nixpkgs/elvish: make direlv search up

.config/nixpkgs/elvish/lib/direlv.elv

@@ -18,12 +18,17 @@ fn get-hash {|@a|
   str:trim-right (echo $dir | sha256sum) "- "
 }
 
-fn state-type {
-  if (path:is-regular "flake.nix") {
+fn state-type {|@a|
+  var dir = $pwd
+  if (> (count $a) 0) {
+    set dir = $a[0]
+  }
+
+  if (path:is-regular $dir"/flake.nix") {
     put "nix"
-  } elif (path:is-regular "shell.nix") {
+  } elif (path:is-regular $dir"/shell.nix") {
     put "nix"
-  } elif (path:is-regular "default.nix") {
+  } elif (path:is-regular $dir"/default.nix") {
     put "nix"
   } else {
     put $nil
@@ -138,27 +143,32 @@ fn env-from-nix-flake {|state-file|
   }
 }
 
-fn push-dir {|type state-file|
-  var env = []
-  if (eq $type "nix") {
-    set @env = (env-from-nix-flake $state-file)
-  }
+fn push-dir {|type state-file path|
+  var env-diff = $nil
 
-  var @env-diff = (diff-env $env)
+  if (not-eq $state-file $nil) {
+    var env = []
+    if (eq $type "nix") {
+      set @env = (env-from-nix-flake $state-file)
+    }
 
-  var entry = [&dir=$pwd &env-diff=$env-diff]
+    set @env-diff = (diff-env $env)
 
-  edit:notify "Entered direlv "$pwd
-  edit:notify (print (apply-env $env))
+    edit:notify "Entered direlv "$path
+    edit:notify (print (apply-env $env))
+  }
 
+  var entry = [&dir=$path &env-diff=$env-diff]
   set dir-stack = [ $entry $@dir-stack ]
 }
 
 fn pop-dir {
   var last = $dir-stack[0]
 
-  edit:notify "Exited direlv "$last[dir]
-  edit:notify (print (apply-env $last[env-diff]))
+  if (not-eq $last[env-diff] $nil) {
+    edit:notify "Exited direlv "$last[dir]
+    edit:notify (print (apply-env $last[env-diff]))
+  }
 
   set dir-stack = $dir-stack[1..]
 }
@@ -209,7 +219,7 @@ edit:add-var direlv~ {|@a|
     if (eq $dir $pwd) {
       pop-dir
     }
-    push-dir $type $state-file
+    push-dir $type $state-file $pwd
   } elif (eq $a[0] "clear") {
     var dir = (current-dir)
     if (not-eq $dir $nil) {
@@ -231,16 +241,38 @@ fn on-chdir {|dir|
     }
   }
 
-  var type = (state-type)
-  if (eq $type $nil) {
-    return
+  var last = "/"
+  if (> (count $dir-stack) 0) {
+    set last = $dir-stack[0][dir]
   }
 
-  var hash = (get-hash)
-  var state-file = $state-dir/$hash'-'$type
+  var current = $pwd
+
+  var candidates = []
+  while (and (str:has-prefix $current $last) (not-eq $current $last)) {
+    set candidates = [ $current $@candidates ]
+
+    if (eq $current "/") {
+      # put this at the end so it can run against `/` once
+      break
+    }
+    set current = (path:dir $current)
+  }
 
-  if (path:is-regular $state-file &follow-symlink=$true) {
-    push-dir $type $state-file
+  for candidate $candidates {
+    var type = (state-type $candidate)
+    if (not-eq $type $nil) {
+      var hash = (get-hash $candidate)
+      var state-file = $state-dir/$hash'-'$type
+
+      if (path:is-regular $state-file &follow-symlink=$true) {
+        push-dir $type $state-file $candidate
+      } else {
+        push-dir $type $nil $candidate
+      }
+    } else {
+      push-dir "none" $nil $candidate
+    }
   }
 }