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More unparse.py fixes:

Browse source 
- parenthesize lambdas, to avoid turning (lambda : int)() into lambda: int()
 - unparse an infinite float literals in the AST as an overflowing finite value

unparse.py now successfully round-trips on all valid Lib/*.py and Lib/test/*.py files.
This commit is contained in:
Mark Dickinson 2010-06-29 10:01:48 +00:00
parent 3eb0290346
commit 8042e28192
2 changed files with 26 additions and 11 deletions
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30
Demo/parser/unparse.py
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@ -1,5 +1,6 @@
"Usage: unparse.py <path to source file>"
import sys
import math
import ast
import tokenize
import io
@ -302,17 +303,22 @@ class Unparser:
self.write("`")
def _Num(self, t):
# Add parentheses around numeric literals to avoid:
#
# (1) turning (-1)**2 into -1**2, and
# (2) turning 3 .__abs__() into 3.__abs__()
#
# For (1), note that Python doesn't actually have negative
# numeric literals, but (at least in Python 2.x) there's a CST
# transformation that can produce negative Nums in the AST.
self.write("(")
self.write(repr(t.n))
self.write(")")
if isinstance(t.n, float):
# A float literal should be nonnegative, and not a nan.
# It could be an infinity, though; in that case we
# substitute an overflowing decimal value.
assert not math.isnan(t.n)
assert math.copysign(1.0, t.n) > 0.0
if math.isinf(t.n):
self.write("1e" + repr(sys.float_info.max_10_exp + 1))
else:
self.write(repr(t.n))
else:
# Parenthesize integer literals to avoid turning
# "3 .__abs__()" into "3.__abs__()".
self.write("(")
self.write(repr(t.n))
self.write(")")
def _List(self, t):
self.write("[")
@ -539,10 +545,12 @@ class Unparser:
self.dispatch(t.value)
def _Lambda(self, t):
self.write("(")
self.write("lambda ")
self.dispatch(t.args)
self.write(": ")
self.dispatch(t.body)
self.write(")")
def _alias(self, t):
self.write(t.name)