Add media library operator.

CHANGES.md

@@ -40,6 +40,9 @@ New:
   [Pico TTS](https://github.com/naggety/picotts) (#2934).
 - Added `"metadata_url"` to the default list of exported metadata (#2946)
 - Added log colors!
+- Added `list.filter_map` and `list.flatten`.
+- Added `medialib` in order to store metadata of files in a folder and query
+  them (#3115).
 
 Changed:
 

doc/content/cookbook.md

@@ -142,6 +142,24 @@ fallback([playlist("http://my/playlist"),
 switch([ ({0h-7h}, night), ({7h-24h}, day) ])
 ```
 
+## Generating playlists from a media library
+
+In order to store all the metadata of the files in a given directory and use
+those to generate playlists, you can use the `medialib` operator which takes as
+argument the directory to index. On first run, it will index all the files of
+the given folder, which can take some time (you are advised to use the
+`persistency` parameter in order to specify a file where metadata will be
+stored, in order to avoid reindexing at each run). The resulting object can then
+be queried with the `find` method in order to return all files matching given
+conditions and thus generate a playlist:
+
+```liquidsoap
+m = medialib(persistency="/tmp/medialib.json", "~/Music/")
+l = m.find(artist_contains="Brassens")
+l = list.shuffle(l)
+output(playlist.list(l))
+```
+
 ## Force a file/playlist to be played at least every XX minutes
 
 It can be useful to have a special playlist that is played at least every 20 minutes for instance (3 times per hour).

doc/dune.inc

@@ -1566,27 +1566,27 @@
  (section doc)
  (package liquidsoap)
  (files
-    (orig/fosdem2020/clock.png as html/fosdem2020/clock.png)
-(orig/fosdem2020/remark.js as html/fosdem2020/remark.js)
-(orig/fosdem2020/radio.gif as html/fosdem2020/radio.gif)
-(orig/fosdem2020/logo.png as html/fosdem2020/logo.png)
-(orig/fosdem2020/index.html as html/fosdem2020/index.html)
-(orig/images/grab.png as html/images/grab.png)
-(orig/images/schema-webradio-inkscape.png as html/images/schema-webradio-inkscape.png)
-(orig/images/liqgraph.png as html/images/liqgraph.png)
-(orig/images/stream.png as html/images/stream.png)
-(orig/images/graph_clocks.png as html/images/graph_clocks.png)
-(orig/images/design/background_page.png as html/images/design/background_page.png)
-(orig/images/design/logo.png as html/images/design/logo.png)
+    (orig/images/grab.png as html/images/grab.png)
 (orig/images/design/background.png as html/images/design/background.png)
-(orig/images/basic-radio-graph.png as html/images/basic-radio-graph.png)
+(orig/images/design/logo.png as html/images/design/logo.png)
+(orig/images/design/background_page.png as html/images/design/background_page.png)
+(orig/images/graph_clocks.png as html/images/graph_clocks.png)
+(orig/images/stream.png as html/images/stream.png)
+(orig/images/schema-webradio-inkscape.png as html/images/schema-webradio-inkscape.png)
 (orig/images/tabs/tab_API.png as html/images/tabs/tab_API.png)
-(orig/images/tabs/tab_developers.png as html/images/tabs/tab_developers.png)
-(orig/images/tabs/tab_snippets.png as html/images/tabs/tab_snippets.png)
-(orig/images/tabs/tab_docs.png as html/images/tabs/tab_docs.png)
 (orig/images/tabs/tab_about.png as html/images/tabs/tab_about.png)
-(orig/css/style.css as html/css/style.css)
