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|
#!/usr/bin/env python3
# SPDX-License-Identifier: BSD-3-Clause
#
# simple cpp-style preprocessor
#
# Understands:
#
# #define NAME
#
# Set an option
# You can use -D on the command line too
#
# #undef NAME
#
# Unset an option if it is set
#
# #if .. #endif / #ifdef .. #endif
#
# Specify a list of options set, eg #ifdef PHASE1 || PHASE2
# The block is only displayed if one of the options is set
#
# #ifn .. #endif / #ifndef .. #endif
#
# Similarly specify a list of options
# The block is displayed if none of the options are set
#
# #include "filename"
#
# include the contents of a file
import sys
import re
debug = False
defines = {}
command_re = re.compile(r"\#(\w+)(\s+(.*))?")
include_re = re.compile(r'\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 arg.startswith("-D"):
name = arg[2:]
defines[name] = True
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 = open(filename)
try:
parse_stream(f)
finally:
f.close()
# #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):
defines[arg] = True
# #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
name = arg.strip()
debug_msg("%s %s >\n" % (command, arg))
# Should we ignore the contents of this block?
sub_ignore = name not in defines
if "n" in command:
sub_ignore = not sub_ignore
# Parse the block
result = 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 = read_block(stream, ignore or (not sub_ignore))
debug_msg("%s %s else < (%s)\n" % (command, arg, result))
# 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]
# Ignore, but keep empty lines
if line == " " * len(line):
print(line)
continue
# Check if this line has a command
match = command_re.match(line)
if match:
command = match.group(1)
arg = match.group(3)
if command == "else" or command == "endif":
return command
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:
print(line)
parse_cmdline()
parse_stream(sys.stdin)
|
