# MIT License
#
# Copyright The SCons Foundation
#
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# a copy of this software and associated documentation files (the
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# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be included
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#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
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# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
"""SCons C Pre-Processor module"""
import os
import re
import SCons.Util
# First "subsystem" of regular expressions that we set up:
#
# Stuff to turn the C preprocessor directives in a file's contents into
# a list of tuples that we can process easily.
#
# A table of regular expressions that fetch the arguments from the rest of
# a C preprocessor line. Different directives have different arguments
# that we want to fetch, using the regular expressions to which the lists
# of preprocessor directives map.
cpp_lines_dict = {
# Fetch the rest of a #if/#elif as one argument,
# with white space optional.
('if', 'elif') : r'\s*(.+)',
# Fetch the rest of a #ifdef/#ifndef as one argument,
# separated from the keyword by white space.
('ifdef', 'ifndef',): r'\s+(.+)',
# Fetch the rest of a #import/#include/#include_next line as one
# argument, with white space optional.
('import', 'include', 'include_next',)
: r'\s*(.+)',
# We don't care what comes after a #else or #endif line.
('else', 'endif',) : '',
# Fetch three arguments from a #define line:
# 1) The #defined keyword.
# 2) The optional parentheses and arguments (if it's a function-like
# macro, '' if it's not).
# 3) The expansion value.
('define',) : r'\s+([_A-Za-z][_A-Za-z0-9_]*)(\([^)]*\))?\s*(.*)',
# Fetch the #undefed keyword from a #undef line.
('undef',) : r'\s+([_A-Za-z][A-Za-z0-9_]*)',
}
# Create a table that maps each individual C preprocessor directive to
# the corresponding compiled regular expression that fetches the arguments
# we care about.
Table = {}
for op_list, expr in cpp_lines_dict.items():
e = re.compile(expr)
for op in op_list:
Table[op] = e
del e
del op
del op_list
# Create a list of the expressions we'll use to match all of the
# preprocessor directives. These are the same as the directives
# themselves *except* that we must use a negative lookahead assertion
# when matching "if" so it doesn't match the "if" in "ifdef" or "ifndef".
override = {
'if' : 'if(?!n?def)',
}
l = [override.get(x, x) for x in Table.keys()]
# Turn the list of expressions into one big honkin' regular expression
# that will match all the preprocessor lines at once. This will return
# a list of tuples, one for each preprocessor line. The preprocessor
# directive will be the first element in each tuple, and the rest of
# the line will be the second element.
e = r'^\s*#\s*(' + '|'.join(l) + ')(.*)$'
# And last but not least, compile the expression.
CPP_Expression = re.compile(e, re.M)
# A list with RE to cleanup CPP Expressions (tuples)
# We should remove all comments and carriage returns (\r) before evaluating
CPP_Expression_Cleaner_List = [
r"/\*.*\*/",
r"/\*.*",
r"//.*",
r"\r"
]
CPP_Expression_Cleaner_RE = re.compile(
r"\s*(" + "|".join(CPP_Expression_Cleaner_List) + ")")
[docs]def Cleanup_CPP_Expressions(ts):
return [(t[0], CPP_Expression_Cleaner_RE.sub("", t[1])) for t in ts]
#
# Second "subsystem" of regular expressions that we set up:
#
# Stuff to translate a C preprocessor expression (as found on a #if or
# #elif line) into an equivalent Python expression that we can eval().
#
# A dictionary that maps the C representation of Boolean operators
# to their Python equivalents.
CPP_to_Python_Ops_Dict = {
'!' : ' not ',
'!=' : ' != ',
'&&' : ' and ',
'||' : ' or ',
'?' : ' and ',
':' : ' or ',
}
CPP_to_Python_Ops_Sub = lambda m: CPP_to_Python_Ops_Dict[m.group(0)]
# We have to sort the keys by length so that longer expressions
# come *before* shorter expressions--in particular, "!=" must
# come before "!" in the alternation. Without this, the Python
# re module, as late as version 2.2.2, empirically matches the
# "!" in "!=" first, instead of finding the longest match.
# What's up with that?
l = sorted(list(CPP_to_Python_Ops_Dict.keys()), key=lambda a: len(a), reverse=True)
# Turn the list of keys into one regular expression that will allow us
# to substitute all of the operators at once.
expr = '|'.join(map(re.escape, l))
# ...and compile the expression.
CPP_to_Python_Ops_Expression = re.compile(expr)
# A separate list of expressions to be evaluated and substituted
# sequentially, not all at once.
CPP_to_Python_Eval_List = [
[r'defined\s+(\w+)', '"\\1" in __dict__'],
[r'defined\s*\((\w+)\)', '"\\1" in __dict__'],
[r'(0x[0-9A-Fa-f]+)(?:L|UL)?', '\\1'],
[r'(\d+)(?:L|UL)?', '\\1'],
]
# Replace the string representations of the regular expressions in the
# list with compiled versions.
for l in CPP_to_Python_Eval_List:
l[0] = re.compile(l[0])
# Wrap up all of the above into a handy function.
[docs]def CPP_to_Python(s):
"""
Converts a C pre-processor expression into an equivalent
Python expression that can be evaluated.
