expvarmon/stack.go

106 lines
1.9 KiB
Go

package main
// DefaultSize specifies maximum number of items in stack.
//
// Values should be enough for sparklines on high-res terminals
// with minimal font size.
const DefaultSize = 1200
// Stack is a limited FIFO for holding sparkline values.
type Stack struct {
Values []VarValue
Len int
Max VarValue
}
// NewStack inits new Stack with default size limit.
func NewStack() *Stack {
return NewStackWithSize(DefaultSize)
}
// NewStackWithSize inits new Stack with size limit.
func NewStackWithSize(size int) *Stack {
return &Stack{
Values: make([]VarValue, size),
Len: size,
}
}
// Push inserts data to stack, preserving constant length.
func (s *Stack) Push(val VarValue) {
s.Values = append(s.Values, val)
if len(s.Values) > s.Len {
s.Values = s.Values[1:]
}
if s.Max == nil {
s.Max = val
return
}
switch val.(type) {
case int64:
switch s.Max.(type) {
case int64:
if val.(int64) > s.Max.(int64) {
s.Max = val
}
case float64:
if float64(val.(int64)) > s.Max.(float64) {
s.Max = val
}
}
case float64:
switch s.Max.(type) {
case int64:
if val.(float64) > float64(s.Max.(int64)) {
s.Max = val
}
case float64:
if val.(float64) > s.Max.(float64) {
s.Max = val
}
}
}
}
// Front returns front value.
func (s *Stack) Front() VarValue {
if len(s.Values) == 0 {
return nil
}
return s.Values[len(s.Values)-1]
}
// IntValues returns stack values explicitly casted to int.
//
// Main case is to use with termui.Sparklines.
func (s *Stack) IntValues() []int {
ret := make([]int, s.Len)
for i, v := range s.Values {
n, ok := v.(int64)
if ok {
ret[i] = int(n)
continue
}
f, ok := v.(float64)
if ok {
// 12.34 (float) -> 1234 (int)
ret[i] = int(f * 100)
continue
}
b, ok := v.(bool)
if ok {
// false => 0, true = 1
if b {
ret[i] = 1
} else {
ret[i] = 0
}
}
}
return ret
}