Re: [Qemu-devel] [PATCH v2 2/4] qapi: Add qobject_is_equal()

[Markus Armbruster]

Max Reitz <address@hidden> writes:

> This generic function (along with its implementations for different
> types) determines whether two QObjects are equal.
>
> Signed-off-by: Max Reitz <address@hidden>
> ---
>  include/qapi/qmp/qbool.h   |  1 +
>  include/qapi/qmp/qdict.h   |  1 +
>  include/qapi/qmp/qfloat.h  |  1 +
>  include/qapi/qmp/qint.h    |  1 +
>  include/qapi/qmp/qlist.h   |  1 +
>  include/qapi/qmp/qnull.h   |  2 ++
>  include/qapi/qmp/qobject.h |  9 +++++++++
>  include/qapi/qmp/qstring.h |  1 +
>  qobject/qbool.c            |  8 ++++++++
>  qobject/qdict.c            | 28 ++++++++++++++++++++++++++++
>  qobject/qfloat.c           |  8 ++++++++
>  qobject/qint.c             |  8 ++++++++
>  qobject/qlist.c            | 30 ++++++++++++++++++++++++++++++
>  qobject/qnull.c            |  5 +++++
>  qobject/qobject.c          | 30 ++++++++++++++++++++++++++++++
>  qobject/qstring.c          |  9 +++++++++
>  16 files changed, 143 insertions(+)

No unit test?

> diff --git a/include/qapi/qmp/qbool.h b/include/qapi/qmp/qbool.h
> index a41111c..f77ea86 100644
> --- a/include/qapi/qmp/qbool.h
> +++ b/include/qapi/qmp/qbool.h
> @@ -24,6 +24,7 @@ typedef struct QBool {
>  QBool *qbool_from_bool(bool value);
>  bool qbool_get_bool(const QBool *qb);
>  QBool *qobject_to_qbool(const QObject *obj);
> +bool qbool_is_equal(const QObject *x, const QObject *y);
>  void qbool_destroy_obj(QObject *obj);
>  
>  #endif /* QBOOL_H */
> diff --git a/include/qapi/qmp/qdict.h b/include/qapi/qmp/qdict.h
> index 188440a..134a526 100644
> --- a/include/qapi/qmp/qdict.h
> +++ b/include/qapi/qmp/qdict.h
> @@ -41,6 +41,7 @@ void qdict_del(QDict *qdict, const char *key);
>  int qdict_haskey(const QDict *qdict, const char *key);
>  QObject *qdict_get(const QDict *qdict, const char *key);
>  QDict *qobject_to_qdict(const QObject *obj);
> +bool qdict_is_equal(const QObject *x, const QObject *y);
>  void qdict_iter(const QDict *qdict,
>                  void (*iter)(const char *key, QObject *obj, void *opaque),
>                  void *opaque);
> diff --git a/include/qapi/qmp/qfloat.h b/include/qapi/qmp/qfloat.h
> index b5d1583..318e91e 100644
> --- a/include/qapi/qmp/qfloat.h
> +++ b/include/qapi/qmp/qfloat.h
> @@ -24,6 +24,7 @@ typedef struct QFloat {
>  QFloat *qfloat_from_double(double value);
>  double qfloat_get_double(const QFloat *qi);
>  QFloat *qobject_to_qfloat(const QObject *obj);
> +bool qfloat_is_equal(const QObject *x, const QObject *y);
>  void qfloat_destroy_obj(QObject *obj);
>  
>  #endif /* QFLOAT_H */
> diff --git a/include/qapi/qmp/qint.h b/include/qapi/qmp/qint.h
> index 3aaff76..20975da 100644
> --- a/include/qapi/qmp/qint.h
> +++ b/include/qapi/qmp/qint.h
> @@ -23,6 +23,7 @@ typedef struct QInt {
>  QInt *qint_from_int(int64_t value);
>  int64_t qint_get_int(const QInt *qi);
>  QInt *qobject_to_qint(const QObject *obj);
> +bool qint_is_equal(const QObject *x, const QObject *y);
>  void qint_destroy_obj(QObject *obj);
>  
>  #endif /* QINT_H */
> diff --git a/include/qapi/qmp/qlist.h b/include/qapi/qmp/qlist.h
> index 5dc4ed9..4380a5b 100644
> --- a/include/qapi/qmp/qlist.h
> +++ b/include/qapi/qmp/qlist.h
> @@ -57,6 +57,7 @@ QObject *qlist_peek(QList *qlist);
>  int qlist_empty(const QList *qlist);
>  size_t qlist_size(const QList *qlist);
>  QList *qobject_to_qlist(const QObject *obj);
> +bool qlist_is_equal(const QObject *x, const QObject *y);
>  void qlist_destroy_obj(QObject *obj);
>  
>  static inline const QListEntry *qlist_first(const QList *qlist)
> diff --git a/include/qapi/qmp/qnull.h b/include/qapi/qmp/qnull.h
> index 69555ac..9299683 100644
> --- a/include/qapi/qmp/qnull.h
> +++ b/include/qapi/qmp/qnull.h
> @@ -23,4 +23,6 @@ static inline QObject *qnull(void)
>      return &qnull_;
>  }
>  
> +bool qnull_is_equal(const QObject *x, const QObject *y);
> +
>  #endif /* QNULL_H */
> diff --git a/include/qapi/qmp/qobject.h b/include/qapi/qmp/qobject.h
> index ef1d1a9..cac72e3 100644
> --- a/include/qapi/qmp/qobject.h
> +++ b/include/qapi/qmp/qobject.h
> @@ -68,6 +68,15 @@ static inline void qobject_incref(QObject *obj)
>  }
>  
>  /**
> + * qobject_is_equal(): Returns whether the two objects are equal.

