add key and reverse parameter to CommentedSeq.sort()

suggested via email by Jannik Klemm

4 files changed, 85 insertions, 5 deletions

diff --git a/README.rst b/README.rst
index 9ea339a..943df7c 100644
--- a/README.rst
+++ b/README.rst
@@ -55,6 +55,7 @@ ChangeLog
 .. should insert NEXT: at the beginning of line for next key (with empty line)
 
 NEXT:
+  - added ``key`` and ``reverse`` parameter (suggested by Jannik Klemm via email)
   - indent root level literal scalars that have directive or document end markers
     at the beginning of a line
 
diff --git a/_test/test_issues.py b/_test/test_issues.py
index 1276381..62c1d92 100644
--- a/_test/test_issues.py
+++ b/_test/test_issues.py
@@ -292,6 +292,81 @@ class TestIssues:
         """)
         assert buf.getvalue() == exp
 
+    def test_issue_221_sort_reverse(self):
+        from ruamel.yaml import YAML
+        from ruamel.yaml.compat import StringIO
+
+        yaml = YAML()
+        inp = dedent("""\
+        - d
+        - a  # 1
+        - c  # 3
+        - e  # 5
+        - b  # 2
+        """)
+        a = yaml.load(dedent(inp))
+        a.sort(reverse=True)
+        buf = StringIO()
+        yaml.dump(a, buf)
+        exp = dedent("""\
+        - e  # 5
+        - d
+        - c  # 3
+        - b  # 2
+        - a  # 1
+        """)
+        assert buf.getvalue() == exp
+
+    def test_issue_221_sort_key(self):
+        from ruamel.yaml import YAML
+        from ruamel.yaml.compat import StringIO
+
+        yaml = YAML()
+        inp = dedent("""\
+        - four
+        - One    # 1
+        - Three  # 3
+        - five   # 5
+        - two    # 2
+        """)
+        a = yaml.load(dedent(inp))
+        a.sort(key=str.lower)
+        buf = StringIO()
+        yaml.dump(a, buf)
+        exp = dedent("""\
+        - five   # 5
+        - four
+        - One    # 1
+        - Three  # 3
+        - two    # 2
+        """)
+        assert buf.getvalue() == exp
+
+    def test_issue_221_sort_key_reverse(self):
+        from ruamel.yaml import YAML
+        from ruamel.yaml.compat import StringIO
+
+        yaml = YAML()
+        inp = dedent("""\
+        - four
+        - One    # 1
+        - Three  # 3
+        - five   # 5
+        - two    # 2
+        """)
+        a = yaml.load(dedent(inp))
+        a.sort(key=str.lower, reverse=True)
+        buf = StringIO()
+        yaml.dump(a, buf)
+        exp = dedent("""\
+        - two    # 2
+        - Three  # 3
+        - One    # 1
+        - four
+        - five   # 5
+        """)
+        assert buf.getvalue() == exp
+
     def test_issue_222(self):
         import ruamel.yaml
         from ruamel.yaml.compat import StringIO
diff --git a/comments.py b/comments.py
index 2ca2d79..9d51a29 100644
--- a/comments.py
+++ b/comments.py
@@ -496,10 +496,14 @@ class CommentedSeq(MutableSliceableSequence, CommentedBase):
         # type: (Any) -> Any
         return self._lst + other
 
-    def sort(self):
-        # type: () -> None
-        tmp_lst = sorted(zip(self._lst, range(len(self._lst))))
-        self._lst = [x[0] for x in tmp_lst]
+    def sort(self, key=None, reverse=False):
+        # type: (Any, bool) -> None
+        if key is None:
+            tmp_lst = sorted(zip(self._lst, range(len(self._lst))), reverse=reverse)
+            self._lst = [x[0] for x in tmp_lst]
+        else:
+            tmp_lst = sorted(zip(map(key, self._lst), range(len(self._lst))), reverse=reverse)
+            self._lst = [self._lst[x[1]] for x in tmp_lst]
         itm = self.ca.items
         self.ca._items = {}
         for idx, x in enumerate(tmp_lst):
diff --git a/emitter.py b/emitter.py
index cb9916a..5bac4ae 100644
--- a/emitter.py
+++ b/emitter.py
@@ -1366,7 +1366,7 @@ class Emitter(object):
     def determine_block_hints(self, text):
         # type: (Any) -> Any
         indent = 0
-        indicator = ''
+        indicator = u''
         hints = u''
         if text:
             if text[0] in u' \n\x85\u2028\u2029':