[Mypy] fix other/least_recently_used (#5814)

* makes LRUCache constructor concrete

* fixes bug in dq_removal in other/least_recently_used

+ deque.remove() operates by value not index

* [mypy] Annotates other/least_recently_used over generic type

+ clean-up: rename key_reference to match type.

* [mypy] updates example to demonstrate LRUCache with complex type

* Adds doctest to other/least_recently_used

* mypy.ini: Remove exclude = (other/least_recently_used.py)

* Various mypy configs

* Delete mypy.ini

* Add mypy to .pre-commit-config.yaml

* mypy --ignore-missing-imports --install-types --non-interactive .

* mypy v0.910

* Pillow=8.3.7

* Pillow==8.3.7

* Pillow==8.3.2

* Update .pre-commit-config.yaml

* Update requirements.txt

* Update pre-commit.yml

* --install-types  # See mirrors-mypy README.md

Co-authored-by: Christian Clauss <cclauss@me.com>

.github/workflows/build.yml

@@ -21,7 +21,7 @@ jobs:
         run: |
           python -m pip install --upgrade pip setuptools six wheel
           python -m pip install mypy pytest-cov -r requirements.txt
-      - run: mypy .  # See `mypy.ini` for configuration settings.
+      - run: mypy --ignore-missing-imports --install-types --non-interactive .
       - name: Run tests
         run: pytest --doctest-modules --ignore=project_euler/ --ignore=scripts/validate_solutions.py --cov-report=term-missing:skip-covered --cov=. .
       - if: ${{ success() }}

.github/workflows/pre-commit.yml

@@ -14,6 +14,8 @@ jobs:
             ~/.cache/pip
           key: ${{ runner.os }}-pre-commit-${{ hashFiles('.pre-commit-config.yaml') }}
       - uses: actions/setup-python@v2
+        with:
+          python-version: 3.9
       - uses: psf/black@21.4b0
       - name: Install pre-commit
         run: |

.pre-commit-config.yaml

@@ -12,22 +12,26 @@ repos:
             data_structures/heap/binomial_heap.py
           )$
       - id: requirements-txt-fixer
+
   - repo: https://github.com/psf/black
     rev: 21.4b0
     hooks:
       - id: black
+
   - repo: https://github.com/PyCQA/isort
     rev: 5.8.0
     hooks:
       - id: isort
         args:
           - --profile=black
+
   - repo: https://github.com/asottile/pyupgrade
     rev: v2.29.0
     hooks:
       - id: pyupgrade
         args:
           - --py39-plus
+
   - repo: https://gitlab.com/pycqa/flake8
     rev: 3.9.1
     hooks:
@@ -36,13 +40,16 @@ repos:
           - --ignore=E203,W503
           - --max-complexity=25
           - --max-line-length=88
-#     FIXME: fix mypy errors and then uncomment this
-#    - repo: https://github.com/pre-commit/mirrors-mypy
-#      rev: v0.782
-#      hooks:
-#        - id: mypy
-#          args:
-#            - --ignore-missing-imports
+
+  - repo: https://github.com/pre-commit/mirrors-mypy
+    rev: v0.910
+    hooks:
+      - id: mypy
+        args:
+          - --ignore-missing-imports
+          - --install-types  # See mirrors-mypy README.md
+          - --non-interactive
+
   - repo: https://github.com/codespell-project/codespell
     rev: v2.0.0
     hooks:
@@ -50,13 +57,13 @@ repos:
         args:
           - --ignore-words-list=ans,crate,fo,followings,hist,iff,mater,secant,som,tim
           - --skip="./.*,./strings/dictionary.txt,./strings/words.txt,./project_euler/problem_022/p022_names.txt"
-          - --quiet-level=2
         exclude: |
           (?x)^(
               strings/dictionary.txt |
               strings/words.txt |
               project_euler/problem_022/p022_names.txt
           )$
+
   - repo: local
     hooks:
       - id: validate-filenames

mypy.ini

@@ -1,5 +0,0 @@
-[mypy]
-ignore_missing_imports = True
-install_types = True
-non_interactive = True
-exclude = (other/least_recently_used.py)

other/least_recently_used.py

@@ -1,20 +1,45 @@
+from __future__ import annotations
+
 import sys
 from collections import deque
+from typing import Generic, TypeVar
+
+T = TypeVar("T")
 
