[RFC PATCH v1] treewide: Prefer `std::string_view` over `const std::string&` in parameters
Laurent Pinchart
laurent.pinchart at ideasonboard.com
Mon Dec 16 00:14:47 CET 2024
On Sun, Dec 15, 2024 at 10:46:35PM +0000, Barnabás Pőcze wrote:
> 2024. december 15., vasárnap 21:56 keltezéssel, Laurent Pinchart írta:
> > On Sun, Dec 15, 2024 at 08:48:06PM +0000, Barnabás Pőcze wrote:
> > > A parameter of type `const std::string&` is not the right choice in
> > > almost all cases. It forces the caller to construct an `std::string`
> > > if they don't already have one, and accessing its data requires
> > > an extra indirection. Furthermore, `std::string` is just one
> > > instantiation of `std::basic_string<>`, using e.g. a different
> > > allocator would immediately make it incompatible.
> >
> > I don't think the allocator is an issue in libcamera.
>
> This is a general argument in favor, not specific to libcamera, indeed. Although
> users can still use different allocators, in which case they would be affected,
> e.g. `CameraManager::get()`.
>
> > > In contrast to that using an `std::string_view` is better if
> > > NUL termination is not needed since no `std::string` construction
> > > is required, and in many cases it can be passed directly in registers.
> >
> > I had a go at this previously, and had very mixed feelings about the
> > result. I'll post a WIP series for discussion.
>
> What were the concerns?
See "[RFC PATCH 0/8] libcamera: Use std::string_view" :-) Let's discuss
it there, as there's a patch in the series that attempts to document
std::string_view usage. I would like to agree on clear rules before we
make tree-wide changes.
> This change only considers a limited subset of all
> `const std::string&` parameters. For example, functions (constructors) where a
> copy of the string made are excluded. Mostly the "find-thing-by-name" style
> functions are converted here.
>
> > > Signed-off-by: Barnabás Pőcze <pobrn at protonmail.com>
> > > ---
> > > include/libcamera/base/utils.h | 10 +++++-----
> > > include/libcamera/camera_manager.h | 3 ++-
> > > .../libcamera/internal/camera_sensor_properties.h | 4 ++--
> > > include/libcamera/internal/device_enumerator.h | 3 ++-
> > > include/libcamera/internal/formats.h | 3 ++-
> > > include/libcamera/internal/media_device.h | 7 ++++---
> > > include/libcamera/internal/pipeline_handler.h | 3 ++-
> > > include/libcamera/internal/v4l2_subdevice.h | 3 ++-
> > > include/libcamera/internal/v4l2_videodevice.h | 3 ++-
> > > include/libcamera/pixel_format.h | 3 ++-
> > > src/apps/cam/capture_script.cpp | 2 +-
> > > src/apps/cam/capture_script.h | 3 ++-
> > > src/apps/cam/drm.cpp | 8 ++++----
> > > src/apps/cam/drm.h | 9 +++++----
> > > src/ipa/libipa/camera_sensor_helper.cpp | 2 +-
> > > src/ipa/libipa/camera_sensor_helper.h | 3 ++-
> > > src/ipa/libipa/module.cpp | 2 +-
> > > src/ipa/libipa/module.h | 4 ++--
> > > src/libcamera/base/utils.cpp | 8 ++++----
> > > src/libcamera/camera_manager.cpp | 2 +-
> > > src/libcamera/device_enumerator.cpp | 2 +-
> > > src/libcamera/device_enumerator_udev.cpp | 2 +-
> > > src/libcamera/formats.cpp | 2 +-
> > > src/libcamera/media_device.cpp | 14 +++++++-------
> > > src/libcamera/pipeline_handler.cpp | 2 +-
> > > src/libcamera/pixel_format.cpp | 2 +-
> > > src/libcamera/sensor/camera_sensor_properties.cpp | 4 ++--
> > > src/libcamera/v4l2_subdevice.cpp | 2 +-
> > > src/libcamera/v4l2_videodevice.cpp | 2 +-
> > > src/py/libcamera/py_camera_manager.h | 2 +-
> > > src/py/libcamera/py_main.cpp | 2 +-
> > > 31 files changed, 66 insertions(+), 55 deletions(-)
> > >
> > > diff --git a/include/libcamera/base/utils.h b/include/libcamera/base/utils.h
> > > index 780aeda6a..3b8b3dea9 100644
> > > --- a/include/libcamera/base/utils.h
> > > +++ b/include/libcamera/base/utils.h
> > > @@ -38,7 +38,7 @@ namespace utils {
> > > const char *basename(const char *path);
