ArrayMap.py (#17)

Author: nedtwigg

.vscode/settings.json

@@ -0,0 +1,3 @@
+{
+    "java.compile.nullAnalysis.mode": "automatic"
+}

python/selfie-lib/selfie_lib/ArrayMap.py

@@ -0,0 +1,119 @@
+from collections.abc import Set, Iterator, Mapping
+from typing import List, TypeVar, Union
+from abc import abstractmethod, ABC
+
+T = TypeVar('T')
+V = TypeVar('V')
+K = TypeVar('K')
+
+class ListBackedSet(Set[T], ABC):
+    @abstractmethod
+    def __len__(self) -> int: ...
+
+    @abstractmethod
+    def __getitem__(self, index: Union[int, slice]) -> Union[T, List[T]]: ...
+
+    def __contains__(self, item: object) -> bool:
+        for i in range(len(self)):
+            if self[i] == item:
+                return True
+        return False
+
+class ArraySet(ListBackedSet[K]):
+    __data: List[K]
+
+    def __init__(self, data: List[K]):
+        raise NotImplementedError("Use ArraySet.empty() instead")
+
+    @classmethod
+    def __create(cls, data: List[K]) -> 'ArraySet[K]':
+        # Create a new instance without calling __init__
+        instance = super().__new__(cls)
+        instance.__data = data
+        return instance
+    
+    def __iter__(self) -> Iterator[K]:
+        return iter(self.__data)
+
+    @classmethod
+    def empty(cls) -> 'ArraySet[K]':
+        if not hasattr(cls, '__EMPTY'):
+            cls.__EMPTY = cls([])
+        return cls.__EMPTY
+
+    def __len__(self) -> int:
+        return len(self.__data)
+
+    def __getitem__(self, index: Union[int, slice]) -> Union[K, List[K]]:
+        if isinstance(index, int):
+            return self.__data[index]
+        elif isinstance(index, slice):
+            return self.__data[index]
+        else:
+            raise TypeError("Invalid argument type.")
+
+    def plusOrThis(self, element: K) -> 'ArraySet[K]':
+        # TODO: use binary search, and also special sort order for strings
+        if element in self.__data:
+            return self
+        else:
+            new_data = self.__data[:]
+            new_data.append(element)
+            new_data.sort() # type: ignore[reportOperatorIssue]
+            return ArraySet.__create(new_data)
+
+
+class ArrayMap(Mapping[K, V]):
+    def __init__(self, data: list):
+        # TODO: hide this constructor as done in ArraySet
+        self.__data = data
+
+    @classmethod
+    def empty(cls) -> 'ArrayMap[K, V]':
+        if not hasattr(cls, '__EMPTY'):
+            cls.__EMPTY = cls([])
+        return cls.__EMPTY
+
+    def __getitem__(self, key: K) -> V:
+        index = self.__binary_search_key(key)
+        if index >= 0:
+            return self.__data[2 * index + 1]
+        raise KeyError(key)
+
+    def __iter__(self) -> Iterator[K]:
+        return (self.__data[i] for i in range(0, len(self.__data), 2))
+
+    def __len__(self) -> int:
+        return len(self.__data) // 2
+
+    def __binary_search_key(self, key: K) -> int: 
+        # TODO: special sort order for strings
+        low, high = 0, (len(self.__data) // 2) - 1
+        while low <= high:
+            mid = (low + high) // 2
+            mid_key = self.__data[2 * mid]
+            if mid_key < key:
+                low = mid + 1
+            elif mid_key > key:
+                high = mid - 1
+            else:
+                return mid
+        return -(low + 1)
+
+    def plus(self, key: K, value: V) -> 'ArrayMap[K, V]':
+        index = self.__binary_search_key(key) 
+        if index >= 0:
+            raise ValueError("Key already exists")
+        insert_at = -(index + 1)
+        new_data = self.__data[:]
+        new_data[insert_at * 2:insert_at * 2] = [key, value]
+        return ArrayMap(new_data)
+
+    def minus_sorted_indices(self, indicesToRemove: List[int]) -> 'ArrayMap[K, V]':
+        if not indicesToRemove:
+            return self
+        newData = []
+        for i in range(0, len(self.__data), 2):
+            if i // 2 not in indicesToRemove:
+                newData.extend(self.__data[i:i + 2])
+        return ArrayMap(newData)

