(no subject)

I use Pyrex a lot for speeding up Python (rather than interfacing to external 
libraries).  For this use, I find it easiest to develop in pure Python, then 
switch over to Pyrex at some point.

To make a long story short, I decided I needed a very simple version of the C 
preprocessor to be able to generate both Pyrex and Python versions from the 
same source file.  I looked around (though admittedly not too hard, because it 
didn't seem like too hard of a problem), didn't see what I wanted, so wrote a 
little script.

This script does two things:

1) It tries to automagically do the right thing with 'cdef' depending on 
context.  For my coding style, it does this pretty much all the time.  The 
right thing is either to strip the 'c' off of 'cdef', strip the 'c' off of cdef 
and add '(object)' right before ':' for classes, or strip the whole line with 
the 'cdef'.  If you use continuation lines a lot your mileage will certainly 
vary.

2) It allows '#if pyrex', '#if !pyrex', '#else', and '#endif' to control the 
output.

The script takes a single parameter, e.g. 'foo' and reads 'foo.src' and writes 
'foo.py' and 'foo.pyx'.

I hope others find this useful (and please let me know if there is a fancier 
version out there somewhere I missed).

Thanks,
Pat

from operator import __mul__
import sys

if len(sys.argv) != 2:
    raise SystemExit("\nExpected exactly one argument.")

fn = sys.argv[1]+'.'

sf = file(fn+'src','r')
df = file(fn+'py','w'), file(fn+'pyx','w')
enable = (1,1)

for line in sf:
    outlines = map(__mul__,enable,[line,line])
    tokens = line.split()
    if tokens:
        tok = tokens[0]
        if tok == 'cdef':
            if tokens[1] == 'class':
                tokens = line.split('cdef',1)
                outlines[0] = 
tokens[0]+tokens[1].lstrip().replace(':','(object):',1)
            elif ':' in line.split('#',1)[0]:
                outlines[0] = line.replace('cdef','def',1)
            else:
                outlines[0] = ''
        elif tok in ('#if','#else','#endif'):
            if tok == '#if':
                assert enable == (1,1) and tokens[1] in ('pyrex','!pyrex')
                enable = ((1,0),(0,1))[tokens[1] == 'pyrex']
            elif tok == '#else':
                assert enable in ((1,0),(0,1))
                enable = ((1,0),(0,1))[enable==(1,0)]
            else:
                assert enable in ((1,0),(0,1))
                enable = (1,1)
            continue #without writing
    for f,l in zip(df,outlines):
        f.write(l)

for f in df:
    f.close()