tvl-depot/users/sterni/nix/html/default.nix
Vincent Ambo aa122cbae7 style: format entire depot with nixpkgs-fmt
This CL can be used to compare the style of nixpkgs-fmt against other
formatters (nixpkgs, alejandra).

Change-Id: I87c6abff6bcb546b02ead15ad0405f81e01b6d9e
Reviewed-on: https://cl.tvl.fyi/c/depot/+/4397
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>
Reviewed-by: lukegb <lukegb@tvl.fyi>
Reviewed-by: wpcarro <wpcarro@gmail.com>
Reviewed-by: Profpatsch <mail@profpatsch.de>
Reviewed-by: kanepyork <rikingcoding@gmail.com>
Reviewed-by: tazjin <tazjin@tvl.su>
Reviewed-by: cynthia <cynthia@tvl.fyi>
Reviewed-by: edef <edef@edef.eu>
Reviewed-by: eta <tvl@eta.st>
Reviewed-by: grfn <grfn@gws.fyi>
2022-01-31 16:11:53 +00:00

122 lines
3.2 KiB
Nix

# Copyright © 2021 sterni
# SPDX-License-Identifier: MIT
#
# This file provides a cursed HTML DSL for nix which works by overloading
# the NIX_PATH lookup operation via angle bracket operations, e. g. `<nixpkgs>`.
{ ... }:
let
/* Escape everything we have to escape in an HTML document if either
in a normal context or an attribute string (`<>&"'`).
A shorthand for this function called `esc` is also provided.
Type: string -> string
Example:
escapeMinimal "<hello>"
=> "&lt;hello&gt;"
*/
escapeMinimal = builtins.replaceStrings
[ "<" ">" "&" "\"" "'" ]
[ "&lt;" "&gt;" "&amp;" "&quot;" "&#039;" ];
/* Return a string with a correctly rendered tag of the given name,
with the given attributes which are automatically escaped.
If the content argument is `null`, the tag will have no children nor a
closing element. If the content argument is a string it is used as the
content as is (unescaped). If the content argument is a list, its
elements are concatenated.
`renderTag` is only an internal function which is reexposed as `__findFile`
to allow for much neater syntax than calling `renderTag` everywhere:
```nix
{ depot, ... }:
let
inherit (depot.users.sterni.nix.html) __findFile esc;
in
<html> {} [
(<head> {} (<title> {} (esc "hello world")))
(<body> {} [
(<h1> {} (esc "hello world"))
(<p> {} (esc "foo bar"))
])
]
```
As you can see, the need to call a function disappears, instead the
`NIX_PATH` lookup operation via `<foo>` is overloaded, so it becomes
`renderTag "foo"` automatically.
Since the content argument may contain the result of other `renderTag`
calls, we can't escape it automatically. Instead this must be done manually
using `esc`.
Type: string -> attrs<string> -> (list<string> | string | null) -> string
Example:
<link> {
rel = "stylesheet";
href = "/css/main.css";
type = "text/css";
} null
renderTag "link" {
rel = "stylesheet";
href = "/css/main.css";
type = "text/css";
} null
=> "<link href=\"/css/main.css\" rel=\"stylesheet\" type=\"text/css\"/>"
<p> {} [
"foo "
(<strong> {} "bar")
]
renderTag "p" {} "foo <strong>bar</strong>"
=> "<p>foo <strong>bar</strong></p>"
*/
renderTag = tag: attrs: content:
let
attrs' = builtins.concatStringsSep "" (
builtins.map
(n:
" ${escapeMinimal n}=\"${escapeMinimal (toString attrs.${n})}\""
)
(builtins.attrNames attrs)
);
content' =
if builtins.isList content
then builtins.concatStringsSep "" content
else content;
in
if content == null
then "<${tag}${attrs'}/>"
else "<${tag}${attrs'}>${content'}</${tag}>";
/* Prepend "<!DOCTYPE html>" to a string.
Type: string -> string
Example:
withDoctype (<body> {} (esc "hello"))
=> "<!DOCTYPE html><body>hello</body>"
*/
withDoctype = doc: "<!DOCTYPE html>" + doc;
in
{
inherit escapeMinimal renderTag withDoctype;
__findFile = _: renderTag;
esc = escapeMinimal;
}