emacs.nix

let
  pkgs = import <nixpkgs> {};
  inherit (pkgs) emacsPackagesNg docbook5 writeText;

  schemas = writeText "schemas.xml" ''
    <locatingRules xmlns="http://thaiopensource.com/ns/locating-rules/1.0">
      <documentElement localName="section" typeId="DocBook"/>
      <documentElement localName="chapter" typeId="DocBook"/>
      <documentElement localName="article" typeId="DocBook"/>
      <documentElement localName="book" typeId="DocBook"/>
      <typeId id="DocBook" uri="${docbook5}/xml/rng/docbook/docbookxi.rnc" />
    </locatingRules>
  '';

in emacsPackagesNg.emacsWithPackages (epkgs: [
  (emacsPackagesNg.trivialBuild {
    pname = "nix-docbook-mode";
    version = "1970-01-01";
    src = writeText "default.el" ''
      (eval-after-load 'rng-loc
        '(add-to-list 'rng-schema-locating-files "${schemas}"))
    '';
  })
])