llvm/utils/gn/build/write_cmake_config.py

   1 #!/usr/bin/env python
   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 '${KEY}' or '@KEY@' with VALUE.
  13
  14 Then, handles these special cases (note that FOO= sets the value of FOO to the
  15 empty string, which is falsy, but FOO=0 sets it to '0' which is truthy):
  16
  17 1.) #cmakedefine01 FOO
  18     Checks if key FOO is set to a truthy value, and depending on that prints
  19     one of the following two lines:
  20
  21         #define FOO 1
  22         #define FOO 0
  23
  24 2.) #cmakedefine FOO [...]
  25     Checks if key FOO is set to a truthy value, and depending on that prints
  26     one of the following two lines:
  27
  28         #define FOO [...]
  29         /* #undef FOO */
  30
  31 Fails if any of the KEY=VALUE arguments aren't needed for processing the
  32 input file, or if the input file references keys that weren't passed in.
  33 """
  34
  35 from __future__ import print_function
  36
  37 import argparse
  38 import os
  39 import re
  40 import sys
  41
  42
  43 def main():
  44     parser = argparse.ArgumentParser(
  45                  epilog=__doc__,
  46                  formatter_class=argparse.RawDescriptionHelpFormatter)
  47     parser.add_argument('input', help='input file')
  48     parser.add_argument('values', nargs='*', help='several KEY=VALUE pairs')
  49     parser.add_argument('-o', '--output', required=True,
  50                         help='output file')
  51     args = parser.parse_args()
  52
  53     values = {}
  54     for value in args.values:
  55         key, val = value.split('=', 1)
  56         if key in values:
  57             print('duplicate key "%s" in args' % key, file=sys.stderr)
  58             return 1
  59         values[key] = val.replace('\\n', '\n')
  60     unused_values = set(values.keys())
  61
  62     # Matches e.g. '${FOO}' or '@FOO@' and captures FOO in group 1 or 2.
  63     var_re = re.compile(r'\$\{([^}]*)\}|@([^@]*)@')
  64
  65     with open(args.input) as f:
  66         in_lines = f.readlines()
  67     out_lines = []
  68     for in_line in in_lines:
  69         def repl(m):
  70             key = m.group(1) or m.group(2)
  71             unused_values.discard(key)
  72             return values[key]
  73         in_line = var_re.sub(repl, in_line)
  74         if in_line.startswith('#cmakedefine01 '):
  75             _, var = in_line.split()
  76             if values[var] == '0':
  77                 print('error: "%s=0" used with #cmakedefine01 %s' % (var, var))
  78                 print("       '0' evaluates as truthy with #cmakedefine01")
  79                 print('       use "%s=" instead' % var)
  80                 return 1
  81             in_line = '#define %s %d\n' % (var, 1 if values[var] else 0)
  82             unused_values.discard(var)
  83         elif in_line.startswith('#cmakedefine '):
  84             _, var = in_line.split(None, 1)
  85             try:
  86                 var, val = var.split(None, 1)
  87                 in_line = '#define %s %s' % (var, val)  # val ends in \n.
  88             except:
  89                 var = var.rstrip()
  90                 in_line = '#define %s\n' % var
  91             if not values[var]:
  92                 in_line = '/* #undef %s */\n' % var
  93             unused_values.discard(var)
  94         out_lines.append(in_line)
  95
  96     if unused_values:
  97         print('unused values args:', file=sys.stderr)
  98         print('    ' + '\n    '.join(unused_values), file=sys.stderr)
  99         return 1
 100
 101     output = ''.join(out_lines)
 102
 103     leftovers = var_re.findall(output)
 104     if leftovers:
 105         print(
 106             'unprocessed values:\n',
 107             '\n'.join([x[0] or x[1] for x in leftovers]),
 108             file=sys.stderr)
 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())