"MRAB" <pyt...@mrabarnett.plus.com> wrote in message
news:4a8b3e2d.7040...@mrabarnett.plus.com...
Ludo wrote:
Hello,
I work in a very large project where we have C++ packages and pieces of
python code.
I've been googleing for days but what I find seems really too complicated
for what I want to do.
My business is, in python, to read enum definitions provided by the
header file of an c++ package.
Of course I could open the .h file, read the enum and transcode it by
hand into a .py file but the package is regularly updated and thus is the
enum.
My question is then simple : do we have :
- either a simple way in python to read the .h file, retrieve the c++
enum and provide an access to it in my python script
- either a simple tool (in a long-term it would be automatically run
when the c++ package is compiled) generating from the .h file a .py file
containing the python definition of the enums ?
Thank you for any suggestion.
Speaking personally, I'd parse the .h file using a regular expression
(re module) and generate a .py file. Compilers typically have a way of
letting you run external scripts (eg batch files in Windows or, in this
case, a Python script) when an application is compiled.
This is what 3rd party library pyparsing is great for:
--------begin code----------
from pyparsing import *
# sample string with enums and other stuff
sample = '''
stuff before
enum hello {
Zero,
One,
Two,
Three,
Five=5,
Six,
Ten=10
}
in the middle
enum blah
{
alpha,
beta,
gamma = 10 ,
zeta = 50
}
at the end
'''
# syntax we don't want to see in the final parse tree
_lcurl = Suppress('{')
_rcurl = Suppress('}')
_equal = Suppress('=')
_comma = Suppress(',')
_enum = Suppress('enum')
identifier = Word(alphas,alphanums+'_')
integer = Word(nums)
enumValue = Group(identifier('name') + Optional(_equal + integer('value')))
enumList = Group(enumValue + ZeroOrMore(_comma + enumValue))
enum = _enum + identifier('enum') + _lcurl + enumList('list') + _rcurl
# find instances of enums ignoring other syntax
for item,start,stop in enum.scanString(sample):
id = 0
for entry in item.list:
if entry.value != '':
id = int(entry.value)
print '%s_%s = %d' % (item.enum.upper(),entry.name.upper(),id)
id += 1
--------------end code------------
Output:
HELLO_ZERO = 0
HELLO_ONE = 1
HELLO_TWO = 2
HELLO_THREE = 3
HELLO_FIVE = 5
HELLO_SIX = 6
HELLO_TEN = 10
BLAH_ALPHA = 0
BLAH_BETA = 1
BLAH_GAMMA = 10
BLAH_ZETA = 50
-Mark
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