"""
s = CPP_to_Python_Ops_Expression.sub(CPP_to_Python_Ops_Sub, s)
for expr, repl in CPP_to_Python_Eval_List:
s = re.sub(expr, repl, s)
return s
del expr
del l
del override
[docs]class FunctionEvaluator:
"""Handles delayed evaluation of a #define function call."""
def __init__(self, name, args, expansion) -> None:
"""
Squirrels away the arguments and expansion value of a #define
macro function for later evaluation when we must actually expand
a value that uses it.
"""
self.name = name
self.args = function_arg_separator.split(args)
try:
expansion = expansion.split('##')
except AttributeError:
pass
self.expansion = expansion
[docs] def __call__(self, *values):
"""
Evaluates the expansion of a #define macro function called
with the specified values.
"""
if len(self.args) != len(values):
raise ValueError("Incorrect number of arguments to `%s'" % self.name)
# Create a dictionary that maps the macro arguments to the
# corresponding values in this "call." We'll use this when we
# eval() the expansion so that arguments will get expanded to
# the right values.
args = self.args
localvars = {k: v for k, v in zip(args, values)}
parts = [s if s in args else repr(s) for s in self.expansion]
statement = ' + '.join(parts)
return eval(statement, globals(), localvars)
# Find line continuations.
line_continuations = re.compile('\\\\\r?\n')
# Search for a "function call" macro on an expansion. Returns the
# two-tuple of the "function" name itself, and a string containing the
# arguments within the call parentheses.
function_name = re.compile(r'(\S+)\(([^)]*)\)')
# Split a string containing comma-separated function call arguments into
# the separate arguments.
function_arg_separator = re.compile(r',\s*')
[docs]class PreProcessor:
"""The main workhorse class for handling C pre-processing."""
def __init__(self, current=os.curdir, cpppath=(), dict={}, all: int=0, depth=-1) -> None:
global Table
cpppath = tuple(cpppath)
self.searchpath = {
'"': (current,) + cpppath,
'<': cpppath + (current,),
}
# Initialize our C preprocessor namespace for tracking the
# values of #defined keywords. We use this namespace to look
# for keywords on #ifdef/#ifndef lines, and to eval() the
# expressions on #if/#elif lines (after massaging them from C to
# Python).
self.cpp_namespace = dict.copy()
self.cpp_namespace['__dict__'] = self.cpp_namespace
# Return all includes without resolving
if all:
self.do_include = self.all_include
# Max depth of nested includes:
# -1 = unlimited
# 0 - disabled nesting
# >0 - number of allowed nested includes
self.depth = depth
# For efficiency, a dispatch table maps each C preprocessor
# directive (#if, #define, etc.) to the method that should be
# called when we see it. We accomodate state changes (#if,
# #ifdef, #ifndef) by pushing the current dispatch table on a
# stack and changing what method gets called for each relevant
# directive we might see next at this level (#else, #elif).
# #endif will simply pop the stack.
d = {'scons_current_file': self.scons_current_file}
for op in Table.keys():
d[op] = getattr(self, 'do_' + op)
self.default_table = d
[docs] def __call__(self, file):
"""
Pre-processes a file.
This is the main public entry point.
"""
self.current_file = file
return self.process_file(file)
[docs] def process_file(self, file):
"""
Pre-processes a file.
This is the main internal entry point.
"""
return self._process_tuples(self.tupleize(self.read_file(file)), file)
[docs] def process_contents(self, contents):
"""
Pre-processes a file contents.
Is used by tests
"""
return self._process_tuples(self.tupleize(contents))
[docs] def _process_tuples(self, tuples, file=None):
self.stack = []
self.dispatch_table = self.default_table.copy()
self.current_file = file
self.tuples = tuples
self.initialize_result(file)
while self.tuples:
t = self.tuples.pop(0)
# Uncomment to see the list of tuples being processed (e.g.,
# to validate the CPP lines are being translated correctly).
# print(t)
self.dispatch_table[t[0]](t)
return self.finalize_result(file)
[docs] def tupleize(self, contents):
"""
Turns the contents of a file into a list of easily-processed
tuples describing the CPP lines in the file.
