Stack using a fixed size array

data_structures/stacks/stack_using_array.py

@@ -0,0 +1,211 @@
+from typing import Generic, TypeVar
+
+T = TypeVar("T")
+
+
+class Stack(Generic[T]):
+    def __init__(self, capacity: int = 100) -> None:
+        """Stack implementation using a static array"""
+
+        self.__capacity = capacity
+        self.__stack = [None] * self.__capacity
+        self.__size = 0
+        self.__top = -1
+
+    def push(self, value: T) -> None:
+        """Insert an item to the top of the stack
+        >>> stack = Stack(3)
+
+        >>> stack.display()
+        []
+
+        >>> stack.push(1)
+        >>> stack.push(2)
+        >>> stack.push(3)
+
+        >>> stack.display()
+        [1, 2, 3]
+        """
+
+        if self.is_full():
+            self.__resize()
+
+        self.__top += 1
+        self.__stack[self.__top] = value
+        self.__size += 1
+
+    def peek(self) -> T:
+        """Return the top item of the stack
+        >>> stack = Stack(3)
+
+        >>> stack.peek()
+        Traceback (most recent call last):
+        ...
+        Exception: The stack is empty
+
+        >>> stack.push(10)
+        >>> stack.peek()
+        10
+
+        >>> stack.push(30)
+        >>> stack.peek()
+        30
+        """
+
+        if self.is_empty():
+            raise Exception("The stack is empty")
+
+        return self.__stack[self.__top]
+
+    def pop(self) -> T:
+        """Remove an item from the top of the stack
+
+        >>> stack = Stack(3)
+
+        >>> stack.pop()
+        Traceback (most recent call last):
+        ...
+        Exception: The stack is empty
+
+        >>> stack.push(56)
+        >>> stack.push(45)
+        >>> stack.push(2)
+
+        >>> stack.pop()
+        2
+        >>> stack.pop()
+        45
+        >>> stack.pop()
+        56
+        """
+
+        if self.is_empty():
+            raise Exception("The stack is empty")
+
+        deleted = self.__stack[self.__top]
+
+        self.__size -= 1
+        self.__top -= 1
+
+        return deleted
+
+    def get_capacity(self) -> int:
+        """Returns the capacity of the stack
+
+        >>> stack = Stack(34)
+
+        >>> stack.get_capacity()
+        34
+
+        >>> stack = Stack()
+
+        >>> stack.get_capacity()
+        100
+
+        """
+        return self.__capacity
+
+    def size(self) -> int:
+        """Returns the length of the stack
+        >>> stack = Stack(3)
+        >>> stack.size()
+        0
+        >>> stack.push(1)
+        >>> stack.size()
+        1
+        >>> stack.pop()
+        1
+        >>> stack.size()
+        0
+        """
+
+        return self.__size
+
+    def is_empty(self) -> bool:
+        """Returns True if the stack is empty
+
+        >>> stack = Stack(3)
+
+        >>> stack.is_empty()
+        True
+
+        >>> stack.push(8)
+
+        >>> stack.is_empty()
+        False
+        """
+
+        return not self.__size
+
+    def display(self) -> None:
+        """Print each item inside the stack
+        >>> stack = Stack(3)
+
+        >>> stack.display()
+        []
+
+        >>> stack.push(13)
+        >>> stack.push(23)
+        >>> stack.push(34)
+
+        >>> stack.display()
+        [13, 23, 34]
+        """
+
+        print("[", end="")
+
+        for i in range(self.__size):
+            print(self.__stack[i], end=", " if i != self.__size - 1 else "")
+
+        print("]")
+
+    def is_full(self) -> bool:
+        """Returns True if the stack is full
+
+        >>> stack = Stack(3)
+
+        >>> stack.is_full()
+        False
+
+        >>> stack.push(1)
+        >>> stack.push(2)
+        >>> stack.push(3)
+
+        >>> stack.is_full()
+        True
+        """
+
+        return self.__size == self.__capacity
+
+    def __resize(self) -> None:
+        """Double the size of the stack when it's full
+
+        >>> stack = Stack(10)
+
+        >>> stack.get_capacity()
+        10
+
+        >>> stack._Stack__resize()
+
+        >>> stack.get_capacity()
+        20
+
+        >>> stack._Stack__resize()
+
+        >>> stack.get_capacity()
+        40
+        """
+
+        self.__capacity *= 2
+        temp_list = [None] * self.__capacity
+
+        for i in range(self.__size):
+            temp_list[i] = self.__stack[i]
+
+        self.__stack = temp_list
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()