Function check_boolean_result 

pub fn check_boolean_result(ast: &Expression) -> Result<()>

Checks if the top level Expression produces a Value::Boolean result.

Examples

use slac::{check_boolean_result, Expression, Operator, Value};

let ast = Expression::Binary {
    left: Box::new(Expression::Literal{value: Value::Boolean(true)}),
    right: Box::new(Expression::Literal{value: Value::Boolean(true)}),
    operator: Operator::And,
};

assert!(check_boolean_result(&ast).is_ok());

Errors

Returns an Error when the top most Expression can’t evaluate to a Value::Boolean.