Golang | Stack

int.go

package main

import "errors"

type Stack interface {
	IsEmpty() bool
	Peek() int
	Pop() error
	Push(x int) error
	Dump() []int
}

type stack struct {
	stack []int
	top   int
	size  int
}

func NewStack(size int) Stack {
	return &stack{
		stack: make([]int, size),
		size:  size,
		top:   -1,
	}
}

func (st *stack) IsEmpty() bool {
	return st.top == -1
}

func (st *stack) Peek() int {
	if st.top == -1 {
		return -1
	}
	return st.stack[st.top]
}

func (st *stack) Pop() error {
	if st.top == -1 {
		return errors.New("stack underflow")
	}
	st.top--
	return nil
}

func (st *stack) Push(x int) error {
	if st.top+1 == st.size {
		return errors.New("stack overflow")
	}
	st.top++
	st.stack[st.top] = x
	return nil
}

func (st *stack) Dump() []int {
	if st.top == -1 {
		return []int{}
	}
	return st.stack[0 : st.top+1]
}

string.go

package main

import (
	"errors"
)

type StackString interface {
	IsEmpty() bool
	Peek() string
	Pop() error
	Push(x string) error
	Dump() []string
}

type stackstr struct {
	stack []string
	top   int
	size  int
}

func NewStackStr(size int) StackString {
	return &stackstr{
		stack: make([]string, size),
		size:  size,
		top:   -1,
	}
}

func (st *stackstr) IsEmpty() bool {
	return st.top == -1
}

func (st *stackstr) Peek() string {
	if st.top == -1 {
		return ""
	}
	return st.stack[st.top]
}

func (st *stackstr) Pop() error {
	if st.top == -1 {
		return errors.New("stack underflow")
	}
	st.top--
	return nil
}

func (st *stackstr) Push(x string) error {
	if st.top+1 == st.size {
		return errors.New("stack overflow")
	}
	st.top++
	st.stack[st.top] = x
	return nil
}

func (st *stackstr) Dump() []string {
	if st.top == -1 {
		return []string{}
	}
	return st.stack[0 : st.top+1]
}