redis-go/datastruct/sortedset/border.go

package sortedset

import (
	"errors"
	"strconv"
)

/*
 * ScoreBorder is a struct represents `min` `max` parameter of redis command `ZRANGEBYSCORE`
 * can accept:
 *   int or float value, such as 2.718, 2, -2.718, -2 ...
 *   exclusive int or float value, such as (2.718, (2, (-2.718, (-2 ...
 *   infinity: +inf, -inf， inf(same as +inf)
 */

const (
	negativeInf int8 = -1
	positiveInf int8 = 1
)

type ScoreBorder struct {
	Inf     int8
	Value   float64
	Exclude bool
}

// if max.greater(score) then the score is within the upper border
// do not use min.greater()
func (border *ScoreBorder) greater(value float64) bool {
	if border.Inf == negativeInf {
		return false
	} else if border.Inf == positiveInf {
		return true
	}
	if border.Exclude {
		return border.Value > value
	} else {
		return border.Value >= value
	}
}

func (border *ScoreBorder) less(value float64) bool {
	if border.Inf == negativeInf {
		return true
	} else if border.Inf == positiveInf {
		return false
	}
	if border.Exclude {
		return border.Value < value
	} else {
		return border.Value <= value
	}
}

var positiveInfBorder = &ScoreBorder{
	Inf: positiveInf,
}

var negativeInfBorder = &ScoreBorder{
	Inf: negativeInf,
}

func ParseScoreBorder(s string) (*ScoreBorder, error) {
	if s == "inf" || s == "+inf" {
		return positiveInfBorder, nil
	}
	if s == "-inf" {
		return negativeInfBorder, nil
	}
	if s[0] == '(' {
		value, err := strconv.ParseFloat(s[1:], 64)
		if err != nil {
			return nil, errors.New("ERR min or max is not a float")
		}
		return &ScoreBorder{
			Inf:     0,
			Value:   value,
			Exclude: true,
		}, nil
	} else {
		value, err := strconv.ParseFloat(s, 64)
		if err != nil {
			return nil, errors.New("ERR min or max is not a float")
		}
		return &ScoreBorder{
			Inf:     0,
			Value:   value,
			Exclude: false,
		}, nil
	}
}