waf

c_preproc.py (27592B)

---

 #!/usr/bin/env python
 # encoding: utf-8
 # Thomas Nagy, 2006-2018 (ita)
 
 """
 C/C++ preprocessor for finding dependencies
 
 Reasons for using the Waf preprocessor by default
 
 #. Some c/c++ extensions (Qt) require a custom preprocessor for obtaining the dependencies (.moc files)
 #. Not all compilers provide .d files for obtaining the dependencies (portability)
 #. A naive file scanner will not catch the constructs such as "#include foo()"
 #. A naive file scanner will catch unnecessary dependencies (change an unused header -> recompile everything)
 
 Regarding the speed concerns:
 
 * the preprocessing is performed only when files must be compiled
 * the macros are evaluated only for #if/#elif/#include
 * system headers are not scanned by default
 
 Now if you do not want the Waf preprocessor, the tool +gccdeps* uses the .d files produced
 during the compilation to track the dependencies (useful when used with the boost libraries).
 It only works with gcc >= 4.4 though.
 
 A dumb preprocessor is also available in the tool *c_dumbpreproc*
 """
 # TODO: more varargs, pragma once
 
 import re, string, traceback
 from waflib import Logs, Utils, Errors
 
 class PreprocError(Errors.WafError):
 	pass
 
 FILE_CACHE_SIZE = 100000
 LINE_CACHE_SIZE = 100000
 
 POPFILE = '-'
 "Constant representing a special token used in :py:meth:`waflib.Tools.c_preproc.c_parser.start` iteration to switch to a header read previously"
 
 recursion_limit = 150
 "Limit on the amount of files to read in the dependency scanner"
 
 go_absolute = False
 "Set to True to track headers on files in /usr/include, else absolute paths are ignored (but it becomes very slow)"
 
 standard_includes = ['/usr/local/include', '/usr/include']
 if Utils.is_win32:
 	standard_includes = []
 
 use_trigraphs = 0
 """Apply trigraph rules (False by default)"""
 
 # obsolete, do not use
 strict_quotes = 0
 
 g_optrans = {
 'not':'!',
 'not_eq':'!',
 'and':'&&',
 'and_eq':'&=',
 'or':'||',
 'or_eq':'|=',
 'xor':'^',
 'xor_eq':'^=',
 'bitand':'&',
 'bitor':'|',
 'compl':'~',
 }
 """Operators such as and/or/xor for c++. Set an empty dict to disable."""
 
 # ignore #warning and #error
 re_lines = re.compile(
 	'^[ \t]*(?:#|%:)[ \t]*(ifdef|ifndef|if|else|elif|endif|include|import|define|undef|pragma)[ \t]*(.*)\r*$',
 	re.IGNORECASE | re.MULTILINE)
 """Match #include lines"""
 
 re_mac = re.compile(r"^[a-zA-Z_]\w*")
 """Match macro definitions"""
 
 re_fun = re.compile('^[a-zA-Z_][a-zA-Z0-9_]*[(]')
 """Match macro functions"""
 
 re_pragma_once = re.compile(r'^\s*once\s*', re.IGNORECASE)
 """Match #pragma once statements"""
 
 re_nl = re.compile('\\\\\r*\n', re.MULTILINE)
 """Match newlines"""
 
 re_cpp = re.compile(r'//.*?$|/\*.*?\*/|\'(?:\\.|[^\\\'])*\'|"(?:\\.|[^\\"])*"', re.DOTALL | re.MULTILINE )
 """Filter C/C++ comments"""
 
 trig_def = [('??'+a, b) for a, b in zip("=-/!'()<>", r'#~\|^[]{}')]
 """Trigraph definitions"""
 
 chr_esc = {'0':0, 'a':7, 'b':8, 't':9, 'n':10, 'f':11, 'v':12, 'r':13, '\\':92, "'":39}
 """Escape characters"""
 
 NUM   = 'i'
 """Number token"""
 
 OP    = 'O'
 """Operator token"""
 
 IDENT = 'T'
 """Identifier token"""
 
 STR   = 's'
 """String token"""
 