> > >
> > > char *secure_getenv(const char *name);
> > > -std::string dirname(const std::string &path);
> > > +std::string dirname(std::string_view path);
> > >
> > > template<typename T>
> > > std::vector<typename T::key_type> map_keys(const T &map)
> > > @@ -143,7 +143,7 @@ size_t strlcpy(char *dst, const char *src, size_t size);
> > >
> > > #ifndef __DOXYGEN__
> > > template<typename Container, typename UnaryOp>
> > > -std::string join(const Container &items, const std::string &sep, UnaryOp op)
> > > +std::string join(const Container &items, std::string_view sep, UnaryOp op)
> > > {
> > > std::ostringstream ss;
> > > bool first = true;
> > > @@ -162,7 +162,7 @@ std::string join(const Container &items, const std::string &sep, UnaryOp op)
> > > }
> > >
> > > template<typename Container>
> > > -std::string join(const Container &items, const std::string &sep)
> > > +std::string join(const Container &items, std::string_view sep)
> > > {
> > > std::ostringstream ss;
> > > bool first = true;
> > > @@ -181,7 +181,7 @@ std::string join(const Container &items, const std::string &sep)
> > > }
> > > #else
> > > template<typename Container, typename UnaryOp>
> > > -std::string join(const Container &items, const std::string &sep, UnaryOp op = nullptr);
> > > +std::string join(const Container &items, std::string_view sep, UnaryOp op = nullptr);
> > > #endif
> > >
> > > namespace details {
> > > @@ -240,7 +240,7 @@ private:
> > >
> > > details::StringSplitter split(const std::string &str, const std::string &delim);
> > >
> > > -std::string toAscii(const std::string &str);
> > > +std::string toAscii(std::string_view str);
> > >
> > > std::string libcameraBuildPath();
> > > std::string libcameraSourcePath();
> > > diff --git a/include/libcamera/camera_manager.h b/include/libcamera/camera_manager.h
> > > index b50df7825..27835500f 100644
> > > --- a/include/libcamera/camera_manager.h
> > > +++ b/include/libcamera/camera_manager.h
> > > @@ -9,6 +9,7 @@
> > >
> > > #include <memory>
> > > #include <string>
> > > +#include <string_view>
> > > #include <sys/types.h>
> > > #include <vector>
> > >
> > > @@ -31,7 +32,7 @@ public:
> > > void stop();
> > >
> > > std::vector<std::shared_ptr<Camera>> cameras() const;
> > > - std::shared_ptr<Camera> get(const std::string &id);
> > > + std::shared_ptr<Camera> get(std::string_view id);
> > >
> > > static const std::string &version() { return version_; }
> > >
> > > diff --git a/include/libcamera/internal/camera_sensor_properties.h b/include/libcamera/internal/camera_sensor_properties.h
> > > index d7d4dab62..b44093906 100644
> > > --- a/include/libcamera/internal/camera_sensor_properties.h
> > > +++ b/include/libcamera/internal/camera_sensor_properties.h
> > > @@ -9,7 +9,7 @@
> > >
> > > #include <map>
> > > #include <stdint.h>
> > > -#include <string>
> > > +#include <string_view>
> > >
> > > #include <libcamera/control_ids.h>
> > > #include <libcamera/geometry.h>
> > > @@ -24,7 +24,7 @@ struct CameraSensorProperties {
> > > uint8_t hblankDelay;
> > > };
> > >
> > > - static const CameraSensorProperties *get(const std::string &sensor);
> > > + static const CameraSensorProperties *get(std::string_view sensor);
> > >
> > > Size unitCellSize;
> > > std::map<controls::draft::TestPatternModeEnum, int32_t> testPatternModes;
> > > diff --git a/include/libcamera/internal/device_enumerator.h b/include/libcamera/internal/device_enumerator.h
> > > index db3532a98..eecc39cfb 100644
> > > --- a/include/libcamera/internal/device_enumerator.h
> > > +++ b/include/libcamera/internal/device_enumerator.h
> > > @@ -9,6 +9,7 @@
> > >
> > > #include <memory>
> > > #include <string>
> > > +#include <string_view>
> > > #include <vector>
> > >
> > > #include <libcamera/base/signal.h>
> > > @@ -48,7 +49,7 @@ public:
> > > protected:
> > > std::unique_ptr<MediaDevice> createDevice(const std::string &deviceNode);
