Mnemonist
Fixed Stack
The FixedStack is a more performant implementation of the Stack requiring a fixed capacity.
This means, however, that you must know beforehand the maximum size your stack will have during iteration (which is often possible - when performing the DFS traversal of a balanced binary tree, for instance).
What’s more, the FixedStack is able to rely on byte arrays and can therefore be very memory-efficient.
const FixedStack = require('mnemonist/fixed-stack');
Constructor
The FixedStack takes two arguments: a array class to use, and the desired capacity.
const stack = new FixedStack(Array, 10);
// Using byte arrays
const stack = new FixedStack(Int8Array, 10);
Static #.from
Alternatively, one can build a FixedStack from an arbitrary JavaScript iterable likewise:
// Attempting the guess the given iterable's length/size
const stack = FixedStack.from([1, 2, 3], Int8Array);
// Providing the desired capacity
const stack = FixedStack.from([1, 2, 3], Int8Array, 10);
Members
Methods
Mutation
Read
Iteration
#.capacity
Maximum number of items the stack is able to store.
const stack = new FixedStack(Array, 10);
stack.capacity
>>> 10
#.size
Number of items in the stack.
const stack = new FixedStack(Array, 10);
stack.size
>>> 0
#.push
Adds an item to the stack.
Will throw if the stack’s capacity is exceeded.
O(1)
const stack = new FixedStack(Array, 10);
stack.push(1);
#.pop
Retrieve & remove the next item of the stack.
O(1)
const stack = new FixedStack(Array, 10);
stack.push(1);
stack.pop();
>>> 1
#.clear
Completely clears the stack.
O(1)
const stack = new FixedStack(Array, 10);
stack.push(1);
stack.clear();
stack.toArray();
>>> []
#.peek
Retrieves the next item of the stack.
O(1)
const stack = new FixedStack(Array, 10);
stack.push(1);
stack.peek();
>>> 1
#.forEach
Iterates over the stack in LIFO order.
const stack = new FixedStack(Array, 10);
stack.push(1);
stack.push(2);
stack.forEach((item, index, stack) => {
console.log(index, item);
});
#.toArray
Converts the stack into a LIFO JavaScript array.
Note that the resulting array will be instantiated using the provided class.
const stack = new FixedStack(Array, 10);
stack.push(1);
stack.push(2);
stack.toArray();
>>> [2, 1]
#.values
Returns an iterator over the stack’s values.
const stack = FixedStack.from([1, 2, 3], Array);
const iterator = stack.values();
iterator.next().value
>>> 3
#.entries
Returns an iterator over the stack’s entries.
const stack = FixedStack.from([1, 2, 3], Array);
const iterator = stack.entries();
iterator.next().value
>>> [0, 3]
Iterable
Alternatively, you can iterate over a stack’s values using ES2015 for...of protocol:
const stack = FixedStack.from([1, 2, 3], Array);
for (const item of stack) {
console.log(item);
}