Implementing a Stack

With the concept of a stack established, the next step is to examine its implementation. A stack is an abstract data type. It defines a set of operations but does not specify how data is stored or managed in memory. A stack can be implemented using different underlying structures, such as an array-backed slice or a linked list.

Using an array-backed slice

In an array-based stack implementation in Go, we can use a slice backed by an array to store stack elements. The elements are stored in order in the underlying array. Since a stack only ever adds and removes elements from the top, we can treat one end of the slice as the top. The first element added sits at index 0, and each new element is placed at the next available position. The most recently added element always sits at the last occupied index.

Think of it like a stack of plates, with the tray as a row of numbered slots. The first plate goes into slot 0, the second into slot 1, and so on. The top plate is always the one in the last occupied slot.

In an array-backed slice, an index called the top is used to track the position of the most recently added element. The size tells us how many elements are currently in the stack. Additionally, a capacity value defines the maximum number of elements the stack can hold; this is the total size we allocate for the underlying storage.

If the backing storage has a fixed size, then the stack has a maximum capacity that cannot be exceeded without resizing. If we use Go's append with a slice, the backing array can grow when needed, although the top position is still managed explicitly to maintain LIFO order.

Here's how an array-based stack works:

As elements are pushed onto the stack, the top index increments. When elements are popped, the top index decrements. The stack only grows and shrinks from one end, making the implementation straightforward and efficient.

Implementation in Go

In Go, an array-based stack can be implemented using a struct and a ...