> > > void addDevice(std::unique_ptr<MediaDevice> media);
> > > - void removeDevice(const std::string &deviceNode);
> > > + void removeDevice(std::string_view deviceNode);
> > >
> > > private:
> > > std::vector<std::shared_ptr<MediaDevice>> devices_;
> > > diff --git a/include/libcamera/internal/formats.h b/include/libcamera/internal/formats.h
> > > index 6a3e9c16a..bd7ac6ed1 100644
> > > --- a/include/libcamera/internal/formats.h
> > > +++ b/include/libcamera/internal/formats.h
> > > @@ -8,6 +8,7 @@
> > > #pragma once
> > >
> > > #include <array>
> > > +#include <string_view>
> > > #include <vector>
> > >
> > > #include <libcamera/geometry.h>
> > > @@ -35,7 +36,7 @@ public:
> > >
> > > static const PixelFormatInfo &info(const PixelFormat &format);
> > > static const PixelFormatInfo &info(const V4L2PixelFormat &format);
> > > - static const PixelFormatInfo &info(const std::string &name);
> > > + static const PixelFormatInfo &info(std::string_view name);
> > >
> > > unsigned int stride(unsigned int width, unsigned int plane,
> > > unsigned int align = 1) const;
> > > diff --git a/include/libcamera/internal/media_device.h b/include/libcamera/internal/media_device.h
> > > index e412d3a0b..91610a7aa 100644
> > > --- a/include/libcamera/internal/media_device.h
> > > +++ b/include/libcamera/internal/media_device.h
> > > @@ -9,6 +9,7 @@
> > >
> > > #include <map>
> > > #include <string>
> > > +#include <string_view>
> > > #include <vector>
> > >
> > > #include <linux/media.h>
> > > @@ -44,10 +45,10 @@ public:
> > > unsigned int hwRevision() const { return hwRevision_; }
> > >
> > > const std::vector<MediaEntity *> &entities() const { return entities_; }
> > > - MediaEntity *getEntityByName(const std::string &name) const;
> > > + MediaEntity *getEntityByName(std::string_view name) const;
> > >
> > > - MediaLink *link(const std::string &sourceName, unsigned int sourceIdx,
> > > - const std::string &sinkName, unsigned int sinkIdx);
> > > + MediaLink *link(std::string_view sourceName, unsigned int sourceIdx,
> > > + std::string_view sinkName, unsigned int sinkIdx);
> > > MediaLink *link(const MediaEntity *source, unsigned int sourceIdx,
> > > const MediaEntity *sink, unsigned int sinkIdx);
> > > MediaLink *link(const MediaPad *source, const MediaPad *sink);
> > > diff --git a/include/libcamera/internal/pipeline_handler.h b/include/libcamera/internal/pipeline_handler.h
> > > index fb28a18d0..45eafce9b 100644
> > > --- a/include/libcamera/internal/pipeline_handler.h
> > > +++ b/include/libcamera/internal/pipeline_handler.h
> > > @@ -10,6 +10,7 @@
> > > #include <memory>
> > > #include <queue>
> > > #include <string>
> > > +#include <string_view>
> > > #include <sys/types.h>
> > > #include <vector>
> > >
> > > @@ -112,7 +113,7 @@ public:
> > > const std::string &name() const { return name_; }
> > >
> > > static std::vector<PipelineHandlerFactoryBase *> &factories();
> > > - static const PipelineHandlerFactoryBase *getFactoryByName(const std::string &name);
> > > + static const PipelineHandlerFactoryBase *getFactoryByName(std::string_view name);
> > >
> > > private:
> > > static void registerType(PipelineHandlerFactoryBase *factory);
> > > diff --git a/include/libcamera/internal/v4l2_subdevice.h b/include/libcamera/internal/v4l2_subdevice.h
> > > index 194382f84..d17365e14 100644
> > > --- a/include/libcamera/internal/v4l2_subdevice.h
> > > +++ b/include/libcamera/internal/v4l2_subdevice.h
> > > @@ -11,6 +11,7 @@
> > > #include <optional>
> > > #include <ostream>
> > > #include <string>
> > > +#include <string_view>
> > > #include <vector>
> > >
> > > #include <linux/v4l2-subdev.h>
> > > @@ -161,7 +162,7 @@ public:
> > > const V4L2SubdeviceCapability &caps() const { return caps_; }
> > >
> > > static std::unique_ptr<V4L2Subdevice>
> > > - fromEntityName(const MediaDevice *media, const std::string &entity);
