diff options
| author | sterni <sternenseemann@systemli.org> | 2021-08-25T00·45+0200 |
|---|---|---|
| committer | sterni <sternenseemann@systemli.org> | 2021-08-26T15·34+0000 |
| commit | 9ed439bfbddee7915c4011f8a6ba7562b3375ac8 (patch) | |
| tree | 6343c44bb40676d684aceec57bab7b26388f7914 /users/sterni/nix/html/default.nix | |
| parent | 17d78867bbef8a3df1271137a2db18b3584cdc39 (diff) | |
feat(users/sterni/nix): cursed nix html DSL r/2784
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>
Diffstat (limited to 'users/sterni/nix/html/default.nix')
| -rw-r--r-- | users/sterni/nix/html/default.nix | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/users/sterni/nix/html/default.nix b/users/sterni/nix/html/default.nix new file mode 100644 index 000000000000..2498d832aadf --- /dev/null +++ b/users/sterni/nix/html/default.nix @@ -0,0 +1,119 @@ +# 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; +} |