9ed439bfbd
Couldn't sleep, so I made a surprisingly neat way to render HTML
documents in Nix using our favorite feature __findFile:
let
inherit (depot.users.sterni.nix.html) __findFile esc;
in
<html> {} [
(<head> {} [
(<meta> { charset = "utf-8"; } null)
(<title> {} (esc "hello"))
])
(<body> {} [
(<h1> {} (esc "hello world"))
])
]
=> "<html><head><meta charset=\"utf-8\"/><title>hello</title></head><body><h1>hello world</h1></body></html>"
Change-Id: Id36808a56ae3da3b5263c06f29342fc22d105c21
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3410
Tested-by: BuildkiteCI
Reviewed-by: tazjin <mail@tazj.in>
119 lines
3.2 KiB
Nix
119 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>"
|
|
=> "<hello>"
|
|
*/
|
|
escapeMinimal = builtins.replaceStrings
|
|
[ "<" ">" "&" "\"" "'" ]
|
|
[ "<" ">" "&" """ "'" ];
|
|
|
|
/* 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;
|
|
}
|