Squashed 'waflib/' content from commit 982416b

git-subtree-dir: waflib
git-subtree-split: 982416b8a6c6728e200243e1be3ab60435c08830

1 files changed, 1091 insertions, 0 deletions

diff --git a/Tools/c_preproc.py b/Tools/c_preproc.py
new file mode 100644
index 00000000..7e04b4a7
--- /dev/null
+++ b/Tools/c_preproc.py
@@ -0,0 +1,1091 @@
+#!/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*$',
+	re.IGNORECASE | re.MULTILINE)
+"""Match #include lines"""
+
+re_mac = re.compile("^[a-zA-Z_]\w*")
+"""Match macro definitions"""
+
+re_fun = re.compile('^[a-zA-Z_][a-zA-Z0-9_]*[(]')
+"""Match macro functions"""
+
+re_pragma_once = re.compile('^\s*once\s*', re.IGNORECASE)
+"""Match #pragma once statements"""
+
+re_nl = re.compile('\\\\\r*\n', re.MULTILINE)
+"""Match newlines"""
+
+re_cpp = re.compile(r'//.*?$|/\*.*?\*/|\'(?:\\.|[^\\\'])*\'|"(?:\\.|[^\\"])*"', 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')
+
+	if lst:
+		p, v = lst[0]
+		if p == IDENT and v not in defs:
+			raise PreprocError('missing macro %r' % lst)
+
+	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('^\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)