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[#145] Reformatted codecs module for PEP-8.
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‎iota/codecs.py

Lines changed: 185 additions & 178 deletions
Original file line numberDiff line numberDiff line change
@@ -1,213 +1,220 @@
11
# coding=utf-8
22
from __future__ import absolute_import, division, print_function, \
3-
unicode_literals
3+
unicode_literals
44

55
from codecs import Codec, CodecInfo, register as lookup_function
66
from warnings import warn
77

8-
from iota.exceptions import with_context
98
from six import PY3, binary_type
109

10+
from iota.exceptions import with_context
11+
1112
__all__ = [
12-
'AsciiTrytesCodec',
13-
'TrytesDecodeError',
13+
'AsciiTrytesCodec',
14+
'TrytesDecodeError',
1415
]
1516

1617

1718
class TrytesDecodeError(ValueError):
18-
"""
19-
Indicates that a tryte string could not be decoded to bytes.
20-
"""
21-
pass
19+
"""
20+
Indicates that a tryte string could not be decoded to bytes.
21+
"""
22+
pass
2223

2324

2425
class AsciiTrytesCodec(Codec):
25-
"""
26-
Legacy codec for converting byte strings into trytes, and vice versa.
27-
28-
This method encodes each pair of trytes as an ASCII code point (and
29-
vice versa when decoding).
30-
31-
The end result requires more space than if the trytes were converted
32-
mathematically, but because the result is ASCII, it's easier to work
33-
with.
34-
35-
Think of this kind of like Base 64 for balanced ternary (:
36-
"""
37-
name = 'trytes_ascii'
38-
39-
compat_name = 'trytes'
40-
"""
41-
Old name for this codec.
42-
Note: Will be removed in PyOTA v2.1!
43-
"""
44-
45-
# :bc: Without the bytearray cast, Python 2 will populate the dict
46-
# with characters instead of integers.
47-
# noinspection SpellCheckingInspection
48-
alphabet = dict(enumerate(bytearray(b'9ABCDEFGHIJKLMNOPQRSTUVWXYZ')))
49-
"""
50-
Used to encode bytes into trytes.
51-
"""
52-
53-
index = dict(zip(alphabet.values(), alphabet.keys()))
54-
"""
55-
Used to decode trytes into bytes.
56-
"""
57-
58-
@classmethod
59-
def get_codec_info(cls):
60-
"""
61-
Returns information used by the codecs library to configure the
62-
codec for use.
6326
"""
64-
codec = cls()
27+
Legacy codec for converting byte strings into trytes, and vice
28+
versa.
6529
66-
codec_info = {
67-
'encode': codec.encode,
68-
'decode': codec.decode,
69-
}
30+
This method encodes each pair of trytes as an ASCII code point (and
31+
vice versa when decoding).
7032
71-
# In Python 2, all codecs are made equal.
72-
# In Python 3, some codecs are more equal than others.
73-
if PY3:
74-
codec_info['_is_text_encoding'] = False
33+
The end result requires more space than if the trytes were converted
34+
mathematically, but because the result is ASCII, it's easier to work
35+
with.
7536
76-
return CodecInfo(**codec_info)
37+
Think of this kind of like Base 64 for balanced ternary (:
38+
"""
39+
name = 'trytes_ascii'
7740

78-
# noinspection PyShadowingBuiltins
79-
def encode(self, input, errors='strict'):
41+
compat_name = 'trytes'
8042
"""
81-
Encodes a byte string into trytes.
43+
Old name for this codec.
44+
Note: Will be removed in PyOTA v2.1!
8245
"""
83-
if isinstance(input, memoryview):
84-
input = input.tobytes()
8546

86-
if not isinstance(input, (binary_type, bytearray)):
87-
raise with_context(
88-
exc = TypeError("Can't encode {type}; byte string expected.".format(
89-
type = type(input).__name__,
90-
)),
91-
92-
context = {
93-
'input': input,
94-
},
95-
)
47+
# :bc: Without the bytearray cast, Python 2 will populate the dict
48+
# with characters instead of integers.
49+
# noinspection SpellCheckingInspection
50+
alphabet = dict(enumerate(bytearray(b'9ABCDEFGHIJKLMNOPQRSTUVWXYZ')))
51+
"""
52+
Used to encode bytes into trytes.
53+
"""
9654