Imperative mood, please: Return whether...

> + *
> + * Any of the pointers may be NULL; will return true if both are. Will always
> + * return false if only one is (therefore a QNull object is not considered 
> equal
> + * to a NULL pointer).
> + */

Humor me: wrap comment lines around column 70, and put two spaces
between sentences.

Same for the other function comments.

> +bool qobject_is_equal(const QObject *x, const QObject *y);
> +
> +/**
>   * qobject_destroy(): Free resources used by the object
>   */
>  void qobject_destroy(QObject *obj);
> diff --git a/include/qapi/qmp/qstring.h b/include/qapi/qmp/qstring.h
> index 10076b7..65c05a9 100644
> --- a/include/qapi/qmp/qstring.h
> +++ b/include/qapi/qmp/qstring.h
> @@ -31,6 +31,7 @@ void qstring_append_int(QString *qstring, int64_t value);
>  void qstring_append(QString *qstring, const char *str);
>  void qstring_append_chr(QString *qstring, int c);
>  QString *qobject_to_qstring(const QObject *obj);
> +bool qstring_is_equal(const QObject *x, const QObject *y);
>  void qstring_destroy_obj(QObject *obj);
>  
>  #endif /* QSTRING_H */
> diff --git a/qobject/qbool.c b/qobject/qbool.c
> index 0606bbd..f1d1719 100644
> --- a/qobject/qbool.c
> +++ b/qobject/qbool.c
> @@ -52,6 +52,14 @@ QBool *qobject_to_qbool(const QObject *obj)
>  }
>  
>  /**
> + * qbool_is_equal(): Tests whether the two QBools are equal

Return whether ...

> + */
> +bool qbool_is_equal(const QObject *x, const QObject *y)
> +{
> +    return qobject_to_qbool(x)->value == qobject_to_qbool(y)->value;
> +}
> +
> +/**
>   * qbool_destroy_obj(): Free all memory allocated by a
>   * QBool object
>   */
> diff --git a/qobject/qdict.c b/qobject/qdict.c
> index 88e2ecd..ca919bc 100644
> --- a/qobject/qdict.c
> +++ b/qobject/qdict.c
> @@ -410,6 +410,34 @@ void qdict_del(QDict *qdict, const char *key)
>  }
>  
>  /**
> + * qdict_is_equal(): Tests whether the two QDicts are equal
> + *
> + * Here, equality means whether they contain the same keys and whether the
> + * respective values are in turn equal (i.e. invoking qobject_is_equal() on 
> them
> + * yields true).
> + */
> +bool qdict_is_equal(const QObject *x, const QObject *y)
> +{
> +    const QDict *dict_x = qobject_to_qdict(x), *dict_y = qobject_to_qdict(y);

I'm fine with multiple initializers in one declaration, but I think this
one would look tidier as

       const QDict *dict_x = qobject_to_qdict(x);
       const QDict *dict_y = qobject_to_qdict(y);

