Re: [Qemu-devel] [PATCH v14 02/21] qdict: implement a qdict_crumple method for un-flattening a dict

[Daniel P. Berrange]

On Tue, Oct 18, 2016 at 04:32:13PM +0200, Markus Armbruster wrote:
> "Daniel P. Berrange" <address@hidden> writes:
> 
> > The qdict_flatten() method will take a dict whose elements are
> > further nested dicts/lists and flatten them by concatenating
> > keys.
> >
> > The qdict_crumple() method aims to do the reverse, taking a flat
> > qdict, and turning it into a set of nested dicts/lists. It will
> > apply nesting based on the key name, with a '.' indicating a
> > new level in the hierarchy. If the keys in the nested structure
> > are all numeric, it will create a list, otherwise it will create
> > a dict.
> >
> > If the keys are a mixture of numeric and non-numeric, or the
> > numeric keys are not in strictly ascending order, an error will
> > be reported.
> >
> > As an example, a flat dict containing
> >
> >  {
> >    'foo.0.bar': 'one',
> >    'foo.0.wizz': '1',
> >    'foo.1.bar': 'two',
> >    'foo.1.wizz': '2'
> >  }
> >
> > will get turned into a dict with one element 'foo' whose
> > value is a list. The list elements will each in turn be
> > dicts.
> >
> >  {
> >    'foo': [
> >      { 'bar': 'one', 'wizz': '1' },
> >      { 'bar': 'two', 'wizz': '2' }
> >    ],
> >  }
> >
> > If the key is intended to contain a literal '.', then it must
> > be escaped as '..'. ie a flat dict
> >
> >   {
> >      'foo..bar': 'wizz',
> >      'bar.foo..bar': 'eek',
> >      'bar.hello': 'world'
> >   }
> >
> > Will end up as
> >
> >   {
> >      'foo.bar': 'wizz',
> >      'bar': {
> >         'foo.bar': 'eek',
> >         'hello': 'world'
> >      }
> >   }
> >
> > The intent of this function is that it allows a set of QemuOpts
> > to be turned into a nested data structure that mirrors the nesting
> > used when the same object is defined over QMP.
> >
> > Reviewed-by: Eric Blake <address@hidden>
> > Reviewed-by: Kevin Wolf <address@hidden>
> > Reviewed-by: Marc-André Lureau <address@hidden>
> > Signed-off-by: Daniel P. Berrange <address@hidden>
> > ---
> >  include/qapi/qmp/qdict.h |   1 +
> >  qobject/qdict.c          | 289 
> > +++++++++++++++++++++++++++++++++++++++++++++++
> >  tests/check-qdict.c      | 261 ++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 551 insertions(+)
> >
> > diff --git a/include/qapi/qmp/qdict.h b/include/qapi/qmp/qdict.h
> > index 71b8eb0..e0d24e1 100644
> > --- a/include/qapi/qmp/qdict.h
> > +++ b/include/qapi/qmp/qdict.h
> > @@ -73,6 +73,7 @@ void qdict_flatten(QDict *qdict);
> >  void qdict_extract_subqdict(QDict *src, QDict **dst, const char *start);
> >  void qdict_array_split(QDict *src, QList **dst);
> >  int qdict_array_entries(QDict *src, const char *subqdict);
> > +QObject *qdict_crumple(const QDict *src, bool recursive, Error **errp);
> >  
> >  void qdict_join(QDict *dest, QDict *src, bool overwrite);
> >  
> > diff --git a/qobject/qdict.c b/qobject/qdict.c
> > index 60f158c..c38e90e 100644
> > --- a/qobject/qdict.c
> > +++ b/qobject/qdict.c
> [...]
> > +/**
> > + * qdict_crumple:
> > + * @src: the original flat dictionary (only scalar values) to crumple
> > + * @recursive: true to recursively crumple nested dictionaries
> 
> Is recursive=false used outside tests in this series?

No, its not used.

It was suggested in a way earlier version by Max, but not sure if his
code uses it or not.

Regards,
Daniel
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