all: DRY for lint descriptions

* use the rustc style for lint descriptions
* add a script to parse all lint descriptions
  and put the generated table into README

util/update_readme.py

@@ -0,0 +1,80 @@
+# Generate a Markdown table of all lints, and put it in README.md.
+# With -n option, only print the new table to stdout.
+
+import os
+import re
+import sys
+
+declare_lint_re = re.compile(r'''
+    declare_lint! \s* [{(] \s*
+    pub \s+ (?P<name>[A-Z_]+) \s*,\s*
+    (?P<level>Forbid|Deny|Warn|Allow) \s*,\s*
+    " (?P<desc>(?:[^"\\]+|\\.)*) " \s* [})]
+''', re.X | re.S)
+
+nl_escape_re = re.compile(r'\\\n\s*')
+
+
+def collect(lints, fp):
+    code = fp.read()
+    for match in declare_lint_re.finditer(code):
+        # remove \-newline escapes from description string
+        desc = nl_escape_re.sub('', match.group('desc'))
+        lints.append((match.group('name').lower(),
+                      match.group('level').lower(),
+                      desc.replace('\\"', '"')))
+
+
+def write_tbl(lints, fp):
+    # first and third column widths
+    w_name = max(len(l[0]) for l in lints)
+    w_desc = max(len(l[2]) for l in lints)
+    # header and underline
+    fp.write('%-*s | default | meaning\n' % (w_name, 'name'))
+    fp.write('%s-|-%s-|-%s\n' % ('-' * w_name, '-' * 7, '-' * w_desc))
+    # one table row per lint
+    for (name, default, meaning) in sorted(lints):
+        fp.write('%-*s | %-7s | %s\n' % (w_name, name, default, meaning))
+
+
+def main(print_only=False):
+    lints = []
+
+    # check directory
+    if not os.path.isfile('src/lib.rs'):
+        print('Error: call this script from clippy checkout directory!')
+        return
+
+    # collect all lints from source files
+    for root, dirs, files in os.walk('src'):
+        for fn in files:
+            if fn.endswith('.rs'):
+                with open(os.path.join(root, fn)) as fp:
+                    collect(lints, fp)
+
+    if print_only:
+        write_tbl(lints, sys.stdout)
+        return
+
+    # read current README.md content
+    with open('README.md') as fp:
+        lines = list(fp)
+
+    # replace old table with new table
+    with open('README.md', 'w') as fp:
+        in_old_tbl = False
+        for line in lines:
+            if line.replace(' ', '').strip() == 'name|default|meaning':
+                # old table starts here
+                write_tbl(lints, fp)
+                in_old_tbl = True
+            if in_old_tbl:
+                # the old table is finished by an empty line
+                if line.strip():
+                    continue
+                in_old_tbl = False
+            fp.write(line)
+
+
+if __name__ == '__main__':
+    main(print_only='-n' in sys.argv)