[libcamera-devel] [PATCH 04/12] libcamera: deviceenumerator: add DeviceMatch class

[Laurent Pinchart]

On Monday, 24 December 2018 12:55:30 EET Jacopo Mondi wrote:
> Hi Niklas,
>   as I've commented on 00/12, I think the DeviceMatcher should be
> replaced by a MediaDeviceDesc and have the MediaDevice do the matching
> on it. Nonethless, I have some questions here, as they might apply
> generally to all our code base.

How about doing it the other way around, having the match() function in the 
MediaDeviceDesc class ? That would keep MediaDevice focused on handling media 
devices, and MediaDeviceDesc on handling matching. We could perhaps rename 
MediaDeviceDesc to MediaDeviceMatch (I don't dislike the MediaDeviceDesc name 
as such, but I don't really like abbreviating Desc).

> On Sun, Dec 23, 2018 at 12:00:33AM +0100, Niklas S??derlund wrote:
> > Provide a DeviceMatch class which represents all properties of a media
> > device a pipeline hander can specify when searching for a device to use
> > in its pipeline.
> > 
> > Signed-off-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
> > ---
> > 
> >  src/libcamera/deviceenumerator.cpp       | 54 ++++++++++++++++++++++++
> >  src/libcamera/include/deviceenumerator.h | 17 ++++++++
> >  2 files changed, 71 insertions(+)
> > 
> > diff --git a/src/libcamera/deviceenumerator.cpp
> > b/src/libcamera/deviceenumerator.cpp index
> > 7c44a65b45472ef3..17b6874d229c791c 100644
> > --- a/src/libcamera/deviceenumerator.cpp
> > +++ b/src/libcamera/deviceenumerator.cpp
> > @@ -75,4 +75,58 @@ bool DeviceInfo::lookup(const std::string &name,
> > std::string &devnode) const
> >  	return true;
> >  }
> > 
> > +/* ----------------------------------------------------------------------
> > + * DeviceMatch
> > + */
> > +
> > +DeviceMatch::DeviceMatch(const std::string &driver)
> > +	: driver_(driver)
> > +{
> > +}
> 
> Is it worth placing constructors with list initializers only in the
> .cpp file?
> 
> > +
> > +void DeviceMatch::add(const std::string &entity)
> > +{
> > +	entities_.push_back(std::string(entity));

Doesn't entities_.push_back(entity); work as expected ?

> > +}
> > +
> > +bool DeviceMatch::match(const DeviceInfo *info) const
> > +{
> > +	std::vector<std::string> entities;
> 
> That's weird. This is clearly unused, but the compiler does not
> complain. Actually I can keep it or remove it without any message from
> g++. Was it here intentionally?
> 
> > +
> > +	if (!matchInfo(info->info()))
> > +		return false;
> > +
> > +	if (!matchEntities(info->entities()))
> > +		return false;
> > +
> > +	return true;

Given how simple the code is I would inline both matchInfo() and 
matchEntities() here.

> > +}
> > +
> > +bool DeviceMatch::matchInfo(const struct media_device_info &info) const
> > +{
> > +	/* TODO: Add more optinal matching pairs from struct media_device_info
> > */
> 
> optional
> 
> > +	/* TODO: Allow for empty driver in DeviceMatch */
> > +	return driver_ == info.driver;
> > +}
> > +
> > +bool DeviceMatch::matchEntities(const std::vector<std::string> &entities)
> > const
> > +{
> > +	for (const std::string &name : entities_) {
> > +		bool found = false;
> > +
> > +		for (const std::string &entity : entities) {
> > +
> 
> nit: unnecessary empty line
> 
> > +			if (name == entity) {
> > +				found = true;
> > +				break;
> > +			}
> > +		}
> > +
> > +		if (!found)
> > +			return false;
> > +	}
> > +
> > +	return true;
> > +}
> > +
> > 
> >  } /* namespace libcamera */
> > 
> > diff --git a/src/libcamera/include/deviceenumerator.h
> > b/src/libcamera/include/deviceenumerator.h index
> > 0136ed6ea23bf65e..fb412b8840cb2ffe 100644
> > --- a/src/libcamera/include/deviceenumerator.h
> > +++ b/src/libcamera/include/deviceenumerator.h
> > @@ -39,6 +39,23 @@ private:
> >  	std::map<std::string, std::string> entities_;
> >  };
> > 
> > +class DeviceMatch
> > +{
> > +public:
> > +	DeviceMatch(const std::string &driver);
> > +
> > +	void add(const std::string &entity);
> > +
> > +	bool match(const DeviceInfo *info) const;
> > +
> > +private:
> > +	std::string driver_;
> > +	std::vector<std::string> entities_;
> > +
> > +	bool matchInfo(const struct media_device_info &info) const;
> > +	bool matchEntities(const std::vector<std::string> &entities) const;
> > +};
> > +
> > 
> >  } /* namespace libcamera */
> >  
> >  #endif	/* __LIBCAMERA_DEVICEENUMERATE_H__ */
> 
> This is less than nit, but shouldn't this be DEVICEENUMERATOR ? :)

-- 
Regards,

Laurent Pinchart