> +    const QDictEntry *e;
> +
> +    if (qdict_size(dict_x) != qdict_size(dict_y)) {
> +        return false;
> +    }
> +
> +    for (e = qdict_first(dict_x); e; e = qdict_next(dict_x, e)) {
> +        const QObject *obj_x = qdict_entry_value(e);
> +        const QObject *obj_y = qdict_get(dict_y, qdict_entry_key(e));
> +
> +        if (!qobject_is_equal(obj_x, obj_y)) {
> +            return false;
> +        }
> +    }
> +
> +    return true;
> +}
> +
> +/**
>   * qdict_destroy_obj(): Free all the memory allocated by a QDict
>   */
>  void qdict_destroy_obj(QObject *obj)
> diff --git a/qobject/qfloat.c b/qobject/qfloat.c
> index d5da847..291ecc4 100644
> --- a/qobject/qfloat.c
> +++ b/qobject/qfloat.c
> @@ -52,6 +52,14 @@ QFloat *qobject_to_qfloat(const QObject *obj)
>  }
>  
>  /**
> + * qfloat_is_equal(): Tests whether the two QFloats are equal
> + */
> +bool qfloat_is_equal(const QObject *x, const QObject *y)
> +{
> +    return qobject_to_qfloat(x)->value == qobject_to_qfloat(y)->value;
> +}
> +
> +/**
>   * qfloat_destroy_obj(): Free all memory allocated by a
>   * QFloat object
>   */
> diff --git a/qobject/qint.c b/qobject/qint.c
> index d7d1b30..f638cb7 100644
> --- a/qobject/qint.c
> +++ b/qobject/qint.c
> @@ -51,6 +51,14 @@ QInt *qobject_to_qint(const QObject *obj)
>  }
>  
>  /**
> + * qint_is_equal(): Tests whether the two QInts are equal
> + */
> +bool qint_is_equal(const QObject *x, const QObject *y)
> +{
> +    return qobject_to_qint(x)->value == qobject_to_qint(y)->value;
> +}
> +
> +/**
>   * qint_destroy_obj(): Free all memory allocated by a
>   * QInt object
>   */
> diff --git a/qobject/qlist.c b/qobject/qlist.c
> index 86b60cb..652fc53 100644
> --- a/qobject/qlist.c
> +++ b/qobject/qlist.c
> @@ -140,6 +140,36 @@ QList *qobject_to_qlist(const QObject *obj)
>  }
>  
>  /**
> + * qlist_is_equal(): Tests whether the two QLists are equal
> + *
> + * In order to be considered equal, the respective two objects at each index 
> of
> + * the two lists have to compare equal (regarding qobject_is_equal()), and 
> both
> + * lists have to have the same number of elements.
> + * That means, both lists have to contain equal objects in equal order.
> + */
> +bool qlist_is_equal(const QObject *x, const QObject *y)
> +{
> +    const QList *list_x = qobject_to_qlist(x), *list_y = qobject_to_qlist(y);
> +    const QListEntry *entry_x, *entry_y;
> +
> +    entry_x = qlist_first(list_x);
> +    entry_y = qlist_first(list_y);
> +
> +    while (entry_x && entry_y) {
> +        if (!qobject_is_equal(qlist_entry_obj(entry_x),
> +                              qlist_entry_obj(entry_y)))
> +        {
> +            return false;
> +        }
> +
> +        entry_x = qlist_next(entry_x);
> +        entry_y = qlist_next(entry_y);
> +    }
> +
> +    return !entry_x && !entry_y;
> +}
> +
> +/**
>   * qlist_destroy_obj(): Free all the memory allocated by a QList
>   */
>  void qlist_destroy_obj(QObject *obj)
> diff --git a/qobject/qnull.c b/qobject/qnull.c
> index b3cc85e..af5453d 100644
> --- a/qobject/qnull.c
> +++ b/qobject/qnull.c
> @@ -19,3 +19,8 @@ QObject qnull_ = {
>      .type = QTYPE_QNULL,
>      .refcnt = 1,
>  };
> +
> +bool qnull_is_equal(const QObject *x, const QObject *y)
> +{
> +    return true;
> +}
> diff --git a/qobject/qobject.c b/qobject/qobject.c
> index fe4fa10..af2869a 100644
> --- a/qobject/qobject.c
> +++ b/qobject/qobject.c
> @@ -28,3 +28,33 @@ void qobject_destroy(QObject *obj)
>      assert(QTYPE_QNULL < obj->type && obj->type < QTYPE__MAX);
>      qdestroy[obj->type](obj);
>  }
> +
> +
> +static bool (*qis_equal[QTYPE__MAX])(const QObject *, const QObject *) = {
> +    [QTYPE_NONE] = NULL,               /* No such object exists */
> +    [QTYPE_QNULL] = qnull_is_equal,
> +    [QTYPE_QINT] = qint_is_equal,
> +    [QTYPE_QSTRING] = qstring_is_equal,
> +    [QTYPE_QDICT] = qdict_is_equal,
> +    [QTYPE_QLIST] = qlist_is_equal,
> +    [QTYPE_QFLOAT] = qfloat_is_equal,
> +    [QTYPE_QBOOL] = qbool_is_equal,
> +};
> +
> +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). */
> +
> +    if (!x && !y) {
> +        return true;
> +    }
> +
> +    if (!x || !y || x->type != y->type) {
> +        return false;
> +    }
> +
> +    assert(QTYPE_NONE < x->type && x->type < QTYPE__MAX);
> +
> +    return qis_equal[x->type](x, y);
> +}
> diff --git a/qobject/qstring.c b/qobject/qstring.c
> index 5da7b5f..a2b51fa 100644
> --- a/qobject/qstring.c
> +++ b/qobject/qstring.c
> @@ -129,6 +129,15 @@ const char *qstring_get_str(const QString *qstring)
>  }
>  
>  /**
> + * qstring_is_equal(): Tests whether the two QStrings are equal
> + */
> +bool qstring_is_equal(const QObject *x, const QObject *y)
> +{
> +    return !strcmp(qobject_to_qstring(x)->string,
> +                   qobject_to_qstring(y)->string);
> +}
> +
> +/**
>   * qstring_destroy_obj(): Free all memory allocated by a QString
>   * object
>   */

Address my nitpicks, and either provide a unit test or convince me it's
not worth the trouble, and you may add
Reviewed-by: Markus Armbruster <address@hidden>