> > > + fromEntityName(const MediaDevice *media, std::string_view entity);
> > >
> > > protected:
> > > std::string logPrefix() const override;
> > > diff --git a/include/libcamera/internal/v4l2_videodevice.h b/include/libcamera/internal/v4l2_videodevice.h
> > > index f021c2a01..c256e82af 100644
> > > --- a/include/libcamera/internal/v4l2_videodevice.h
> > > +++ b/include/libcamera/internal/v4l2_videodevice.h
> > > @@ -14,6 +14,7 @@
> > > #include <ostream>
> > > #include <stdint.h>
> > > #include <string>
> > > +#include <string_view>
> > > #include <unordered_set>
> > > #include <vector>
> > >
> > > @@ -228,7 +229,7 @@ public:
> > > Signal<> dequeueTimeout;
> > >
> > > static std::unique_ptr<V4L2VideoDevice>
> > > - fromEntityName(const MediaDevice *media, const std::string &entity);
> > > + fromEntityName(const MediaDevice *media, std::string_view entity);
> > >
> > > V4L2PixelFormat toV4L2PixelFormat(const PixelFormat &pixelFormat) const;
> > >
> > > diff --git a/include/libcamera/pixel_format.h b/include/libcamera/pixel_format.h
> > > index 1b4d8c7c8..874b2528b 100644
> > > --- a/include/libcamera/pixel_format.h
> > > +++ b/include/libcamera/pixel_format.h
> > > @@ -10,6 +10,7 @@
> > > #include <ostream>
> > > #include <stdint.h>
> > > #include <string>
> > > +#include <string_view>
> > >
> > > namespace libcamera {
> > >
> > > @@ -38,7 +39,7 @@ public:
> > >
> > > std::string toString() const;
> > >
> > > - static PixelFormat fromString(const std::string &name);
> > > + static PixelFormat fromString(std::string_view name);
> > >
> > > private:
> > > uint32_t fourcc_;
> > > diff --git a/src/apps/cam/capture_script.cpp b/src/apps/cam/capture_script.cpp
> > > index fc1dfa75f..d4760ea78 100644
> > > --- a/src/apps/cam/capture_script.cpp
> > > +++ b/src/apps/cam/capture_script.cpp
> > > @@ -432,7 +432,7 @@ std::vector<std::string> CaptureScript::parseSingleArray()
> > > }
> > > }
> > >
> > > -void CaptureScript::unpackFailure(const ControlId *id, const std::string &repr)
> > > +void CaptureScript::unpackFailure(const ControlId *id, std::string_view repr)
> > > {
> > > static const std::map<unsigned int, const char *> typeNames = {
> > > { ControlTypeNone, "none" },
> > > diff --git a/src/apps/cam/capture_script.h b/src/apps/cam/capture_script.h
> > > index 294b92036..fb40371f2 100644
> > > --- a/src/apps/cam/capture_script.h
> > > +++ b/src/apps/cam/capture_script.h
> > > @@ -10,6 +10,7 @@
> > > #include <map>
> > > #include <memory>
> > > #include <string>
> > > +#include <string_view>
> > >
> > > #include <libcamera/camera.h>
> > > #include <libcamera/controls.h>
> > > @@ -67,7 +68,7 @@ private:
> > > std::vector<std::string> parseSingleArray();
> > >
> > > void unpackFailure(const libcamera::ControlId *id,
> > > - const std::string &repr);
> > > + std::string_view repr);
> > > libcamera::ControlValue unpackControl(const libcamera::ControlId *id);
> > > libcamera::Rectangle unpackRectangle(const std::vector<std::string> &strVec);
> > > };
> > > diff --git a/src/apps/cam/drm.cpp b/src/apps/cam/drm.cpp
> > > index 47bbb6b05..fd9c59ec4 100644
> > > --- a/src/apps/cam/drm.cpp
> > > +++ b/src/apps/cam/drm.cpp
> > > @@ -57,7 +57,7 @@ Object::~Object()
> > > {
> > > }
> > >
> > > -const Property *Object::property(const std::string &name) const
> > > +const Property *Object::property(std::string_view name) const
> > > {
> > > for (const PropertyValue &pv : properties_) {
> > > const Property *property = static_cast<const Property *>(dev_->object(pv.id()));
> > > @@ -68,7 +68,7 @@ const Property *Object::property(const std::string &name) const
> > > return nullptr;
> > > }
> > >
> > > -const PropertyValue *Object::propertyValue(const std::string &name) const
> > > +const PropertyValue *Object::propertyValue(std::string_view name) const
> > > {
> > > for (const PropertyValue &pv : properties_) {
