[libcamera-devel] [PATCH v7 01/14] libcamera: yaml_parser: Replace ok flag to get() with std::optional
Naushir Patuck
naush at raspberrypi.com
Wed Jul 27 11:34:50 CEST 2022
Hi Laurent,
Thank you for your patch.
On Wed, 27 Jul 2022 at 03:38, Laurent Pinchart <
laurent.pinchart at ideasonboard.com> wrote:
> The YamlObject::get() function takes a default value and an optional
> bool ok flag to handle parsing errors. This ad-hoc mechanism complicates
> error handling in callers.
>
> A better API is possible by dropping the default value and ok flag and
> returning an std::optional. Not only does it simplify the calls, it also
> lets callers handle errors through the standard std::optional class
> instead of the current ad-hoc mechanism.
>
> Provide a convenience get() wrapper around std::optional::value_or() to
> further simplify callers that don't need any specific error handling.
>
s/convenience/convenient/ ?
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
>
This is much cleaner for error handling!
Reviewed-by: Naushir Patuck <naush at raspberrypi.com>
> ---
> include/libcamera/internal/yaml_parser.h | 9 +-
> src/libcamera/yaml_parser.cpp | 138 +++++++++--------------
> test/yaml-parser.cpp | 71 ++++++------
> 3 files changed, 96 insertions(+), 122 deletions(-)
>
> diff --git a/include/libcamera/internal/yaml_parser.h
> b/include/libcamera/internal/yaml_parser.h
> index 064cf44381d7..61f2223223a7 100644
> --- a/include/libcamera/internal/yaml_parser.h
> +++ b/include/libcamera/internal/yaml_parser.h
> @@ -9,6 +9,7 @@
>
> #include <iterator>
> #include <map>
> +#include <optional>
> #include <string>
> #include <vector>
>
> @@ -165,7 +166,13 @@ public:
> #else
> template<typename T>
> #endif
> - T get(const T &defaultValue, bool *ok = nullptr) const;
> + std::optional<T> get() const;
> +
> + template<typename T>
> + T get(const T &defaultValue) const
> + {
> + return get<T>().value_or(defaultValue);
> + }
>
> DictAdapter asDict() const { return DictAdapter{ dictionary_ }; }
> ListAdapter asList() const { return ListAdapter{ list_ }; }
> diff --git a/src/libcamera/yaml_parser.cpp b/src/libcamera/yaml_parser.cpp
> index 5c45e44e49c3..4299f5abd38a 100644
> --- a/src/libcamera/yaml_parser.cpp
> +++ b/src/libcamera/yaml_parser.cpp
> @@ -31,12 +31,6 @@ namespace {
> /* Empty static YamlObject as a safe result for invalid operations */
> static const YamlObject empty;
>
> -void setOk(bool *ok, bool result)
> -{
> - if (ok)
> - *ok = result;
> -}
> -
> } /* namespace */
>
> /**
> @@ -100,54 +94,52 @@ std::size_t YamlObject::size() const
> }
>
> /**
> - * \fn template<typename T> YamlObject::get<T>(
> - * const T &defaultValue, bool *ok) const
> + * \fn template<typename T> YamlObject::get<T>() const
> + * \brief Parse the YamlObject as a \a T value
> + *
> + * This function parses the value of the YamlObject as a \a T object, and
> + * returns the value. If parsing fails (usually because the YamlObject
> doesn't
> + * store a \a T value), std::nullopt is returned.
> + *
> + * \return The YamlObject value, or std::nullopt if parsing failed
> + */
> +
> +/**
> + * \fn template<typename T> YamlObject::get<T>(const T &defaultValue)
> const
> * \brief Parse the YamlObject as a \a T value
> * \param[in] defaultValue The default value when failing to parse
> - * \param[out] ok The result of whether the parse succeeded
> *
> * This function parses the value of the YamlObject as a \a T object, and
> * returns the value. If parsing fails (usually because the YamlObject
> doesn't
> - * store a \a T value), the \a defaultValue is returned, and \a ok is set
> to
> - * false. Otherwise, the YamlObject value is returned, and \a ok is set
> to true.
