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1# Copyright (c) 2012 The Chromium Authors. All rights reserved.
2# Use of this source code is governed by a BSD-style license that can be
3# found in the LICENSE file.
4
5import re
6
7
8class CSSChecker(object):
9
10  def __init__(self, input_api, output_api, file_filter=None):
11    self.input_api = input_api
12    self.output_api = output_api
13    self.file_filter = file_filter
14
15  def RunChecks(self):
16    # We use this a lot, so make a nick name variable.
17    def _collapseable_hex(s):
18      return (len(s) == 6 and s[0] == s[1] and s[2] == s[3] and s[4] == s[5])
19
20    def _is_gray(s):
21      return s[0] == s[1] == s[2] if len(s) == 3 else s[0:2] == s[2:4] == s[4:6]
22
23    def _remove_all(s):
24      return _remove_grit(_remove_ats(_remove_comments(s)))
25
26    def _remove_ats(s):
27      return re.sub(re.compile(r'@\w+.*?{(.*{.*?})+.*?}', re.DOTALL), '\\1', s)
28
29    def _remove_comments(s):
30      return re.sub(re.compile(r'/\*.*?\*/', re.DOTALL), '', s)
31
32    def _remove_grit(s):
33      grit_reg = r'<if[^>]+>.*?<\s*/\s*if[^>]*>|<include[^>]+>'
34      return re.sub(re.compile(grit_reg, re.DOTALL), '', s)
35
36    def _rgb_from_hex(s):
37      if len(s) == 3:
38        r, g, b = s[0] + s[0], s[1] + s[1], s[2] + s[2]
39      else:
40        r, g, b = s[0:2], s[2:4], s[4:6]
41      return int(r, base=16), int(g, base=16), int(b, base=16)
42
43    def alphabetize_props(contents):
44      errors = []
45      for rule in re.finditer(r'{(.*?)}', contents, re.DOTALL):
46        semis = map(lambda t: t.strip(), rule.group(1).split(';'))[:-1]
47        rules = filter(lambda r: ': ' in r, semis)
48        props = map(lambda r: r[0:r.find(':')], rules)
49        if props != sorted(props):
50          errors.append('    %s;\nExpected: %s' % (
51                        ';\n    '.join(rules), ','.join(list(sorted(props)))))
52      return errors
53
54    def braces_have_space_before_and_nothing_after(line):
55      return re.search(r'(?:^|\S){|{\s*\S+\s*$', line)
56
57    def classes_use_dashes(line):
58      # Intentionally dumbed down version of CSS 2.1 grammar for class without
59      # non-ASCII, escape chars, or whitespace.
60      m = re.search(r'\.(-?[_a-zA-Z0-9-]+).*[,{]\s*$', line)
61      return (m and (m.group(1).lower() != m.group(1) or
62                     m.group(1).find('_') >= 0))
63
64    # Ignore single frames in a @keyframe, i.e. 0% { margin: 50px; }
65    frame_reg = r'\s*\d+%\s*{\s*[_a-zA-Z0-9-]+:(\s*[_a-zA-Z0-9-]+)+\s*;\s*}\s*'
66
67    def close_brace_on_new_line(line):
68      return (line.find('}') >= 0 and re.search(r'[^ }]', line) and
69              not re.match(frame_reg, line))
70
71    def colons_have_space_after(line):
72      return re.search(r'(?<!data):(?!//)\S[^;]+;\s*', line)
73
74    def favor_single_quotes(line):
75      return line.find('"') >= 0
76
77    # Shared between hex_could_be_shorter and rgb_if_not_gray.
78    hex_reg = (r'#([a-fA-F0-9]{3}|[a-fA-F0-9]{6})(?=[^_a-zA-Z0-9-]|$)'
79               r'(?!.*(?:{.*|,\s*)$)')
80
81    def hex_could_be_shorter(line):
82      m = re.search(hex_reg, line)
83      return (m and _is_gray(m.group(1)) and _collapseable_hex(m.group(1)))
84
85    small_seconds = r'(?:^|[^_a-zA-Z0-9-])(0?\.[0-9]+)s(?!-?[_a-zA-Z0-9-])'
86
87    def milliseconds_for_small_times(line):
88      return re.search(small_seconds, line)
89
90    def no_data_uris_in_source_files(line):
91      return re.search(r'\(\s*\'?\s*data:', line)
92
93    def one_rule_per_line(line):
94      return re.search(r'[_a-zA-Z0-9-](?<!data):(?!//)[^;]+;\s*[^ }]\s*', line)
95
96    any_reg = re.compile(r':(?:-webkit-)?any\(.*?\)', re.DOTALL)
97    multi_sels = re.compile(r'(?:}[\n\s]*)?([^,]+,(?=[^{}]+?{).*[,{])\s*$',
98                            re.MULTILINE)
99
100    def one_selector_per_line(contents):
101      errors = []
102      for b in re.finditer(multi_sels, re.sub(any_reg, '', contents)):
103        errors.append('    ' + b.group(1).strip().splitlines()[-1:][0])
104      return errors
105
106    def rgb_if_not_gray(line):
107      m = re.search(hex_reg, line)
108      return (m and not _is_gray(m.group(1)))
109
110    def suggest_ms_from_s(line):
111      ms = int(float(re.search(small_seconds, line).group(1)) * 1000)
112      return ' (replace with %dms)' % ms
113
114    def suggest_rgb_from_hex(line):
115      suggestions = ['rgb(%d, %d, %d)' % _rgb_from_hex(h.group(1))
116                     for h in re.finditer(hex_reg, line)]
117      return ' (replace with %s)' % ', '.join(suggestions)
118
119    def suggest_short_hex(line):
120      h = re.search(hex_reg, line).group(1)
121      return ' (replace with #%s)' % (h[0] + h[2] + h[4])
122
123    hsl = r'hsl\([^\)]*(?:[, ]|(?<=\())(?:0?\.?)?0%'
124    zeros = (r'^.*(?:^|\D)'
125             r'(?:\.0|0(?:\.0?|px|em|%|in|cm|mm|pc|pt|ex|deg|g?rad|m?s|k?hz))'
126             r'(?:\D|$)(?=[^{}]+?}).*$')
127
128    def zero_length_values(contents):
129      errors = []
