#! /usr/bin/env python

# Read #define's and translate to Python code.
# Handle #include statements.
# Handle #define macros with one argument.
# Anything that isn't recognized or doesn't translate into valid
# Python is ignored.

# Without filename arguments, acts as a filter.
# If one or more filenames are given, output is written to corresponding
# filenames in the local directory, translated to all uppercase, with
# the extension replaced by ".py".

# By passing one or more options of the form "-i regular_expression"
# you can specify additional strings to be ignored.  This is useful
# e.g. to ignore casts to u_long: simply specify "-i '(u_long)'".

# XXX To do:
# - turn trailing C comments into Python comments
# - turn C Boolean operators "&& || !" into Python "and or not"
# - what to do about #if(def)?
# - what to do about macros with multiple parameters?

import sys, re, getopt, os

p_define = re.compile('^[\t ]*#[\t ]*define[\t ]+([a-zA-Z0-9_]+)[\t ]+')

p_macro = re.compile(
 '^[\t ]*#[\t ]*define[\t ]+'
 '([a-zA-Z0-9_]+)\(([_a-zA-Z][_a-zA-Z0-9]*)\)[\t ]+')

p_include = re.compile('^[\t ]*#[\t ]*include[\t ]+<([a-zA-Z0-9_/\.]+)')

p_comment = re.compile(r'/\*([^*]+|\*+[^/])*(\*+/)?')
p_cpp_comment = re.compile('//.*')

ignores = [p_comment, p_cpp_comment]

p_char = re.compile(r"'(\\.[^\\]*|[^\\])'")

p_hex = re.compile(r"0x([0-9a-fA-F]+)L?")

filedict = {}
importable = {}

try:
   searchdirs=os.environ['include'].split(';')
except KeyError:
   try:
       searchdirs=os.environ['INCLUDE'].split(';')
   except KeyError:
       try:
           if  sys.platform.find("beos") == 0:
               searchdirs=os.environ['BEINCLUDES'].split(';')
           elif sys.platform.startswith("atheos"):
               searchdirs=os.environ['C_INCLUDE_PATH'].split(':')
           else:
               raise KeyError
       except KeyError:
           searchdirs=['/usr/include']

def main():
   global filedict
   opts, args = getopt.getopt(sys.argv[1:], 'i:')
   for o, a in opts:
       if o == '-i':
           ignores.append(re.compile(a))
   if not args:
       args = ['-']
   for filename in args:
       if filename == '-':
           sys.stdout.write('# Generated by h2py from stdin\n')
           process(sys.stdin, sys.stdout)
       else:
           fp = open(filename, 'r')
           outfile = os.path.basename(filename)
           i = outfile.rfind('.')
           if i > 0: outfile = outfile[:i]
           modname = outfile.upper()
           outfile = modname + '.py'
           outfp = open(outfile, 'w')
           outfp.write('# Generated by h2py from %s\n' % filename)
           filedict = {}
           for dir in searchdirs:
               if filename[:len(dir)] == dir:
                   filedict[filename[len(dir)+1:]] = None  # no '/' trailing
                   importable[filename[len(dir)+1:]] = modname
                   break
           process(fp, outfp)
           outfp.close()
           fp.close()

def pytify(body):
   # replace ignored patterns by spaces
   for p in ignores:
       body = p.sub(' ', body)
   # replace char literals by ord(...)
   body = p_char.sub('ord(\\0)', body)
   # Compute negative hexadecimal constants
   start = 0
   UMAX = 2*(sys.maxint+1)
   while 1:
       m = p_hex.search(body, start)
       if not m: break
       s,e = m.span()
       val = long(body[slice(*m.span(1))], 16)
       if val > sys.maxint:
           val -= UMAX
           body = body[:s] + "(" + str(val) + ")" + body[e:]
       start = s + 1
   return body

def process(fp, outfp, env = {}):
   lineno = 0
   while 1:
       line = fp.readline()
       if not line: break
       lineno = lineno + 1
       match = p_define.match(line)
       if match:
           # gobble up continuation lines
           while line[-2:] == '\\\n':
               nextline = fp.readline()
               if not nextline: break
               lineno = lineno + 1
               line = line + nextline
           name = match.group(1)
           body = line[match.end():]
           body = pytify(body)
           ok = 0
           stmt = '%s = %s\n' % (name, body.strip())
           try:
               exec stmt in env
           except:
               sys.stderr.write('Skipping: %s' % stmt)
           else:
               outfp.write(stmt)
       match = p_macro.match(line)
       if match:
           macro, arg = match.group(1, 2)
           body = line[match.end():]
           body = pytify(body)
           stmt = 'def %s(%s): return %s\n' % (macro, arg, body)
           try:
               exec stmt in env
           except:
               sys.stderr.write('Skipping: %s' % stmt)
           else:
               outfp.write(stmt)
       match = p_include.match(line)
       if match:
           regs = match.regs
           a, b = regs[1]
           filename = line[a:b]
           if importable.has_key(filename):
               outfp.write('from %s import *\n' % importable[filename])
           elif not filedict.has_key(filename):
               filedict[filename] = None
               inclfp = None
               for dir in searchdirs:
                   try:
                       inclfp = open(dir + '/' + filename)
                       break
                   except IOError:
                       pass
               if inclfp:
                   outfp.write(
                           '\n# Included from %s\n' % filename)
                   process(inclfp, outfp, env)
               else:
                   sys.stderr.write('Warning - could not find file %s\n' %
                                    filename)

if __name__ == '__main__':
   main()