Add command helpers

euphoxide-bot/src/command/prefixed.rs

@@ -0,0 +1,43 @@
+use async_trait::async_trait;
+use euphoxide::api::Message;
+
+use super::{Command, Context, Info, Propagate};
+
+pub struct Prefixed<C> {
+    prefix: String,
+    inner: C,
+}
+
+impl<C> Prefixed<C> {
+    pub fn new<S: ToString>(prefix: S, inner: C) -> Self {
+        Self {
+            prefix: prefix.to_string(),
+            inner,
+        }
+    }
+}
+
+#[async_trait]
+impl<B, E, C> Command<B, E> for Prefixed<C>
+where
+    B: Send,
+    C: Command<B, E> + Send + Sync,
+{
+    fn info(&self, ctx: &Context) -> Info {
+        self.inner.info(ctx).with_prepended_trigger(&self.prefix)
+    }
+
+    async fn execute(
+        &self,
+        arg: &str,
+        msg: &Message,
+        ctx: &Context,
+        bot: &mut B,
+    ) -> Result<Propagate, E> {
+        if let Some(rest) = arg.trim_start().strip_prefix(&self.prefix) {
+            self.inner.execute(rest, msg, ctx, bot).await
+        } else {
+            Ok(Propagate::Yes)
+        }
+    }
+}