chrome/browser/web_dev_style/css_checker.py

   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
   5 """Presubmit script for Chromium WebUI resources.
   6
   7 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
   8 for more details about the presubmit API built into depot_tools, and see
   9 http://www.chromium.org/developers/web-development-style-guide for the rules
  10 we're checking against here.
  11 """
  12
  13 # TODO(dbeam): Real CSS parser? https://github.com/danbeam/css-py/tree/css3
  14
  15 class CSSChecker(object):
  16   def __init__(self, input_api, output_api, file_filter=None):
  17     self.input_api = input_api
  18     self.output_api = output_api
  19     self.file_filter = file_filter
  20
  21   def RunChecks(self):
  22     # We use this a lot, so make a nick name variable.
  23     re = self.input_api.re
  24
  25     def _collapseable_hex(s):
  26       return (len(s) == 6 and s[0] == s[1] and s[2] == s[3] and s[4] == s[5])
  27
  28     def _is_gray(s):
  29       return s[0] == s[1] == s[2] if len(s) == 3 else s[0:2] == s[2:4] == s[4:6]
  30
  31     def _remove_all(s):
  32       s = _remove_grit(s)
  33       s = _remove_ats(s)
  34       s = _remove_comments(s)
  35       s = _remove_template_expressions(s)
  36       s = _remove_mixins(s)
  37       return s
  38
  39     def _remove_ats(s):
  40       at_reg = re.compile(r"""
  41           @(?!\d+x\b)\w+[^'"]*?{  # @at-keyword selector junk {, not @2x
  42           (.*{.*?})+              # inner { curly } blocks, rules, and selector
  43           .*?}                    # stuff up to the first end curly }
  44           """,
  45           re.DOTALL | re.VERBOSE)
  46       return at_reg.sub('\\1', s)
  47
  48     def _remove_comments(s):
  49       return re.sub(re.compile(r'/\*.*?\*/', re.DOTALL), '', s)
  50
  51     def _remove_mixins(s):
  52       return re.sub(re.compile(r'--[\d\w-]+: {.*?};', re.DOTALL), '', s)
  53
  54     def _remove_template_expressions(s):
  55       return re.sub(re.compile(r'\${[^}]*}', re.DOTALL), '', s)
  56
  57     def _remove_grit(s):
  58       grit_reg = re.compile(r"""
  59           <if[^>]+>.*?<\s*/\s*if[^>]*>|  # <if> contents </if>
  60           <include[^>]+>                 # <include>
  61           """,
  62           re.DOTALL | re.VERBOSE)
  63       return re.sub(grit_reg, '', s)
  64
  65     def _rgb_from_hex(s):
  66       if len(s) == 3:
  67         r, g, b = s[0] + s[0], s[1] + s[1], s[2] + s[2]
  68       else:
  69         r, g, b = s[0:2], s[2:4], s[4:6]
  70       return int(r, base=16), int(g, base=16), int(b, base=16)
  71
  72     def _strip_prefix(s):
  73       return re.sub(r'^-(?:o|ms|moz|khtml|webkit)-', '', s)
  74
  75     def alphabetize_props(contents):
  76       errors = []
  77       # TODO(dbeam): make this smart enough to detect issues in mixins.
  78       for rule in re.finditer(r'{(.*?)}', contents, re.DOTALL):
  79         semis = map(lambda t: t.strip(), rule.group(1).split(';'))[:-1]
  80         rules = filter(lambda r: ': ' in r, semis)
  81         props = map(lambda r: r[0:r.find(':')], rules)
  82         if props != sorted(props):
  83           errors.append('    %s;\n' % (';\n    '.join(rules)))
  84       return errors
  85
  86     def braces_have_space_before_and_nothing_after(line):
  87       brace_space_reg = re.compile(r"""
  88           (?:^|\S){|  # selector{ or selector\n{ or
  89           {\s*\S+\s*  # selector { with stuff after it
  90           $           # must be at the end of a line
  91           """,
  92           re.VERBOSE)
  93       return brace_space_reg.search(line)
  94
  95     def classes_use_dashes(line):
  96       # Intentionally dumbed down version of CSS 2.1 grammar for class without
  97       # non-ASCII, escape chars, or whitespace.
