kode4food/ale

package types

// Pair describes a pair of typed Values
type Pair struct {
    basic
    car  Type
    cdr  Type
    name string
}

// MakeCons declares a new PairType that will only allow a MakeListOf with elements of
// the provided elem Type
func MakeCons(left, right Type) Type {
    return &Pair{
        basic: BasicCons,
        name:  BasicCons.Name(),
        car:   left,
        cdr:   right,
    }
}

func (p *Pair) Car() Type {
    return p.car
}

func (p *Pair) Cdr() Type {
    return p.cdr
}

func (p *Pair) Name() string {
    return p.name
}

func (p *Pair) Accepts(c *Checker, other Type) bool {
    if p == other {
        return true
    }
    if other, ok := other.(*Pair); ok {
        return p.basic.Accepts(c, other) &&
            c.AcceptsChild(p.car, other.Car()) &&
            c.AcceptsChild(p.cdr, other.Cdr())
    }
    return false
}

func (p *Pair) Equal(other Type) bool {
    if p == other {
        return true
    }
    if other, ok := other.(*Pair); ok {
        return p.name == other.name &&
            p.basic.Equal(other.basic) &&
            p.car.Equal(other.car) &&
            p.cdr.Equal(other.cdr)
    }
    return false
}