Re: [Qemu-devel] [PATCH v3 2/5] qapi: Add qobject_is_equal()

[Eric Blake]

On 07/03/2017 07:25 AM, Max Reitz wrote:
> This generic function (along with its implementations for different
> types) determines whether two QObjects are equal.
> 
> Signed-off-by: Max Reitz <address@hidden>
> ---

> +++ b/qobject/qnum.c

> +    case QNUM_DOUBLE:
> +        switch (num_y->kind) {
> +        case QNUM_I64:
> +            return qnum_is_equal(y, x);
> +        case QNUM_U64:
> +            return qnum_is_equal(y, x);
> +        case QNUM_DOUBLE:
> +            /* Comparison in native double type */
> +            return num_x->u.dbl == num_y->u.dbl;

Which returns false if we allow NaN (in general, JSON does not, so I'm
not sure if we allow NaN in a QNum)

> +++ b/qobject/qobject.c

> +bool qobject_is_equal(const QObject *x, const QObject *y)
> +{
> +    /* We cannot test x == y because an object does not need to be
> +     * equal to itself (e.g. NaN floats are not). */

But this comment matches the code above in QNum.

> +
> +    if (!x && !y) {
> +        return true;
> +    }
> +
> +    if (!x || !y || x->type != y->type) {
> +        return false;
> +    }

I like that there is no implicit conversion between bool and int; the
only conversions that still allow equality are within the subtypes of QNum.

Reviewed-by: Eric Blake <address@hidden>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

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