 CHAR  = 'c'
 """Character token"""
 
 tok_types = [NUM, STR, IDENT, OP]
 """Token types"""
 
 exp_types = [
 	r"""0[xX](?P<hex>[a-fA-F0-9]+)(?P<qual1>[uUlL]*)|L*?'(?P<char>(\\.|[^\\'])+)'|(?P<n1>\d+)[Ee](?P<exp0>[+-]*?\d+)(?P<float0>[fFlL]*)|(?P<n2>\d*\.\d+)([Ee](?P<exp1>[+-]*?\d+))?(?P<float1>[fFlL]*)|(?P<n4>\d+\.\d*)([Ee](?P<exp2>[+-]*?\d+))?(?P<float2>[fFlL]*)|(?P<oct>0*)(?P<n0>\d+)(?P<qual2>[uUlL]*)""",
 	r'L?"([^"\\]|\\.)*"',
 	r'[a-zA-Z_]\w*',
 	r'%:%:|<<=|>>=|\.\.\.|<<|<%|<:|<=|>>|>=|\+\+|\+=|--|->|-=|\*=|/=|%:|%=|%>|==|&&|&=|\|\||\|=|\^=|:>|!=|##|[\(\)\{\}\[\]<>\?\|\^\*\+&=:!#;,%/\-\?\~\.]',
 ]
 """Expression types"""
 
 re_clexer = re.compile('|'.join(["(?P<%s>%s)" % (name, part) for name, part in zip(tok_types, exp_types)]), re.M)
 """Match expressions into tokens"""
 
 accepted  = 'a'
 """Parser state is *accepted*"""
 
 ignored   = 'i'
 """Parser state is *ignored*, for example preprocessor lines in an #if 0 block"""
 
 undefined = 'u'
 """Parser state is *undefined* at the moment"""
 
 skipped   = 's'
 """Parser state is *skipped*, for example preprocessor lines in a #elif 0 block"""
 
 def repl(m):
 	"""Replace function used with :py:attr:`waflib.Tools.c_preproc.re_cpp`"""
 	s = m.group()
 	if s[0] == '/':
 		return ' '
 	return s
 
 prec = {}
 """
 Operator precedence rules required for parsing expressions of the form::
 
 	#if 1 && 2 != 0
 """
 ops = ['* / %', '+ -', '<< >>', '< <= >= >', '== !=', '& | ^', '&& ||', ',']
 for x, syms in enumerate(ops):
 	for u in syms.split():
 		prec[u] = x
 
 def reduce_nums(val_1, val_2, val_op):
 	"""
 	Apply arithmetic rules to compute a result
 
 	:param val1: input parameter
 	:type val1: int or string
 	:param val2: input parameter
 	:type val2: int or string
 	:param val_op: C operator in *+*, */*, *-*, etc
 	:type val_op: string
 	:rtype: int
 	"""
 	#print val_1, val_2, val_op
 
 	# now perform the operation, make certain a and b are numeric
 	try:
 		a = 0 + val_1
 	except TypeError:
 		a = int(val_1)
 	try:
 		b = 0 + val_2
 	except TypeError:
 		b = int(val_2)
 
 	d = val_op
 	if d == '%':
 		c = a % b
 	elif d=='+':
 		c = a + b
 	elif d=='-':
 		c = a - b
 	elif d=='*':
 		c = a * b
 	elif d=='/':
 		c = a / b
 	elif d=='^':
 		c = a ^ b
 	elif d=='==':
 		c = int(a == b)
 	elif d=='|'  or d == 'bitor':
 		c = a | b
 	elif d=='||' or d == 'or' :
 		c = int(a or b)
 	elif d=='&'  or d == 'bitand':
 		c = a & b
 	elif d=='&&' or d == 'and':
 		c = int(a and b)
 	elif d=='!=' or d == 'not_eq':
 		c = int(a != b)
 	elif d=='^'  or d == 'xor':
 		c = int(a^b)
 	elif d=='<=':
 		c = int(a <= b)
 	elif d=='<':
 		c = int(a < b)
 	elif d=='>':
 		c = int(a > b)
 	elif d=='>=':
 		c = int(a >= b)
 	elif d=='<<':
 		c = a << b
 	elif d=='>>':
 		c = a >> b
 	else:
 		c = 0
 	return c
 
 def get_num(lst):
 	"""
 	Try to obtain a number from a list of tokens. The token types are defined in :py:attr:`waflib.Tools.ccroot.tok_types`.
 