> + * store a \a T value), the \a defaultValue is returned.
> *
> - * The \a ok pointer is optional and can be a nullptr if the caller
> doesn't
> - * need to know if parsing succeeded.
> - *
> - * \return Value as a bool type
> + * \return The YamlObject value, or \a defaultValue if parsing failed
> */
>
> #ifndef __DOXYGEN__
>
> template<>
> -bool YamlObject::get(const bool &defaultValue, bool *ok) const
> +std::optional<bool> YamlObject::get() const
> {
> - setOk(ok, false);
> -
> if (type_ != Type::Value)
> - return defaultValue;
> + return {};
>
> - if (value_ == "true") {
> - setOk(ok, true);
> + if (value_ == "true")
> return true;
> - } else if (value_ == "false") {
> - setOk(ok, true);
> + else if (value_ == "false")
> return false;
> - }
>
> - return defaultValue;
> + return {};
> }
>
> template<>
> -int16_t YamlObject::get(const int16_t &defaultValue, bool *ok) const
> +std::optional<int16_t> YamlObject::get() const
> {
> - setOk(ok, false);
> -
> if (type_ != Type::Value)
> - return defaultValue;
> + return {};
>
> if (value_ == "")
> - return defaultValue;
> + return {};
>
> char *end;
>
> @@ -157,22 +149,19 @@ int16_t YamlObject::get(const int16_t &defaultValue,
> bool *ok) const
> if ('\0' != *end || errno == ERANGE ||
> value < std::numeric_limits<int16_t>::min() ||
> value > std::numeric_limits<int16_t>::max())
> - return defaultValue;
> + return {};
>
> - setOk(ok, true);
> return value;
> }
>
> template<>
> -uint16_t YamlObject::get(const uint16_t &defaultValue, bool *ok) const
> +std::optional<uint16_t> YamlObject::get() const
> {
> - setOk(ok, false);
> -
> if (type_ != Type::Value)
> - return defaultValue;
> + return {};
>
> if (value_ == "")
> - return defaultValue;
> + return {};
>
> /*
> * libyaml parses all scalar values as strings. When a string has
> @@ -183,7 +172,7 @@ uint16_t YamlObject::get(const uint16_t &defaultValue,
> bool *ok) const
> */
> std::size_t found = value_.find_first_not_of(" \t");
> if (found != std::string::npos && value_[found] == '-')
> - return defaultValue;
> + return {};
>
> char *end;
>
> @@ -193,22 +182,19 @@ uint16_t YamlObject::get(const uint16_t
> &defaultValue, bool *ok) const
> if ('\0' != *end || errno == ERANGE ||
> value < std::numeric_limits<uint16_t>::min() ||
> value > std::numeric_limits<uint16_t>::max())
> - return defaultValue;
> + return {};
>
> - setOk(ok, true);
> return value;
> }
>
> template<>
> -int32_t YamlObject::get(const int32_t &defaultValue, bool *ok) const
> +std::optional<int32_t> YamlObject::get() const
> {
> - setOk(ok, false);
> -
> if (type_ != Type::Value)
> - return defaultValue;
> + return {};
>
> if (value_ == "")
> - return defaultValue;
> + return {};
>
> char *end;
>
> @@ -218,22 +204,19 @@ int32_t YamlObject::get(const int32_t &defaultValue,
> bool *ok) const
> if ('\0' != *end || errno == ERANGE ||
> value < std::numeric_limits<int32_t>::min() ||
> value > std::numeric_limits<int32_t>::max())
> - return defaultValue;
> + return {};
>
> - setOk(ok, true);
> return value;
> }
>
> template<>
> -uint32_t YamlObject::get(const uint32_t &defaultValue, bool *ok) const
> +std::optional<uint32_t> YamlObject::get() const
> {
> - setOk(ok, false);
> -
> if (type_ != Type::Value)
> - return defaultValue;
> + return {};
>
> if (value_ == "")
