Function rewriteIsOp

query/expr/parser.go:241–270

(expr Expr)

}

func rewriteIsOp(expr Expr) (Token, error) {
	affirmative := true
	if unary, ok := expr.(*UnaryExpr); ok {
		if unary.Op == NOT {
			affirmative = false
			expr = unary.Expr
		} else {
			return IS, fmt.Errorf("bad literal %s following IS", expr.String())
		}
	}
	switch e := expr.(type) {
	case *NullLiteral:
		if affirmative {
			return IS_NULL, nil
		}
		return IS_NOT_NULL, nil
	case *UnknownLiteral:
		if affirmative {
			return IS_NULL, nil
		}
		return IS_NOT_NULL, nil
	case *BooleanLiteral:
		if affirmative == e.Val {
			return IS_TRUE, nil
		}

		return IS_FALSE, nil
	}
	return IS, fmt.Errorf("bad literal %s following IS (NOT)", expr.String())
}

func rewriteIsExpr(expr Expr) (Expr, error) {
	e, ok := expr.(*BinaryExpr)