fix pattern matching exercise solution

[mustafapc]

my solution works on more complex Expressions and Operations than the old one

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[gribozavr]

Sorry, the change looks like a stylistic refactoring to me. What's the motivation?

[mustafapc]

@gribozavr the motivation is that the solution used on the tutorial only works on trees that's two or three operation deep and mine can work with complex trees, try a operation for example ((((4 + 7) * (8 - 2)) / ((9 + 14) * (16 - 4))) + 5) or something even deeper than this my solution would work and the one in tutorial won't

[gribozavr]

@mustafapc Sorry, I can't reproduce the problem yet. I translated the expression you provided into a test and it passes:

#[test]
fn test_complex_expression() {
    // ((((4 + 7) * (8 - 2)) / ((9 + 14) * (16 - 4))) + 5)
    let term1 = Expression::Op { // (4 + 7) * (8 - 2)
        op: Operation::Mul,
        left: Box::new(Expression::Op {
            op: Operation::Add,
            left: Box::new(Expression::Value(4)),
            right: Box::new(Expression::Value(7)),
        }),
        right: Box::new(Expression::Op {
            op: Operation::Sub,
            left: Box::new(Expression::Value(8)),
            right: Box::new(Expression::Value(2)),
        }),
    };
    let term2 = Expression::Op { // (9 + 14) * (16 - 4)
        op: Operation::Mul,
        left: Box::new(Expression::Op {
            op: Operation::Add,
            left: Box::new(Expression::Value(9)),
            right: Box::new(Expression::Value(14)),
        }),
        right: Box::new(Expression::Op {
            op: Operation::Sub,
            left: Box::new(Expression::Value(16)),
            right: Box::new(Expression::Value(4)),
        }),
    };
    let expr = Expression::Op { // term1 / term2 + 5
        op: Operation::Add,
        left: Box::new(Expression::Op {
            op: Operation::Div,
            left: Box::new(term1),
            right: Box::new(term2),
        }),
        right: Box::new(Expression::Value(5)),
    };
    assert_eq!(eval(expr), 5);
}

Could you provide a test that fails and demonstrates the bug?

[mustafapc]

@mustafapc Sorry, I can't reproduce the problem yet. I translated the expression you provided into a test and it passes:

#[test]
fn test_complex_expression() {
    // ((((4 + 7) * (8 - 2)) / ((9 + 14) * (16 - 4))) + 5)
    let term1 = Expression::Op { // (4 + 7) * (8 - 2)
        op: Operation::Mul,
        left: Box::new(Expression::Op {
            op: Operation::Add,
            left: Box::new(Expression::Value(4)),
            right: Box::new(Expression::Value(7)),
        }),
        right: Box::new(Expression::Op {
            op: Operation::Sub,
            left: Box::new(Expression::Value(8)),
            right: Box::new(Expression::Value(2)),
        }),
    };
    let term2 = Expression::Op { // (9 + 14) * (16 - 4)
        op: Operation::Mul,
        left: Box::new(Expression::Op {
            op: Operation::Add,
            left: Box::new(Expression::Value(9)),
            right: Box::new(Expression::Value(14)),
        }),
        right: Box::new(Expression::Op {
            op: Operation::Sub,
            left: Box::new(Expression::Value(16)),
            right: Box::new(Expression::Value(4)),
        }),
    };
    let expr = Expression::Op { // term1 / term2 + 5
        op: Operation::Add,
        left: Box::new(Expression::Op {
            op: Operation::Div,
            left: Box::new(term1),
            right: Box::new(term2),
        }),
        right: Box::new(Expression::Value(5)),
    };
    assert_eq!(eval(expr), 5);
}

Could you provide a test that fails and demonstrates the bug?

I don't write rust anymore, have fun doing rust