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bounds.go
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bounds.go
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// Copyright (c) 2018 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package models
import (
"fmt"
"math"
"time"
)
// Bounds are the time bounds, start time is inclusive but end is exclusive.
type Bounds struct {
Start time.Time
Duration time.Duration
StepSize time.Duration
}
// TimeForIndex returns the start time for a given index assuming
// a uniform step size.
func (b Bounds) TimeForIndex(idx int) (time.Time, error) {
duration := time.Duration(idx) * b.StepSize
if b.Steps() == 0 || duration >= b.Duration {
return time.Time{}, fmt.Errorf("out of bounds, %d", idx)
}
return b.Start.Add(duration), nil
}
// End calculates the end time for the block and is exclusive.
func (b Bounds) End() time.Time {
return b.Start.Add(b.Duration)
}
// Steps calculates the number of steps for the bounds.
func (b Bounds) Steps() int {
if b.StepSize <= 0 {
return 0
}
return int(b.Duration / b.StepSize)
}
// Contains returns whether the time lies between the bounds.
func (b Bounds) Contains(t time.Time) bool {
diff := b.Start.Sub(t)
return diff >= 0 && diff < b.Duration
}
// Next returns the nth next bound from the current bound.
func (b Bounds) Next(n int) Bounds {
return b.nth(n, true)
}
// Previous returns the nth previous bound from the current bound.
func (b Bounds) Previous(n int) Bounds {
return b.nth(n, false)
}
func (b Bounds) nth(n int, forward bool) Bounds {
multiplier := time.Duration(n)
if !forward {
multiplier *= -1
}
blockDuration := b.Duration
start := b.Start.Add(blockDuration * multiplier)
return Bounds{
Start: start,
Duration: blockDuration,
StepSize: b.StepSize,
}
}
// Blocks returns the number of blocks until time t.
func (b Bounds) Blocks(t time.Time) int {
return int(b.Start.Sub(t) / b.Duration)
}
// String representation of the bounds.
func (b Bounds) String() string {
return fmt.Sprintf("start: %v, duration: %v, stepSize: %v, steps: %d",
b.Start, b.Duration, b.StepSize, b.Steps())
}
// Nearest returns the nearest bound before the given time.
func (b Bounds) Nearest(t time.Time) Bounds {
startTime := b.Start
duration := b.Duration
endTime := startTime.Add(duration)
step := b.StepSize
if t.After(startTime) {
for endTime.Before(t) {
startTime = endTime
endTime = endTime.Add(duration)
}
return Bounds{
Start: startTime,
Duration: duration,
StepSize: step,
}
}
if startTime.After(t) {
diff := startTime.Sub(t)
timeDiff := math.Ceil(float64(diff) / float64(step))
startTime = startTime.Add(-1 * time.Duration(timeDiff) * step)
}
return Bounds{
Start: startTime,
Duration: duration,
StepSize: step,
}
}
// Equals is true if two bounds are equal, including step size.
func (b Bounds) Equals(other Bounds) bool {
if b.StepSize != other.StepSize {
return false
}
return b.Start.Equal(other.Start) && b.Duration == other.Duration
}