 	:param lst: list of preprocessor tokens
 	:type lst: list of tuple (tokentype, value)
 	:return: a pair containing the number and the rest of the list
 	:rtype: tuple(value, list)
 	"""
 	if not lst:
 		raise PreprocError('empty list for get_num')
 	(p, v) = lst[0]
 	if p == OP:
 		if v == '(':
 			count_par = 1
 			i = 1
 			while i < len(lst):
 				(p, v) = lst[i]
 
 				if p == OP:
 					if v == ')':
 						count_par -= 1
 						if count_par == 0:
 							break
 					elif v == '(':
 						count_par += 1
 				i += 1
 			else:
 				raise PreprocError('rparen expected %r' % lst)
 
 			(num, _) = get_term(lst[1:i])
 			return (num, lst[i+1:])
 
 		elif v == '+':
 			return get_num(lst[1:])
 		elif v == '-':
 			num, lst = get_num(lst[1:])
 			return (reduce_nums('-1', num, '*'), lst)
 		elif v == '!':
 			num, lst = get_num(lst[1:])
 			return (int(not int(num)), lst)
 		elif v == '~':
 			num, lst = get_num(lst[1:])
 			return (~ int(num), lst)
 		else:
 			raise PreprocError('Invalid op token %r for get_num' % lst)
 	elif p == NUM:
 		return v, lst[1:]
 	elif p == IDENT:
 		# all macros should have been replaced, remaining identifiers eval to 0
 		return 0, lst[1:]
 	else:
 		raise PreprocError('Invalid token %r for get_num' % lst)
 
 def get_term(lst):
 	"""
 	Evaluate an expression recursively, for example::
 
 		1+1+1 -> 2+1 -> 3
 
 	:param lst: list of tokens
 	:type lst: list of tuple(token, value)
 	:return: the value and the remaining tokens
 	:rtype: value, list
 	"""
 
 	if not lst:
 		raise PreprocError('empty list for get_term')
 	num, lst = get_num(lst)
 	if not lst:
 		return (num, [])
 	(p, v) = lst[0]
 	if p == OP:
 		if v == ',':
 			# skip
 			return get_term(lst[1:])
 		elif v == '?':
 			count_par = 0
 			i = 1
 			while i < len(lst):
 				(p, v) = lst[i]
 
 				if p == OP:
 					if v == ')':
 						count_par -= 1
 					elif v == '(':
 						count_par += 1
 					elif v == ':':
 						if count_par == 0:
 							break
 				i += 1
 			else:
 				raise PreprocError('rparen expected %r' % lst)
 
 			if int(num):
 				return get_term(lst[1:i])
 			else:
 				return get_term(lst[i+1:])
 
 		else:
 			num2, lst = get_num(lst[1:])
 
 			if not lst:
 				# no more tokens to process
 				num2 = reduce_nums(num, num2, v)
 				return get_term([(NUM, num2)] + lst)
 
 			# operator precedence
 			p2, v2 = lst[0]
 			if p2 != OP:
 				raise PreprocError('op expected %r' % lst)
 
 			if prec[v2] >= prec[v]:
 				num2 = reduce_nums(num, num2, v)
 				return get_term([(NUM, num2)] + lst)
 			else:
 				num3, lst = get_num(lst[1:])
 				num3 = reduce_nums(num2, num3, v2)
 				return get_term([(NUM, num), (p, v), (NUM, num3)] + lst)
 
 
 	raise PreprocError('cannot reduce %r' % lst)
 
 def reduce_eval(lst):
 	"""
 	Take a list of tokens and output true or false for #if/#elif conditions.
 
 	:param lst: a list of tokens
 	:type lst: list of tuple(token, value)
 	:return: a token
 	:rtype: tuple(NUM, int)
 	"""
 	num, lst = get_term(lst)
 	return (NUM, num)
 
 def stringize(lst):
 	"""
 	Merge a list of tokens into a string
 
 	:param lst: a list of tokens
 	:type lst: list of tuple(token, value)
 	:rtype: string
 	"""
 	lst = [str(v2) for (p2, v2) in lst]
 	return "".join(lst)
 
 def paste_tokens(t1, t2):
 	"""
 	Token pasting works between identifiers, particular operators, and identifiers and numbers::
 
 		a ## b  ->  ab
 		> ## =  ->  >=
 		a ## 2  ->  a2
 
 	:param t1: token
 	:type t1: tuple(type, value)
 	:param t2: token
 	:type t2: tuple(type, value)
 	"""
 	p1 = None
 	if t1[0] == OP and t2[0] == OP:
 		p1 = OP
 	elif t1[0] == IDENT and (t2[0] == IDENT or t2[0] == NUM):
 		p1 = IDENT
 	elif t1[0] == NUM and t2[0] == NUM:
 		p1 = NUM
 	if not p1:
 		raise PreprocError('tokens do not make a valid paste %r and %r' % (t1, t2))
 	return (p1, t1[1] + t2[1])
 
 def reduce_tokens(lst, defs, ban=[]):
 	"""
 	Replace the tokens in lst, using the macros provided in defs, and a list of macros that cannot be re-applied
 
