1 // Copyright 2022 Google LLC 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 package stack 16 17 type Stack interface { 18 Pop() (Stack, interface{}) 19 Push(o interface{}) Stack 20 Size() int 21 } 22 23 type stack []interface{} 24 25 func New() Stack { 26 return make(stack, 0) 27 } 28 29 func (s stack) Pop() (Stack, interface{}) { 30 return s[:len(s)-1], s[len(s)-1] 31 } 32 33 func (s stack) Push(o interface{}) Stack { 34 return append(s, o) 35 } 36 37 func (s stack) Size() int { 38 return len(s) 39 } 40