+def CheckForNonConstReference(filename, clean_lines, linenum,
+ nesting_state, error):
+ """Check for non-const references.
+
+ Separate from CheckLanguage since it scans backwards from current
+ line, instead of scanning forward.
+
+ Args:
+ filename: The name of the current file.
+ clean_lines: A CleansedLines instance containing the file.
+ linenum: The number of the line to check.
+ nesting_state: A _NestingState instance which maintains information about
+ the current stack of nested blocks being parsed.
+ error: The function to call with any errors found.
+ """
+ # Do nothing if there is no '&' on current line.
+ line = clean_lines.elided[linenum]
+ if '&' not in line:
+ return
+
+ # Long type names may be broken across multiple lines, usually in one
+ # of these forms:
+ # LongType
+ # ::LongTypeContinued &identifier
+ # LongType::
+ # LongTypeContinued &identifier
+ # LongType<
+ # ...>::LongTypeContinued &identifier
+ #
+ # If we detected a type split across two lines, join the previous
+ # line to current line so that we can match const references
+ # accordingly.
+ #
+ # Note that this only scans back one line, since scanning back
+ # arbitrary number of lines would be expensive. If you have a type
+ # that spans more than 2 lines, please use a typedef.
+ if linenum > 1:
+ previous = None
+ if Match(r'\s*::(?:[\w<>]|::)+\s*&\s*\S', line):
+ # previous_line\n + ::current_line
+ previous = Search(r'\b((?:const\s*)?(?:[\w<>]|::)+[\w<>])\s*$',
+ clean_lines.elided[linenum - 1])
+ elif Match(r'\s*[a-zA-Z_]([\w<>]|::)+\s*&\s*\S', line):
+ # previous_line::\n + current_line
+ previous = Search(r'\b((?:const\s*)?(?:[\w<>]|::)+::)\s*$',
+ clean_lines.elided[linenum - 1])
+ if previous:
+ line = previous.group(1) + line.lstrip()
+ else:
+ # Check for templated parameter that is split across multiple lines
+ endpos = line.rfind('>')
+ if endpos > -1:
+ (_, startline, startpos) = ReverseCloseExpression(
+ clean_lines, linenum, endpos)
+ if startpos > -1 and startline < linenum:
+ # Found the matching < on an earlier line, collect all
+ # pieces up to current line.
+ line = ''
+ for i in xrange(startline, linenum + 1):
+ line += clean_lines.elided[i].strip()
+
+ # Check for non-const references in function parameters. A single '&' may
+ # found in the following places:
+ # inside expression: binary & for bitwise AND
+ # inside expression: unary & for taking the address of something
+ # inside declarators: reference parameter
+ # We will exclude the first two cases by checking that we are not inside a
+ # function body, including one that was just introduced by a trailing '{'.
+ # TODO(unknwon): Doesn't account for preprocessor directives.
+ # TODO(unknown): Doesn't account for 'catch(Exception& e)' [rare].
+ check_params = False
+ if not nesting_state.stack:
+ check_params = True # top level
+ elif (isinstance(nesting_state.stack[-1], _ClassInfo) or
+ isinstance(nesting_state.stack[-1], _NamespaceInfo)):
+ check_params = True # within class or namespace
+ elif Match(r'.*{\s*$', line):
+ if (len(nesting_state.stack) == 1 or
+ isinstance(nesting_state.stack[-2], _ClassInfo) or
+ isinstance(nesting_state.stack[-2], _NamespaceInfo)):
+ check_params = True # just opened global/class/namespace block
+ # We allow non-const references in a few standard places, like functions
+ # called "swap()" or iostream operators like "<<" or ">>". Do not check
+ # those function parameters.
+ #
+ # We also accept & in static_assert, which looks like a function but
+ # it's actually a declaration expression.
+ whitelisted_functions = (r'(?:[sS]wap(?:<\w:+>)?|'
+ r'operator\s*[<>][<>]|'
+ r'static_assert|COMPILE_ASSERT'
+ r')\s*\(')
+ if Search(whitelisted_functions, line):
+ check_params = False
+ elif not Search(r'\S+\([^)]*$', line):
+ # Don't see a whitelisted function on this line. Actually we
+ # didn't see any function name on this line, so this is likely a
+ # multi-line parameter list. Try a bit harder to catch this case.
+ for i in xrange(2):
+ if (linenum > i and
+ Search(whitelisted_functions, clean_lines.elided[linenum - i - 1])):
+ check_params = False
+ break
+
+ if check_params:
+ decls = ReplaceAll(r'{[^}]*}', ' ', line) # exclude function body
+ for parameter in re.findall(_RE_PATTERN_REF_PARAM, decls):
+ if not Match(_RE_PATTERN_CONST_REF_PARAM, parameter):
+ error(filename, linenum, 'runtime/references', 2,
+ 'Is this a non-const reference? '
+ 'If so, make const or use a pointer: ' +
+ ReplaceAll(' *<', '<', parameter))
+