ref: a11819e2f42b1a05251f19b9c9ed41e516eec5f3
dir: /man/simplecpp/
#!/usr/bin/env python3
#
# Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
# Contributors to the Freedoom project. All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
# * Neither the name of the freedoom project nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
# IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
# TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
# OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
#
# simple cpp-style preprocessor
#
# Understands most features of the C preprocessor, including:
# #if .. #elif .. #else .. #endif
# - with expressions
# #ifdef
# #define
# #include
#
import collections
import io
import sys
import re
debug = False
defines = collections.defaultdict(lambda: False)
command_re = re.compile(r"\#(\w+)(\s+(.*))?")
include_re = re.compile(r"\s*\"(.*)\"\s*")
define_re = re.compile(r"\s*(\S+)\s*(.*?)\s*$")
def debug_msg(message):
if debug:
sys.stderr.write(message)
# Parse command line options
def parse_cmdline():
for arg in sys.argv[1:]:
if not arg.startswith("-D"):
continue
name = arg[2:]
if '=' in name:
name, value = name.split('=', 1)
else:
value = True
defines[name] = value
def parse_stream(stream):
result = read_block(stream, False)
if result is not None:
raise Exception("Mismatched #if in '%s'" % stream.name)
def parse_file(filename):
f = io.open(filename, encoding='UTF-8')
try:
parse_stream(f)
finally:
f.close()
# Evaluate an expression using Python's eval() function.
def eval_expr(expr):
expr = expr.replace("||", " or ") \
.replace("&&", " and ") \
.replace("!", "not ")
code = compile(expr, "", "eval")
result = eval(code, {}, defines)
return result
# #include
def cmd_include(arg):
# Extract the filename
match = include_re.match(arg)
if not match:
raise Exception("Invalid 'include' command")
filename = match.group(1)
# Open the file and process it
parse_file(filename)
# #define
def cmd_define(arg):
match = define_re.match(arg)
name = match.group(1)
value = match.group(2)
if value == '':
value = True
defines[name] = value
# #undef
def cmd_undef(arg):
if arg in defines:
del defines[arg]
# #ifdef/#ifndef
def cmd_ifdef(arg, command, stream, ignore):
# Get the define name
debug_msg("%s %s >\n" % (command, arg))
# Should we ignore the contents of this block?
sub_ignore = not eval_expr(arg)
if "n" in command:
sub_ignore = not sub_ignore
# Parse the block
result, newarg = read_block(stream, ignore or sub_ignore)
debug_msg("%s %s < (%s)\n" % (command, arg, result))
# There may be a second "else" block to parse:
if result == "else":
debug_msg("%s %s else >\n" % (command, arg))
result, arg = read_block(stream, ignore or (not sub_ignore))
debug_msg("%s %s else < (%s)\n" % (command, arg, result))
if result == "elif":
debug_msg("%s %s elif %s>\n" % (command, arg, newarg))
cmd_ifdef(newarg, "if", stream, ignore or (not sub_ignore))
result = "endif"
# Should end in an endif:
if result != "endif":
raise Exception("'if' block did not end in an 'endif'")
commands = {
"include" : cmd_include,
"define" : cmd_define,
"undef" : cmd_undef,
"if" : cmd_ifdef,
"ifdef" : cmd_ifdef,
"ifn" : cmd_ifdef,
"ifndef" : cmd_ifdef,
}
# Recursive block reading function
# if 'ignore' argument is 1, contents are ignored
def read_block(stream, ignore):
for line in stream:
# Remove newline
line = line[0:-1]
# Check if this line has a command
match = command_re.match(line)
if match:
command = match.group(1)
arg = match.group(3)
if command in ("else", "elif", "endif"):
return (command, arg)
elif command not in commands:
raise Exception("Unknown command: '%s'" % \
command)
# Get the callback function.
func = commands[command]
# Invoke the callback function. #ifdef commands
# are a special case and need extra arguments.
# Other commands are only executed if we are not
# ignoring this block.
if func == cmd_ifdef:
cmd_ifdef(arg, command=command,
stream=stream,
ignore=ignore)
elif not ignore:
func(arg)
else:
if not ignore:
for key, value in defines.items():
if isinstance(value, str):
line = line.replace(key, value)
print(line)
parse_cmdline()
parse_stream(sys.stdin)