linear.go

package intrange

import "math/rand"

// NewLinear returns a linear range
// between min and max
func NewLinear(min, max int) Range {
	if max == min {
		return Constant(min)
	}
	flipped := false
	if max < min {
		max, min = min, max
		flipped = true
	}
	return linear{min, max, nowRand(), flipped}
}

// NewSpread returns a linear range from base - s to base + s
func NewSpread(base, s int) Range {
	if s == 0 {
		return Constant(base)
	}
	if s < 0 {
		s *= -1
	}
	return linear{base - s, base + s, nowRand(), false}
}

// Linear polls on a linear scale
// between a minimum and a maximum
// linear is private so that the maximum cannot
// be changed to be less than the minimum.
type linear struct {
	Min, Max int
	rng      *rand.Rand
	flipped  bool
}

func (lir linear) Poll() int {
	return lir.rng.Intn((lir.Max+1)-lir.Min) + lir.Min
}

func (lir linear) Mult(i float64) Range {
	lir.Max = int(float64(lir.Max) * i)
	lir.Min = int(float64(lir.Min) * i)
	return lir
}

func (lir linear) InRange(i int) bool {
	return (i > lir.Min) == (i < lir.Max)
}

func (lir linear) EnforceRange(i int) int {
	if i < lir.Min {
		return lir.Min
	} else if i > lir.Max {
		return lir.Max
	}
	return i
}

func (lir linear) Percentile(f float64) int {
	diff := float64(lir.Max-lir.Min) * f // 0 - 255 * .1 = -25 + 255 = 230 // 255 - 0 * .1 = 25
	if lir.flipped {
		return lir.Max - int(diff)
	}
	return lir.Min + int(diff)
}