130      for z in re.finditer(re.compile(zeros, re.MULTILINE), contents):
131        first_line = z.group(0).strip().splitlines()[0]
132        if not re.search(hsl, first_line):
133          errors.append('    ' + first_line)
134      return errors
135
136    added_or_modified_files_checks = [
137        {
138            'desc': 'Alphabetize properties and list vendor specific (i.e. '
139                    '-webkit) above standard.',
140            'test': alphabetize_props,
141            'multiline': True,
142        },
143        {
144            'desc': 'Start braces ({) end a selector, have a space before them '
145                    'and no rules after.',
146            'test': braces_have_space_before_and_nothing_after,
147        },
148        {
149            'desc': 'Classes use .dash-form.',
150            'test': classes_use_dashes,
151        },
152        {
153            'desc': 'Always put a rule closing brace (}) on a new line.',
154            'test': close_brace_on_new_line,
155        },
156        {
157            'desc': 'Colons (:) should have a space after them.',
158            'test': colons_have_space_after,
159        },
160        {
161            'desc': 'Use single quotes (\') instead of double quotes (") in '
162                    'strings.',
163            'test': favor_single_quotes,
164        },
165        {
166            'desc': 'Use abbreviated hex (#rgb) when in form #rrggbb.',
167            'test': hex_could_be_shorter,
168            'after': suggest_short_hex,
169        },
170        {
171            'desc': 'Use milliseconds for time measurements under 1 second.',
172            'test': milliseconds_for_small_times,
173            'after': suggest_ms_from_s,
174        },
175        {
176            'desc': 'Don\'t use data URIs in source files. Use grit instead.',
177            'test': no_data_uris_in_source_files,
178        },
179        {
180            'desc': 'One rule per line '
181                    '(what not to do: color: red; margin: 0;).',
182            'test': one_rule_per_line,
183        },
184        {
185            'desc': 'One selector per line (what not to do: a, b {}).',
186            'test': one_selector_per_line,
187            'multiline': True,
188        },
189        {
190            'desc': 'Use rgb() over #hex when not a shade of gray (like #333).',
191            'test': rgb_if_not_gray,
192            'after': suggest_rgb_from_hex,
193        },
194        {
195            'desc': 'Make all zero length terms (i.e. 0px) 0 unless inside of '
196                    'hsl() or part of @keyframe.',
197            'test': zero_length_values,
198            'multiline': True,
199        },
200    ]
201
202    results = []
203    affected_files = self.input_api.AffectedFiles(include_deletes=False,
204                                                  file_filter=self.file_filter)
205    files = []
206    for f in affected_files:
207      # Remove all /*comments*/, @at-keywords, and grit <if|include> tags; we're
208      # not using a real parser. TODO(dbeam): Check alpha in <if> blocks.
209      file_contents = _remove_all('\n'.join(f.new_contents))
210      files.append((f.filename, file_contents))
211
212    # Only look at CSS files for now.
213    for f in filter(lambda f: f[0].endswith('.css'), files):
214      file_errors = []
215      for check in added_or_modified_files_checks:
216        # If the check is multiline, it receieves the whole file and gives us
217        # back a list of things wrong. If the check isn't multiline, we pass it
218        # each line and the check returns something truthy if there's an issue.
219        if ('multiline' in check and check['multiline']):
220          check_errors = check['test'](f[1])
221          if len(check_errors) > 0:
222            # There are currently no multiline checks with ['after'].
223            file_errors.append(
224                '- %s\n%s' % (check['desc'], '\n'.join(check_errors).rstrip()))
225        else:
226          check_errors = []
227          lines = f[1].splitlines()
228          for lnum in range(0, len(lines)):
229            line = lines[lnum]
230            if check['test'](line):
231              error = '    ' + line.strip()
232              if 'after' in check:
233                error += check['after'](line)
234              check_errors.append(error)
235          if len(check_errors) > 0:
236            file_errors.append(
237                '- %s\n%s' % (check['desc'], '\n'.join(check_errors)))
238      if file_errors:
239        results.append(self.output_api.PresubmitPromptWarning(
240            '%s:\n%s' % (f[0], '\n\n'.join(file_errors))))
241
242    if results:
243      # Add your name if you're here often mucking around in the code.
244      authors = ['dbeam@chromium.org']
245      results.append(self.output_api.PresubmitNotifyResult(
246          'Was the CSS checker useful? Send feedback or hate mail to %s.' %
247          ', '.join(authors)))
248
249    return results
250