 	:param lst: list of tokens
 	:type lst: list of tuple(token, value)
 	:param defs: macro definitions
 	:type defs: dict
 	:param ban: macros that cannot be substituted (recursion is not allowed)
 	:type ban: list of string
 	:return: the new list of tokens
 	:rtype: value, list
 	"""
 
 	i = 0
 	while i < len(lst):
 		(p, v) = lst[i]
 
 		if p == IDENT and v == "defined":
 			del lst[i]
 			if i < len(lst):
 				(p2, v2) = lst[i]
 				if p2 == IDENT:
 					if v2 in defs:
 						lst[i] = (NUM, 1)
 					else:
 						lst[i] = (NUM, 0)
 				elif p2 == OP and v2 == '(':
 					del lst[i]
 					(p2, v2) = lst[i]
 					del lst[i] # remove the ident, and change the ) for the value
 					if v2 in defs:
 						lst[i] = (NUM, 1)
 					else:
 						lst[i] = (NUM, 0)
 				else:
 					raise PreprocError('Invalid define expression %r' % lst)
 
 		elif p == IDENT and v in defs:
 
 			if isinstance(defs[v], str):
 				a, b = extract_macro(defs[v])
 				defs[v] = b
 			macro_def = defs[v]
 			to_add = macro_def[1]
 
 			if isinstance(macro_def[0], list):
 				# macro without arguments
 				del lst[i]
 				accu = to_add[:]
 				reduce_tokens(accu, defs, ban+[v])
 				for tmp in accu:
 					lst.insert(i, tmp)
 					i += 1
 			else:
 				# collect the arguments for the funcall
 
 				args = []
 				del lst[i]
 
 				if i >= len(lst):
 					raise PreprocError('expected ( after %r (got nothing)' % v)
 
 				(p2, v2) = lst[i]
 				if p2 != OP or v2 != '(':
 					raise PreprocError('expected ( after %r' % v)
 
 				del lst[i]
 
 				one_param = []
 				count_paren = 0
 				while i < len(lst):
 					p2, v2 = lst[i]
 
 					del lst[i]
 					if p2 == OP and count_paren == 0:
 						if v2 == '(':
 							one_param.append((p2, v2))
 							count_paren += 1
 						elif v2 == ')':
 							if one_param:
 								args.append(one_param)
 							break
 						elif v2 == ',':
 							if not one_param:
 								raise PreprocError('empty param in funcall %r' % v)
 							args.append(one_param)
 							one_param = []
 						else:
 							one_param.append((p2, v2))
 					else:
 						one_param.append((p2, v2))
 						if   v2 == '(':
 							count_paren += 1
 						elif v2 == ')':
 							count_paren -= 1
 				else:
 					raise PreprocError('malformed macro')
 
 				# substitute the arguments within the define expression
 				accu = []
 				arg_table = macro_def[0]
 				j = 0
 				while j < len(to_add):
 					(p2, v2) = to_add[j]
 
 					if p2 == OP and v2 == '#':
 						# stringize is for arguments only
 						if j+1 < len(to_add) and to_add[j+1][0] == IDENT and to_add[j+1][1] in arg_table:
 							toks = args[arg_table[to_add[j+1][1]]]
 							accu.append((STR, stringize(toks)))
 							j += 1
 						else:
 							accu.append((p2, v2))
 					elif p2 == OP and v2 == '##':
 						# token pasting, how can man invent such a complicated system?
 						if accu and j+1 < len(to_add):
 							# we have at least two tokens
 
 							t1 = accu[-1]
 
 							if to_add[j+1][0] == IDENT and to_add[j+1][1] in arg_table:
 								toks = args[arg_table[to_add[j+1][1]]]
 