> > > const Property *property = static_cast<const Property *>(dev_->object(pv.id()));
> > > @@ -320,7 +320,7 @@ AtomicRequest::~AtomicRequest()
> > > drmModeAtomicFree(request_);
> > > }
> > >
> > > -int AtomicRequest::addProperty(const Object *object, const std::string &property,
> > > +int AtomicRequest::addProperty(const Object *object, std::string_view property,
> > > uint64_t value)
> > > {
> > > if (!valid_)
> > > @@ -335,7 +335,7 @@ int AtomicRequest::addProperty(const Object *object, const std::string &property
> > > return addProperty(object->id(), prop->id(), value);
> > > }
> > >
> > > -int AtomicRequest::addProperty(const Object *object, const std::string &property,
> > > +int AtomicRequest::addProperty(const Object *object, std::string_view property,
> > > std::unique_ptr<Blob> blob)
> > > {
> > > if (!valid_)
> > > diff --git a/src/apps/cam/drm.h b/src/apps/cam/drm.h
> > > index 1ba83b6eb..aa1b06400 100644
> > > --- a/src/apps/cam/drm.h
> > > +++ b/src/apps/cam/drm.h
> > > @@ -13,6 +13,7 @@
> > > #include <memory>
> > > #include <stdint.h>
> > > #include <string>
> > > +#include <string_view>
> > > #include <vector>
> > >
> > > #include <libcamera/base/signal.h>
> > > @@ -57,8 +58,8 @@ public:
> > > uint32_t id() const { return id_; }
> > > Type type() const { return type_; }
> > >
> > > - const Property *property(const std::string &name) const;
> > > - const PropertyValue *propertyValue(const std::string &name) const;
> > > + const Property *property(std::string_view name) const;
> > > + const PropertyValue *propertyValue(std::string_view name) const;
> > > const std::vector<PropertyValue> &properties() const { return properties_; }
> > >
> > > protected:
> > > @@ -260,9 +261,9 @@ public:
> > > Device *device() const { return dev_; }
> > > bool isValid() const { return valid_; }
> > >
> > > - int addProperty(const Object *object, const std::string &property,
> > > + int addProperty(const Object *object, std::string_view property,
> > > uint64_t value);
> > > - int addProperty(const Object *object, const std::string &property,
> > > + int addProperty(const Object *object, std::string_view property,
> > > std::unique_ptr<Blob> blob);
> > > int commit(unsigned int flags = 0);
> > >
> > > diff --git a/src/ipa/libipa/camera_sensor_helper.cpp b/src/ipa/libipa/camera_sensor_helper.cpp
> > > index 7c66cd57d..4ed050b14 100644
> > > --- a/src/ipa/libipa/camera_sensor_helper.cpp
> > > +++ b/src/ipa/libipa/camera_sensor_helper.cpp
> > > @@ -240,7 +240,7 @@ CameraSensorHelperFactoryBase::CameraSensorHelperFactoryBase(const std::string n
> > > * corresponding to the named factory or a null pointer if no such factory
> > > * exists
> > > */
> > > -std::unique_ptr<CameraSensorHelper> CameraSensorHelperFactoryBase::create(const std::string &name)
> > > +std::unique_ptr<CameraSensorHelper> CameraSensorHelperFactoryBase::create(std::string_view name)
> > > {
> > > const std::vector<CameraSensorHelperFactoryBase *> &factories =
> > > CameraSensorHelperFactoryBase::factories();
> > > diff --git a/src/ipa/libipa/camera_sensor_helper.h b/src/ipa/libipa/camera_sensor_helper.h
> > > index a9300a64f..eedc80114 100644
> > > --- a/src/ipa/libipa/camera_sensor_helper.h
> > > +++ b/src/ipa/libipa/camera_sensor_helper.h
> > > @@ -11,6 +11,7 @@
> > > #include <optional>
> > > #include <stdint.h>
> > > #include <string>
> > > +#include <string_view>
> > > #include <variant>
> > > #include <vector>
> > >
> > > @@ -56,7 +57,7 @@ public:
> > > CameraSensorHelperFactoryBase(const std::string name);
> > > virtual ~CameraSensorHelperFactoryBase() = default;
> > >
> > > - static std::unique_ptr<CameraSensorHelper> create(const std::string &name);
> > > + static std::unique_ptr<CameraSensorHelper> create(std::string_view name);
> > >
> > > static std::vector<CameraSensorHelperFactoryBase *> &factories();
