feat: add node builder helpers

crates/node/builder/src/builder/mod.rs

@@ -170,6 +170,18 @@ impl<ChainSpec> NodeBuilder<(), ChainSpec> {
     {
         f(self)
     }
+
+    /// Apply a function to the builder, if the condition is `true`.
+    pub fn apply_if<F>(self, cond: bool, f: F) -> Self
+    where
+        F: FnOnce(Self) -> Self,
+    {
+        if cond {
+            f(self)
+        } else {
+            self
+        }
+    }
 }
 
 impl<DB, ChainSpec> NodeBuilder<DB, ChainSpec> {
@@ -421,6 +433,18 @@ where
         f(self)
     }
 
+    /// Apply a function to the builder, if the condition is `true`.
+    pub fn apply_if<F>(self, cond: bool, f: F) -> Self
+    where
+        F: FnOnce(Self) -> Self,
+    {
+        if cond {
+            f(self)
+        } else {
+            self
+        }
+    }
+
     /// Sets the hook that is run once the node's components are initialized.
     pub fn on_component_initialized<F>(self, hook: F) -> Self
     where
@@ -482,6 +506,24 @@ where
         }
     }
 
+    /// Installs an `ExEx` (Execution Extension) in the node if the condition is true.
+    ///
+    /// # Note
+    ///
+    /// The `ExEx` ID must be unique.
+    pub fn install_exex_if<F, R, E>(self, cond: bool, exex_id: impl Into<String>, exex: F) -> Self
+    where
+        F: FnOnce(ExExContext<NodeAdapter<T, CB::Components>>) -> R + Send + 'static,
+        R: Future<Output = eyre::Result<E>> + Send,
+        E: Future<Output = eyre::Result<()>> + Send,
+    {
+        if cond {
+            self.install_exex(exex_id, exex)
+        } else {
+            self
+        }
+    }
+
     /// Launches the node with the given launcher.
     pub async fn launch_with<L>(self, launcher: L) -> eyre::Result<L::Node>
     where