Add list-ordering rule

This is based on the key-ordering rule and behaves the same with regards to locales.

Closes #454

docs/configuration.rst

@@ -243,9 +243,9 @@ It is possible to set the ``locale`` option globally. This is passed to Python's
 so an empty string ``""`` will use the system default locale, while e.g.
 ``"en_US.UTF-8"`` will use that.
 
-Currently this only affects the ``key-ordering`` rule. The default will order
+Currently this only affects the ``key-ordering`` and ``list-ordering`` rules.
-by Unicode code point number, while locales will sort case and accents
+The default will order by Unicode code point number, while locales will sort
-properly as well.
+case and accents properly as well.
 
 .. code-block:: yaml
 

docs/rules.rst

@@ -95,6 +95,11 @@ line-length
 
 .. automodule:: yamllint.rules.line_length
 
+list-ordering
+--------------
+
+.. automodule:: yamllint.rules.list_ordering
+
 new-line-at-end-of-file
 -----------------------
 

tests/rules/test_list_ordering.py

@@ -0,0 +1,133 @@
+# Copyright (C) 2023 Johannes F. Knauf and Kevin Wojniak
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import locale
+
+from tests.common import RuleTestCase
+
+
+class ListOrderingTestCase(RuleTestCase):
+    rule_id = 'list-ordering'
+
+    def test_disabled(self):
+        conf = 'list-ordering: disable'
+        self.check('---\n'
+                   '- seconditem\n'
+                   '- firstitem\n', conf)
+        self.check('---\n'
+                   '[seconditem, firstitem]\n', conf)
+        self.check('---\n'
+                   '- second\n'
+                   '- at\n', conf)
+
+    def test_enabled(self):
+        conf = 'list-ordering: enable'
+        self.check('---\n'
+                   '- seconditem\n'
+                   '- firstitem\n', conf,
+                   problem=(3, 3))
+        self.check('---\n'
+                   '[seconditem, firstitem]\n', conf,
+                   problem=(2, 14))
+        self.check('---\n'
+                   '- second\n'
+                   '- at\n', conf,
+                   problem=(3, 3))
+        self.check('---\n'
+                   'nested but OK:\n'
+                   '  - third: [second]\n'
+                   '  - first\n', conf)
+        self.check('---\n'
+                   'nested failure:\n'
+                   '  - third\n'
+                   '  - first:\n'
+                   '    items:\n'
+                   '      - z\n'
+                   '      - a\n', conf,
+                   problem=(7, 9))
+
+    def test_word_length(self):
+        conf = 'list-ordering: enable'
+        self.check('---\n'
+                   '- a\n'
+                   '- ab\n'
+                   '- abc\n', conf)
+        self.check('---\n'
+                   '- a\n'
+                   '- abc\n'
+                   '- ab\n', conf,
+                   problem=(4, 3))
+
+    def test_case(self):
+        conf = 'list-ordering: enable'
+        self.check('---\n'
+                   '- T-shirt\n'
+                   '- T-shirts\n'
+                   '- t-shirt\n'
+                   '- t-shirts\n', conf)
+        self.check('---\n'
+                   '- T-shirt\n'
+                   '- t-shirt\n'
+                   '- T-shirts\n'
+                   '- t-shirts\n', conf,
+                   problem=(4, 3))
+
+    def test_accents(self):
+        conf = 'list-ordering: enable'
+        self.check('---\n'
+                   '- hair\n'
+                   '- hais\n'
+                   '- haïr\n'
+                   '- haïssable\n', conf)
+        self.check('---\n'
+                   '- haïr\n'
+                   '- hais\n', conf,
+                   problem=(3, 3))
+
+    def test_locale_case(self):
+        self.addCleanup(locale.setlocale, locale.LC_ALL, (None, None))
+        try:
+            locale.setlocale(locale.LC_ALL, 'en_US.UTF-8')
+        except locale.Error:  # pragma: no cover
+            self.skipTest('locale en_US.UTF-8 not available')
+        conf = ('list-ordering: enable')
+        self.check('---\n'
+                   '- t-shirt\n'
+                   '- T-shirt\n'
+                   '- t-shirts\n'
+                   '- T-shirts\n', conf)
+        self.check('---\n'
+                   '- t-shirt\n'
+                   '- t-shirts\n'
+                   '- T-shirt\n'
+                   '- T-shirts\n', conf,
+                   problem=(4, 3))
+
+    def test_locale_accents(self):
+        self.addCleanup(locale.setlocale, locale.LC_ALL, (None, None))
+        try:
+            locale.setlocale(locale.LC_ALL, 'en_US.UTF-8')
+        except locale.Error:  # pragma: no cover
+            self.skipTest('locale en_US.UTF-8 not available')
+        conf = ('list-ordering: enable')
+        self.check('---\n'
+                   '- hair\n'
+                   '- haïr\n'
+                   '- hais\n'
+                   '- haïssable\n', conf)
+        self.check('---\n'
+                   '- hais\n'
+                   '- haïr\n', conf,
+                   problem=(3, 3))