 								if toks:
 									accu[-1] = paste_tokens(t1, toks[0]) #(IDENT, accu[-1][1] + toks[0][1])
 									accu.extend(toks[1:])
 								else:
 									# error, case "a##"
 									accu.append((p2, v2))
 									accu.extend(toks)
 							elif to_add[j+1][0] == IDENT and to_add[j+1][1] == '__VA_ARGS__':
 								# first collect the tokens
 								va_toks = []
 								st = len(macro_def[0])
 								pt = len(args)
 								for x in args[pt-st+1:]:
 									va_toks.extend(x)
 									va_toks.append((OP, ','))
 								if va_toks:
 									va_toks.pop() # extra comma
 								if len(accu)>1:
 									(p3, v3) = accu[-1]
 									(p4, v4) = accu[-2]
 									if v3 == '##':
 										# remove the token paste
 										accu.pop()
 										if v4 == ',' and pt < st:
 											# remove the comma
 											accu.pop()
 								accu += va_toks
 							else:
 								accu[-1] = paste_tokens(t1, to_add[j+1])
 
 							j += 1
 						else:
 							# Invalid paste, case    "##a" or "b##"
 							accu.append((p2, v2))
 
 					elif p2 == IDENT and v2 in arg_table:
 						toks = args[arg_table[v2]]
 						reduce_tokens(toks, defs, ban+[v])
 						accu.extend(toks)
 					else:
 						accu.append((p2, v2))
 
 					j += 1
 
 
 				reduce_tokens(accu, defs, ban+[v])
 
 				for x in range(len(accu)-1, -1, -1):
 					lst.insert(i, accu[x])
 
 		i += 1
 
 
 def eval_macro(lst, defs):
 	"""
 	Reduce the tokens by :py:func:`waflib.Tools.c_preproc.reduce_tokens` and try to return a 0/1 result by :py:func:`waflib.Tools.c_preproc.reduce_eval`.
 
 	:param lst: list of tokens
 	:type lst: list of tuple(token, value)
 	:param defs: macro definitions
 	:type defs: dict
 	:rtype: int
 	"""
 	reduce_tokens(lst, defs, [])
 	if not lst:
 		raise PreprocError('missing tokens to evaluate')
 
 	p, v = reduce_eval(lst)
 	return int(v) != 0
 
 def extract_macro(txt):
 	"""
 	Process a macro definition of the form::
 		 #define f(x, y) x * y
 
 	into a function or a simple macro without arguments
 
 	:param txt: expression to exact a macro definition from
 	:type txt: string
 	:return: a tuple containing the name, the list of arguments and the replacement
 	:rtype: tuple(string, [list, list])
 	"""
 	t = tokenize(txt)
 	if re_fun.search(txt):
 		p, name = t[0]
 
 		p, v = t[1]
 		if p != OP:
 			raise PreprocError('expected (')
 
 		i = 1
 		pindex = 0
 		params = {}
 		prev = '('
 
 		while 1:
 			i += 1
 			p, v = t[i]
 
 			if prev == '(':
 				if p == IDENT:
 					params[v] = pindex
 					pindex += 1
 					prev = p
 				elif p == OP and v == ')':
 					break
 				else:
 					raise PreprocError('unexpected token (3)')
 			elif prev == IDENT:
 				if p == OP and v == ',':
 					prev = v
 				elif p == OP and v == ')':
 					break
 				else:
 					raise PreprocError('comma or ... expected')
 			elif prev == ',':
 				if p == IDENT:
 					params[v] = pindex
 					pindex += 1
 					prev = p
 				elif p == OP and v == '...':
 					raise PreprocError('not implemented (1)')
 				else:
 					raise PreprocError('comma or ... expected (2)')
 			elif prev == '...':
 				raise PreprocError('not implemented (2)')
 			else:
 				raise PreprocError('unexpected else')
 
 		#~ print (name, [params, t[i+1:]])
 		return (name, [params, t[i+1:]])
 	else:
 		(p, v) = t[0]
 		if len(t) > 1:
 			return (v, [[], t[1:]])
 		else:
 			# empty define, assign an empty token
 			return (v, [[], [('T','')]])
 
 re_include = re.compile(r'^\s*(<(?:.*)>|"(?:.*)")')
 def extract_include(txt, defs):
 	"""
 	Process a line in the form::
 
 		#include foo
 
 	:param txt: include line to process
 	:type txt: string
 	:param defs: macro definitions
 	:type defs: dict
 	:return: the file name
 	:rtype: string
 	"""
 	m = re_include.search(txt)
 	if m:
 		txt = m.group(1)
 		return txt[0], txt[1:-1]
 
