[document-start] adds min/max empty lines after document start/end

tests/rules/test_document_start.py

@@ -102,3 +102,65 @@ def test_directives(self):
  '---\n'
  'doc: 2\n'
  '...\n', conf)
+
+ def test_empty_lines(self):
+ conf = ('document-start:\n'
+ ' present: true\n'
+ ' max-empty-lines-after: 0\n')
+
+ self.check('%YAML 1.2\n'
+ '---\n'
+ 'doc: ument\n', conf)
+
+ self.check('%YAML 1.2\n'
+ '---\n'
+ '\n'
+ 'doc: ument\n', conf, problem=(4, 1))
+
+ conf = ('document-start:\n'
+ ' present: true\n'
+ ' max-empty-lines-after: 1\n')
+
+ self.check('%YAML 1.2\n'
+ '---\n'
+ '\n'
+ 'doc: ument\n', conf)
+
+ self.check('%YAML 1.2\n'
+ '---\n'
+ '\n'
+ '\n'
+ 'doc: ument\n', conf, problem=(5, 1))
+
+ conf = ('document-start:\n'
+ ' present: true\n'
+ ' min-empty-lines-after: 1\n')
+
+ self.check('%YAML 1.2\n'
+ '---\n'
+ '\n'
+ 'doc: ument\n', conf)
+
+ self.check('%YAML 1.2\n'
+ '---\n'
+ 'doc: ument\n', conf, problem=(3, 1))
+
+ conf = ('document-start:\n'
+ ' present: true\n'
+ ' max-empty-lines-after: 1\n'
+ ' min-empty-lines-after: 1\n')
+
+ self.check('%YAML 1.2\n'
+ '---\n'
+ '\n'
+ 'doc: ument\n', conf)
+
+ self.check('%YAML 1.2\n'
+ '---\n'
+ 'doc: ument\n', conf, problem=(3, 1))
+
+ self.check('%YAML 1.2\n'
+ '---\n'
+ '\n'
+ '\n'
+ 'doc: ument\n', conf, problem=(5, 1))

yamllint/rules/document_start.py

@@ -21,6 +21,10 @@
 
 * Set ``present`` to ``true`` when the document start marker is required, or to
  ``false`` when it is forbidden.
+* ``min-empty-lines-after`` defines the minimal number of empty lines after the
+ document start marker.
+* ``max-empty-lines-after`` defines the maximal number of empty lines after the
+ document start marker.
 
 .. rubric:: Default values (when enabled)
 
@@ -79,8 +83,12 @@
 
 ID = 'document-start'
 TYPE = 'token'
-CONF = {'present': bool}
-DEFAULT = {'present': True}
+CONF = {'present': bool,
+ 'max-empty-lines-after': int,
+ 'min-empty-lines-after': int}
+DEFAULT = {'present': True,
+ 'max-empty-lines-after': -1,
+ 'min-empty-lines-after': 0}
 
 
 def check(conf, token, prev, next, nextnext, context):
@@ -94,6 +102,21 @@ def check(conf, token, prev, next, nextnext, context):
  yield LintProblem(token.start_mark.line + 1, 1,
  'missing document start "---"')
 
+ if isinstance(prev, yaml.DocumentStartToken):
+ empty_lines = token.start_mark.line - prev.start_mark.line - 1
+
+ if (conf['max-empty-lines-after'] >= 0 and
+ empty_lines > conf['max-empty-lines-after']):
+ yield LintProblem(token.start_mark.line + 1,
+ token.start_mark.column + 1,
+ 'too many empty lines after document start')
+
+ if (conf['min-empty-lines-after'] > 0 and
+ empty_lines < conf['min-empty-lines-after']):
+ yield LintProblem(token.start_mark.line + 1,
+ token.start_mark.column + 1,
+ 'too few empty lines after document start')
+
  else:
  if isinstance(token, yaml.DocumentStartToken):
  yield LintProblem(token.start_mark.line + 1,