[alexxy/gromacs.git] / src / gromacs / utility / stringutil.h

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/*! \file
 * \brief
 * Declares common string utility and formatting routines.
 *
 * \author Teemu Murtola <teemu.murtola@gmail.com>
 * \inpublicapi
 * \ingroup module_utility
 */
#ifndef GMX_UTILITY_STRINGUTIL_H
#define GMX_UTILITY_STRINGUTIL_H

#include <cstring>

#include <string>
#include <vector>

namespace gmx
{

//! \addtogroup module_utility
//! \{

/*! \brief
 * Tests whether a string is null or empty.
 *
 * Does not throw.
 */
bool inline isNullOrEmpty(const char *str)
{
    return str == NULL || str[0] == '\0';
}

/*! \brief
 * Tests whether a string starts with another string.
 *
 * \param[in] str    String to process.
 * \param[in] prefix Prefix to find.
 * \returns   true if \p str starts with \p prefix.
 *
 * Returns true if \p prefix is empty.
 * Does not throw.
 */
bool inline startsWith(const std::string &str, const std::string &prefix)
{
    return str.compare(0, prefix.length(), prefix) == 0;
}
//! \copydoc startsWith(const std::string &, const std::string &)
bool inline startsWith(const char *str, const char *prefix)
{
    return std::strncmp(str, prefix, std::strlen(prefix)) == 0;
}

/*! \brief
 * Tests whether a string ends with another string.
 *
 * \param[in] str    String to process.
 * \param[in] suffix Suffix to find.
 * \returns   true if \p str ends with \p suffix.
 *
 * Returns true if \p suffix is NULL or empty.
 * Does not throw.
 */
bool endsWith(const std::string &str, const char *suffix);

/*! \brief
 * Removes a suffix from a string.
 *
 * \param[in] str    String to process.
 * \param[in] suffix Suffix to remove.
 * \returns   \p str with \p suffix removed, or \p str unmodified if it does
 *      not end with \p suffix.
 * \throws    std::bad_alloc if out of memory.
 *
 * Returns \p str if \p suffix is NULL or empty.
 */
std::string stripSuffixIfPresent(const std::string &str, const char *suffix);
/*! \brief
 * Removes leading and trailing whitespace from a string.
 *
 * \param[in] str  String to process.
 * \returns   \p str with leading and trailing whitespaces removed.
 * \throws    std::bad_alloc if out of memory.
 */
std::string stripString(const std::string &str);

/*! \brief
 * Formats a string (snprintf() wrapper).
 *
 * \throws  std::bad_alloc if out of memory.
 *
 * This function works like sprintf(), except that it returns an std::string
 * instead of requiring a preallocated buffer.  Arbitrary length output is
 * supported.
 */
std::string formatString(const char *fmt, ...);

/*! \brief Function object that wraps a call to formatString() that
 * expects a single conversion argument, for use with algorithms. */
class StringFormatter
{
    public:
        /*! \brief Constructor
         *
         * \param[in] format The printf-style format string that will
         *     be applied to convert values of type T to
         *     string. Exactly one argument to the conversion
         *     specification(s) in `format` is supported. */
        explicit StringFormatter(const char *format) : format_(format)
        {
        }

        //! Implements the formatting functionality
        template <typename T>
        std::string operator()(const T &value) const
        {
            return formatString(format_, value);
        }

    private:
        //! Format string to use
        const char *format_;
};

/*! \brief Function object to implement the same interface as
 * `StringFormatter` to use with strings that should not be formatted
 * further. */
class IdentityFormatter
{
    public:
        //! Implements the formatting non-functionality
        std::string operator()(const std::string &value) const
        {
            return value;
        }
};

/*! \brief Formats all the range as strings, and then joins them with
 * a separator in between.
 *
 * \param[in] begin      Iterator the beginning of the range to join.
 * \param[in] end        Iterator the end of the range to join.
 * \param[in] separator  String to put in between the joined strings.
 * \param[in] formatter  Function object to format the objects in
 *     `container` as strings
 * \returns   All objects in the range from `begin` to `end` formatted
 *     as strings and concatenated with `separator` between each pair.
 * \throws    std::bad_alloc if out of memory.
 */
template <typename InputIterator, typename FormatterType>
std::string formatAndJoin(InputIterator begin, InputIterator end, const char *separator, const FormatterType &formatter)
{
    std::string result;
    const char *currentSeparator = "";
    for (InputIterator i = begin; i != end; ++i)
    {
        result.append(currentSeparator);
        result.append(formatter(*i));
        currentSeparator = separator;
    }
    return result;
}