> - return defaultValue;
> + return {};
>
> /*
> * libyaml parses all scalar values as strings. When a string has
> @@ -244,7 +227,7 @@ uint32_t YamlObject::get(const uint32_t &defaultValue,
> bool *ok) const
> */
> std::size_t found = value_.find_first_not_of(" \t");
> if (found != std::string::npos && value_[found] == '-')
> - return defaultValue;
> + return {};
>
> char *end;
>
> @@ -254,22 +237,19 @@ uint32_t YamlObject::get(const uint32_t
> &defaultValue, bool *ok) const
> if ('\0' != *end || errno == ERANGE ||
> value < std::numeric_limits<uint32_t>::min() ||
> value > std::numeric_limits<uint32_t>::max())
> - return defaultValue;
> + return {};
>
> - setOk(ok, true);
> return value;
> }
>
> template<>
> -double YamlObject::get(const double &defaultValue, bool *ok) const
> +std::optional<double> YamlObject::get() const
> {
> - setOk(ok, false);
> -
> if (type_ != Type::Value)
> - return defaultValue;
> + return {};
>
> if (value_ == "")
> - return defaultValue;
> + return {};
>
> char *end;
>
> @@ -277,50 +257,38 @@ double YamlObject::get(const double &defaultValue,
> bool *ok) const
> double value = std::strtod(value_.c_str(), &end);
>
> if ('\0' != *end || errno == ERANGE)
> - return defaultValue;
> + return {};
>
> - setOk(ok, true);
> return value;
> }
>
> template<>
> -std::string YamlObject::get(const std::string &defaultValue, bool *ok)
> const
> +std::optional<std::string> YamlObject::get() const
> {
> - setOk(ok, false);
> -
> if (type_ != Type::Value)
> - return defaultValue;
> + return {};
>
> - setOk(ok, true);
> return value_;
> }
>
> template<>
> -Size YamlObject::get(const Size &defaultValue, bool *ok) const
> +std::optional<Size> YamlObject::get() const
> {
> - setOk(ok, false);
> -
> if (type_ != Type::List)
> - return defaultValue;
> + return {};
>
> if (list_.size() != 2)
> - return defaultValue;
> + return {};
>
> - /*
> - * Add a local variable to validate each dimension in case
> - * that ok == nullptr.
> - */
> - bool valid;
> - uint32_t width = list_[0]->get<uint32_t>(0, &valid);
> - if (!valid)
> - return defaultValue;
> + auto width = list_[0]->get<uint32_t>();
> + if (!width)
> + return {};
>
> - uint32_t height = list_[1]->get<uint32_t>(0, &valid);
> - if (!valid)
> - return defaultValue;
> + auto height = list_[1]->get<uint32_t>();
> + if (!height)
> + return {};
>
> - setOk(ok, true);
> - return Size(width, height);
> + return Size(*width, *height);
> }
>
> #endif /* __DOXYGEN__ */
> diff --git a/test/yaml-parser.cpp b/test/yaml-parser.cpp
> index 38f848232fa6..ebb654f2ef9c 100644
> --- a/test/yaml-parser.cpp
> +++ b/test/yaml-parser.cpp
> @@ -148,7 +148,6 @@ protected:
> }
>
> /* Test string object */
> - bool ok;
> auto &strObj = (*root)["string"];
>
> if (strObj.isDictionary()) {
> @@ -161,27 +160,27 @@ protected:
> return TestFail;
> }
>
> - if (strObj.get<string>("", &ok) != "libcamera" || !ok) {
> + if (strObj.get<string>().value_or("") != "libcamera") {
> cerr << "String object parse as wrong content" <<
> std::endl;
> return TestFail;
> }
>
> - if (strObj.get<int32_t>(-1, &ok) != -1 || ok) {
> + if (strObj.get<int32_t>()) {
> cerr << "String object parse as integer" <<
> std::endl;
> return TestFail;
> }
>
> - if (strObj.get<uint32_t>(1, &ok) != 1 || ok) {
> + if (strObj.get<uint32_t>()) {