  98       class_reg = re.compile(r"""
  99           \.(-?[\w-]+).*  # ., then maybe -, then alpha numeric and -
 100           [,{]\s*$        # selectors should end with a , or {
 101           """,
 102           re.VERBOSE)
 103       m = class_reg.search(line)
 104       if not m:
 105         return False
 106       class_name = m.group(1)
 107       return class_name.lower() != class_name or '_' in class_name
 108
 109     end_mixin_reg = re.compile(r'\s*};\s*$')
 110
 111     def close_brace_on_new_line(line):
 112       # Ignore single frames in a @keyframe, i.e. 0% { margin: 50px; }
 113       frame_reg = re.compile(r"""
 114           \s*(from|to|\d+%)\s*{   # 50% {
 115           \s*[\w-]+:              # rule:
 116           (\s*[\w\(\), -]+)+\s*;  # value;
 117           \s*}\s*                 # }
 118           """,
 119           re.VERBOSE)
 120       return ('}' in line and re.search(r'[^ }]', line) and
 121               not frame_reg.match(line) and not end_mixin_reg.match(line))
 122
 123     def colons_have_space_after(line):
 124       colon_space_reg = re.compile(r"""
 125           (?<!data)    # ignore data URIs
 126           :(?!//)      # ignore url(http://), etc.
 127           \S[^;]+;\s*  # only catch one-line rules for now
 128           """,
 129           re.VERBOSE)
 130       return colon_space_reg.search(line)
 131
 132     def favor_single_quotes(line):
 133       return '"' in line
 134
 135     # Shared between hex_could_be_shorter and rgb_if_not_gray.
 136     hex_reg = re.compile(r"""
 137         \#([a-fA-F0-9]{3}|[a-fA-F0-9]{6})  # pound followed by 3 or 6 hex digits
 138         (?=[^\w-]|$)                       # no more alphanum chars or at EOL
 139         (?!.*(?:{.*|,\s*)$)                # not in a selector
 140         """,
 141         re.VERBOSE)
 142
 143     def hex_could_be_shorter(line):
 144       m = hex_reg.search(line)
 145       return (m and _is_gray(m.group(1)) and _collapseable_hex(m.group(1)))
 146
 147     def rgb_if_not_gray(line):
 148       m = hex_reg.search(line)
 149       return (m and not _is_gray(m.group(1)))
 150
 151     small_seconds_reg = re.compile(r"""
 152         (?:^|[^\w-])   # start of a line or a non-alphanumeric char
 153         (0?\.[0-9]+)s  # 1.0s
 154         (?!-?[\w-])    # no following - or alphanumeric chars
 155         """,
 156         re.VERBOSE)
 157
 158     def milliseconds_for_small_times(line):
 159       return small_seconds_reg.search(line)
 160
 161     def suggest_ms_from_s(line):
 162       ms = int(float(small_seconds_reg.search(line).group(1)) * 1000)
 163       return ' (replace with %dms)' % ms
 164
 165     def no_data_uris_in_source_files(line):
 166       return re.search(r'\(\s*\s*data:', line)
 167
 168     def no_quotes_in_url(line):
 169       return re.search('url\s*\(\s*["\']', line, re.IGNORECASE)
 170
 171     def one_rule_per_line(line):
 172       one_rule_reg = re.compile(r"""
 173           [\w-](?<!data):  # a rule: but no data URIs
 174           (?!//)[^;]+;     # value; ignoring colons in protocols:// and };
 175           \s*[^ }]\s*      # any non-space after the end colon
 176           """,
 177           re.VERBOSE)
 178       return one_rule_reg.search(line) and not end_mixin_reg.match(line)
 179
 180     def pseudo_elements_double_colon(contents):
 181       pseudo_elements = ['after',
 182                          'before',
 183                          'calendar-picker-indicator',
 184                          'color-swatch',
 185                          'color-swatch-wrapper',
 186                          'date-and-time-container',
 187                          'date-and-time-value',
 188                          'datetime-edit',
 189                          'datetime-edit-ampm-field',
 190                          'datetime-edit-day-field',
 191                          'datetime-edit-hour-field',
 192                          'datetime-edit-millisecond-field',
 193                          'datetime-edit-minute-field',
 194                          'datetime-edit-month-field',
 195                          'datetime-edit-second-field',
 196                          'datetime-edit-text',
 197                          'datetime-edit-week-field',
 198                          'datetime-edit-year-field',
 199                          'details-marker',
 200                          'file-upload-button',
 201                          'first-letter',
 202                          'first-line',
 203                          'inner-spin-button',
 204                          'input-placeholder',
 205                          'input-speech-button',
 206                          'keygen-select',
 207                          'media-slider-container',
 208                          'media-slider-thumb',
 209                          'meter-bar',