> > >
> > > diff --git a/src/ipa/libipa/module.cpp b/src/ipa/libipa/module.cpp
> > > index 64ca91419..91fb588e7 100644
> > > --- a/src/ipa/libipa/module.cpp
> > > +++ b/src/ipa/libipa/module.cpp
> > > @@ -107,7 +107,7 @@ namespace ipa {
> > > */
> > >
> > > /**
> > > - * \fn Module::createAlgorithm(const std::string &name)
> > > + * \fn Module::createAlgorithm(std::string_view name)
> > > * \brief Create an instance of an Algorithm by name
> > > * \param[in] name The algorithm name
> > > *
> > > diff --git a/src/ipa/libipa/module.h b/src/ipa/libipa/module.h
> > > index 0fb51916f..62c700a64 100644
> > > --- a/src/ipa/libipa/module.h
> > > +++ b/src/ipa/libipa/module.h
> > > @@ -9,7 +9,7 @@
> > >
> > > #include <list>
> > > #include <memory>
> > > -#include <string>
> > > +#include <string_view>
> > > #include <vector>
> > >
> > > #include <libcamera/base/log.h>
> > > @@ -95,7 +95,7 @@ private:
> > > return 0;
> > > }
> > >
> > > - static std::unique_ptr<Algorithm<Module>> createAlgorithm(const std::string &name)
> > > + static std::unique_ptr<Algorithm<Module>> createAlgorithm(std::string_view name)
> > > {
> > > for (const AlgorithmFactoryBase<Module> *factory : factories()) {
> > > if (factory->name() == name)
> > > diff --git a/src/libcamera/base/utils.cpp b/src/libcamera/base/utils.cpp
> > > index bcfc1941a..de6e2afd6 100644
> > > --- a/src/libcamera/base/utils.cpp
> > > +++ b/src/libcamera/base/utils.cpp
> > > @@ -80,7 +80,7 @@ char *secure_getenv(const char *name)
> > > *
> > > * \return A string of the directory component of the path
> > > */
> > > -std::string dirname(const std::string &path)
> > > +std::string dirname(std::string_view path)
> > > {
> > > if (path.empty())
> > > return ".";
> > > @@ -116,7 +116,7 @@ std::string dirname(const std::string &path)
> > > pos--;
> > > }
> > >
> > > - return path.substr(0, pos + 1);
> > > + return std::string(path.substr(0, pos + 1));
> > > }
> > >
> > > /**
> > > @@ -278,7 +278,7 @@ std::string details::StringSplitter::iterator::operator*() const
> > >
> > > /**
> > > * \fn template<typename Container, typename UnaryOp> \
> > > - * std::string utils::join(const Container &items, const std::string &sep, UnaryOp op)
> > > + * std::string utils::join(const Container &items, std::string_view sep, UnaryOp op)
> > > * \brief Join elements of a container in a string with a separator
> > > * \param[in] items The container
> > > * \param[in] sep The separator to add between elements
> > > @@ -319,7 +319,7 @@ details::StringSplitter split(const std::string &str, const std::string &delim)
> > > *
> > > * \return A string equal to \a str stripped out of all non-ASCII characters
> > > */
> > > -std::string toAscii(const std::string &str)
> > > +std::string toAscii(std::string_view str)
> > > {
> > > std::string ret;
> > > for (const char &c : str)
> > > diff --git a/src/libcamera/camera_manager.cpp b/src/libcamera/camera_manager.cpp
> > > index 87e6717ec..179fa37ea 100644
> > > --- a/src/libcamera/camera_manager.cpp
> > > +++ b/src/libcamera/camera_manager.cpp
> > > @@ -382,7 +382,7 @@ std::vector<std::shared_ptr<Camera>> CameraManager::cameras() const
> > > *
> > > * \return Shared pointer to Camera object or nullptr if camera not found
> > > */
> > > -std::shared_ptr<Camera> CameraManager::get(const std::string &id)
> > > +std::shared_ptr<Camera> CameraManager::get(std::string_view id)
> > > {
> > > Private *const d = _d();
> > >
> > > diff --git a/src/libcamera/device_enumerator.cpp b/src/libcamera/device_enumerator.cpp
> > > index ae17862f6..8744a90f3 100644
> > > --- a/src/libcamera/device_enumerator.cpp
> > > +++ b/src/libcamera/device_enumerator.cpp
> > > @@ -272,7 +272,7 @@ void DeviceEnumerator::addDevice(std::unique_ptr<MediaDevice> media)
> > > * enumerator with addDevice(). The media device's MediaDevice::disconnected
> > > * signal is emitted.
