stack-typescript

Simple Typescript Stack with generics type templating and support for iterator and iterable protocols.

This stack uses the linked-list-typescript as the underlying datastructure.

See Also:

• linked-list-typescript
• hashlist-typescript
• queue-typescript

Installation

npm:

npm install --save stack-typescript

yarn:

yarn add stack-typescript

Building from source

install dev dependencies. There are no production dependencies.

yarn
npm install

build using the options in tsconfig.json

yarn|npm run build

run all package tests

yarn|npm run test

see the test coverage report

yarn|npm run coverage
yarn|npm run coverage:report

Usage

Importing:

import { Stack } from 'stack-typescript';
const { Stack } = require('stack-typescript')

API

Stack(...values: T[])

Stack()

Create an empty stack by omitting any arguments during instantiation.

let stack = new Stack<number>()

Stack(...values: T[])

Create a new stack and initialize it with values. Values will be added from top to bottom. i.e. the first argument will be at the top and the last argument will be at the bottom.

Specify the type using the typescript templating to enable type-checking of all values going into and out of the stack.

let items: number[] = [4, 5, 6, 7];
let stack = new Stack<number>(...items);

let items: string[] = ['one', 'two', 'three', 'four'];
let stack = new Stack<string>(...items);

Typescript will check if the values match the type given to the template when initializing the new stack.

let items: = ['one', 'two', 'three', 4];
let stack = new Stack<string>(...items); // arguments are not all strings

Stack(...values: Foo[])

Create a new stack using custom types or classes. All values are retained as references and not copies so removed values can be compared using strict comparison.

class Foo {
  private val:number;
  constructor(val: number) {
    this.val = val;
  }
  get bar(): number { return this.val }
}

let foo1 = new Foo(1);
let foo2 = new Foo(2);
let foo3 = new Foo(3);

let fooStack = new Stack<Foo>(foo1, foo2, foo3)

fooStack.top.bar // => 1
let val = stack.pop()
val // => foo1

Stack(...values: any[])

Specify any to allow the stack to take values of any type.

let stack = new Stack<any>(4, 'hello' { hello: 'world' })
stack.size // => 3
stack.top // => 4

Stack#[Symbol.iterator]

The stack supports both iterator and iterable protocols allowing it to be used with the for...of and ...spread operators and with deconstruction.

for...of:

let items: number[] = [4, 5, 6];
let stack = new Stack<number>(...items);

for (let item of stack) {
  console.log(item)
}
//4
//5
//6

...spread:

let items: number[] = [4, 5, 6];
let stack = new Stack<number>(...items);

function manyArgs(...args) {
  for (let i in args) {
    console.log(args[i])
  }
}
manyArgs(...stack);
//4
//5
//6

deconstruction:

let items: number[] = [4, 5, 6, 7];
let stack = new Stack<number>(...items);

let [a, b, c] = stack;
//a => 4
//b => 5
//c => 6

Stack#top :T

Peek at the top of the stack. This will not remove the value from the stack.

let items: number[] = [4, 5, 6, 7];
let stack = new Stack<number>(...items);
stack.top // => 4

Stack#size :number

Query the size of the stack. An empty stack will return 0.

let items: number[] = [4, 5, 6, 7];
let stack = new Stack<number>(...items);
stack.size // => 4

Stack#push(val: T): boolean

Push an item to the top of the stack. The new item will replace the previous top item and subsequent calls to Stack#top will now recall the new item.

let items: number[] = [4, 5, 6, 7];
let stack = new Stack<number>(...items);
stack.size // => 4
stack.push(8)
stack.size // => 5

Stack#pop(): T

Removes the item at the top of the stack and returns the item.

let items: number[] = [4, 5, 6, 7];
let stack = new Stack<number>(...items);
stack.size // => 4
let val = stack.pop()
stack.size // => 3
stack.top // => 5
val // => 4

Stack#toArray(): T[]

This method simply returns [...this].

Converts the stack into an array and returns the array representation. This method does not mutate the stack in any way.

Objects are not copied, so all non-primitive items in the array are still referencing the stack items.

let items: number[] = [4, 5, 6, 7];
let stack = new Stack<number>(...items);
let result = stack.toArray()
result // => [4, 5, 6, 7]

License

MIT © Michael Sutherland