then find-with-depth (depth + 1) x.section.content
else [ ])
content;
in
sections ++ subsections;
in
{
inherit def;
processed = process-with-depth 1 def.value;
validation = find-with-depth 1 def.value;
};
processed = map find-and-attach defs;
all-sections = flatten (map (p: p.validation) processed);
too-deep = filter (sec: sec.depth > 6) all-sections;
in
if too-deep != [ ] then
throw ''
The option `${lib.options.showOption loc}` has sections nested too deeply:
${concatMapStrings (sec: " - depth ${toString sec.depth} section in ${toString sec.file}\n") too-deep}
Section hierarchy must not be deeper than 6 levels.''
else baseType.merge loc (map (p: p.def // { value = p.processed; }) processed);
};
in
# HACK: bail out for now
with-section-constraints
# TODO: find a reasonable cut-off for where to place raw content
(listOf (either str (attrTag categories.flow)));
default = [ ];
};
};
config.categories = [ ];
config.__toString = self: with lib;
print-element name self.attrs (join "\n" (map toString-unwrap self.content));
};
section = { config, name, ... }: {
imports = [ element ];
options = {
# setting to an attribute set will wrap the section in `<section>`
attrs = mkOption {
type = with types; nullOr (submodule { options = global-attrs; });
default = null;
};
heading = mkOption {
# XXX: while there are no explicit rules on whether sections should contain headers,
# sections should have content that would be listed in an outline.
#
# https://html.spec.whatwg.org/multipage/sections.html#use-div-for-wrappers
#
# such an outline is rather meaningless without headings for navigation,
# which is why we enforce headings in sections.
# arguably, and this is encoded here, a section *is defined* by its heading.
type = with types; submodule ({ config, ... }: {
imports = [ element ];
options = {
attrs = mkAttrs { };
# setting to an attribute set will wrap the section in `<hgroup>`
hgroup.attrs = mkOption {
type = with types; nullOr (submodule { options = global-attrs; });
default = with lib; mkIf (!isNull config.before || !isNull config.after) { };
};
# https://html.spec.whatwg.org/multipage/sections.html#the-hgroup-element
before = mkOption {
type = with types; listOf (attrTag ({ inherit (element-types) p; } // categories.scripting));
default = [ ];
};
content = mkOption {
# https://html.spec.whatwg.org/multipage/sections.html#the-h1,-h2,-h3,-h4,-h5,-and-h6-elements
type = with types; either str (listOf (attrTag categories.phrasing));
};
after = mkOption {
type = with types;
listOf (attrTag ({ inherit (element-types) p; } // categories.scripting));
default = [ ];
};
};
});
};
# https://html.spec.whatwg.org/multipage/sections.html#headings-and-outlines
content = mkOption {
type = with types; listOf (either str (attrTag categories.flow));
default = [ ];
};
};
options.heading-level = mkOption {
# XXX: this will proudly fail if the invariant is violated,
# but the error message will be inscrutable
type = with types; ints.between 1 6;
internal = true;
};
config = {
categories = [ "flow" "sectioning" "palpable" ];
__toString = self: with lib;
let
n = toString config.heading-level;
heading = ''<h${n}${print-attrs self.heading.attrs}>${self.heading.content}</h${n}>'';
hgroup = with lib; print-element "hgroup" self.heading.hgroup.attrs (squash ''
${optionalString (!isNull self.heading.before) (toString-unwrap self.heading.before)}
${heading}
${optionalString (!isNull self.heading.after) (toString-unwrap self.heading.after)}
'');
content = if isNull self.heading.hgroup.attrs then heading else hgroup
+ join "\n" (map toString-unwrap self.content);
in
if !isNull self.attrs
then print-element name self.attrs content
else content;
};
};
p = { name, ... }: {
imports = [ element ];
options = {
attrs = mkAttrs { };
content = mkOption {
type = with types; either str (listOf (attrTag categories.phrasing));
};
};
config.categories = [ "flow" "palpable" ];
config.__toString = self: print-element name self.attrs (toString self.content);
};
dl = { config, name, ... }: {
imports = [ element ];
options = {
attrs = mkAttrs { };
content = mkOption {
type = with types; listOf (submodule ({ ... }: {
options = {
# TODO: wrap in `<div>` if set
div.attrs = mkOption {
type = with types; nullOr (submodule { options = global-attrs; });
default = null;
};
before = mkOption {
type = with types; listOf (attrTag categories.scripting);
default = [ ];
};
terms = mkOption {
type = with types; nonEmptyListOf (submodule dt);
};
between = mkOption {
type = with types; listOf (attrTag categories.scripting);
default = [ ];
};
descriptions = mkOption {
type = with types; nonEmptyListOf (submodule dd);
};
after = mkOption {
type = with types; listOf (attrTag categories.scripting);
default = [ ];
};
};
}));
};
};
config.categories = [ "flow" ] ++ [ "palpable" ];
config.__toString = self:
with lib;
let
content = map
(entry:
let
list = squash ''
${join "\n" entry.before}
${join "\n" entry.terms}
${join "\n" entry.between}
${join "\n" entry.descriptions}
${join "\n" entry.after}
'';
in
if !isNull entry.div.attrs
then print-element "div" entry.div.attrs list
else list
)
self.content;
in
print-element name self.attrs (join "\n" content);
};
dt = { config, ... }: {
imports = [ element ];
options = {
attrs = mkAttrs { };
dt = mkOption {
type = with types; either str (submodule (attrTag (
# TODO: test
with lib; removeAttrs
(filterAttrs
(name: value: ! any (c: elem c [ "sectioning" "heading" ]) value.categories)
categories.flow
)
[ "header" "footer" ]
)));
};
};
config.categories = [ ];
config.__toString = self: print-element "dt" self.attrs self.dt;
};
dd = { config, ... }: {
imports = [ element ];
options = {
attrs = mkAttrs { };
dd = mkOption {
type = with types; either str (submodule (attrTag categories.flow));
};
};
config.categories = [ ];
config.__toString = self: print-element "dd" self.attrs self.dd;
};
};
in
{
imports = [ element ];
options = {
inherit (element-types) html;
};
config.categories = [ ];
config.__toString = self: ''
<!DOCTYPE HTML >
${self.html}
'';
}