The first element of each tuple is the line's preprocessor
directive (#if, #include, #define, etc., minus the initial '#').
The remaining elements are specific to the type of directive, as
pulled apart by the regular expression.
"""
return self._match_tuples(self._parse_tuples(contents))
[docs] def _parse_tuples(self, contents):
global CPP_Expression
contents = line_continuations.sub('', contents)
tuples = CPP_Expression.findall(contents)
return Cleanup_CPP_Expressions(tuples)
[docs] def _match_tuples(self, tuples):
global Table
result = []
for t in tuples:
m = Table[t[0]].match(t[1])
if m:
result.append((t[0],) + m.groups())
return result
# Dispatch table stack manipulation methods.
[docs] def save(self) -> None:
"""
Pushes the current dispatch table on the stack and re-initializes
the current dispatch table to the default.
"""
self.stack.append(self.dispatch_table)
self.dispatch_table = self.default_table.copy()
[docs] def restore(self) -> None:
"""
Pops the previous dispatch table off the stack and makes it the
current one.
"""
try: self.dispatch_table = self.stack.pop()
except IndexError: pass
# Utility methods.
[docs] def do_nothing(self, t) -> None:
"""
Null method for when we explicitly want the action for a
specific preprocessor directive to do nothing.
"""
pass
[docs] def scons_current_file(self, t) -> None:
self.current_file = t[1]
[docs] def eval_expression(self, t):
"""
Evaluates a C preprocessor expression.
This is done by converting it to a Python equivalent and
eval()ing it in the C preprocessor namespace we use to
track #define values.
"""
t = CPP_to_Python(' '.join(t[1:]))
try:
return eval(t, self.cpp_namespace)
except (NameError, TypeError, SyntaxError):
return 0
[docs] def initialize_result(self, fname) -> None:
self.result = [fname]
[docs] def finalize_result(self, fname):
return self.result[1:]
[docs] def find_include_file(self, t):
"""
Finds the #include file for a given preprocessor tuple.
"""
fname = t[2]
for d in self.searchpath[t[1]]:
if d == os.curdir:
f = fname
else:
f = os.path.join(d, fname)
if os.path.isfile(f):
return f
return None
[docs] def read_file(self, file) -> str:
with open(file, 'rb') as f:
return SCons.Util.to_Text(f.read())
# Start and stop processing include lines.
[docs] def start_handling_includes(self, t=None) -> None:
"""
Causes the PreProcessor object to start processing #import,
#include and #include_next lines.
This method will be called when a #if, #ifdef, #ifndef or #elif
evaluates True, or when we reach the #else in a #if, #ifdef,
#ifndef or #elif block where a condition already evaluated
False.
"""
d = self.dispatch_table
p = self.stack[-1] if self.stack else self.default_table
for k in ('import', 'include', 'include_next', 'define', 'undef'):
d[k] = p[k]
[docs] def stop_handling_includes(self, t=None) -> None:
"""
Causes the PreProcessor object to stop processing #import,
#include and #include_next lines.
This method will be called when a #if, #ifdef, #ifndef or #elif
evaluates False, or when we reach the #else in a #if, #ifdef,
#ifndef or #elif block where a condition already evaluated True.
"""
d = self.dispatch_table
d['import'] = self.do_nothing
d['include'] = self.do_nothing
d['include_next'] = self.do_nothing
d['define'] = self.do_nothing
d['undef'] = self.do_nothing
# Default methods for handling all of the preprocessor directives.
# (Note that what actually gets called for a given directive at any
# point in time is really controlled by the dispatch_table.)
[docs] def _do_if_else_condition(self, condition) -> None:
"""
Common logic for evaluating the conditions on #if, #ifdef and
#ifndef lines.
"""
self.save()
d = self.dispatch_table
if condition:
self.start_handling_includes()
d['elif'] = self.stop_handling_includes
d['else'] = self.stop_handling_includes
else:
self.stop_handling_includes()
d['elif'] = self.do_elif
d['else'] = self.start_handling_includes
[docs] def do_ifdef(self, t) -> None:
"""
Default handling of a #ifdef line.
"""
self._do_if_else_condition(t[1] in self.cpp_namespace)
[docs] def do_ifndef(self, t) -> None:
"""
Default handling of a #ifndef line.
"""
self._do_if_else_condition(t[1] not in self.cpp_namespace)
[docs] def do_if(self, t) -> None:
"""
Default handling of a #if line.
"""
self._do_if_else_condition(self.eval_expression(t))
[docs] def do_elif(self, t) -> None:
"""
Default handling of a #elif line.
