87 lines
2 KiB
Go
87 lines
2 KiB
Go
package server
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// Stack interface
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type Stack interface {
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// Push pushes an item to the stack. Returns an error if it fails.
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Push(item interface{})
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// Pop retrieves an item from the stack and removes it.
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Pop() interface{}
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// Top peeks at an item from the stack.
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Top() interface{}
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// IsEmpty returns bool indicating if the stack is empty.
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IsEmpty() bool
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// Capacity returns the capacity of the stack.
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Capacity() int
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// Size returns the size of the stack
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Size() int
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}
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// StringStack is a stack that holds string objects
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type StringStack struct {
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index int
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capacity int
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items []string
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}
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// MakeStringStack initializes a new StringStack pointer.
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func MakeStringStack(capacity int) *StringStack {
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st := StringStack{}
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st.capacity = capacity
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st.index = 0
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st.items = make([]string, capacity, capacity)
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return &st
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}
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// Push pushes an item of type string to the stack.
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func (st *StringStack) Push(item interface{}) {
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if st.index == st.Capacity() {
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panic(StackOverflowError)
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}
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value, ok := item.(string)
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if ok == false {
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panic(StackInvalidTypeError)
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}
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st.items[st.index] = value
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st.index++
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}
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// Pop returns the last pushed item from the stack and removes it
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func (st *StringStack) Pop() interface{} {
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if st.Size() == 0 {
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panic(StackUnderflowError)
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}
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st.index--
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return st.items[st.index]
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}
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// Top return the last pushed item from the stack without removing it.
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func (st *StringStack) Top() interface{} {
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if st.Size() == 0 {
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panic(StackUnderflowError)
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}
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return st.items[st.index-1]
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}
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// IsEmpty returns true if the stack contains no items.
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func (st *StringStack) IsEmpty() bool {
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return st.Size() == 0
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}
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// Capacity returns the maximum items the stack can hold.
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func (st *StringStack) Capacity() int {
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return st.capacity
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}
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// Size returns number of items the stack currently holds.
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func (st *StringStack) Size() int {
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return st.index
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}
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// Items returns an array of the stack items as a copy.
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func (st StringStack) Items() []string {
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return st.items
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}
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