> cerr << "String object parse as unsigned integer"
> << std::endl;
> return TestFail;
> }
>
> - if (strObj.get<double>(1.0, &ok) != 1.0 || ok) {
> + if (strObj.get<double>()) {
> cerr << "String object parse as double" <<
> std::endl;
> return TestFail;
> }
>
> - if (strObj.get<Size>(Size(0, 0), &ok) != Size(0, 0) || ok)
> {
> + if (strObj.get<Size>()) {
> cerr << "String object parse as Size" << std::endl;
> return TestFail;
> }
> @@ -199,27 +198,27 @@ protected:
> return TestFail;
> }
>
> - if (int32Obj.get<int32_t>(-100, &ok) != -100 || !ok) {
> + if (int32Obj.get<int32_t>().value_or(0) != -100) {
> cerr << "Integer object parse as wrong value" <<
> std::endl;
> return TestFail;
> }
>
> - if (int32Obj.get<string>("", &ok) != "-100" || !ok) {
> + if (int32Obj.get<string>().value_or("") != "-100") {
> cerr << "Integer object fail to parse as string"
> << std::endl;
> return TestFail;
> }
>
> - if (int32Obj.get<double>(1.0, &ok) != -100.0 || !ok) {
> + if (int32Obj.get<double>().value_or(0.0) != -100.0) {
> cerr << "Integer object fail to parse as double"
> << std::endl;
> return TestFail;
> }
>
> - if (int32Obj.get<uint32_t>(1, &ok) != 1 || ok) {
> + if (int32Obj.get<uint32_t>()) {
> cerr << "Negative integer object parse as unsigned
> integer" << std::endl;
> return TestFail;
> }
>
> - if (int32Obj.get<Size>(Size(0, 0), &ok) != Size(0, 0) ||
> ok) {
> + if (int32Obj.get<Size>()) {
> cerr << "Integer object parse as Size" <<
> std::endl;
> return TestFail;
> }
> @@ -237,27 +236,27 @@ protected:
> return TestFail;
> }
>
> - if (uint32Obj.get<int32_t>(-1, &ok) != 100 || !ok) {
> + if (uint32Obj.get<int32_t>().value_or(0) != 100) {
> cerr << "Unsigned integer object fail to parse as
> integer" << std::endl;
> return TestFail;
> }
>
> - if (uint32Obj.get<string>("", &ok) != "100" || !ok) {
> + if (uint32Obj.get<string>().value_or("") != "100") {
> cerr << "Unsigned integer object fail to parse as
> string" << std::endl;
> return TestFail;
> }
>
> - if (uint32Obj.get<double>(1.0, &ok) != 100.0 || !ok) {
> + if (uint32Obj.get<double>().value_or(0.0) != 100.0) {
> cerr << "Unsigned integer object fail to parse as
> double" << std::endl;
> return TestFail;
> }
>
> - if (uint32Obj.get<uint32_t>(100, &ok) != 100 || !ok) {
> + if (uint32Obj.get<uint32_t>().value_or(0) != 100) {
> cerr << "Unsigned integer object parsed as wrong
> value" << std::endl;
> return TestFail;
> }
>
> - if (uint32Obj.get<Size>(Size(0, 0), &ok) != Size(0, 0) ||
> ok) {
> + if (uint32Obj.get<Size>()) {
> cerr << "Unsigned integer object parsed as Size"
> << std::endl;
> return TestFail;
> }
> @@ -275,27 +274,27 @@ protected:
> return TestFail;
> }
>
> - if (doubleObj.get<string>("", &ok) != "3.14159" || !ok) {
> + if (doubleObj.get<string>().value_or("") != "3.14159") {
> cerr << "Double object fail to parse as string" <<
> std::endl;
> return TestFail;
> }
>
> - if (doubleObj.get<double>(1.0, &ok) != 3.14159 || !ok) {
> + if (doubleObj.get<double>().value_or(0.0) != 3.14159) {
> cerr << "Double object parse as wrong value" <<
> std::endl;
> return TestFail;
> }
>
> - if (doubleObj.get<int32_t>(-1, &ok) != -1 || ok) {
> + if (doubleObj.get<int32_t>()) {
> cerr << "Double object parse as integer" <<
> std::endl;
> return TestFail;
> }
>