 	# perform preprocessing and look at the result, it must match an include
 	toks = tokenize(txt)
 	reduce_tokens(toks, defs, ['waf_include'])
 
 	if not toks:
 		raise PreprocError('could not parse include %r' % txt)
 
 	if len(toks) == 1:
 		if toks[0][0] == STR:
 			return '"', toks[0][1]
 	else:
 		if toks[0][1] == '<' and toks[-1][1] == '>':
 			ret = '<', stringize(toks).lstrip('<').rstrip('>')
 			return ret
 
 	raise PreprocError('could not parse include %r' % txt)
 
 def parse_char(txt):
 	"""
 	Parse a c character
 
 	:param txt: character to parse
 	:type txt: string
 	:return: a character literal
 	:rtype: string
 	"""
 
 	if not txt:
 		raise PreprocError('attempted to parse a null char')
 	if txt[0] != '\\':
 		return ord(txt)
 	c = txt[1]
 	if c == 'x':
 		if len(txt) == 4 and txt[3] in string.hexdigits:
 			return int(txt[2:], 16)
 		return int(txt[2:], 16)
 	elif c.isdigit():
 		if c == '0' and len(txt)==2:
 			return 0
 		for i in 3, 2, 1:
 			if len(txt) > i and txt[1:1+i].isdigit():
 				return (1+i, int(txt[1:1+i], 8))
 	else:
 		try:
 			return chr_esc[c]
 		except KeyError:
 			raise PreprocError('could not parse char literal %r' % txt)
 
 def tokenize(s):
 	"""
 	Convert a string into a list of tokens (shlex.split does not apply to c/c++/d)
 
 	:param s: input to tokenize
 	:type s: string
 	:return: a list of tokens
 	:rtype: list of tuple(token, value)
 	"""
 	return tokenize_private(s)[:] # force a copy of the results
 
 def tokenize_private(s):
 	ret = []
 	for match in re_clexer.finditer(s):
 		m = match.group
 		for name in tok_types:
 			v = m(name)
 			if v:
 				if name == IDENT:
 					if v in g_optrans:
 						name = OP
 					elif v.lower() == "true":
 						v = 1
 						name = NUM
 					elif v.lower() == "false":
 						v = 0
 						name = NUM
 				elif name == NUM:
 					if m('oct'):
 						v = int(v, 8)
 					elif m('hex'):
 						v = int(m('hex'), 16)
 					elif m('n0'):
 						v = m('n0')
 					else:
 						v = m('char')
 						if v:
 							v = parse_char(v)
 						else:
 							v = m('n2') or m('n4')
 				elif name == OP:
 					if v == '%:':
 						v = '#'
 					elif v == '%:%:':
 						v = '##'
 				elif name == STR:
 					# remove the quotes around the string
 					v = v[1:-1]
 				ret.append((name, v))
 				break
 	return ret
 
 def format_defines(lst):
 	ret = []
 	for y in lst:
 		if y:
 			pos = y.find('=')
 			if pos == -1:
 				# "-DFOO" should give "#define FOO 1"
 				ret.append(y)
 			elif pos > 0:
 				# all others are assumed to be -DX=Y
 				ret.append('%s %s' % (y[:pos], y[pos+1:]))
 			else:
 				raise ValueError('Invalid define expression %r' % y)
 	return ret
 
 class c_parser(object):
 	"""
 	Used by :py:func:`waflib.Tools.c_preproc.scan` to parse c/h files. Note that by default,
 	only project headers are parsed.
 	"""
 	def __init__(self, nodepaths=None, defines=None):
 		self.lines = []
 		"""list of lines read"""
 
 		if defines is None:
 			self.defs  = {}
 		else:
 			self.defs  = dict(defines) # make a copy
 		self.state = []
 
 		self.count_files = 0
 		self.currentnode_stack = []
 
 		self.nodepaths = nodepaths or []
 		"""Include paths"""
 
 		self.nodes = []
 		"""List of :py:class:`waflib.Node.Node` found so far"""
 
 		self.names = []
 		"""List of file names that could not be matched by any file"""
 
 		self.curfile = ''
 		"""Current file"""
 
 		self.ban_includes = set()
 		"""Includes that must not be read (#pragma once)"""
 
 		self.listed = set()
 		"""Include nodes/names already listed to avoid duplicates in self.nodes/self.names"""
 
 	def cached_find_resource(self, node, filename):
 		"""
 		Find a file from the input directory
 