 
-class LRUCache:
-    """Page Replacement Algorithm, Least Recently Used (LRU) Caching."""
+class LRUCache(Generic[T]):
+    """
+    Page Replacement Algorithm, Least Recently Used (LRU) Caching.
 
-    dq_store = object()  # Cache store of keys
-    key_reference_map = object()  # References of the keys in cache
+    >>> lru_cache: LRUCache[str | int] = LRUCache(4)
+    >>> lru_cache.refer("A")
+    >>> lru_cache.refer(2)
+    >>> lru_cache.refer(3)
+
+    >>> lru_cache
+    LRUCache(4) => [3, 2, 'A']
+
+    >>> lru_cache.refer("A")
+    >>> lru_cache
+    LRUCache(4) => ['A', 3, 2]
+
+    >>> lru_cache.refer(4)
+    >>> lru_cache.refer(5)
+    >>> lru_cache
+    LRUCache(4) => [5, 4, 'A', 3]
+
+    """
+
+    dq_store: deque[T]  # Cache store of keys
+    key_reference: set[T]  # References of the keys in cache
     _MAX_CAPACITY: int = 10  # Maximum capacity of cache
 
-    def __init__(self, n: int):
+    def __init__(self, n: int) -> None:
         """Creates an empty store and map for the keys.
         The LRUCache is set the size n.
         """
         self.dq_store = deque()
-        self.key_reference_map = set()
+        self.key_reference = set()
         if not n:
             LRUCache._MAX_CAPACITY = sys.maxsize
         elif n < 0:
@@ -22,41 +47,46 @@ class LRUCache:
         else:
             LRUCache._MAX_CAPACITY = n
 
-    def refer(self, x):
+    def refer(self, x: T) -> None:
         """
         Looks for a page in the cache store and adds reference to the set.
         Remove the least recently used key if the store is full.
         Update store to reflect recent access.
         """
-        if x not in self.key_reference_map:
+        if x not in self.key_reference:
             if len(self.dq_store) == LRUCache._MAX_CAPACITY:
                 last_element = self.dq_store.pop()
-                self.key_reference_map.remove(last_element)
+                self.key_reference.remove(last_element)
         else:
-            index_remove = 0
-            for idx, key in enumerate(self.dq_store):
-                if key == x:
-                    index_remove = idx
-                    break
-            self.dq_store.remove(index_remove)
+            self.dq_store.remove(x)
 
         self.dq_store.appendleft(x)
-        self.key_reference_map.add(x)
+        self.key_reference.add(x)
 
-    def display(self):
+    def display(self) -> None:
         """
         Prints all the elements in the store.
         """
         for k in self.dq_store:
             print(k)
 
+    def __repr__(self) -> str:
+        return f"LRUCache({self._MAX_CAPACITY}) => {list(self.dq_store)}"
+
 
 if __name__ == "__main__":
-    lru_cache = LRUCache(4)
-    lru_cache.refer(1)
+    import doctest
+
+    doctest.testmod()
+
+    lru_cache: LRUCache[str | int] = LRUCache(4)
+    lru_cache.refer("A")
     lru_cache.refer(2)
     lru_cache.refer(3)
-    lru_cache.refer(1)
+    lru_cache.refer("A")
     lru_cache.refer(4)
     lru_cache.refer(5)
     lru_cache.display()
+
+    print(lru_cache)
+    assert str(lru_cache) == "LRUCache(4) => [5, 4, 'A', 3]"

requirements.txt

@@ -16,5 +16,4 @@ sympy
 tensorflow
 texttable
 tweepy
-types-requests
 xgboost