add finders for finding new package versions

src/default.nix

@@ -41,10 +41,12 @@ let
     inherit (config) allowBuiltinFetchers;
   };
 
+  # updater modules to find newest package versions
+  finders = callPackageDream ./finders {};
+
   # the translator modules and utils for all subsystems
   translators = callPackageDream ./translators {};
 
-
   # the location of the dream2nix framework for self references (update scripts, etc.)
   location = ./.;
 
@@ -52,7 +54,7 @@ in
 
 rec {
 
-  inherit apps builders fetchers location translators;
+  inherit apps builders fetchers finders location translators;
 
   # automatically find a suitable builder for a given generic lock
   findBuilder = dreamLock:

src/finders/default.nix

@@ -0,0 +1,64 @@
+{
+  curl,
+  gnugrep,
+  jq,
+  lib,
+  python3,
+  writeText,
+
+  # dream2nix inputs
+  utils,
+  ...
+}:
+
+{
+  githubNewestReleaseTag =
+    {
+      owner,
+      repo,
+      ...
+    }:
+    utils.writePureShellScript [ curl jq ] ''
+      curl -s "https://api.github.com/repos/${owner}/${repo}/releases?per_page=1" | jq -r '.[0].tag_name'
+    '';
+  
+  pypiNewestReleaseVersion =
+    {
+      pname,
+      ...
+    }:
+    utils.writePureShellScript [ curl jq ] ''
+      curl -s https://pypi.org/pypi/${pname}/json | jq -r '.info.version'
+    '';
+
+  npmNewestReleaseVersion =
+    {
+      pname,
+      ...
+    }:
+    # api docs: https://github.com/npm/registry/blob/master/docs/REGISTRY-API.md#get
+    utils.writePureShellScript [ curl jq ] ''
+      curl -s https://registry.npmjs.com/${pname} | jq -r '."dist-tags".latest'
+    '';
+
+  urlRegexPython = 
+    # Don't forget to use double quoted strings
+    #   or double escape ('\\' instead of '\').
+    # Expects named group 'rev' to be defined.
+    # Example regex:
+    #   ''[Pp]ython-(?P<ver>[\d\.]+)\.tgz''
+    {
+      url,
+      regex,
+      ...
+    }:
+    let
+      reFile = writeText "regex" regex;
+    in
+      utils.writePureShellScript [ curl gnugrep python3 ] ''
+        curl -s ${url} \
+        | python3 -c \
+          'import re, sys; print(re.search(open("${reFile}").read(), sys.stdin.read()).group("ver"), end="")'
+      '';
+  
+}

src/utils.nix

@@ -1,7 +1,9 @@
 {
+  coreutils,
   lib,
   nix,
   runCommand,
+  writeScriptBin,
   ...
 }:
 let
@@ -60,4 +62,15 @@ rec {
     in
       b.readFile hashFile;
 
+  writePureShellScript = availablePrograms: script: writeScriptBin "run" ''
+    export PATH="${lib.makeBinPath availablePrograms}"
+    tmpdir=$(${coreutils}/bin/mktemp -d)
+    cd $tmpdir
+
+    ${script}
+
+    cd
+    ${coreutils}/bin/rm -rf $tmpdir
+  '';
+
 }