yamllint/conf/default.yaml

@@ -25,6 +25,7 @@ rules:
   key-duplicates: enable
   key-ordering: disable
   line-length: enable
+  list-ordering: disable
   new-line-at-end-of-file: enable
   new-lines: enable
   octal-values: disable

yamllint/rules/__init__.py

@@ -29,6 +29,7 @@ from yamllint.rules import (
     key_duplicates,
     key_ordering,
     line_length,
+    list_ordering,
     new_line_at_end_of_file,
     new_lines,
     octal_values,
@@ -55,6 +56,7 @@ _RULES = {
     key_duplicates.ID: key_duplicates,
     key_ordering.ID: key_ordering,
     line_length.ID: line_length,
+    list_ordering.ID: list_ordering,
     new_line_at_end_of_file.ID: new_line_at_end_of_file,
     new_lines.ID: new_lines,
     octal_values.ID: octal_values,

yamllint/rules/list_ordering.py

@@ -0,0 +1,119 @@
+# Copyright (C) 2023 Johannes F. Knauf and Kevin Wojniak
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+"""
+Use this rule to enforce alphabetical ordering of items in lists. The sorting
+order uses the Unicode code point number as a default. As a result, the
+ordering is case-sensitive and not accent-friendly (see examples below).
+This can be changed by setting the global ``locale`` option.  This allows one
+to sort case and accents properly.
+
+.. rubric:: Examples
+
+#. With ``list-ordering: {}``
+
+   the following code snippets would **PASS**:
+   ::
+
+    - key 1
+    - key 2
+    - key 3
+
+    - [a, b, c]
+
+    - T-shirt
+    - T-shirts
+    - t-shirt
+    - t-shirts
+
+    - hair
+    - hais
+    - haïr
+    - haïssable
+
+   the following code snippets would **FAIL**:
+   ::
+
+    - key 2
+    - key 1
+
+    - [b, a]
+
+    - T-shirt
+    - t-shirt
+    - T-shirts
+    - t-shirts
+
+    - haïr
+    - hais
+
+#. With global option ``locale: "en_US.UTF-8"`` and rule ``list-ordering: {}``
+
+   as opposed to before, the following code snippets would now **PASS**:
+   ::
+
+    - t-shirt
+    - T-shirt
+    - t-shirts
+    - T-shirts
+
+    - hair
+    - haïr
+    - hais
+    - haïssable
+"""
+
+from locale import strcoll
+
+import yaml
+
+from yamllint.linter import LintProblem
+
+
+ID = 'list-ordering'
+TYPE = 'token'
+
+MAP, SEQ = range(2)
+
+
+class Parent:
+    def __init__(self, type):
+        self.type = type
+        self.items = []
+
+
+def check(conf, token, prev, next, nextnext, context):
+    if 'stack' not in context:
+        context['stack'] = []
+
+    if isinstance(token, (yaml.BlockMappingStartToken,
+                          yaml.FlowMappingStartToken)):
+        context['stack'].append(Parent(MAP))
+    elif isinstance(token, (yaml.BlockSequenceStartToken,
+                            yaml.FlowSequenceStartToken)):
+        context['stack'].append(Parent(SEQ))
+    elif isinstance(token, (yaml.BlockEndToken,
+                            yaml.FlowMappingEndToken,
+                            yaml.FlowSequenceEndToken)):
+        context['stack'].pop()
+    elif isinstance(token, yaml.ScalarToken):
+        if len(context['stack']) > 0 and context['stack'][-1].type == SEQ:
+            if any(strcoll(token.value, item) < 0
+                   for item in context['stack'][-1].items):
+                yield LintProblem(
+                    token.start_mark.line + 1, token.start_mark.column + 1,
+                    'wrong list item order "%s"' % token.value)
+            else:
+                context['stack'][-1].items.append(token.value)