 		:param node: directory
 		:type node: :py:class:`waflib.Node.Node`
 		:param filename: header to find
 		:type filename: string
 		:return: the node if found, or None
 		:rtype: :py:class:`waflib.Node.Node`
 		"""
 		try:
 			cache = node.ctx.preproc_cache_node
 		except AttributeError:
 			cache = node.ctx.preproc_cache_node = Utils.lru_cache(FILE_CACHE_SIZE)
 
 		key = (node, filename)
 		try:
 			return cache[key]
 		except KeyError:
 			ret = node.find_resource(filename)
 			if ret:
 				if getattr(ret, 'children', None):
 					ret = None
 				elif ret.is_child_of(node.ctx.bldnode):
 					tmp = node.ctx.srcnode.search_node(ret.path_from(node.ctx.bldnode))
 					if tmp and getattr(tmp, 'children', None):
 						ret = None
 			cache[key] = ret
 			return ret
 
 	def tryfind(self, filename, kind='"', env=None):
 		"""
 		Try to obtain a node from the filename based from the include paths. Will add
 		the node found to :py:attr:`waflib.Tools.c_preproc.c_parser.nodes` or the file name to
 		:py:attr:`waflib.Tools.c_preproc.c_parser.names` if no corresponding file is found. Called by
 		:py:attr:`waflib.Tools.c_preproc.c_parser.start`.
 
 		:param filename: header to find
 		:type filename: string
 		:return: the node if found
 		:rtype: :py:class:`waflib.Node.Node`
 		"""
 		if filename.endswith('.moc'):
 			# we could let the qt4 module use a subclass, but then the function "scan" below must be duplicated
 			# in the qt4 and in the qt5 classes. So we have two lines here and it is sufficient.
 			self.names.append(filename)
 			return None
 
 		self.curfile = filename
 
 		found = None
 		if kind == '"':
 			if env.MSVC_VERSION:
 				for n in reversed(self.currentnode_stack):
 					found = self.cached_find_resource(n, filename)
 					if found:
 						break
 			else:
 				found = self.cached_find_resource(self.currentnode_stack[-1], filename)
 
 		if not found:
 			for n in self.nodepaths:
 				found = self.cached_find_resource(n, filename)
 				if found:
 					break
 
 		listed = self.listed
 		if found and not found in self.ban_includes:
 			if found not in listed:
 				listed.add(found)
 				self.nodes.append(found)
 			self.addlines(found)
 		else:
 			if filename not in listed:
 				listed.add(filename)
 				self.names.append(filename)
 		return found
 
 	def filter_comments(self, node):
 		"""
 		Filter the comments from a c/h file, and return the preprocessor lines.
 		The regexps :py:attr:`waflib.Tools.c_preproc.re_cpp`, :py:attr:`waflib.Tools.c_preproc.re_nl` and :py:attr:`waflib.Tools.c_preproc.re_lines` are used internally.
 
 		:return: the preprocessor directives as a list of (keyword, line)
 		:rtype: a list of string pairs
 		"""
 		# return a list of tuples : keyword, line
 		code = node.read()
 		if use_trigraphs:
 			for (a, b) in trig_def:
 				code = code.split(a).join(b)
 		code = re_nl.sub('', code)
 		code = re_cpp.sub(repl, code)
 		return re_lines.findall(code)
 
 	def parse_lines(self, node):
 		try:
 			cache = node.ctx.preproc_cache_lines
 		except AttributeError:
 			cache = node.ctx.preproc_cache_lines = Utils.lru_cache(LINE_CACHE_SIZE)
 		try:
 			return cache[node]
 		except KeyError:
 			cache[node] = lines = self.filter_comments(node)
 			lines.append((POPFILE, ''))
 			lines.reverse()
 			return lines
 
 	def addlines(self, node):
 		"""
 		Add the lines from a header in the list of preprocessor lines to parse
 
 		:param node: header
 		:type node: :py:class:`waflib.Node.Node`
 		"""
 
 		self.currentnode_stack.append(node.parent)
 
 		self.count_files += 1
 		if self.count_files > recursion_limit:
 			# issue #812
 			raise PreprocError('recursion limit exceeded')
 
 		if Logs.verbose:
 			Logs.debug('preproc: reading file %r', node)
 		try:
 			lines = self.parse_lines(node)
 		except EnvironmentError:
 			raise PreprocError('could not read the file %r' % node)
 		except Exception:
 			if Logs.verbose > 0:
 				Logs.error('parsing %r failed %s', node, traceback.format_exc())
 		else:
 			self.lines.extend(lines)
 
 	def start(self, node, env):
 		"""
 		Preprocess a source file to obtain the dependencies, which are accumulated to :py:attr:`waflib.Tools.c_preproc.c_parser.nodes`
 		and :py:attr:`waflib.Tools.c_preproc.c_parser.names`.
 
