[libcamera-devel] [PATCH 1/3] libcamera: utils: Add string splitter utility function

[Kieran Bingham]

Hi Laurent,

On 13/02/2020 13:09, Kieran Bingham wrote:
> From: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> 
> Add a utils::split() function that splits a string for the purpose of
> iterating over substrings. It returns an object of unspecified type that
> can be used in range-based for loops.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

This is really helpful, thanks

Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

> ---
>  Documentation/Doxyfile.in     |  1 +
>  src/libcamera/include/utils.h | 34 +++++++++++++++++++
>  src/libcamera/utils.cpp       | 62 +++++++++++++++++++++++++++++++++++
>  3 files changed, 97 insertions(+)
> 
> diff --git a/Documentation/Doxyfile.in b/Documentation/Doxyfile.in
> index 1c46b04b3f7e..beeaf6d3cf48 100644
> --- a/Documentation/Doxyfile.in
> +++ b/Documentation/Doxyfile.in
> @@ -880,6 +880,7 @@ EXCLUDE_SYMBOLS        = libcamera::BoundMethodArgs \
>                           libcamera::BoundMethodStatic \
>                           libcamera::SignalBase \
>                           libcamera::*::Private \
> +                         libcamera::*::details::* \
>                           std::*
>  
>  # The EXAMPLE_PATH tag can be used to specify one or more files or directories
> diff --git a/src/libcamera/include/utils.h b/src/libcamera/include/utils.h
> index e467eb21c518..080ea6614de0 100644
> --- a/src/libcamera/include/utils.h
> +++ b/src/libcamera/include/utils.h
> @@ -108,6 +108,40 @@ inline _hex hex<uint64_t>(uint64_t value, unsigned int width)
>  
>  size_t strlcpy(char *dst, const char *src, size_t size);
>  
> +namespace details {
> +
> +class StringSplitter
> +{
> +public:
> +	StringSplitter(const std::string &str, const std::string &delim);
> +
> +	class iterator
> +	{
> +	public:
> +		iterator(const StringSplitter *ss, std::string::size_type pos);
> +
> +		iterator &operator++();
> +		std::string operator*() const;
> +		bool operator!=(const iterator &other) const;
> +
> +	private:
> +		const StringSplitter *ss_;
> +		std::string::size_type pos_;
> +		std::string::size_type next_;
> +	};
> +
> +	iterator begin() const;
> +	iterator end() const;
> +
> +private:
> +	std::string str_;
> +	std::string delim_;
> +};
> +
> +} /* namespace details */
> +
> +details::StringSplitter split(const std::string &str, const std::string &delim);
> +
>  } /* namespace utils */
>  
>  } /* namespace libcamera */
> diff --git a/src/libcamera/utils.cpp b/src/libcamera/utils.cpp
> index 4beffdab5eb6..fe027c0b009c 100644
> --- a/src/libcamera/utils.cpp
> +++ b/src/libcamera/utils.cpp
> @@ -199,6 +199,68 @@ size_t strlcpy(char *dst, const char *src, size_t size)
>  	return strlen(src);
>  }
>  
> +details::StringSplitter::StringSplitter(const std::string &str, const std::string &delim)
> +	: str_(str), delim_(delim)
> +{
> +}
> +
> +details::StringSplitter::iterator::iterator(const details::StringSplitter *ss, std::string::size_type pos)
> +	: ss_(ss), pos_(pos)
> +{
> +	next_ = ss_->str_.find(ss_->delim_, pos_);
> +}
> +
> +details::StringSplitter::iterator &details::StringSplitter::iterator::operator++()
> +{
> +	pos_ = next_;
> +	if (pos_ != std::string::npos) {
> +		pos_ += ss_->delim_.length();
> +		next_ = ss_->str_.find(ss_->delim_, pos_);
> +	}
> +
> +	return *this;
> +}
> +
> +std::string details::StringSplitter::iterator::operator*() const
> +{
> +	std::string::size_type count;
> +	count = next_ != std::string::npos ? next_ - pos_ : next_;
> +	return ss_->str_.substr(pos_, count);
> +}
> +
> +bool details::StringSplitter::iterator::operator!=(const details::StringSplitter::iterator &other) const
> +{
> +	return pos_ != other.pos_;
> +}
> +
> +details::StringSplitter::iterator details::StringSplitter::begin() const
> +{
> +	return iterator(this, 0);
> +}
> +
> +details::StringSplitter::iterator details::StringSplitter::end() const
> +{
> +	return iterator(this, std::string::npos);
> +}
> +
> +/**
> + * \fn split(const std::string &str, const std::string &delim)
> + * \brief Split a string based on a delimiter
> + * \param[in] str The string to split
> + * \param[in] delim The delimiter string
> + *
> + * This function splits the string \a str into substrings based on the
> + * delimiter \a delim. It returns an object of unspecified type that can be
> + * used in a range-based for loop and yields the substrings in sequence.
> + *
> + * \return An object that can be used in a range-based for loop to iterate over
> + * the substrings
> + */
> +details::StringSplitter split(const std::string &str, const std::string &delim)
> +{
> +	return details::StringSplitter(str, delim);
> +}
> +
>  } /* namespace utils */
>  
>  } /* namespace libcamera */
> 

-- 
Regards
--
Kieran