construct: Remove Python 2 compatibility layer

Remove the compatibility layer `py3compat`.

PS: There is eliben#548 to migrate
from the interned version of `construct` back to "Construct 2.10+" now
that it is maintained again. When that happens, this change will become
moot. Until then restore some sanity back into our copy as handling
Python type annotations for both Python 2 and 3 is a major pain.

Signed-off-by: Philipp Hahn <[email protected]>

Author: pmhahn

elftools/construct/__init__.py

@@ -22,7 +22,7 @@
     ... )
     >>> s.parse("\\x01\\x02\\x03")
     Container(a = 1, b = 515)
-    >>> print s.parse("\\x01\\x02\\x03")
+    >>> print(s.parse("\\x01\\x02\\x03"))
     Container:
         a = 1
         b = 515

elftools/construct/adapters.py

@@ -1,7 +1,8 @@
+from io import BytesIO
+
 from .core import Adapter, AdaptationError, Pass
 from .lib import int_to_bin, bin_to_int, swap_bytes
 from .lib import FlagsContainer, HexString
-from .lib.py3compat import BytesIO, decodebytes
 
 
 #===============================================================================

elftools/construct/core.py

@@ -1,6 +1,6 @@
+from io import BytesIO
 from struct import Struct as Packer
 
-from .lib.py3compat import BytesIO, advance_iterator, bchr
 from .lib import Container, ListContainer, LazyContainer
 
 
@@ -520,13 +520,13 @@ def _build(self, obj, stream, context):
             if self.subcon.conflags & self.FLAG_COPY_CONTEXT:
                 for subobj in obj:
                     if isinstance(obj, bytes):
-                        subobj = bchr(subobj)
+                        subobj = bytes((subobj,))
                     self.subcon._build(subobj, stream, context.__copy__())
                     cnt += 1
             else:
                 for subobj in obj:
                     if isinstance(obj, bytes):
-                        subobj = bchr(subobj)
+                        subobj = bytes((subobj,))
                     self.subcon._build(subobj, stream, context)
                     cnt += 1
         except ConstructError as ex:
@@ -587,7 +587,7 @@ def _build(self, obj, stream, context):
                     break
         else:
             for subobj in obj:
-                subobj = bchr(subobj)
+                subobj = bytes((subobj,))
                 self.subcon._build(subobj, stream, context.__copy__())
                 if self.predicate(subobj, context):
                     terminated = True
@@ -722,7 +722,7 @@ def _build(self, obj, stream, context):
             elif sc.name is None:
                 subobj = None
             else:
-                subobj = advance_iterator(objiter)
+                subobj = next(objiter)
                 context[sc.name] = subobj
             sc._build(subobj, stream, context)
 

elftools/construct/lib/binary.py

@@ -1,6 +1,3 @@
-from .py3compat import int2byte
-
-
 def int_to_bin(number, width=32):
     r"""
     Convert an integer into its binary representation in a bytes object.
@@ -32,13 +29,6 @@ def int_to_bin(number, width=32):
     1: 1,
     48: 0, # '0'
     49: 1, # '1'
-
-    # The following are for Python 2, in which iteration over a bytes object
-    # yields single-character bytes and not integers.
-    '\x00': 0,
-    '\x01': 1,
-    '0': 0,
-    '1': 1,
     }
 
 def bin_to_int(bits, signed=False):
@@ -81,7 +71,7 @@ def swap_bytes(bits, bytesize=8):
 _char_to_bin = {}
 _bin_to_char = {}
 for i in range(256):
-    ch = int2byte(i)
+    ch = bytes((i,))
     bin = int_to_bin(i, 8)
     # Populate with for both keys i and ch, to support Python 2 & 3
     _char_to_bin[ch] = bin

elftools/construct/lib/container.py

@@ -2,8 +2,9 @@
 Various containers.
 """
 
+from collections.abc import MutableMapping
 from pprint import pformat
-from .py3compat import MutableMapping
+
 
 def recursion_lock(retval, lock_name = "__recursion_lock__"):
     def decorator(func):

elftools/construct/lib/hex.py

@@ -1,9 +1,6 @@
-from .py3compat import byte2int, int2byte, bytes2str
-
-
 # Map an integer in the inclusive range 0-255 to its string byte representation
 _printable = dict((i, ".") for i in range(256))
-_printable.update((i, bytes2str(int2byte(i))) for i in range(32, 128))
+_printable.update((i, chr(i)) for i in range(32, 128))
 
 
 def hexdump(data, linesize):
@@ -18,8 +15,8 @@ def hexdump(data, linesize):
     fmt = fmt % (3 * linesize - 1,)
     for i in range(0, len(data), linesize):
         line = data[i : i + linesize]
-        hextext = " ".join('%02x' % byte2int(b) for b in line)
-        rawtext = "".join(_printable[byte2int(b)] for b in line)
+        hextext = " ".join('%02x' % b for b in line)
+        rawtext = "".join(_printable[b] for b in line)
         prettylines.append(fmt % (i, str(hextext), str(rawtext)))
     return prettylines
 

elftools/construct/lib/py3compat.py

@@ -1,4 +1,3 @@
-from .lib.py3compat import int2byte
 from .lib import (BitStreamReader, BitStreamWriter, encode_bin,
     decode_bin)
 from .core import (Struct, MetaField, StaticField, FormatField,
@@ -103,7 +102,7 @@ def Flag(name, truth = 1, falsehood = 0, default = False):
     """
 
     return SymmetricMapping(Field(name, 1),
-        {True : int2byte(truth), False : int2byte(falsehood)},
+        {True : bytes((truth,)), False : bytes((falsehood,))},
         default = default,
     )