depot/third_party/nixpkgs/pkgs/pkgs-lib/formats/java-properties/default.nix

91 lines
2.7 KiB
Nix
Raw Normal View History

{ lib, pkgs }:
{
javaProperties = { comment ? "Generated with Nix" }: {
type = lib.types.attrsOf lib.types.str;
generate = name: value:
pkgs.runCommandLocal name
{
# Requirements
# ============
#
# 1. Strings in Nix carry over to the same
# strings in Java => need proper escapes
# 2. Generate files quickly
# - A JVM would have to match the app's
# JVM to avoid build closure bloat
# - Even then, JVM startup would slow
# down config generation.
#
#
# Implementation
# ==============
#
# Escaping has two steps
#
# 1. jq
# Escape known separators, in order not
# to break up the keys and values.
# This handles typical whitespace correctly,
# but may produce garbage for other control
# characters.
#
# 2. iconv
# Escape >ascii code points to java escapes,
# as .properties files are supposed to be
# encoded in ISO 8859-1. It's an old format.
# UTF-8 behavior may exist in some apps and
# libraries, but we can't rely on this in
# general.
passAsFile = [ "value" ];
value = builtins.toJSON value;
nativeBuildInputs = [
pkgs.jq
pkgs.libiconvReal
];
jqCode =
let
main = ''
to_entries
| .[]
| "\(
.key
| ${commonEscapes}
| gsub(" "; "\\ ")
| gsub("="; "\\=")
) = \(
.value
| ${commonEscapes}
| gsub("^ "; "\\ ")
| gsub("\\n "; "\n\\ ")
)"
'';
# Most escapes are equal for both keys and values.
commonEscapes = ''
gsub("\\\\"; "\\\\")
| gsub("\\n"; "\\n\\\n")
| gsub("#"; "\\#")
| gsub("!"; "\\!")
| gsub("\\t"; "\\t")
| gsub("\r"; "\\r")
'';
in
main;
inputEncoding = "UTF-8";
inherit comment;
} ''
(
echo "$comment" | while read -r ln; do echo "# $ln"; done
echo
jq -r --arg hash '#' "$jqCode" "$valuePath" \
| iconv --from-code "$inputEncoding" --to-code JAVA \
) > "$out"
'';
};
}