cxx-qt-gen: simplify C++ header include writer

crates/cxx-qt-gen/src/writer/cpp/header.rs

@@ -103,8 +103,40 @@ fn qobjects_header(generated: &GeneratedCppBlocks) -> Vec<String> {
 
 /// For a given GeneratedCppBlocks write this into a C++ header
 pub fn write_cpp_header(generated: &GeneratedCppBlocks) -> String {
-    // Headers included:
-    // <memory> - unique_ptr to the Rust object.
+    let includes = {
+        let mut include_set = BTreeSet::new();
+        include_set.extend(
+            generated
+                .includes
+                .iter()
+                .chain(
+                    generated
+                        .qobjects
+                        .iter()
+                        .flat_map(|qobject| &qobject.blocks.includes),
+                )
+                .chain(
+                    generated
+                        .extern_cxx_qt
+                        .iter()
+                        .flat_map(|block| &block.includes),
+                ),
+        );
+        include_set
+            .into_iter()
+            .cloned()
+            .collect::<Vec<String>>()
+            .join("\n")
+    };
+    let extern_cxx_qt = generated
+        .extern_cxx_qt
+        .iter()
+        .filter_map(|block| {
+            pair_as_header(&block.method).map(|method| namespaced(&block.namespace, &method))
+        })
+        .collect::<Vec<String>>()
+        .join("\n");
+
     formatdoc! {r#"
         #pragma once
 
@@ -119,23 +151,6 @@ pub fn write_cpp_header(generated: &GeneratedCppBlocks) -> String {
     cxx_file_stem = generated.cxx_file_stem,
     forward_declare = forward_declare(generated).join("\n"),
     qobjects = qobjects_header(generated).join("\n"),
-    extern_cxx_qt = {
-        let mut out = vec![];
-        for block in &generated.extern_cxx_qt {
-            if let Some(method) = pair_as_header(&block.method) {
-                out.push(namespaced(&block.namespace, &method));
-            }
-        }
-        out.join("\n")
-    },
-    includes = generated.qobjects.iter()
-    .fold(generated.includes.clone(), |mut acc, qobject| {
-        acc.extend(qobject.blocks.includes.iter().cloned());
-        acc
-    }).into_iter().chain(generated.extern_cxx_qt.iter().fold(BTreeSet::<String>::default(), |mut acc, block| {
-        acc.extend(block.includes.iter().cloned());
-        acc
-    })).collect::<Vec<String>>().join("\n"),
     }
 }