> - if (doubleObj.get<uint32_t>(1, &ok) != 1 || ok) {
> + if (doubleObj.get<uint32_t>()) {
> cerr << "Double object parse as unsigned integer"
> << std::endl;
> return TestFail;
> }
>
> - if (doubleObj.get<Size>(Size(0, 0), &ok) != Size(0, 0) ||
> ok) {
> + if (doubleObj.get<Size>()) {
> cerr << "Double object parse as Size" << std::endl;
> return TestFail;
> }
> @@ -313,27 +312,27 @@ protected:
> return TestFail;
> }
>
> - if (sizeObj.get<string>("", &ok) != "" || ok) {
> + if (sizeObj.get<string>()) {
> cerr << "Size object parse as string" << std::endl;
> return TestFail;
> }
>
> - if (sizeObj.get<double>(1.0, &ok) != 1.0 || ok) {
> + if (sizeObj.get<double>()) {
> cerr << "Size object parse as double" << std::endl;
> return TestFail;
> }
>
> - if (sizeObj.get<int32_t>(-1, &ok) != -1 || ok) {
> + if (sizeObj.get<int32_t>()) {
> cerr << "Size object parse as integer" <<
> std::endl;
> return TestFail;
> }
>
> - if (sizeObj.get<uint32_t>(1, &ok) != 1 || ok) {
> + if (sizeObj.get<uint32_t>()) {
> cerr << "Size object parse as unsigned integer" <<
> std::endl;
> return TestFail;
> }
>
> - if (sizeObj.get<Size>(Size(0, 0), &ok) != Size(1920, 1080)
> || !ok) {
> + if (sizeObj.get<Size>().value_or(Size(0, 0)) != Size(1920,
> 1080)) {
> cerr << "Size object parse as wrong value" <<
> std::endl;
> return TestFail;
> }
> @@ -351,27 +350,27 @@ protected:
> return TestFail;
> }
>
> - if (listObj.get<string>("", &ok) != "" || ok) {
> + if (listObj.get<string>()) {
> cerr << "List object parse as string" << std::endl;
> return TestFail;
> }
>
> - if (listObj.get<double>(1.0, &ok) != 1.0 || ok) {
> + if (listObj.get<double>()) {
> cerr << "List object parse as double" << std::endl;
> return TestFail;
> }
>
> - if (listObj.get<int32_t>(-1, &ok) != -1 || ok) {
> + if (listObj.get<int32_t>()) {
> cerr << "List object parse as integer" <<
> std::endl;
> return TestFail;
> }
>
> - if (listObj.get<uint32_t>(1, &ok) != 1 || ok) {
> + if (listObj.get<uint32_t>()) {
> cerr << "List object parse as unsigne integer" <<
> std::endl;
> return TestFail;
> }
>
> - if (listObj.get<Size>(Size(0, 0), &ok) != Size(0, 0) ||
> ok) {
> + if (listObj.get<Size>()) {
> cerr << "String list object parse as Size" <<
> std::endl;
> return TestFail;
> }
> @@ -424,27 +423,27 @@ protected:
> return TestFail;
> }
>
> - if (dictObj.get<string>("", &ok) != "" || ok) {
> + if (dictObj.get<string>()) {
> cerr << "Dictionary object parse as string" <<
> std::endl;
> return TestFail;
> }
>
> - if (dictObj.get<double>(1.0, &ok) != 1.0 || ok) {
> + if (dictObj.get<double>()) {
> cerr << "Dictionary object parse as double" <<
> std::endl;
> return TestFail;
> }
>
> - if (dictObj.get<int32_t>(-1, &ok) != -1 || ok) {
> + if (dictObj.get<int32_t>()) {
> cerr << "Dictionary object parse as integer" <<
> std::endl;
> return TestFail;
> }
>
> - if (dictObj.get<uint32_t>(1, &ok) != 1 || ok) {
> + if (dictObj.get<uint32_t>()) {
> cerr << "Dictionary object parse as unsigned
> integer" << std::endl;
> return TestFail;
> }
>
> - if (dictObj.get<Size>(Size(0, 0), &ok) != Size(0, 0) ||
> ok) {
> + if (dictObj.get<Size>()) {
> cerr << "Dictionary object parse as Size" <<
> std::endl;
> return TestFail;
> }
> --
> Regards,
>
> Laurent Pinchart
>
>
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