mirror of https://github.com/docker/cli.git
86 lines
1.8 KiB
Go
86 lines
1.8 KiB
Go
|
package utils
|
||
|
|
|
||
|
|
import (
|
||
|
|
"fmt"
|
||
|
|
"sync"
|
||
|
|
)
|
||
|
|
|
||
|
|
// ErrEmptyStack is used when an action that requires some
|
||
|
|
// content is invoked and the stack is empty
|
||
|
|
type ErrEmptyStack struct {
|
||
|
|
action string
|
||
|
|
}
|
||
|
|
|
||
|
|
func (err ErrEmptyStack) Error() string {
|
||
|
|
return fmt.Sprintf("attempted to %s with empty stack", err.action)
|
||
|
|
}
|
||
|
|
|
||
|
|
// ErrBadTypeCast is used by PopX functions when the item
|
||
|
|
// cannot be typed to X
|
||
|
|
type ErrBadTypeCast struct{}
|
||
|
|
|
||
|
|
func (err ErrBadTypeCast) Error() string {
|
||
|
|
return "attempted to do a typed pop and item was not of type"
|
||
|
|
}
|
||
|
|
|
||
|
|
// Stack is a simple type agnostic stack implementation
|
||
|
|
type Stack struct {
|
||
|
|
s []interface{}
|
||
|
|
l sync.Mutex
|
||
|
|
}
|
||
|
|
|
||
|
|
// NewStack create a new stack
|
||
|
|
func NewStack() *Stack {
|
||
|
|
s := &Stack{
|
||
|
|
s: make([]interface{}, 0),
|
||
|
|
}
|
||
|
|
return s
|
||
|
|
}
|
||
|
|
|
||
|
|
// Push adds an item to the top of the stack.
|
||
|
|
func (s *Stack) Push(item interface{}) {
|
||
|
|
s.l.Lock()
|
||
|
|
defer s.l.Unlock()
|
||
|
|
s.s = append(s.s, item)
|
||
|
|
}
|
||
|
|
|
||
|
|
// Pop removes and returns the top item on the stack, or returns
|
||
|
|
// ErrEmptyStack if the stack has no content
|
||
|
|
func (s *Stack) Pop() (interface{}, error) {
|
||
|
|
s.l.Lock()
|
||
|
|
defer s.l.Unlock()
|
||
|
|
l := len(s.s)
|
||
|
|
if l > 0 {
|
||
|
|
item := s.s[l-1]
|
||
|
|
s.s = s.s[:l-1]
|
||
|
|
return item, nil
|
||
|
|
}
|
||
|
|
return nil, ErrEmptyStack{action: "Pop"}
|
||
|
|
}
|
||
|
|
|
||
|
|
// PopString attempts to cast the top item on the stack to the string type.
|
||
|
|
// If this succeeds, it removes and returns the top item. If the item
|
||
|
|
// is not of the string type, ErrBadTypeCast is returned. If the stack
|
||
|
|
// is empty, ErrEmptyStack is returned
|
||
|
|
func (s *Stack) PopString() (string, error) {
|
||
|
|
s.l.Lock()
|
||
|
|
defer s.l.Unlock()
|
||
|
|
l := len(s.s)
|
||
|
|
if l > 0 {
|
||
|
|
item := s.s[l-1]
|
||
|
|
if item, ok := item.(string); ok {
|
||
|
|
s.s = s.s[:l-1]
|
||
|
|
return item, nil
|
||
|
|
}
|
||
|
|
return "", ErrBadTypeCast{}
|
||
|
|
}
|
||
|
|
return "", ErrEmptyStack{action: "PopString"}
|
||
|
|
}
|
||
|
|
|
||
|
|
// Empty returns true if the stack is empty
|
||
|
|
func (s *Stack) Empty() bool {
|
||
|
|
s.l.Lock()
|
||
|
|
defer s.l.Unlock()
|
||
|
|
return len(s.s) == 0
|
||
|
|
}
|