hyphen: Add min-spaces-after and check-scalars options

This permits checking style when people want sequences to have a fixed
number of spaces greater than 1 for example.
We may also use these options to identify typos where we expect
everything starting with an hyphen to be a sequence.

tests/rules/test_hyphens.py

@@ -15,12 +15,25 @@
 
 from tests.common import RuleTestCase
 
+from yamllint import config
+
 
 class HyphenTestCase(RuleTestCase):
     rule_id = 'hyphens'
 
     def test_disabled(self):
-        conf = 'hyphens: disable'
+        self.run_disabled_test('hyphens: disable')
+        self.run_disabled_test('hyphens:\n'
+                               '  max-spaces-after: 5\n'
+                               '  min-spaces-after: -1\n')
+        self.run_disabled_test('hyphens:\n'
+                               '  max-spaces-after: -1\n'
+                               '  min-spaces-after: -1\n')
+        self.run_disabled_test('hyphens:\n'
+                               '  max-spaces-after: -1\n'
+                               '  min-spaces-after: 0\n')
+
+    def run_disabled_test(self, conf):
         self.check('---\n'
                    '- elem1\n'
                    '- elem2\n', conf)
@@ -51,6 +64,9 @@ def test_disabled(self):
                    '  subobject:\n'
                    '    -  elem1\n'
                    '    -  elem2\n', conf)
+        self.check('---\n'
+                   'object:\n'
+                   '  -elem2\n', conf)
 
     def test_enabled(self):
         conf = 'hyphens: {max-spaces-after: 1}'
@@ -103,3 +119,42 @@ def test_max_3(self):
                    '  b:\n'
                    '    -    elem1\n'
                    '    -    elem2\n', conf, problem1=(4, 9), problem2=(5, 9))
+
+    def test_invalid_spaces(self):
+        conf = 'hyphens: {max-spaces-after: 0}'
+        self.assertRaises(config.YamlLintConfigError, self.check, '', conf)
+
+        conf = 'hyphens: {min-spaces-after: 3}'
+        self.assertRaises(config.YamlLintConfigError, self.check, '', conf)
+
+    def test_min_space(self):
+        conf = 'hyphens: {max-spaces-after: 4, min-spaces-after: 3}'
+        self.check('---\n'
+                   'object:\n'
+                   '  -   elem1\n'
+                   '  -   elem2\n', conf)
+        self.check('---\n'
+                   'object:\n'
+                   '  -    elem1\n'
+                   '  -    elem2: -foo\n'
+                   '-bar:\n', conf)
+        self.check('---\n'
+                   'object:\n'
+                   '  -  elem1\n'
+                   '  -  elem2\n', conf, problem1=(3, 6), problem2=(4, 6))
+
+        conf = ('hyphens:\n'
+                '  max-spaces-after: 4\n'
+                '  min-spaces-after: 3\n'
+                '  check-scalars: true\n')
+        self.check('---\n'
+                   'foo\n'
+                   '-bar\n', conf)
+        self.check('---\n'
+                   'object:\n'
+                   '  -    elem1\n'
+                   '  -    elem2\n'
+                   'key: -value\n', conf, problem=(5, 6))
+        self.check('---\n'
+                   'list:\n'
+                   '  -value\n', conf, problem=(3, 3))

yamllint/rules/hyphens.py

@@ -19,7 +19,20 @@
 .. rubric:: Options
 
 * ``max-spaces-after`` defines the maximal number of spaces allowed after
-  hyphens.
+  hyphens. Set to a negative integer if you want to allow any number of
+  spaces.
+* ``min-spaces-after`` defines the minimal number of spaces expected after
+  hyphens. Set to a negative integer if you want to allow any number of
+  spaces. When set to a positive value, cannot be greater than
+  ``max-spaces-after``.
+* YAMLLint will consider ``-xx`` as a scalar. However you may consider
+  that, in your context, such a syntax is a typo and is actually a sequence
+  and as a consequence there should be a space after the hyphen. As this is
+  not a standard behaviour, you explicitly need to enable this control by
+  setting the option ``check-scalars`` to ``true``.  **Use with caution**
+  as all scalars will be checked and non-solvable false positive might be
+  identified. Has no effect when set to ``true`` but ``min-spaces-after``
+  is disabled (< 0).
 
 .. rubric:: Default values (when enabled)
 
@@ -28,6 +41,8 @@
  rules:
    hyphens:
      max-spaces-after: 1
+     min-spaces-after: -1  # Disabled
+     check-scalars: false
 
 .. rubric:: Examples
 
@@ -72,24 +87,97 @@
     -    key
     -   key2
     -  key42
+
+#. With ``hyphens: {min-spaces-after: 3}``
+
+   the following code snippet would **PASS**:
+   ::
+
+    list:
+    -   key
+    -    key2
+    -     key42
+    -foo:  # starter of a new sequence named "-foo";
+           # without the colon, a syntax error will be raised.
+
+   the following code snippet would **FAIL**:
+   ::
+
+    -  key
+    -   key2
+    -  key42
+
+#. With ``hyphens: {min-spaces-after: 3, check-scalars: true}``
+
+   the following code snippet would **PASS**:
+   ::
+
+    list:
+    -   key
+    -    key2
+    -     key42
+    key: -value
+
+   the following code snippets would **FAIL**:
+   ::
+
+    ---
+    -item0
+
+   ::
+
+    sequence:
+      -key  # Mind the spaces before the hyphen to enforce
+            # the sequence and avoid a syntax error
 """
 
 
 import yaml
 
+from yamllint.linter import LintProblem
 from yamllint.rules.common import spaces_after
 
 
 ID = 'hyphens'
 TYPE = 'token'
-CONF = {'max-spaces-after': int}
-DEFAULT = {'max-spaces-after': 1}
+CONF = {'max-spaces-after': int,
+        'min-spaces-after': int,
+        'check-scalars': bool}
+DEFAULT = {'max-spaces-after': 1,
+           'min-spaces-after': -1,
+           'check-scalars': False}
+
+
+def VALIDATE(conf):
+    if conf['max-spaces-after'] == 0:
+        return '"max-spaces-after" cannot be set to 0'
+    if (conf['min-spaces-after'] > 0 and
+            conf['min-spaces-after'] > conf['max-spaces-after']):
+        return '"min-spaces-after" cannot be greater than "max-spaces-after"'
 
 
 def check(conf, token, prev, next, nextnext, context):
     if isinstance(token, yaml.BlockEntryToken):
-        problem = spaces_after(token, prev, next,
-                               max=conf['max-spaces-after'],
-                               max_desc='too many spaces after hyphen')
-        if problem is not None:
-            yield problem
+        if conf['max-spaces-after'] > 0:
+            problem = spaces_after(token, prev, next,
+                                   max=conf['max-spaces-after'],
+                                   max_desc='too many spaces after hyphen')
+            if problem is not None:
+                yield problem
+
+        if conf['min-spaces-after'] > 0:
+            problem = spaces_after(token, prev, next,
+                                   min=conf['min-spaces-after'],
+                                   min_desc='too few spaces after hyphen')
+            if problem is not None:
+                yield problem
+
+    if (conf['check-scalars'] and conf['min-spaces-after'] > 0
+            and isinstance(token, yaml.ScalarToken)):
+        # Token identified as a scalar so there is no space after the
+        # hyphen: no need to count
+        if token.value.startswith('-'):
+            yield LintProblem(
+                    token.start_mark.line + 1,
+                    token.start_mark.column + 1,
+                    'too few spaces after hyphen')