netdata/netdata

// SPDX-License-Identifier: GPL-3.0-or-later

package selector

import "fmt"

type Expr struct {
    Allow []string `yaml:"allow" json:"allow"`
    Deny  []string `yaml:"deny" json:"deny"`
}

func (e Expr) Empty() bool {
    return len(e.Allow) == 0 && len(e.Deny) == 0

}

func (e Expr) Parse() (Selector, error) {
    if e.Empty() {
        return nil, nil
    }

    var srs []Selector
    var allow Selector
    var deny Selector

    for _, item := range e.Allow {
        sr, err := Parse(item)
        if err != nil {
            return nil, fmt.Errorf("parse selector '%s': %v", item, err)
        }
        srs = append(srs, sr)
    }

    switch len(srs) {
    case 0:
        allow = trueSelector{}
    case 1:
        allow = srs[0]
    default:
        allow = Or(srs[0], srs[1], srs[2:]...)
    }

    srs = srs[:0]
    for _, item := range e.Deny {
        sr, err := Parse(item)
        if err != nil {
            return nil, fmt.Errorf("parse selector '%s': %v", item, err)
        }
        srs = append(srs, sr)
    }

    switch len(srs) {
    case 0:
        deny = falseSelector{}
    case 1:
        deny = srs[0]
    default:
        deny = Or(srs[0], srs[1], srs[2:]...)
    }

    return And(allow, Not(deny)), nil
}