feat: wrap metadata API and add one usage example

Signed-off-by: Christopher Arndt <chris@chrisarndt.de>

examples/jacket_list_all_properties.nim

@@ -0,0 +1,46 @@
+import std/[logging, strformat]
+import jacket
+
+var
+    jclient: ClientP
+    status: cint
+    descs: ptr UncheckedArray[Description]
+
+var log = newConsoleLogger(when defined(release): lvlInfo else: lvlDebug)
+
+proc errorCb(msg: cstring) {.cdecl.} =
+    # Suppress verbose JACK error messages when server is not available by 
+    # default. Pass ``lvlAll`` when creating the logger to enable them.
+    debug "JACK error: " & $msg
+
+addHandler(log)
+setErrorFunction(errorCb)
+jclient = clientOpen("jacket_property", NullOption.ord, status.addr)
+debug "JACK server status: " & $status
+
+if jclient == nil:
+    error getJackStatusErrorString(status)
+    quit 1
+
+let numDescs = getAllProperties(descs)
+
+if numDescs != -1:
+    var desc: Description
+
+    for i in 0..<numDescs:
+        desc = descs[i]
+        echo fmt"Subject: {desc.subject}"
+
+        if desc.property_cnt > 0:
+            for p in 0..<desc.property_cnt:
+                var prop = desc.properties[p]
+                echo fmt"* {prop.key}: {prop.data} (type: {prop.type})"
+
+        echo ""
+        freeDescription(desc.addr, 0)
+
+    free(descs)
+else:
+    error "Could not get properties!"
+
+discard jclient.clientClose

src/jacket.nim

@@ -167,6 +167,27 @@ const
     EXTENDED_TIME_INFO* = true
     JACK_TICK_DOUBLE* = true
 
+# Metadata
+
+type
+    Property* = object
+        key*: cstring
+        data*: cstring
+        `type`*: cstring
+
+    PropertyChange* {.size: sizeof(cint).} = enum
+        PropertyCreated,
+        PropertyChanged,
+        PropertyDeleted
+
+    Description* = object
+        subject*: Uuid
+        property_cnt*: uint32
+        properties*: ptr UncheckedArray[Property]
+        property_size*: uint32
+
+    DescriptionP* = ptr Description
+
 # Callback function types
 
 type
@@ -192,6 +213,11 @@ type
     JackTimebaseCallback* = proc (state: TransportState; nframes: NFrames; pos: ptr Position; newPos: cint;
                                   arg: pointer) {.cdecl.}
 
+    JackPropertyChangeCallback* = proc (subject: Uuid, key: cstring, change: JackPropertyChange, arg: pointer) {.cdecl.}
+
+
+    PropertyChangeCallback* = proc (subject: Uuid, key: cstring, change: PropertyChange, arg: pointer) {.cdecl.}
+
 
 # ----------------------------- Version info ------------------------------
 
@@ -603,6 +629,37 @@ void jack_get_transport_info (jack_client_t *client, jack_transport_info_t *tinf
 void jack_set_transport_info (jack_client_t *client, jack_transport_info_t *tinfo)
 ]#
 
+# ------------------------------- Metadata --------------------------------
+
+# int jack_set_property (jack_client_t*, jack_uuid_t subject, const char* key, const char* value, const char* type)
+proc setProperty*(client: ClientP, subject: Uuid, key, value, `type`: cstring): cint {.importc: "jack_set_property".}
+
+# int jack_get_property (jack_uuid_t subject, const char* key, char** value, char** type)
+proc getProperty*(subject: Uuid, key: cstring, value, `type`: ptr cstring): cint {.importc: "jack_get_property".}
+
+# void jack_free_description (jack_description_t* desc, int free_description_itself)
+proc freeDescription*(desc: DescriptionP, freeDescriptionItself: cint) {.importc: "jack_free_description".}
+
+# int jack_get_properties (jack_uuid_t subject, jack_description_t* desc)
+proc getProperties*(subject: Uuid, desc: DescriptionP): cint {.importc: "jack_get_properties".}
+
+# int jack_get_all_properties (jack_description_t** descs)
+proc getAllProperties*(descs: var ptr UncheckedArray[Description]): cint {.importc: "jack_get_all_properties".}
+
+# int jack_remove_property (jack_client_t* client, jack_uuid_t subject, const char* key)
+proc removeProperty*(client: ClientP, subject: Uuid): cint {.importc: "jack_remove_property".}
+
+# int jack_remove_properties (jack_client_t* client, jack_uuid_t subject)
+proc removeProperties*(client: ClientP, subject: Uuid): cint {.importc: "jack_remove_properties".}
+
+# int jack_remove_all_properties (jack_client_t* client)
+proc removeAllProperties*(client: ClientP): cint {.importc: "jack_remove_all_properties".}
+
+# int jack_set_property_change_callback (jack_client_t* client, JackPropertyChangeCallback callback, void* arg)
+proc setPropertyChangeCallback*(client: ClientP, callback: PropertyChangeCallback, arg: pointer): cint {.
+    importc: "jack_set_property_change_callback".}
+
+
 # ---------------------------- Error handling -----------------------------
 
 proc setErrorFunction*(errorCallback: JackErrorCallback) {.importc: "jack_set_error_function".}