Project cleanup

Author: razvan

.github/workflows/lint.yml

@@ -0,0 +1,27 @@
+name: Run linters
+
+on: [ push ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: [ "3.10", "3.11" ]
+    steps:
+      - uses: actions/checkout@v3
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v3
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install --editable .
+          pip install '.[lint]'
+      - name: Analysing the code with pylint
+        run: |
+          pylint $(git ls-files '*.py')
+      - name: Analysing the code with mypy
+        run: |
+          mypy --install-types --non-interactive $(git ls-files '*.py')

.pre-commit-config.yaml

@@ -1,37 +1,34 @@
 # See https://pre-commit.com for more information
 # See https://pre-commit.com/hooks.html for more hooks
 repos:
--   repo: https://github.com/pre-commit/pre-commit-hooks
+  - repo: https://github.com/pre-commit/pre-commit-hooks
     rev: v3.2.0
     hooks:
-    -   id: trailing-whitespace
-    -   id: end-of-file-fixer
-    -   id: check-yaml
-    -   id: check-added-large-files
--   repo: https://github.com/Yelp/detect-secrets
+      - id: trailing-whitespace
+      - id: end-of-file-fixer
+      - id: check-yaml
+      - id: check-added-large-files
+  - repo: https://github.com/Yelp/detect-secrets
     rev: v1.4.0
     hooks:
-    -   id: detect-secrets
--   repo: https://github.com/PyCQA/pylint
-    rev: v2.16.1
+      - id: detect-secrets
+  - repo: https://github.com/pre-commit/mirrors-autopep8
+    rev: v2.0.1
+    hooks:
+      - id: autopep8
+        entry: autopep8
+  - repo: local
+    # These hooks are run from the local virtual env (and it's assumed they are there)
+    # to allow these tools to find project dependencies.
     hooks:
-    -   id: pylint
+      - id: pylint
         name: pylint
         entry: pylint
         language: system
-        types: [python]
--   repo:  https://github.com/pre-commit/mirrors-mypy
-    rev: 'v1.0.0'
-    hooks:
-    -   id: mypy
+        types: [ python ]
+      - id: mypy
         name: mypy
         entry: mypy
         language: system
-        types: [python]
--   repo: https://github.com/pre-commit/mirrors-autopep8
-    rev: v2.0.1
-    hooks:
-    -   id: autopep8
-        entry: autopep8
-        language: system
-        types: [python]
+        types: [ python ]
+        args: [ '--install-types', '--non-interactive' ]

ccspp/ch2/cannibals.py

@@ -5,7 +5,7 @@
 from __future__ import annotations
 from attrs import define, field, Factory
 from typing import List, Optional, Iterator
-from ch2.maze import bfs, to_path
+from .maze import bfs, to_path
 
 MAX_NUM: int = 3
 

ccspp/ch3/__init__.py

@@ -0,0 +1 @@
+"""Constraint satisfaction problems."""

ccspp/ch3/csp.py

@@ -0,0 +1,71 @@
+"""Constraint solvers."""
+
+from abc import ABC, abstractmethod
+from dataclasses import dataclass, field
+from typing import Generic, TypeVar, List, Dict, Set, Iterable, Optional
+
+V = TypeVar("V")  # variable type
+D = TypeVar("D")  # domain type
+
+
+@dataclass(frozen=True)
+class Constraint(Generic[V, D], ABC):
+    """Base class for all constraints."""
+    variables: Set[V] = field()
+
+    @abstractmethod
+    def satisfied(self, assignment: Dict[V, D]) -> bool:
+        """Verify that the constraint satisfies the assignment."""
+
+
+def _validate_empty_difference(set1: Set[V], set2: Iterable[V], /):
+    diff = set1.difference(set2)
+    if diff:
+        raise LookupError(f"Unknown variables: [{diff}]")
+
+
+@dataclass(frozen=True)
+class CSP(Generic[V, D]):
+    """A constraint satisfaction problem has variables of type V
+    that have ranges of values known as domains D and constraints
+    that determine if a variable's domain selection is satisfied."""
+    variables: Set[V] = field()
+    domains: Dict[V, List[D]] = field()
+    constraints: Dict[V, List[Constraint[V, D]]] = field(default_factory=dict)
+
+    def __post_init__(self) -> None:
+        _validate_empty_difference(self.variables, self.domains.keys())
+
+    def append_constraint(self, constraint: Constraint[V, D]) -> None:
+        """Update constraints"""
+        _validate_empty_difference(self.variables, constraint.variables)
+        for convar in constraint.variables:
+            if convar in self.constraints:
+                self.constraints[convar].append(constraint)
+            else:
+                self.constraints[convar] = [constraint]
+
+    def is_consistent(self, variable: V, assignment: Dict[V, D]) -> bool:
+        """Verify that all constraints of variable are satisfied by the assignment."""
+        return all((c.satisfied(assignment) for c in self.constraints[variable]))
+
+    def backtracking_search(self, assignment: Dict[V, D]) -> Optional[Dict[V, D]]:
+        """Use backtracking to search for an assignment that satisfies all constraints
+        for all variables."""
+        if not assignment:
+            assignment = {}
+
+        if len(assignment) == len(self.variables):
+            return assignment
+
+        unassigned = self.variables.difference(assignment.keys())
+        first: V = next(iter(unassigned))
+        for domain in self.domains[first]:
+            local_assignment = assignment.copy()
+            local_assignment[first] = domain
+            if self.is_consistent(first, local_assignment):
+                result: Optional[Dict[V, D]] = self.backtracking_search(
+                    local_assignment)
+                if result:
+                    return result
+        return None

pyproject.toml

@@ -0,0 +1,25 @@
+[project]
+name = "ccspp_razvan"
+version = "0.0.1"
+authors = [
+    { name = "Razvan Mihai", email = "[email protected]" },
+]
+description = "Classic computer science problems in Python."
+readme = "README.md"
+requires-python = ">=3.9"
+classifiers = [
+    "Programming Language :: Python :: 3",
+    "License :: OSI Approved :: Apache Software License",
+    "Operating System :: OS Independent",
+]
+dependencies = [
+    "attrs==22.2.0", # todo: remove
+]
+
+[project.optional-dependencies]
+lint = ['pylint', 'mypy']
+dev = ['pre-commit']
+
+[project.urls]
+"Homepage" = "https://github.com/razvan/classic-compsci-python"
+"Bug Tracker" = "https://github.com/razvan/classic-compsci-python/issues"