> > > */
> > > -void DeviceEnumerator::removeDevice(const std::string &deviceNode)
> > > +void DeviceEnumerator::removeDevice(std::string_view deviceNode)
> > > {
> > > std::shared_ptr<MediaDevice> media;
> > >
> > > diff --git a/src/libcamera/device_enumerator_udev.cpp b/src/libcamera/device_enumerator_udev.cpp
> > > index 4e20a3cc0..c330f30bc 100644
> > > --- a/src/libcamera/device_enumerator_udev.cpp
> > > +++ b/src/libcamera/device_enumerator_udev.cpp
> > > @@ -351,7 +351,7 @@ void DeviceEnumeratorUdev::udevNotify()
> > > } else if (action == "remove") {
> > > const char *subsystem = udev_device_get_subsystem(dev);
> > > if (subsystem && !strcmp(subsystem, "media"))
> > > - removeDevice(std::string(deviceNode));
> > > + removeDevice(deviceNode);
> > > }
> > >
> > > udev_device_unref(dev);
> > > diff --git a/src/libcamera/formats.cpp b/src/libcamera/formats.cpp
> > > index bfcdfc089..112dfe66b 100644
> > > --- a/src/libcamera/formats.cpp
> > > +++ b/src/libcamera/formats.cpp
> > > @@ -1037,7 +1037,7 @@ const PixelFormatInfo &PixelFormatInfo::info(const V4L2PixelFormat &format)
> > > * \return The PixelFormatInfo describing the PixelFormat matching the
> > > * \a name if known, or an invalid PixelFormatInfo otherwise
> > > */
> > > -const PixelFormatInfo &PixelFormatInfo::info(const std::string &name)
> > > +const PixelFormatInfo &PixelFormatInfo::info(std::string_view name)
> > > {
> > > for (const auto &info : pixelFormatInfo) {
> > > if (info.second.name == name)
> > > diff --git a/src/libcamera/media_device.cpp b/src/libcamera/media_device.cpp
> > > index d71dad74d..131b34446 100644
> > > --- a/src/libcamera/media_device.cpp
> > > +++ b/src/libcamera/media_device.cpp
> > > @@ -331,7 +331,7 @@ done:
> > > * \param[in] name The entity name
> > > * \return The entity with \a name, or nullptr if no such entity is found
> > > */
> > > -MediaEntity *MediaDevice::getEntityByName(const std::string &name) const
> > > +MediaEntity *MediaDevice::getEntityByName(std::string_view name) const
> > > {
> > > for (MediaEntity *e : entities_)
> > > if (e->name() == name)
> > > @@ -359,8 +359,8 @@ MediaEntity *MediaDevice::getEntityByName(const std::string &name) const
> > > * \return The link that connects the two pads, or nullptr if no such a link
> > > * exists
> > > */
> > > -MediaLink *MediaDevice::link(const std::string &sourceName, unsigned int sourceIdx,
> > > - const std::string &sinkName, unsigned int sinkIdx)
> > > +MediaLink *MediaDevice::link(std::string_view sourceName, unsigned int sourceIdx,
> > > + std::string_view sinkName, unsigned int sinkIdx)
> > > {
> > > const MediaEntity *source = getEntityByName(sourceName);
> > > const MediaEntity *sink = getEntityByName(sinkName);
> > > @@ -382,8 +382,8 @@ MediaLink *MediaDevice::link(const std::string &sourceName, unsigned int sourceI
> > > * entity \a source, to the pad at index \a sinkIdx of the sink entity \a
> > > * sink, if any.
> > > *
> > > - * \sa link(const std::string &sourceName, unsigned int sourceIdx,
> > > - * const std::string &sinkName, unsigned int sinkIdx)
> > > + * \sa link(std::string_view sourceName, unsigned int sourceIdx,
> > > + * std::string_view sinkName, unsigned int sinkIdx)
> > > * \sa link(const MediaPad *source, const MediaPad *sink)
> > > *
> > > * \return The link that connects the two pads, or nullptr if no such a link
> > > @@ -406,8 +406,8 @@ MediaLink *MediaDevice::link(const MediaEntity *source, unsigned int sourceIdx,
> > > * \param[in] source The source pad
> > > * \param[in] sink The sink pad
> > > *
> > > - * \sa link(const std::string &sourceName, unsigned int sourceIdx,
> > > - * const std::string &sinkName, unsigned int sinkIdx)
> > > + * \sa link(std::string_view sourceName, unsigned int sourceIdx,
> > > + * std::string_view sinkName, unsigned int sinkIdx)
> > > * \sa link(const MediaEntity *source, unsigned int sourceIdx,
> > > * const MediaEntity *sink, unsigned int sinkIdx)
> > > *
> > > diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
> > > index caa5c20e7..6b395c666 100644
> > > --- a/src/libcamera/pipeline_handler.cpp
> > > +++ b/src/libcamera/pipeline_handler.cpp
> > > @@ -852,7 +852,7 @@ std::vector<PipelineHandlerFactoryBase *> &PipelineHandlerFactoryBase::factories
> > > * \param[in] name The pipeline handler name
> > > * \return The factory of the pipeline with name \a name, or nullptr if not found
> > > */
> > > -const PipelineHandlerFactoryBase *PipelineHandlerFactoryBase::getFactoryByName(const std::string &name)
> > > +const PipelineHandlerFactoryBase *PipelineHandlerFactoryBase::getFactoryByName(std::string_view name)
> > > {
> > > const std::vector<PipelineHandlerFactoryBase *> &factories =
> > > PipelineHandlerFactoryBase::factories();
> > > diff --git a/src/libcamera/pixel_format.cpp b/src/libcamera/pixel_format.cpp
> > > index 314179a81..22f1520fd 100644
> > > --- a/src/libcamera/pixel_format.cpp
> > > +++ b/src/libcamera/pixel_format.cpp
> > > @@ -135,7 +135,7 @@ std::string PixelFormat::toString() const
> > > * \return The PixelFormat represented by the \a name if known, or an
> > > * invalid pixel format otherwise.