/*! \brief Formats all elements of the container as strings, and then
 * joins them with a separator in between.
 *
 * \param[in] container  Objects to join.
 * \param[in] separator  String to put in between the joined strings.
 * \param[in] formatter  Function object to format the objects in
 *     `container` as strings
 * \returns   All objects from `container` formatted as strings and
 *     concatenated with `separator` between each pair.
 * \throws    std::bad_alloc if out of memory.
 */
template <typename ContainerType, typename FormatterType>
std::string formatAndJoin(const ContainerType &container, const char *separator, const FormatterType &formatter)
{
    return formatAndJoin(container.begin(), container.end(), separator, formatter);
}

/*! \brief
 * Joins strings from a range with a separator in between.
 *
 * \param[in] begin      Iterator the beginning of the range to join.
 * \param[in] end        Iterator the end of the range to join.
 * \param[in] separator  String to put in between the joined strings.
 * \returns   All strings from (`begin`, `end`) concatenated with `separator`
 *     between each pair.
 * \throws    std::bad_alloc if out of memory.
 */
template <typename InputIterator>
std::string joinStrings(InputIterator begin, InputIterator end,
                        const char *separator)
{
    return formatAndJoin(begin, end, separator, IdentityFormatter());
}

/*! \brief
 * Joins strings from a container with a separator in between.
 *
 * \param[in] container  Strings to join.
 * \param[in] separator  String to put in between the joined strings.
 * \returns   All strings from `container` concatenated with `separator`
 *     between each pair.
 * \throws    std::bad_alloc if out of memory.
 */
template <typename ContainerType>
std::string joinStrings(const ContainerType &container, const char *separator)
{
    return joinStrings(container.begin(), container.end(), separator);
}

/*! \brief
 * Joins strings from an array with a separator in between.
 *
 * \param[in] array      Array of strings to join.
 * \param[in] separator  String to put in between the joined strings.
 * \tparam    count      Deduced number of elements in \p array.
 * \returns   All strings from `aray` concatenated with `separator`
 *     between each pair.
 * \throws    std::bad_alloc if out of memory.
 */
template <size_t count>
std::string joinStrings(const char *const (&array)[count], const char *separator)
{
    return joinStrings(array, array + count, separator);
}

/*! \brief
 * Splits a string to whitespace separated tokens.
 *
 * \param[in] str  String to process.
 * \returns   \p str split into tokens at each whitespace sequence.
 * \throws    std::bad_alloc if out of memory.
 *
 * This function works like `split` in Python, i.e., leading and trailing
 * whitespace is ignored, and consecutive whitespaces are treated as a single
 * separator.
 */
std::vector<std::string> splitString(const std::string &str);

/*! \brief
 * Replace all occurrences of a string with another string.
 *
 * \param[in] input  Input string.
 * \param[in] from   String to find.
 * \param[in] to     String to use to replace \p from.
 * \returns   Copy of \p input with all occurrences of \p from replaced with \p to.
 * \throws    std::bad_alloc if out of memory.
 *
 * The replacement is greedy and not recursive: starting from the beginning of
 * \p input, each match of \p from is replaced with \p to, and the search for
 * the next match begins after the end of the previous match.
 *
 * Compexity is O(N), where N is length of output.
 *
 * \see replaceAllWords()
 */
std::string replaceAll(const std::string &input,
                       const char *from, const char *to);
//! \copydoc replaceAll(const std::string &, const char *, const char *)
std::string replaceAll(const std::string &input,
                       const std::string &from, const std::string &to);
/*! \brief
 * Replace whole words with others.
 *
 * \param[in] input  Input string.
 * \param[in] from   String to find.
 * \param[in] to     String to use to replace \p from.
 * \returns   Copy of \p input with all \p from words replaced with \p to.
 * \throws    std::bad_alloc if out of memory.
 *
 * Works as replaceAll(), but a match is only considered if it is delimited by
 * non-alphanumeric characters.
 *
 * \see replaceAll()
 */
std::string replaceAllWords(const std::string &input,
                            const char *from, const char *to);
//! \copydoc replaceAllWords(const std::string &, const char *, const char *)
std::string replaceAllWords(const std::string &input,
                            const std::string &from, const std::string &to);

class TextLineWrapper;

