Interface Expr

pkg/sql/sem/tree/expr.go:28–48

Expr represents an expression.

// Expr represents an expression.
type Expr interface {
	fmt.Stringer
	NodeFormatter
	// Walk recursively walks all children using WalkExpr. If any children are changed, it returns a
	// copy of this node updated to point to the new children. Otherwise the receiver is returned.
	// For childless (leaf) Exprs, its implementation is empty.
	Walk(Visitor) Expr
	// TypeCheck transforms the Expr into a well-typed TypedExpr, which further permits
	// evaluation and type introspection, or an error if the expression cannot be well-typed.
	// When type checking is complete, if no error was reported, the expression and all
	// sub-expressions will be guaranteed to be well-typed, meaning that the method effectively
	// maps the Expr tree into a TypedExpr tree.
	//
	// The ctx parameter defines the context in which to perform type checking.
	// The desired parameter hints the desired type that the method's caller wants from
	// the resulting TypedExpr. It is not valid to call TypeCheck with a nil desired
	// type. Instead, call it with wildcard type types.Any if no specific type is
	// desired. This restriction is also true of most methods and functions related
	// to type checking.
	TypeCheck(ctx *SemaContext, desired *types.T) (TypedExpr, error)
}

// TypedExpr represents a well-typed expression.
type TypedExpr interface {