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gen_exp_to_imap.py
101 lines (83 loc) · 3.54 KB
/
gen_exp_to_imap.py
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""" GenExpToImap transforms generator expressions into iterators. """
from pythran.analyses import OptimizableComprehension
from pythran.passmanager import Transformation
from pythran.transformations.normalize_tuples import ConvertToTuple
from pythran.conversion import mangle
import gast as ast
import sys
if sys.version_info.major == 2:
MODULE = 'itertools'
IMAP = 'imap'
IFILTER = 'ifilter'
else:
MODULE = '__builtin__'
IMAP = 'map'
IFILTER = 'filter'
ASMODULE = mangle(MODULE)
class GenExpToImap(Transformation):
'''
Transforms generator expressions into iterators.
>>> import gast as ast
>>> from pythran import passmanager, backend
>>> node = ast.parse("(x*x for x in range(10))")
>>> pm = passmanager.PassManager("test")
>>> _, node = pm.apply(GenExpToImap, node)
>>> print pm.dump(backend.Python, node)
import itertools as __pythran_import_itertools
__pythran_import_itertools.imap((lambda x: (x * x)), range(10))
'''
def __init__(self):
Transformation.__init__(self, OptimizableComprehension)
def visit_Module(self, node):
self.generic_visit(node)
importIt = ast.Import(names=[ast.alias(name=MODULE, asname=ASMODULE)])
node.body.insert(0, importIt)
return node
def make_Iterator(self, gen):
if gen.ifs:
ldFilter = ast.Lambda(
ast.arguments([ast.Name(gen.target.id, ast.Param(), None)],
None, [], [], None, []),
ast.BoolOp(ast.And(), gen.ifs)
if len(gen.ifs) > 1 else gen.ifs[0])
ifilterName = ast.Attribute(
value=ast.Name(id=ASMODULE,
ctx=ast.Load(),
annotation=None),
attr=IFILTER, ctx=ast.Load())
return ast.Call(ifilterName, [ldFilter, gen.iter], [])
else:
return gen.iter
def visit_GeneratorExp(self, node):
if node in self.optimizable_comprehension:
self.update = True
self.generic_visit(node)
iters = [self.make_Iterator(gen) for gen in node.generators]
variables = [ast.Name(gen.target.id, ast.Param(), None)
for gen in node.generators]
# If dim = 1, product is useless
if len(iters) == 1:
iterAST = iters[0]
varAST = ast.arguments([variables[0]], None, [], [], None, [])
else:
prodName = ast.Attribute(
value=ast.Name(id=mangle('itertools'),
ctx=ast.Load(),
annotation=None),
attr='product', ctx=ast.Load())
varid = variables[0].id # retarget this id, it's free
renamings = {v.id: (i,) for i, v in enumerate(variables)}
node.elt = ConvertToTuple(varid, renamings).visit(node.elt)
iterAST = ast.Call(prodName, iters, [])
varAST = ast.arguments([ast.Name(varid, ast.Param(), None)],
None, [], [], None, [])
imapName = ast.Attribute(
value=ast.Name(id=ASMODULE,
ctx=ast.Load(),
annotation=None),
attr=IMAP, ctx=ast.Load())
ldBodyimap = node.elt
ldimap = ast.Lambda(varAST, ldBodyimap)
return ast.Call(imapName, [ldimap, iterAST], [])
else:
return self.generic_visit(node)