/*! \brief
 * Stores settings for line wrapping.
 *
 * Methods in this class do not throw.
 *
 * \see TextLineWrapper
 *
 * \inpublicapi
 */
class TextLineWrapperSettings
{
    public:
        /*! \brief
         * Initializes default wrapper settings.
         *
         * Default settings are:
         *  - No maximum line width (only explicit line breaks).
         *  - No indentation.
         *  - No continuation characters.
         *  - Ignore whitespace after an explicit newline.
         */
        TextLineWrapperSettings();

        /*! \brief
         * Sets the maximum length for output lines.
         *
         * \param[in] length  Maximum length for the lines after wrapping.
         *
         * If this method is not called, or is called with zero \p length, the
         * wrapper has no maximum length (only wraps at explicit line breaks).
         */
        void setLineLength(int length) { maxLength_ = length; }
        /*! \brief
         * Sets the indentation for output lines.
         *
         * \param[in] indent  Number of spaces to add for indentation.
         *
         * If this method is not called, the wrapper does not add indentation.
         */
        void setIndent(int indent) { indent_ = indent; }
        /*! \brief
         * Sets the indentation for first output line after a line break.
         *
         * \param[in] indent  Number of spaces to add for indentation.
         *
         * If this method is not called, or called with \p indent equal to -1,
         * the value set with setIndent() is used.
         */
        void setFirstLineIndent(int indent) { firstLineIndent_ = indent; }
        /*! \brief
         * Sets whether to remove spaces after an explicit newline.
         *
         * \param[in] bStrip  If true, spaces after newline are ignored.
         *
         * If not removed, the space is added to the indentation set with
         * setIndent().
         * The default is to not strip such whitespace.
         */
        void setStripLeadingWhitespace(bool bStrip)
        {
            bStripLeadingWhitespace_ = bStrip;
        }
        /*! \brief
         * Sets a continuation marker for wrapped lines.
         *
         * \param[in] continuationChar  Character to use to mark continuation
         *      lines.
         *
         * If set to non-zero character code, this character is added at the
         * end of each line where a line break is added by TextLineWrapper
         * (but not after lines produced by explicit line breaks).
         * The default (\c '\0') is to not add continuation markers.
         *
         * Note that currently, the continuation char may cause the output line
         * length to exceed the value set with setLineLength() by at most two
         * characters.
         */
        void setContinuationChar(char continuationChar)
        {
            continuationChar_ = continuationChar;
        }

        //! Returns the maximum length set with setLineLength().
        int lineLength() const { return maxLength_; }
        //! Returns the indentation set with setIndent().
        int indent() const { return indent_; }
        /*! \brief
         * Returns the indentation set with setFirstLineIndent().
         *
         * If setFirstLineIndent() has not been called or has been called with
         * -1, indent() is returned.
         */
        int firstLineIndent() const
        {
            return (firstLineIndent_ >= 0 ? firstLineIndent_ : indent_);
        }

    private:
        //! Maximum length of output lines, or <= 0 if no limit.
        int                     maxLength_;
        //! Number of spaces to indent each output line with.
        int                     indent_;
        /*! \brief
         * Number of spaces to indent the first line after a newline.
         *
         * If -1, \a indent_ is used.
         */
        int                     firstLineIndent_;
        //! Whether to ignore or preserve space after a newline.
        bool                    bStripLeadingWhitespace_;
        //! If not \c '\0', mark each wrapping point with this character.
        char                    continuationChar_;

        //! Needed to access the members.
        friend class TextLineWrapper;
};

/*! \brief
 * Wraps lines to a predefined length.
 *
 * This utility class wraps lines at word breaks to produce lines that are not
 * longer than a predefined length.  Explicit newlines ('\\n') are preserved.
 * Only space is considered a word separator.  If a single word exceeds the
 * maximum line length, it is still printed on a single line.
 * Extra whitespace is stripped from the end of produced lines.
 * Other options on the wrapping, such as the line length or indentation,
 * can be changed using a TextLineWrapperSettings object.
 *
 * Two interfaces to do the wrapping are provided:
 *  -# High-level interface using either wrapToString() (produces a single
 *     string with embedded newlines) or wrapToVector() (produces a vector of
 *     strings with each line as one element).
 *     These methods operate on std::string and wrap the entire input string.
 *  -# Low-level interface using findNextLine() and formatLine().
 *     findNextLine() operates either on a C string or an std::string, and does
 *     not do any memory allocation (so it does not throw).  It finds the next
 *     line to be wrapped, considering the wrapping settings.
 *     formatLine() does whitespace operations on the line found by
 *     findNextLine() and returns an std::string.
 *     These methods allow custom wrapping implementation to either avoid
 *     exceptions or to wrap only a part of the input string.
 *
 * Typical usage:
 * \code
   gmx::TextLineWrapper wrapper;
   wrapper.settings().setLineLength(78);
   printf("%s\n", wrapper.wrapToString(textToWrap).c_str());
   \endcode
 *
 * \inpublicapi
 */
class TextLineWrapper
{
    public:
        /*! \brief
         * Constructs a new line wrapper with default settings.
         *
         * Does not throw.
         */
        TextLineWrapper()
        {
        }
        /*! \brief
         * Constructs a new line wrapper with given settings.
         *
         * \param[in] settings  Wrapping settings.
         *
         * Does not throw.
         */
        explicit TextLineWrapper(const TextLineWrapperSettings &settings)
            : settings_(settings)
        {
        }