97-
# :bc: In Python 2, iterating over a byte string yields characters
98-
# instead of integers.
99-
if not isinstance(input, bytearray):
100-
input = bytearray(input)
55+
index = dict(zip(alphabet.values(), alphabet.keys()))
56+
"""
57+
Used to decode trytes into bytes.
58+
"""
10159

102-
trytes = bytearray()
60+
@classmethod
61+
def get_codec_info(cls):
62+
"""
63+
Returns information used by the codecs library to configure the
64+
codec for use.
65+
"""
66+
codec = cls()
67+
68+
codec_info = {
69+
'encode': codec.encode,
70+
'decode': codec.decode,
71+
}
72+
73+
# In Python 2, all codecs are made equal.
74+
# In Python 3, some codecs are more equal than others.
75+
if PY3:
76+
codec_info['_is_text_encoding'] = False
77+
78+
return CodecInfo(**codec_info)
79+
80+
# noinspection PyShadowingBuiltins
81+
def encode(self, input, errors='strict'):
82+
"""
83+
Encodes a byte string into trytes.
84+
"""
85+
if isinstance(input, memoryview):
86+
input = input.tobytes()
87+
88+
if not isinstance(input, (binary_type, bytearray)):
89+
raise with_context(
90+
exc=TypeError(
91+
"Can't encode {type}; byte string expected.".format(
92+
type=type(input).__name__,
93+
)),
94+
95+
context={
96+
'input': input,
97+
},
98+
)
99+
100+
# :bc: In Python 2, iterating over a byte string yields
101+
# characters instead of integers.
102+
if not isinstance(input, bytearray):
103+
input = bytearray(input)
104+
105+
trytes = bytearray()
106+
107+
for c in input:
108+
second, first = divmod(c, len(self.alphabet))
109+
110+
trytes.append(self.alphabet[first])
111+
trytes.append(self.alphabet[second])
112+
113+
return binary_type(trytes), len(input)
114+
115+
# noinspection PyShadowingBuiltins
116+
def decode(self, input, errors='strict'):
117+
"""
118+
Decodes a tryte string into bytes.
119+
"""
120+
if isinstance(input, memoryview):
121+
input = input.tobytes()
122+
123+
if not isinstance(input, (binary_type, bytearray)):
124+
raise with_context(
125+
exc=TypeError(
126+
"Can't decode {type}; byte string expected.".format(
127+
type=type(input).__name__,
128+
)),
129+
130+
context={
131+
'input': input,
132+
},
133+
)
134+
135+
# :bc: In Python 2, iterating over a byte string yields
136+
# characters instead of integers.
137+
if not isinstance(input, bytearray):
138+
input = bytearray(input)
139+
140+
bytes_ = bytearray()
141+
142+
for i in range(0, len(input), 2):
143+
try:
144+
first, second = input[i:i + 2]
145+
except ValueError:
146+
if errors == 'strict':
147+
raise with_context(
148+
exc=TrytesDecodeError(
149+
"'{name}' codec can't decode value; "
150+
"tryte sequence has odd length.".format(
151+
name=self.name,
152+
),
153+
),
154+
155+
context={
156+
'input': input,
157+
},
158+
)
159+
elif errors == 'replace':
160+
bytes_ += b'?'
161+
162+
continue
163+
164+
try:
165+
bytes_.append(
166+
self.index[first]
167+
+ (self.index[second] * len(self.index))
168+
)
169+
except ValueError:
170+
# This combination of trytes yields a value > 255 when
171+
# decoded.
172+
# Naturally, we can't represent this using ASCII.
173+
if errors == 'strict':
174+
raise with_context(
175+
exc=TrytesDecodeError(
176+
"'{name}' codec can't decode trytes {pair} "
177+
"at position {i}-{j}: "
178+
"ordinal not in range(255)".format(
179+
name=self.name,
180+
pair=chr(first) + chr(second),
181+
i=i,
182+
j=i + 1,
183+
),
184+
),
185+
186+
context={
187+
'input': input,
188+
}
189+
)
190+
elif errors == 'replace':
191+
bytes_ += b'?'
192+
193+
return binary_type(bytes_), len(input)
103194

104-
for c in input:
105-
second, first = divmod(c, len(self.alphabet))
106195

107-
trytes.append(self.alphabet[first])
108-
trytes.append(self.alphabet[second])
196+
@lookup_function
197+
def check_trytes_codec(encoding):
198+
"""
199+
Determines which codec to use for the specified encoding.
109200
110-
return binary_type(trytes), len(input)
201+
References:
111202
112-
# noinspection PyShadowingBuiltins
113-
def decode(self, input, errors='strict'):
114-
"""
115-
Decodes a tryte string into bytes.
203+
- https://docs.python.org/3/library/codecs.html#codecs.register
116204
"""
117-
if isinstance(input, memoryview):
118-
input = input.tobytes()
119-
120-
if not isinstance(input, (binary_type, bytearray)):
121-
raise with_context(
122-
exc = TypeError("Can't decode {type}; byte string expected.".format(
123-
type = type(input).__name__,
124-
)),
125-
126-
context = {
127-
'input': input,
128-
},
129-
)
130-
131-
# :bc: In Python 2, iterating over a byte string yields characters
132-
# instead of integers.
133-
if not isinstance(input, bytearray):
134-
input = bytearray(input)
135-
136-
bytes_ = bytearray()
137-
138-
for i in range(0, len(input), 2):
139-
try:
140-
first, second = input[i:i+2]
141-
except ValueError:
142-
if errors == 'strict':
143-
raise with_context(
144-
exc = TrytesDecodeError(
145-
"'{name}' codec can't decode value; "
146-
"tryte sequence has odd length.".format(
147-
name = self.name,
148-
),
205+
if encoding == AsciiTrytesCodec.name:
206+
return AsciiTrytesCodec.get_codec_info()
207+
208+
elif encoding == AsciiTrytesCodec.compat_name:
209+
warn(
210+
'"{old_codec}" codec will be removed in PyOTA v2.1. '
211+
'Use "{new_codec}" instead.'.format(
212+
new_codec=AsciiTrytesCodec.name,
213+
old_codec=AsciiTrytesCodec.compat_name,
149214
),
150215

151-
context = {
152-
'input': input,
153-
},
154-
)
155-
elif errors == 'replace':
156-
bytes_ += b'?'
157-
158-
continue
159-
160-
try:
161-
bytes_.append(
162-
self.index[first]
163-
+ (self.index[second] * len(self.index))
216+
DeprecationWarning,
164217
)
165-
except ValueError:
166-
# This combination of trytes yields a value > 255 when
167-
# decoded. Naturally, we can't represent this using ASCII.
168-
if errors == 'strict':
169-
raise with_context(
170-
exc = TrytesDecodeError(
171-
"'{name}' codec can't decode trytes {pair} at position {i}-{j}: "
172-
"ordinal not in range(255)".format(
173-
name = self.name,
174-
pair = chr(first) + chr(second),
175-
i = i,
176-
j = i+1,
177-
),
178-
),
179-
180-
context = {
181-
'input': input,
182-
}
183-
)
184-
elif errors == 'replace':
185-
bytes_ += b'?'
218+
return AsciiTrytesCodec.get_codec_info()
186219

187-
return binary_type(bytes_), len(input)
188-
189-
190-
@lookup_function
191-
def check_trytes_codec(encoding):
192-
"""
193-
Determines which codec to use for the specified encoding.
194-
195-
References:
196-
- https://docs.python.org/3/library/codecs.html#codecs.register
197-
"""
198-
if encoding == AsciiTrytesCodec.name:
199-
return AsciiTrytesCodec.get_codec_info()
200-
201-
elif encoding == AsciiTrytesCodec.compat_name:
202-
warn(
203-
'"{old_codec}" codec will be removed in PyOTA v2.1. '
204-
'Use "{new_codec}" instead.'.format(
205-
new_codec = AsciiTrytesCodec.name,
206-
old_codec = AsciiTrytesCodec.compat_name,
207-
),
208-
209-
DeprecationWarning,
210-
)
211-
return AsciiTrytesCodec.get_codec_info()
212-
213-
return None
220+
return None

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