 		:param node: source file
 		:type node: :py:class:`waflib.Node.Node`
 		:param env: config set containing additional defines to take into account
 		:type env: :py:class:`waflib.ConfigSet.ConfigSet`
 		"""
 		Logs.debug('preproc: scanning %s (in %s)', node.name, node.parent.name)
 
 		self.current_file = node
 		self.addlines(node)
 
 		# macros may be defined on the command-line, so they must be parsed as if they were part of the file
 		if env.DEFINES:
 			lst = format_defines(env.DEFINES)
 			lst.reverse()
 			self.lines.extend([('define', x) for x in lst])
 
 		while self.lines:
 			(token, line) = self.lines.pop()
 			if token == POPFILE:
 				self.count_files -= 1
 				self.currentnode_stack.pop()
 				continue
 
 			try:
 				state = self.state
 
 				# make certain we define the state if we are about to enter in an if block
 				if token[:2] == 'if':
 					state.append(undefined)
 				elif token == 'endif':
 					state.pop()
 
 				# skip lines when in a dead 'if' branch, wait for the endif
 				if token[0] != 'e':
 					if skipped in self.state or ignored in self.state:
 						continue
 
 				if token == 'if':
 					ret = eval_macro(tokenize(line), self.defs)
 					if ret:
 						state[-1] = accepted
 					else:
 						state[-1] = ignored
 				elif token == 'ifdef':
 					m = re_mac.match(line)
 					if m and m.group() in self.defs:
 						state[-1] = accepted
 					else:
 						state[-1] = ignored
 				elif token == 'ifndef':
 					m = re_mac.match(line)
 					if m and m.group() in self.defs:
 						state[-1] = ignored
 					else:
 						state[-1] = accepted
 				elif token == 'include' or token == 'import':
 					(kind, inc) = extract_include(line, self.defs)
 					self.current_file = self.tryfind(inc, kind, env)
 					if token == 'import':
 						self.ban_includes.add(self.current_file)
 				elif token == 'elif':
 					if state[-1] == accepted:
 						state[-1] = skipped
 					elif state[-1] == ignored:
 						if eval_macro(tokenize(line), self.defs):
 							state[-1] = accepted
 				elif token == 'else':
 					if state[-1] == accepted:
 						state[-1] = skipped
 					elif state[-1] == ignored:
 						state[-1] = accepted
 				elif token == 'define':
 					try:
 						self.defs[self.define_name(line)] = line
 					except AttributeError:
 						raise PreprocError('Invalid define line %r' % line)
 				elif token == 'undef':
 					m = re_mac.match(line)
 					if m and m.group() in self.defs:
 						self.defs.__delitem__(m.group())
 						#print "undef %s" % name
 				elif token == 'pragma':
 					if re_pragma_once.match(line.lower()):
 						self.ban_includes.add(self.current_file)
 			except Exception as e:
 				if Logs.verbose:
 					Logs.debug('preproc: line parsing failed (%s): %s %s', e, line, traceback.format_exc())
 
 	def define_name(self, line):
 		"""
 		:param line: define line
 		:type line: string
 		:rtype: string
 		:return: the define name
 		"""
 		return re_mac.match(line).group()
 
 def scan(task):
 	"""
 	Get the dependencies using a c/c++ preprocessor, this is required for finding dependencies of the kind::
 
 		#include some_macro()
 
 	This function is bound as a task method on :py:class:`waflib.Tools.c.c` and :py:class:`waflib.Tools.cxx.cxx` for example
 	"""
 	try:
 		incn = task.generator.includes_nodes
 	except AttributeError:
 		raise Errors.WafError('%r is missing a feature such as "c", "cxx" or "includes": ' % task.generator)
 
 	if go_absolute:
 		nodepaths = incn + [task.generator.bld.root.find_dir(x) for x in standard_includes]
 	else:
 		nodepaths = [x for x in incn if x.is_child_of(x.ctx.srcnode) or x.is_child_of(x.ctx.bldnode)]
 
 	tmp = c_parser(nodepaths)
 	tmp.start(task.inputs[0], task.env)
 	return (tmp.nodes, tmp.names)