+(orig/images/tabs/tab_docs.png as html/images/tabs/tab_docs.png)
+(orig/images/tabs/tab_snippets.png as html/images/tabs/tab_snippets.png)
+(orig/images/tabs/tab_developers.png as html/images/tabs/tab_developers.png)
+(orig/images/liqgraph.png as html/images/liqgraph.png)
+(orig/images/basic-radio-graph.png as html/images/basic-radio-graph.png)
+(orig/fosdem2020/logo.png as html/fosdem2020/logo.png)
+(orig/fosdem2020/index.html as html/fosdem2020/index.html)
+(orig/fosdem2020/clock.png as html/fosdem2020/clock.png)
+(orig/fosdem2020/radio.gif as html/fosdem2020/radio.gif)
+(orig/fosdem2020/remark.js as html/fosdem2020/remark.js)
 (orig/css/homepage.css as html/css/homepage.css)
+(orig/css/style.css as html/css/style.css)
     (protocols.html as html/protocols.html)
 (reference.html as html/reference.html)
 (reference-extras.html as html/reference-extras.html)

src/core/builtins/builtins_files.ml

@@ -97,6 +97,15 @@ let _ =
         Lang.int ret
       with _ -> Lang.int 0)
 
+let _ =
+  Lang.add_builtin ~base:file "mtime" ~category:`File
+    ~descr:"Last modification time."
+    [("", Lang.string_t, None, None)]
+    Lang.float_t
+    (fun p ->
+      let fname = List.assoc "" p |> Lang.to_string in
+      try Lang.float (Unix.stat fname).st_mtime with _ -> Lang.float 0.)
+
 let _ =
   Lang.add_builtin ~base:file "mkdir" ~category:`File
     ~descr:"Create a directory."
@@ -486,6 +495,21 @@ let () =
                  in
                  Lang.metadata (Frame.metadata_of_list m)))))
 
+let _ =
+  Lang.add_builtin ~base:file_metadata "native" ~category:`File
+    [
+      ( "",
+        Lang.string_t,
+        None,
+        Some "File from which the metadata should be read." );
+    ]
+    Lang.metadata_t ~descr:"Read metadata from a file using the native decoder."
+    (fun p ->
+      let file = List.assoc "" p |> Lang.to_string in
+      let m = try Metadata.parse_file file with _ -> [] in
+      let m = List.map (fun (k, v) -> (String.lowercase_ascii k, v)) m in
+      Lang.metadata (Frame.metadata_of_list m))
+
 let _ =
   Lang.add_builtin ~base:file "which" ~category:`File
     ~descr:

src/js/dune.inc

@@ -11,51 +11,52 @@
   (:stdlib_js ./stdlib_js.liq)
   (source_tree ../libs))
  (action
-  (run js_of_ocaml build-fs -I . -I ../libs -o %{target} %{stdlib_js} visualization.liq
-resolvers.liq
+  (run js_of_ocaml build-fs -I . -I ../libs -o %{target} %{stdlib_js} profiler.liq
 externals.liq
-gstreamer.liq
-log.liq
+io.liq
+native.liq
+audio.liq
+http.liq
 utils.liq
-thread.liq
-source.liq
-process.liq
-ref.liq
-fades.liq
-profiler.liq
 null.liq
-math.liq
-socket.liq
-error.liq
-request.liq
-string.liq
-stdlib.liq
-deprecations.liq
-liquidsoap.liq
-audio.liq
-clock.liq
-protocols.liq
+source.liq
 video.liq
-ffmpeg.liq
-native.liq
-interactive.liq
 http_codes.liq
-predicate.liq
-file.liq
+log.liq
+string.liq
+replaygain.liq
+process.liq
+telnet.liq
 getter.liq
-io.liq
+ffmpeg.liq
+http_extra.liq
+deprecations.liq
+socket.liq
+hls.liq
 switches.liq
-list.liq
-telnet.liq
-replaygain.liq
-http.liq
-metadata.liq
-lastfm.liq
 playlist.liq
+fades.liq
+ref.liq
+settings.liq
+lastfm.liq
 testing.liq
-hls.liq
-runtime.liq
 icecast.liq
-http_extra.liq
+interactive.liq
+stdlib.liq
+request.liq
+list.liq
+file.liq
+liquidsoap.liq
+medialib.liq
 server.liq
