patch-cmake.py

#!/usr/bin/env python
'''
This script patches a CMake script to add a check before every macro and
function definition to make sure that an existing definition is not being
replaced.
'''

import sys

from cmakeast import ast
from cmakeast import ast_visitor


if len(sys.argv) != 2:
  print('Usage: python3 patch.py CMakeLists.txt', file=sys.stderr)
  sys.exit(1)


patches = []

def patch(name, node, depth):
  patchee = node.header.arguments[0].contents
  patches.append((patchee, node.line))

with open(sys.argv[1], 'r') as f:
  body = f.read()
  ast_visitor.recurse(
    ast.parse(body),
    macro_def=patch,
    function_def=patch
  )

# Insert the patch lines
lines = body.splitlines()
offset = -1
for patchee, line in patches:
  print('Patching', patchee)
  newlines = [
    'if(COMMAND %s)' % patchee,
    '    message(FATAL_ERROR "Redefinition of %s!")' % patchee,
    'endif()'
  ]
  lines[line+offset:line+offset] = newlines
  offset += len(newlines)

with open(sys.argv[1], 'w') as f:
  f.write('\n'.join(lines))