 210                          'meter-even-less-good-value',
 211                          'meter-inner-element',
 212                          'meter-optimum-value',
 213                          'meter-suboptimum-value',
 214                          'progress-bar',
 215                          'progress-inner-element',
 216                          'progress-value',
 217                          'resizer',
 218                          'scrollbar',
 219                          'scrollbar-button',
 220                          'scrollbar-corner',
 221                          'scrollbar-thumb',
 222                          'scrollbar-track',
 223                          'scrollbar-track-piece',
 224                          'search-cancel-button',
 225                          'search-decoration',
 226                          'search-results-button',
 227                          'search-results-decoration',
 228                          'selection',
 229                          'slider-container',
 230                          'slider-runnable-track',
 231                          'slider-thumb',
 232                          'textfield-decoration-container',
 233                          'validation-bubble',
 234                          'validation-bubble-arrow',
 235                          'validation-bubble-arrow-clipper',
 236                          'validation-bubble-heading',
 237                          'validation-bubble-message',
 238                          'validation-bubble-text-block']
 239       pseudo_reg = re.compile(r"""
 240           (?<!:):       # a single colon, i.e. :after but not ::after
 241           ([a-zA-Z-]+)  # a pseudo element, class, or function
 242           (?=[^{}]+?{)  # make sure a selector, not inside { rules }
 243           """,
 244           re.MULTILINE | re.VERBOSE)
 245       errors = []
 246       for p in re.finditer(pseudo_reg, contents):
 247         pseudo = p.group(1).strip().splitlines()[0]
 248         if _strip_prefix(pseudo.lower()) in pseudo_elements:
 249           errors.append('    :%s (should be ::%s)' % (pseudo, pseudo))
 250       return errors
 251
 252     def one_selector_per_line(contents):
 253       any_reg = re.compile(r"""
 254           :(?:-webkit-)?any\(.*?\)  # :-webkit-any(a, b, i) selector
 255           """,
 256           re.DOTALL | re.VERBOSE)
 257       multi_sels_reg = re.compile(r"""
 258           (?:}\s*)?            # ignore 0% { blah: blah; }, from @keyframes
 259           ([^,]+,(?=[^{}]+?{)  # selector junk {, not in a { rule }
 260           .*[,{])\s*$          # has to end with , or {
 261           """,
 262           re.MULTILINE | re.VERBOSE)
 263       errors = []
 264       for b in re.finditer(multi_sels_reg, re.sub(any_reg, '', contents)):
 265         errors.append('    ' + b.group(1).strip().splitlines()[-1:][0])
 266       return errors
 267
 268     def suggest_rgb_from_hex(line):
 269       suggestions = ['rgb(%d, %d, %d)' % _rgb_from_hex(h.group(1))
 270           for h in re.finditer(hex_reg, line)]
 271       return ' (replace with %s)' % ', '.join(suggestions)
 272
 273     def suggest_short_hex(line):
 274       h = hex_reg.search(line).group(1)
 275       return ' (replace with #%s)' % (h[0] + h[2] + h[4])
 276
 277     webkit_before_or_after_reg = re.compile(r'-webkit-(\w+-)(after|before):')
 278
 279     def suggest_top_or_bottom(line):
 280       prop, pos = webkit_before_or_after_reg.search(line).groups()
 281       top_or_bottom = 'top' if pos == 'before' else 'bottom'
 282       return ' (replace with %s)' % (prop + top_or_bottom)
 283
 284     def webkit_before_or_after(line):
 285       return webkit_before_or_after_reg.search(line)
 286
 287     def zero_width_lengths(contents):
 288       hsl_reg = re.compile(r"""
 289           hsl\([^\)]*       # hsl(maybestuff
 290           (?:[, ]|(?<=\())  # a comma or space not followed by a (
 291           (?:0?\.?)?0%      # some equivalent to 0%
 292           """,
 293           re.VERBOSE)
 294       zeros_reg = re.compile(r"""
 295           ^.*(?:^|[^0-9.])              # start/non-number
 296           (?:\.0|0(?:\.0?               # .0, 0, or 0.0
 297           |px|em|%|in|cm|mm|pc|pt|ex))  # a length unit
 298           (?:\D|$)                      # non-number/end
 299           (?=[^{}]+?}).*$               # only { rules }
 300           """,
 301           re.MULTILINE | re.VERBOSE)
 302       errors = []
 303       for z in re.finditer(zeros_reg, contents):
 304         first_line = z.group(0).strip().splitlines()[0]
 305         if not hsl_reg.search(first_line):
 306           errors.append('    ' + first_line)
 307       return errors
 308
 309     # NOTE: Currently multi-line checks don't support 'after'. Instead, add
 310     # suggestions while parsing the file so another pass isn't necessary.