-settings.liq)))
+metadata.liq
+predicate.liq
+math.liq
+visualization.liq
+resolvers.liq
+clock.liq
+thread.liq
+protocols.liq
+runtime.liq
+error.liq
+gstreamer.liq)))

src/libs/dune.inc

@@ -5,51 +5,52 @@
    (liquidsoap-lang libs)))
  (package liquidsoap-libs)
  (files
-    visualization.liq
-resolvers.liq
+    profiler.liq
 externals.liq
-gstreamer.liq
-log.liq
+io.liq
+native.liq
+audio.liq
+http.liq
 utils.liq
-thread.liq
-source.liq
-process.liq
-ref.liq
-fades.liq
-profiler.liq
 null.liq
-math.liq
-socket.liq
-error.liq
-request.liq
-string.liq
-stdlib.liq
-deprecations.liq
-liquidsoap.liq
-audio.liq
-clock.liq
-protocols.liq
+source.liq
 video.liq
-ffmpeg.liq
-native.liq
-interactive.liq
 http_codes.liq
-predicate.liq
-file.liq
+log.liq
+string.liq
+replaygain.liq
+process.liq
+telnet.liq
 getter.liq
-io.liq
+ffmpeg.liq
+http_extra.liq
+deprecations.liq
+socket.liq
+hls.liq
 switches.liq
-list.liq
-telnet.liq
-replaygain.liq
-http.liq
-metadata.liq
-lastfm.liq
 playlist.liq
+fades.liq
+ref.liq
+settings.liq
+lastfm.liq
 testing.liq
-hls.liq
-runtime.liq
 icecast.liq
-http_extra.liq
+interactive.liq
+stdlib.liq
+request.liq
+list.liq
+file.liq
+liquidsoap.liq
+medialib.liq
 server.liq
-settings.liq))
+metadata.liq
+predicate.liq
+math.liq
+visualization.liq
+resolvers.liq
+clock.liq
+thread.liq
+protocols.liq
+runtime.liq
+error.liq
+gstreamer.liq))

src/libs/list.liq

@@ -110,6 +110,12 @@ def list.fold.right(f, x, l)
   list.ind(l, x, fun (e, _, r) -> f(e, r))
 end
 
+# Concatenate all the elements of a list of lists.
+# @category List
+def list.flatten(l)
+  list.fold(fun(l,s) -> list.append(l,s), [], l)
+end
+
 # Filter a list according to a predicate. The order in which elements are
 # handled is not specified (and is currently implemented from the right).
 # @category List
@@ -121,6 +127,23 @@ def list.filter(~remove=fun(_)->(), p, l)
   list.ind(l, [], fun(x, _, l) -> if p(x) then list.cons(x, l) else (remove(x):unit); l end)
 end
 
+# Map a function on a list (like `list.map`) excepting that the value is removed
+# if the function returns `null`.
+# @category List
+# @param f Function called on every element of the list.
+# @param l The list.
+def list.filter_map(f, l)
+  def f(x, _, l)
+    y = f(x)
+    if null.defined(y) then
+      list.cons(null.get(y), l)
+    else
+      l
+    end
+  end
+  list.ind(l, [], f)
+end
+
 # Associate a value to a key in an association list. This functions raises
 # `error.not_found` if no default value is specified.
 # @category List
@@ -147,6 +170,14 @@ def list.assoc.filter(p, l)
   list.filter(p, l)
 end
 
+# Map a function of every element of the associative list, removing the entry if
+# the function returns `null`.
+# @category List
+def list.assoc.filter_map(f, l)
+  def f(kv) = f(fst(kv), snd(kv)) end
+  list.filter_map(f, l)
+end
+
 # Remove the first pair from an associative list.
 # @category List
 # @param key Key of pair to be removed.
@@ -237,7 +268,7 @@ def list.index(p, l)
   list.ind(l, 0, fun (x, _, r) -> if p(x) then 0 else r+1 end)
 end
 
-# list.assoc.mem(key,l) returns true if l contains a pair (key,value).
+# `list.assoc.mem(key,l)` returns `true` if `l` contains a pair (key,value).
 # @category List
 # @param a Key to look for
 # @param l List of pairs (key,value)