llvm/utils/gn/build/write_cmake_config.py

   1 #!/usr/bin/env python3
   2 r"""Emulates the bits of CMake's configure_file() function needed in LLVM.
   3
   4 The CMake build uses configure_file() for several things.  This emulates that
   5 function for the GN build.  In the GN build, this runs at build time instead
   6 of at generator time.
   7
   8 Takes a list of KEY=VALUE pairs (where VALUE can be empty).
   9
  10 The sequence `\` `n` in each VALUE is replaced by a newline character.
  11
  12 On each line, replaces '${KEY}' or '@KEY@' with VALUE.
  13
  14 Then, handles these special cases (note that FOO= sets the value of FOO to the
  15 empty string, which is falsy, but FOO=0 sets it to '0' which is truthy):
  16
  17 1.) #cmakedefine01 FOO
  18     Checks if key FOO is set to a truthy value, and depending on that prints
  19     one of the following two lines:
  20
  21         #define FOO 1
  22         #define FOO 0
  23
  24 2.) #cmakedefine FOO [...]
  25     Checks if key FOO is set to a truthy value, and depending on that prints
  26     one of the following two lines:
  27
  28         #define FOO [...]
  29         /* #undef FOO */
  30
  31 Fails if any of the KEY=VALUE arguments aren't needed for processing the
  32 input file, or if the input file references keys that weren't passed in.
  33 """
  34
  35 import argparse
  36 import os
  37 import re
  38 import sys
  39
  40
  41 def main():
  42     parser = argparse.ArgumentParser(
  43         epilog=__doc__, formatter_class=argparse.RawDescriptionHelpFormatter
  44     )
  45     parser.add_argument("input", help="input file")
  46     parser.add_argument("values", nargs="*", help="several KEY=VALUE pairs")
  47     parser.add_argument("-o", "--output", required=True, help="output file")
  48     args = parser.parse_args()
  49
  50     values = {}
  51     for value in args.values:
  52         key, val = value.split("=", 1)
  53         if key in values:
  54             print('duplicate key "%s" in args' % key, file=sys.stderr)
  55             return 1
  56         values[key] = val.replace("\\n", "\n")
  57     unused_values = set(values.keys())
  58
  59     # Matches e.g. '${FOO}' or '@FOO@' and captures FOO in group 1 or 2.
  60     var_re = re.compile(r"\$\{([^}]*)\}|@([^@]*)@")
  61
  62     with open(args.input) as f:
  63         in_lines = f.readlines()
  64     out_lines = []
  65     for in_line in in_lines:
  66
  67         def repl(m):
  68             key = m.group(1) or m.group(2)
  69             unused_values.discard(key)
  70             return values[key]
  71
  72         in_line = var_re.sub(repl, in_line)
  73         if in_line.startswith("#cmakedefine01 "):
  74             _, var = in_line.split()
  75             if values[var] == "0":
  76                 print('error: "%s=0" used with #cmakedefine01 %s' % (var, var))
  77                 print("       '0' evaluates as truthy with #cmakedefine01")
  78                 print('       use "%s=" instead' % var)
  79                 return 1
  80             in_line = "#define %s %d\n" % (var, 1 if values[var] else 0)
  81             unused_values.discard(var)
  82         elif in_line.startswith("#cmakedefine "):
  83             _, var = in_line.split(None, 1)
  84             try:
  85                 var, val = var.split(None, 1)
  86                 in_line = "#define %s %s" % (var, val)  # val ends in \n.
  87             except:
  88                 var = var.rstrip()
  89                 in_line = "#define %s\n" % var
  90             if not values[var]:
  91                 in_line = "/* #undef %s */\n" % var
  92             unused_values.discard(var)
  93         out_lines.append(in_line)
  94
  95     if unused_values:
  96         print("unused values args:", file=sys.stderr)
  97         print("    " + "\n    ".join(unused_values), file=sys.stderr)
  98         return 1
  99
 100     output = "".join(out_lines)
 101
 102     leftovers = var_re.findall(output)
 103     if leftovers:
 104         print(
 105             "unprocessed values:\n",
 106             "\n".join([x[0] or x[1] for x in leftovers]),
 107             file=sys.stderr,
 108         )
 109         return 1
 110
 111     def read(filename):
 112         with open(args.output) as f:
 113             return f.read()
 114
 115     if not os.path.exists(args.output) or read(args.output) != output:
 116         with open(args.output, "w") as f:
 117             f.write(output)
 118         os.chmod(args.output, os.stat(args.input).st_mode & 0o777)
 119
 120
 121 if __name__ == "__main__":
 122     sys.exit(main())