> > > */
> > > -PixelFormat PixelFormat::fromString(const std::string &name)
> > > +PixelFormat PixelFormat::fromString(std::string_view name)
> > > {
> > > return PixelFormatInfo::info(name).format;
> > > }
> > > diff --git a/src/libcamera/sensor/camera_sensor_properties.cpp b/src/libcamera/sensor/camera_sensor_properties.cpp
> > > index 2b06c5a1a..4283cacfa 100644
> > > --- a/src/libcamera/sensor/camera_sensor_properties.cpp
> > > +++ b/src/libcamera/sensor/camera_sensor_properties.cpp
> > > @@ -78,9 +78,9 @@ LOG_DEFINE_CATEGORY(CameraSensorProperties)
> > > * \return A pointer to the CameraSensorProperties instance associated with a sensor
> > > * or nullptr if the sensor is not supported
> > > */
> > > -const CameraSensorProperties *CameraSensorProperties::get(const std::string &sensor)
> > > +const CameraSensorProperties *CameraSensorProperties::get(std::string_view sensor)
> > > {
> > > - static const std::map<std::string, const CameraSensorProperties> sensorProps = {
> > > + static const std::map<std::string_view, const CameraSensorProperties> sensorProps = {
> > > { "ar0144", {
> > > .unitCellSize = { 3000, 3000 },
> > > .testPatternModes = {
> > > diff --git a/src/libcamera/v4l2_subdevice.cpp b/src/libcamera/v4l2_subdevice.cpp
> > > index 3a0d075f9..7e85b33be 100644
> > > --- a/src/libcamera/v4l2_subdevice.cpp
> > > +++ b/src/libcamera/v4l2_subdevice.cpp
> > > @@ -1688,7 +1688,7 @@ const std::string &V4L2Subdevice::model()
> > > */
> > > std::unique_ptr<V4L2Subdevice>
> > > V4L2Subdevice::fromEntityName(const MediaDevice *media,
> > > - const std::string &entity)
> > > + std::string_view entity)
> > > {
> > > MediaEntity *mediaEntity = media->getEntityByName(entity);
> > > if (!mediaEntity)
> > > diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp
> > > index a5cf67845..834a1bd0d 100644
> > > --- a/src/libcamera/v4l2_videodevice.cpp
> > > +++ b/src/libcamera/v4l2_videodevice.cpp
> > > @@ -2077,7 +2077,7 @@ void V4L2VideoDevice::watchdogExpired()
> > > */
> > > std::unique_ptr<V4L2VideoDevice>
> > > V4L2VideoDevice::fromEntityName(const MediaDevice *media,
> > > - const std::string &entity)
> > > + std::string_view entity)
> > > {
> > > MediaEntity *mediaEntity = media->getEntityByName(entity);
> > > if (!mediaEntity)
> > > diff --git a/src/py/libcamera/py_camera_manager.h b/src/py/libcamera/py_camera_manager.h
> > > index 3574db236..af69b915e 100644
> > > --- a/src/py/libcamera/py_camera_manager.h
> > > +++ b/src/py/libcamera/py_camera_manager.h
> > > @@ -20,7 +20,7 @@ public:
> > > ~PyCameraManager();
> > >
> > > pybind11::list cameras();
> > > - std::shared_ptr<Camera> get(const std::string &name) { return cameraManager_->get(name); }
> > > + std::shared_ptr<Camera> get(std::string_view name) { return cameraManager_->get(name); }
> > >
> > > static const std::string &version() { return CameraManager::version(); }
> > >
> > > diff --git a/src/py/libcamera/py_main.cpp b/src/py/libcamera/py_main.cpp
> > > index 441a70ab4..820768c24 100644
> > > --- a/src/py/libcamera/py_main.cpp
> > > +++ b/src/py/libcamera/py_main.cpp
> > > @@ -510,7 +510,7 @@ PYBIND11_MODULE(_libcamera, m)
> > > pyPixelFormat
> > > .def(py::init<>())
> > > .def(py::init<uint32_t, uint64_t>())
> > > - .def(py::init<>([](const std::string &str) {
> > > + .def(py::init<>([](std::string_view str) {
> > > return PixelFormat::fromString(str);
> > > }))
> > > .def_property_readonly("fourcc", &PixelFormat::fourcc)
--
Regards,
Laurent Pinchart
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