        /*! \brief
         * Provides access to settings of this wrapper.
         *
         * \returns  The settings object for this wrapper.
         *
         * The returned object can be used to modify settings for the wrapper.
         * All subsequent calls to wrapToString() and wrapToVector() use the
         * modified settings.
         *
         * Does not throw.
         */
        TextLineWrapperSettings &settings() { return settings_; }

        /*! \brief
         * Finds the next line to be wrapped.
         *
         * \param[in] input     String to wrap.
         * \param[in] lineStart Index of first character of the line to find.
         * \returns   Index of first character of the next line.
         *
         * If this is the last line, returns the length of \p input.
         * In determining the length of the returned line, this function
         * considers the maximum line length, leaving space for indentation,
         * and also whitespace stripping behavior.
         * Thus, the line returned may be longer than the maximum line length
         * if it has leading and/or trailing space.
         * When wrapping a line on a space (not on an explicit line break),
         * the returned index is always on a non-whitespace character after the
         * space.
         *
         * To iterate over lines in a string, use the following code:
         * \code
           gmx::TextLineWrapper wrapper;
           // <set desired wrapping settings>
           size_t lineStart = 0;
           size_t length = input.length();
           while (lineStart < length)
           {
               size_t nextLineStart = wrapper.findNextLine(input, lineStart);
               std::string line = wrapper.formatLine(input, lineStart, nextLineStart));
               // <do something with the line>
               lineStart = nextLineStart;
           }
           return result;
           \endcode
         *
         * Does not throw.
         */
        size_t findNextLine(const char *input, size_t lineStart) const;
        //! \copydoc findNextLine(const char *, size_t)const
        size_t findNextLine(const std::string &input, size_t lineStart) const;
        /*! \brief
         * Formats a single line for output according to wrapping settings.
         *
         * \param[in] input     Input string.
         * \param[in] lineStart Index of first character of the line to format.
         * \param[in] lineEnd   Index of first character of the next line.
         * \returns   The line with leading and/or trailing whitespace removed
         *      and indentation applied.
         * \throws    std::bad_alloc if out of memory.
         *
         * Intended to be used on the lines found by findNextLine().
         * When used with the lines returned from findNextLine(), the returned
         * line conforms to the wrapper settings.
         * Trailing whitespace is always stripped (including any newlines,
         * i.e., the return value does not contain a newline).
         */
        std::string formatLine(const std::string &input,
                               size_t lineStart, size_t lineEnd) const;

        /*! \brief
         * Formats a string, producing a single string with all the lines.
         *
         * \param[in] input  String to wrap.
         * \returns   \p input with added newlines such that maximum line
         *      length is not exceeded.
         * \throws    std::bad_alloc if out of memory.
         *
         * Newlines in the input are preserved, including terminal newlines.
         * Note that if the input does not contain a terminal newline, the
         * output does not either.
         */
        std::string wrapToString(const std::string &input) const;
        /*! \brief
         * Formats a string, producing a vector with all the lines.
         *
         * \param[in] input  String to wrap.
         * \returns   \p input split into lines such that maximum line length
         *      is not exceeded.
         * \throws    std::bad_alloc if out of memory.
         *
         * The strings in the returned vector do not contain newlines at the
         * end.
         * Note that a single terminal newline does not affect the output:
         * "line\\n" and "line" both produce the same output (but "line\\n\\n"
         * produces two lines, the second of which is empty).
         */
        std::vector<std::string> wrapToVector(const std::string &input) const;

    private:
        TextLineWrapperSettings settings_;
};

//! \}

} // namespace gmx

#endif