Add 'reader config dump' command.

For #177.

src/reader/_cli.py

@@ -341,6 +341,25 @@ def search_entries(reader, query):
         click.echo("{} {}".format(entry.feed.url, entry.link or entry.id))
 
 
+@cli.group()
+def config():
+    """Do various things related to config."""
+
+
+class Dumper(yaml.SafeDumper):
+    def ignore_aliases(self, data):
+        return True
+
+
+@config.command()
+@click.option('--merge/--no-merge')
+@click.pass_obj
+def dump(config, merge):
+    if merge:
+        config = config.merge_all()
+    click.echo(yaml.dump(config.data, sort_keys=False, Dumper=Dumper))
+
+
 try:
     from reader._app.cli import serve
 

src/reader/_config.py

@@ -94,6 +94,11 @@ def __post_init__(self):
                 section: self.data.pop(section) for section in unknown_sections
             }
 
+            # default is always first
+            for section in list(self.data):
+                if section != self.default_section:
+                    self.data[section] = self.data.pop(section)
+
         for section in self.sections:
             self.data.setdefault(section, {})
 
@@ -108,6 +113,13 @@ def merged(self, section, overrides=None):
             merge_keys=self.merge_keys,
         )
 
+    def merge_all(self):
+        config = copy.deepcopy(self)
+        for section in list(config.data):
+            if section != config.default_section:
+                config.data[section] = config.merged(section)
+        return config
+
     def make_reader(self, section, **kwargs):
         return make_reader_from_config(
             **self.merged(section, {'reader': kwargs}).get('reader', {}),