"""
d = self.dispatch_table
if self.eval_expression(t):
self.start_handling_includes()
d['elif'] = self.stop_handling_includes
d['else'] = self.stop_handling_includes
[docs] def do_else(self, t) -> None:
"""
Default handling of a #else line.
"""
pass
[docs] def do_endif(self, t) -> None:
"""
Default handling of a #endif line.
"""
self.restore()
[docs] def do_define(self, t) -> None:
"""
Default handling of a #define line.
"""
_, name, args, expansion = t
try:
expansion = int(expansion)
except (TypeError, ValueError):
# handle "defined" chain "! (defined (A) || defined (B)" ...
if "defined " in expansion:
self.cpp_namespace[name] = self.eval_expression(t[2:])
return
if args:
evaluator = FunctionEvaluator(name, args[1:-1], expansion)
self.cpp_namespace[name] = evaluator
else:
self.cpp_namespace[name] = expansion
[docs] def do_undef(self, t) -> None:
"""
Default handling of a #undef line.
"""
try: del self.cpp_namespace[t[1]]
except KeyError: pass
[docs] def do_import(self, t) -> None:
"""
Default handling of a #import line.
"""
# XXX finish this -- maybe borrow/share logic from do_include()...?
pass
[docs] def do_include(self, t) -> None:
"""
Default handling of a #include line.
"""
t = self.resolve_include(t)
if not t:
return
include_file = self.find_include_file(t)
# avoid infinite recursion
if not include_file or include_file in self.result:
return
self.result.append(include_file)
# print include_file, len(self.tuples)
# Handle maximum depth of nested includes
if self.depth != -1:
current_depth = 0
for t in self.tuples:
if t[0] == "scons_current_file":
current_depth += 1
if current_depth >= self.depth:
return
new_tuples = [('scons_current_file', include_file)] + \
self.tupleize(self.read_file(include_file)) + \
[('scons_current_file', self.current_file)]
self.tuples[:] = new_tuples + self.tuples
# From: Stefan Seefeld <seefeld@sympatico.ca> (22 Nov 2005)
#
# By the way, #include_next is not the same as #include. The difference
# being that #include_next starts its search in the path following the
# path that let to the including file. In other words, if your system
# include paths are ['/foo', '/bar'], and you are looking at a header
# '/foo/baz.h', it might issue an '#include_next <baz.h>' which would
# correctly resolve to '/bar/baz.h' (if that exists), but *not* see
# '/foo/baz.h' again. See
# https://gcc.gnu.org/onlinedocs/cpp/Wrapper-Headers.html for more notes.
#
# I have no idea in what context #import might be used.
# Update: possibly these notes?
# https://github.com/MicrosoftDocs/cpp-docs/blob/main/docs/preprocessor/hash-import-directive-cpp.md
# XXX is #include_next really the same as #include ?
do_include_next = do_include
# Utility methods for handling resolution of include files.
[docs] def resolve_include(self, t):
"""Resolve a tuple-ized #include line.
This handles recursive expansion of values without "" or <>
surrounding the name until an initial " or < is found, to handle
#include FILE where FILE is a #define somewhere else.
"""
s = t[1].strip()
while not s[0] in '<"':
try:
s = self.cpp_namespace[s]
# strip backslashes from the computed include (-DFOO_H=\"foo.h\")
for c in '<">':
s = s.replace(f"\\{c}", c)
except KeyError:
m = function_name.search(s)
# Date: Mon, 28 Nov 2016 17:47:13 UTC
# From: Ivan Kravets <ikravets@platformio.org>
#
# Ignore `#include` directive that depends on dynamic macro
# which is not located in state TABLE
# For example, `#include MYCONFIG_FILE`
if not m:
return None
s = self.cpp_namespace[m.group(1)]
if callable(s):
args = function_arg_separator.split(m.group(2))
s = s(*args)
if not s:
return None
return (t[0], s[0], s[1:-1])
[docs] def all_include(self, t) -> None:
"""
"""
self.result.append(self.resolve_include(t))
[docs]class DumbPreProcessor(PreProcessor):
"""A preprocessor that ignores all #if/#elif/#else/#endif directives
and just reports back *all* of the #include files (like the classic
SCons scanner did).
This is functionally equivalent to using a regular expression to
find all of the #include lines, only slower. It exists mainly as
an example of how the main PreProcessor class can be sub-classed
to tailor its behavior.
"""
def __init__(self, *args, **kw) -> None:
PreProcessor.__init__(self, *args, **kw)
d = self.default_table
for func in ['if', 'elif', 'else', 'endif', 'ifdef', 'ifndef']:
d[func] = d[func] = self.do_nothing
# Local Variables:
# tab-width:4
# indent-tabs-mode:nil
# End:
# vim: set expandtab tabstop=4 shiftwidth=4: