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#!/usr/bin/env PYTHONHASHSEED=1234 python3
# Copyright 2014-2024 Brett Slatkin, Pearson Education Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
### 책 예제에 맞는 환경 설정을 시작함
import random
random.seed(1234)
import logging
from pprint import pprint
from sys import stdout as STDOUT
# 모든 출력을 임시 디렉터리로 보냄
import atexit
import gc
import io
import os
import tempfile
TEST_DIR = tempfile.TemporaryDirectory()
atexit.register(TEST_DIR.cleanup)
# 윈도우에서 프로세스가 제대로 종료되도록 함
OLD_CWD = os.getcwd()
atexit.register(lambda: os.chdir(OLD_CWD))
os.chdir(TEST_DIR.name)
def close_open_files():
everything = gc.get_objects()
for obj in everything:
if isinstance(obj, io.IOBase):
obj.close()
atexit.register(close_open_files)
### 책 예제에 맞는 환경설정 끝
print("아이템 57")
print("Example 1")
class FrequencyList(list):
def __init__(self, members):
super().__init__(members)
def frequency(self):
counts = {}
for item in self:
counts[item] = counts.get(item, 0) + 1
return counts
print("Example 2")
foo = FrequencyList(["a", "b", "a", "c", "b", "a", "d"])
print("길이: ", len(foo))
foo.pop() # 맨 끝의 "d" 삭제
print("pop한 다음:", repr(foo))
print("빈도: ", foo.frequency())
print("Example 3")
class BinaryNode:
def __init__(self, value, left=None, right=None):
self.value = value
self.left = left
self.right = right
print("Example 4")
bar = [1, 2, 3]
bar[0]
print("Example 5")
bar.__getitem__(0)
print("Example 6")
class IndexableNode(BinaryNode):
def _traverse(self):
if self.left is not None:
yield from self.left._traverse()
yield self
if self.right is not None:
yield from self.right._traverse()
def __getitem__(self, index):
for i, item in enumerate(self._traverse()):
if i == index:
return item.value
raise IndexError(f"Index {index} is out of range")
print("Example 7")
tree = IndexableNode(
10,
left=IndexableNode(
5,
left=IndexableNode(2),
right=IndexableNode(6, right=IndexableNode(7)),
),
right=IndexableNode(15, left=IndexableNode(11)),
)
print("Example 8")
print("왼쪽.오른쪽.오른쪽:", tree.left.right.right.value)
print("인덱스 0: ", tree[0])
print("인덱스 1: ", tree[1])
print("11이 트리에 있나? ", 11 in tree)
print("17이 트리에 있나? ", 17 in tree)
print("트리: ", list(tree))
try:
tree[100]
except IndexError:
pass
else:
assert False
print("Example 9")
try:
len(tree)
except:
logging.exception('이 예외가 발생해야 함')
else:
assert False
print("Example 10")
class SequenceNode(IndexableNode):
def __len__(self):
count = 0
for _ in self._traverse():
count += 1
return count
print("Example 11")
tree = SequenceNode(
10,
left=SequenceNode(
5,
left=SequenceNode(2),
right=SequenceNode(6, right=SequenceNode(7)),
),
right=SequenceNode(15, left=SequenceNode(11)),
)
print("트리 길이는", len(tree))
print("Example 12")
try:
# Make sure that this doesn't work
tree.count(4)
except:
logging.exception('이 예외가 발생해야 함')
else:
assert False
print("Example 13")
try:
from collections.abc import Sequence
class BadType(Sequence):
pass
foo = BadType()
except:
logging.exception('이 예외가 발생해야 함')
else:
assert False
print("Example 14")
class BetterNode(SequenceNode, Sequence):
pass
tree = BetterNode(
10,
left=BetterNode(
5,
left=BetterNode(2),
right=BetterNode(6, right=BetterNode(7)),
),
right=BetterNode(15, left=BetterNode(11)),
)
print("7의 인덱스는", tree.index(7))
print("10이 등장한 횟수는", tree.count(10))