sql

type Catalog struct {
	Databases []Database
}

type Database interface {
	Nameable
	Tables() map[string]Table
}

type Expression interface {
	Resolvable
	Type() Type
	Name() string
	Eval(Row) interface{}
	TransformUp(func(Expression) Expression) Expression
}

type Field struct {
	Name string
	Type Type
}

type MemoryRow []interface{}

type Nameable interface {
	Name() string
}

type Node interface {
	Resolvable
	Transformable
	Schema() Schema
	Children() []Node
	RowIter() (RowIter, error)
}

type Resolvable interface {
	Resolved() bool
}

type Row interface {
	Fields() []interface{}
}

type RowIter interface {
	Next() (Row, error)
}

type Schema []Field

type Table interface {
	Nameable
	Node
}

type Transformable interface {
	TransformUp(func(Node) Node) Node
	TransformExpressionsUp(func(Expression) Expression) Node
}

type Type interface {
	Name() string
	InternalType() reflect.Kind
	Check(interface{}) bool
	Convert(interface{}) (interface{}, error)
	Compare(interface{}, interface{}) int
}

type UnresolvedDatabase struct{}