query

type AND struct {
	Filters []Filter
}

type Builder struct {
	// contains filtered or unexported fields
}

type EQ struct {
	Key string
	Val interface{}
}

type Filter interface {
	Parse(interface{}) error
}

type IN struct {
	Key  string
	Vals []interface{}
}

type OR struct {
	Filters []Filter
}

type Pagination struct {
	Limit int    `json:"limit"`
	Token string `json:"token,omitempty"`
}

type Query struct {
	Filters map[string]interface{} `json:"filter"`
	Sort    []Sorting              `json:"sort"`
	Page    Pagination             `json:"page"`

	// derived from Filters
	Filter Filter
}

type Sorting struct {
	Key   string `json:"key"`
	Order string `json:"order,omitempty"`
}

type Visitor interface {
	// returns "equal" expression
	VisitEQ(*EQ) (string, error)
	// returns "in" expression
	VisitIN(*IN) (string, error)
	// returns "and" expression
	VisitAND(*AND) (string, error)
	// returns "or" expression
	VisitOR(*OR) (string, error)
	// receives concatenated filters and finalizes the native query
	Finalize(string, *Query) error
}