Preserve flow style when outputting user-defined fields

src/base/AnyMap.cpp

@@ -259,6 +259,9 @@ struct convert<Cantera::AnyMap> {
 
     static bool decode(const Node& node, Cantera::AnyMap& target) {
         target.setLoc(node.Mark().line, node.Mark().column);
+        if (node.Style() == YAML::EmitterStyle::Flow) {
+            target.setFlowStyle();
+        }
         if (node.IsSequence()) {
             // Convert a top-level list to a map with the key "items"
             target["items"] = node.as<AnyValue>();

test/python/test_composite.py

@@ -2,6 +2,7 @@
 
 import numpy as np
 import pickle
+import re
 
 import pytest
 from .utilities import allow_deprecated
@@ -1238,8 +1239,9 @@ def test_yaml_strings(self):
         gas.species(3).update_user_data({"note": note3})
         gas.species(4).update_user_data({"note": note4})
 
-        gas.write_yaml(self.test_work_path / "h2o2-generated-user-header.yaml")
-        gas2 = ct.Solution(self.test_work_path / "h2o2-generated-user-header.yaml")
+        generated_file = self.test_work_path / "h2o2-generated-user-header.yaml"
+        gas.write_yaml(generated_file)
+        gas2 = ct.Solution(generated_file)
 
         # Ideally, multi-line YAML emitter would indicate stripping of the final newline
         # (element annotated with '|-' instead of just '|') but this doesn't seem to be
@@ -1254,6 +1256,11 @@ def test_yaml_strings(self):
         assert gas2.input_data["extra"]["key1"] == "1.0"
         assert gas2.input_data["extra"]["key2"] == 2.0
 
+        # User-defined input in flow style should remain in flow style
+        yaml_gen = generated_file.read_text()
+        assert re.search("extra:.*key1.*key2", yaml_gen)
+
+
     def test_duplicate_reactions(self):
         gas = ct.Solution('h2o2.yaml', transport_model=None)