Added bookmark module (nushell#509)

* initial commit

* updated (module) README to include `bm` and removed missing `cdpath` and `up`

* added comments to commands

* removed missing function

* updated to use `XDG_DATA_HOME`

* added remove command

* updated def and def-env commands

* updated change_prev to use list

* updated README to have some info on use

* updated `get_path` to search `BM_PATH` > `XDG_DATA_HOME` > `~/.local/share`

* Updated to use relative paths, added `save_path` function

* added `main` with general information.

* Updated help text to give more information.

* Added Win support

* Added if dir doesn't exist, it creates it

Author: Tiggax

modules/README.md

@@ -61,8 +61,7 @@ An extensive example of a wrapper for docker operations, with nushell completion
 
 ## filesystem
 
-- [cdpath](./filesystem/cdpath.nu) - ???
-- [up](./filesystem/up.nu) - Cd up `X` times
+- [bm](./filesystem/bm.nu) - A Simple bookmarking module. It uses `XGD_DATA_HOME` to save bookmarks.
 
 ## formats
 Examples of input/output formatters:

modules/filesystem/bm.nu

@@ -0,0 +1,117 @@
+# simple bookmark module
+
+# Prints general information about bm.
+export def main [] {
+  print -n (help bm)
+
+  print (
+  [
+    $"(ansi green)Environment(ansi reset):"
+    $"    (ansi cyan)BM_PATH(ansi reset) - path to save bookmarks to with ('add' | nu-highlight). Alternatively searches for  (ansi cyan)XDG_DATA_HOME(ansi reset) or (ansi cyan)~/.local/share/(ansi reset)"
+  ] |
+  str join "\n" |
+  nu-highlight
+  )
+}
+
+# List all bookmarked paths
+export def list [] {
+  let bm_path = (get_path)
+
+  if (not ($bm_path | path exists))  {
+    [] | save $bm_path
+  }
+    open ($bm_path)
+}
+
+def get_path [] {
+  $env.BM_PATH? |
+  default (
+    $env.XDG_DATA_HOME? |
+    default (
+      $env.HOME | path join ".local" "share" |
+      default (
+        $env.USERPROFILE? | path join "bm"
+      )
+    )
+  ) |
+    if (not ($in | path exists)) {
+      mkdir $in
+      $in
+    } | 
+    path join "bookmarks.nuon"
+  )
+}
+
+def save_path [] {
+  $in |
+  update path { str replace $env.HOME '~' } |
+  save -f (get_path)
+}
+
+# Reset the bookmarks
+export def reset [] {
+  list |
+  where name == "prev" |
+  save -f (get_path)
+}
+
+# Add a new bookmark with an optional name
+export def add [
+  pth: path       # Path to bookmark to.
+  name?: string   # Optional name to give to it
+                    ] {
+  if (($pth | path type) == "dir") and ($pth | path exists) {
+    list | 
+    append {name: $name, path: $pth} |
+    save_path
+  }
+}
+
+# remove one or more bookmarks
+export def remove [] {
+  let rm_these = (
+    list | 
+    where name != "prev" |
+    input list -m
+  )
+
+  list | where {|it|
+    not $it in $rm_these
+  } |
+  print
+  
+}
+
+def marks [] {
+  list | each {|it| 
+    {
+    value: $it.path,
+    description: $it.name
+    }
+  }
+}
+
+# Goto your bookmark
+export def-env goto [
+  pth: path@marks # Path to "go to"
+  ] {
+  let prev = $env.PWD
+  cd $pth
+  change_prev $prev
+}
+
+# Experimental use of `input` instead of completion
+export def-env goto_alternative [] {
+  let prev = $env.PWD
+  list | input list -f | cd $in.path
+  change_prev $prev
+}
+
+def change_prev [new_path: path] {
+    ( list | 
+      where name != "prev" 
+    ) |
+    append {name: prev, path: $new_path} |
+    save_path
+}