python/selfie-lib/tests/ArrayMap_test.py

@@ -0,0 +1,125 @@
+import pytest
+from selfie_lib.ArrayMap import ArrayMap
+
+def assertEmpty(map):
+    assert len(map) == 0
+    assert list(map.keys()) == []
+    assert list(map.values()) == []
+    assert list(map.items()) == []
+    with pytest.raises(KeyError):
+        _ = map["key"]
+    assert map == {}
+    assert map == ArrayMap.empty()
+
+def assertSingle(map, key, value):
+    assert len(map) == 1
+    assert set(map.keys()) == {key}
+    assert list(map.values()) == [value]
+    assert set(map.items()) == {(key, value)}
+    assert map[key] == value
+    with pytest.raises(KeyError):
+        _ = map[key + "blah"]
+    assert map == {key: value}
+    assert map == ArrayMap.empty().plus(key, value)
+
+def assertDouble(map, key1, value1, key2, value2):
+    assert len(map) == 2
+    assert set(map.keys()) == {key1, key2}
+    assert list(map.values()) == [value1, value2]
+    assert set(map.items()) == {(key1, value1), (key2, value2)}
+    assert map[key1] == value1
+    assert map[key2] == value2
+    with pytest.raises(KeyError):
+        _ = map[key1 + "blah"]
+    assert map == {key1: value1, key2: value2}
+    assert map == {key2: value2, key1: value1}
+    assert map == ArrayMap.empty().plus(key1, value1).plus(key2, value2)
+    assert map == ArrayMap.empty().plus(key2, value2).plus(key1, value1)
+
+def assertTriple(map, key1, value1, key2, value2, key3, value3):
+    assert len(map) == 3
+    assert set(map.keys()) == {key1, key2, key3}
+    assert list(map.values()) == [value1, value2, value3]
+    assert set(map.items()) == {(key1, value1), (key2, value2), (key3, value3)}
+    assert map[key1] == value1
+    assert map[key2] == value2
+    assert map[key3] == value3
+    with pytest.raises(KeyError):
+        _ = map[key1 + "blah"]
+    assert map == {key1: value1, key2: value2, key3: value3}
+    assert map == ArrayMap.empty().plus(key1, value1).plus(key2, value2).plus(key3, value3)
+
+def test_empty():
+    assertEmpty(ArrayMap.empty())
+
+def test_single():
+    empty = ArrayMap.empty()
+    single = empty.plus("one", "1")
+    assertEmpty(empty)
+    assertSingle(single, "one", "1")
+
+def test_double():
+    empty = ArrayMap.empty()
+    single = empty.plus("one", "1")
+    double = single.plus("two", "2")
+    assertEmpty(empty)
+    assertSingle(single, "one", "1")
+    assertDouble(double, "one", "1", "two", "2")
+    assertDouble(single.plus("a", "sorted"), "a", "sorted", "one", "1")
+
+    with pytest.raises(ValueError) as context:
+        single.plus("one", "2")
+    assert str(context.value) == "Key already exists"
+
+def test_triple():
+    triple = ArrayMap.empty().plus("1", "one").plus("2", "two").plus("3", "three")
+    assertTriple(triple, "1", "one", "2", "two", "3", "three")
+
+def test_multi():
+    test_triple()  # Calling another test function directly is unusual but works
+    triple = ArrayMap.empty().plus("2", "two").plus("3", "three").plus("1", "one")
+    assertTriple(triple, "1", "one", "2", "two", "3", "three")
+    triple = ArrayMap.empty().plus("3", "three").plus("1", "one").plus("2", "two")
+    assertTriple(triple, "1", "one", "2", "two", "3", "three")
+
+def test_minus_sorted_indices():
+    initial_map = ArrayMap.empty().plus("1", "one").plus("2", "two").plus("3", "three").plus("4", "four")
+    modified_map = initial_map.minus_sorted_indices([1, 3])
+    assert len(modified_map) == 2
+    assert list(modified_map.keys()) == ["1", "3"]
+    assert list(modified_map.values()) == ["one", "three"]
+    with pytest.raises(KeyError):
+        _ = modified_map["2"]
+    with pytest.raises(KeyError):
+        _ = modified_map["4"]
+    assert modified_map == {"1": "one", "3": "three"}
+
+def test_plus_with_existing_keys():
+    map_with_duplicates = ArrayMap.empty().plus("a", "alpha").plus("b", "beta")
+    with pytest.raises(ValueError):
+        map_with_duplicates.plus("a", "new alpha")
+    updated_map = map_with_duplicates.plus("c", "gamma")
+    assert len(updated_map) == 3
+    assert updated_map["a"] == "alpha"
+    assert updated_map["b"] == "beta"
+    assert updated_map["c"] == "gamma"
+    modified_map = map_with_duplicates.minus_sorted_indices([0]).plus("a", "updated alpha")
+    assert len(modified_map) == 2
+    assert modified_map["a"] == "updated alpha"
+    assert modified_map["b"] == "beta"
+
+def test_map_length():
+    map = ArrayMap.empty()
+    assert len(map) == 0, "Length should be 0 for an empty map"
+    map = map.plus("key1", "value1")
+    assert len(map) == 1, "Length should be 1 after adding one item"
+    map = map.plus("key2", "value2")
+    assert len(map) == 2, "Length should be 2 after adding another item"
+    map = map.plus("key3", "value3")
+    assert len(map) == 3, "Length should be 3 after adding a third item"
+    map = map.minus_sorted_indices([1])
+    assert len(map) == 2, "Length should be 2 after removing one item"
+    map = map.minus_sorted_indices([0]) 
+    assert len(map) == 1, "Length should be 1 after removing another item"
+    map = map.minus_sorted_indices([0])  
+    assert len(map) == 0, "Length should be 0 after removing all items"