 311     added_or_modified_files_checks = [
 312         { 'desc': 'Alphabetize properties and list vendor specific (i.e. '
 313                   '-webkit) above standard.',
 314           'test': alphabetize_props,
 315           'multiline': True,
 316         },
 317         { 'desc': 'Start braces ({) end a selector, have a space before them '
 318                   'and no rules after.',
 319           'test': braces_have_space_before_and_nothing_after,
 320         },
 321         { 'desc': 'Classes use .dash-form.',
 322           'test': classes_use_dashes,
 323         },
 324         { 'desc': 'Always put a rule closing brace (}) on a new line.',
 325           'test': close_brace_on_new_line,
 326         },
 327         { 'desc': 'Colons (:) should have a space after them.',
 328           'test': colons_have_space_after,
 329         },
 330         { 'desc': 'Use single quotes (\') instead of double quotes (") in '
 331                   'strings.',
 332           'test': favor_single_quotes,
 333         },
 334         { 'desc': 'Use abbreviated hex (#rgb) when in form #rrggbb.',
 335           'test': hex_could_be_shorter,
 336           'after': suggest_short_hex,
 337         },
 338         { 'desc': 'Use milliseconds for time measurements under 1 second.',
 339           'test': milliseconds_for_small_times,
 340           'after': suggest_ms_from_s,
 341         },
 342         { 'desc': "Don't use data URIs in source files. Use grit instead.",
 343           'test': no_data_uris_in_source_files,
 344         },
 345         { 'desc': "Don't use quotes in url().",
 346           'test': no_quotes_in_url,
 347         },
 348         { 'desc': 'One rule per line (what not to do: color: red; margin: 0;).',
 349           'test': one_rule_per_line,
 350         },
 351         { 'desc': 'One selector per line (what not to do: a, b {}).',
 352           'test': one_selector_per_line,
 353           'multiline': True,
 354         },
 355         { 'desc': 'Pseudo-elements should use double colon (i.e. ::after).',
 356           'test': pseudo_elements_double_colon,
 357           'multiline': True,
 358         },
 359         { 'desc': 'Use rgb() over #hex when not a shade of gray (like #333).',
 360           'test': rgb_if_not_gray,
 361           'after': suggest_rgb_from_hex,
 362         },
 363         { 'desc': 'Use *-top/bottom instead of -webkit-*-before/after.',
 364           'test': webkit_before_or_after,
 365           'after': suggest_top_or_bottom,
 366         },
 367         { 'desc': 'Use "0" for zero-width lengths (i.e. 0px -> 0)',
 368           'test': zero_width_lengths,
 369           'multiline': True,
 370         },
 371     ]
 372
 373     results = []
 374     affected_files = self.input_api.AffectedFiles(include_deletes=False,
 375                                                   file_filter=self.file_filter)
 376     files = []
 377     for f in affected_files:
 378       # Remove all /*comments*/, @at-keywords, and grit <if|include> tags; we're
 379       # not using a real parser. TODO(dbeam): Check alpha in <if> blocks.
 380       file_contents = _remove_all('\n'.join(f.NewContents()))
 381       files.append((f.LocalPath(), file_contents))
 382
 383     # Only look at CSS files for now.
 384     for f in filter(lambda f: f[0].endswith('.css'), files):
 385       file_errors = []
 386       for check in added_or_modified_files_checks:
 387         # If the check is multiline, it receieves the whole file and gives us
 388         # back a list of things wrong. If the check isn't multiline, we pass it
 389         # each line and the check returns something truthy if there's an issue.
 390         if ('multiline' in check and check['multiline']):
 391           assert not 'after' in check
 392           check_errors = check['test'](f[1])
 393           if len(check_errors) > 0:
 394             file_errors.append('- %s\n%s' %
 395                 (check['desc'], '\n'.join(check_errors).rstrip()))
 396         else:
 397           check_errors = []
 398           lines = f[1].splitlines()
 399           for lnum, line in enumerate(lines):
 400             if check['test'](line):
 401               error = '    ' + line.strip()
 402               if 'after' in check:
 403                 error += check['after'](line)
 404               check_errors.append(error)
 405           if len(check_errors) > 0:
 406             file_errors.append('- %s\n%s' %
 407                 (check['desc'], '\n'.join(check_errors)))
 408       if file_errors:
 409         results.append(self.output_api.PresubmitPromptWarning(
 410             '%s:\n%s' % (f[0], '\n\n'.join(file_errors))))
 411
 412     return results