SpaceConsistencyBear: Add leading_blankline option

Add allow_trailing_blanklines option for whether to allow
leading blanklines in starting of a file.

Closes coala#2207

bears/general/SpaceConsistencyBear.py

@@ -18,6 +18,7 @@ def run(self,
             file,
             use_spaces: bool,
             allow_trailing_whitespace: bool=False,
+            allow_leading_blanklines: bool=False,
             indent_size: int=SpacingHelper.DEFAULT_TAB_WIDTH,
             enforce_newline_at_EOF: bool=True):
         '''
@@ -29,6 +30,9 @@ def run(self,
             True if spaces are to be used instead of tabs.
         :param allow_trailing_whitespace:
             Whether to allow trailing whitespace or not.
+        :param allow_leading_blanklines:
+            Whether to allow leading blanklines
+            at start of file or not.
         :param indent_size:
             Number of spaces per indentation level.
         :param enforce_newline_at_EOF:
@@ -38,7 +42,50 @@ def run(self,
         result_texts = []
         additional_info_texts = []
 
-        for line_number, line in enumerate(file, start=1):
+        def get_blanklines_nr_end():
+            line_nr_end = False
+            enumerated_zip_obj = zip(range(1, len(file) + 1),
+                                     file)
+            enumerated_tuple = tuple(enumerated_zip_obj)
+
+            for line_number, line in enumerated_tuple:
+                replacement = line
+                if replacement.strip() == '':
+                    line_nr_end = line_number
+                else:
+                    break
+
+            return line_nr_end
+
+        if allow_leading_blanklines:
+            start_line_of_file = 1
+
+        else:
+            blanklines_nr_end = get_blanklines_nr_end()
+            start_line_of_file = 1
+            if blanklines_nr_end:
+                start_line_of_file = blanklines_nr_end + 1
+                result_texts.append('Leading blanklines.')
+                additional_info_texts.append(
+                    'Your source code contains leading blanklines.'
+                    'Those usually have no meaning. Please consider'
+                    'removing them.')
+                diff = Diff(file)
+                diff.delete_lines(1, blanklines_nr_end)
+                inconsistencies = ''.join('\n- ' + string
+                                          for string in result_texts)
+                yield Result.from_values(
+                    self,
+                    'Line contains following spacing inconsistencies:'
+                    + inconsistencies,
+                    diffs={filename: diff},
+                    file=filename,
+                    additional_info='\n\n'.join(additional_info_texts))
+                result_texts = []
+                additional_info_texts = []
+
+        for line_number, line in enumerate(file[start_line_of_file - 1:],
+                                           start=start_line_of_file):
             replacement = line
 
             if enforce_newline_at_EOF:

tests/c_languages/ClangBearTest.py

@@ -1,4 +1,3 @@
-
 from bears.c_languages.ClangBear import ClangBear
 from coalib.testing.LocalBearTestHelper import verify_local_bear
 

tests/general/SpaceConsistencyBearTest.py

@@ -44,21 +44,27 @@ def test_data_sets_tabs(self):
         self.section.append(Setting('use_spaces', 'false'))
         self.section.append(Setting('allow_trailing_whitespace', 'true'))
         self.section.append(Setting('enforce_newline_at_EOF', 'false'))
+        self.section.append(Setting('allow_leading_blanklines', 'false'))
 
         self.check_invalidity(self.uut, ['    t'])
         self.check_validity(self.uut, ['t \n'])
         self.check_validity(self.uut, ['\tt\n'])
+        self.check_validity(self.uut, [])
 
     def test_enforce_newline_at_eof(self):
         self.section.append(Setting('use_spaces', 'true'))
         self.section.append(Setting('allow_trailing_whitespace', 'true'))
         self.section.append(Setting('enforce_newline_at_EOF', 'true'))
+        self.section.append(Setting('allow_leading_blanklines', 'true'))
 
         self.check_validity(self.uut,
                             ['hello world  \n'],
                             force_linebreaks=False)
         self.check_validity(self.uut,
-                            ['def somecode():\n',
+                            [' \n',
+                             '\n',
+                             '     \n',
+                             'def somecode():\n',
                              "    print('funny')\n",
                              "    print('funny end.')\n"],
                             force_linebreaks=False)
@@ -70,3 +76,20 @@ def test_enforce_newline_at_eof(self):
                                "    print('funny')\n",
                                "    print('the result is not funny...')"],
                               force_linebreaks=False)
+
+    def test_leading_blanklines(self):
+        self.section.append(Setting('use_spaces', 'true'))
+        self.section.append(Setting('allow_trailing_whitespace', 'false'))
+        self.section.append(Setting('enforce_newline_at_EOF', 'true'))
+        self.section.append(Setting('allow_leading_blanklines', 'false'))
+
+        self.check_invalidity(self.uut,
+                              ['\n',
+                               '  \n',
+                               'def code():\n',
+                               "  print('Am I coding?')\n"],
+                              force_linebreaks=False)
+        self.check_validity(self.uut,
+                            ['def code():\n',
+                             "  print('Am I coding?')\n"],
+                            force_linebreaks=False)

tests/go/GoImportsBearTest.py

@@ -1,4 +1,3 @@
-
 from bears.go.GoImportsBear import GoImportsBear
 from coalib.testing.LocalBearTestHelper import verify_local_bear