include/lcdf/straccum.hh

// -*- related-file-name: "../../liblcdf/straccum.cc" -*-
#ifndef LCDF_STRACCUM_HH
#define LCDF_STRACCUM_HH
#include <string.h>
#include <assert.h>
#include <lcdf/string.hh>
#if HAVE_PERMSTRING
# include <lcdf/permstr.hh>
#endif
#if __GNUC__ > 4
# define LCDF_SNPRINTF_ATTR __attribute__((__format__(__printf__, 3, 4)))
#else
# define LCDF_SNPRINTF_ATTR /* nothing */
#endif
template<typename T> class Vector;

/** @file <lcdf/straccum.hh>
    @brief Click's StringAccum class, used to construct Strings efficiently from pieces.
*/

class StringAccum { public:

    /** @brief Construct an empty StringAccum (with length 0). */
    StringAccum()
	: _s(0), _len(0), _cap(0) {
    }

    /** @brief Construct a StringAccum with room for at least @a capacity
     * characters.
     * @param capacity initial capacity
     *
     * If @a capacity <= 0, the StringAccum is created empty.  If @a capacity
     * is too large (so that @a capacity bytes of memory can't be allocated),
     * the StringAccum falls back to a smaller capacity (possibly zero). */
    explicit inline StringAccum(int capacity);

    /** @brief Construct a StringAccum containing the characters in @a s. */
    explicit inline StringAccum(const char *cstr)
	: _s(0), _len(0), _cap(0) {
	append(cstr);
    }

    /** @brief Construct a StringAccum containing the characters in @a s. */
    inline StringAccum(const char *s, int len)
	: _s(0), _len(0), _cap(0) {
	append(s, len);
    }

    /** @brief Construct a StringAccum containing the characters in @a str. */
    StringAccum(const String &str)
	: _s(0), _len(0), _cap(0) {
	append(str.begin(), str.end());
    }

    /** @brief Construct a StringAccum containing a copy of @a x. */
    StringAccum(const StringAccum &x)
	: _s(0), _len(0), _cap(0) {
	append(x.data(), x.length());
    }

    /** @brief Destroy a StringAccum, freeing its memory. */
    ~StringAccum() {
	if (_cap > 0)
	    delete[] (_s - MEMO_SPACE);
    }


    /** @brief Return the contents of the StringAccum.
     * @return The StringAccum's contents.
     *
     * The return value is null if the StringAccum is empty or out-of-memory.
     * The returned data() value points to writable memory (unless the
     * StringAccum itself is const). */
    inline const char *data() const {
	return reinterpret_cast<const char *>(_s);
    }

    /** @overload */
    inline char *data() {
	return reinterpret_cast<char *>(_s);
    }

    inline const unsigned char* udata() const {
	return _s;
    }

    inline unsigned char* udata() {
	return _s;
    }

    /** @brief Return true iff the StringAccum is empty or out-of-memory. */
    bool empty() const {
	return _len == 0;
    }

    /** @brief Return the length of the StringAccum. */
    int length() const {
	return _len;
    }

    /** @brief Return the StringAccum's current capacity.
     *
     * The capacity is the maximum length the StringAccum can hold without
     * incurring a memory allocation.  Returns -1 for out-of-memory
     * StringAccums. */
    int capacity() const {
	return _cap;
    }


    typedef const char *const_iterator;
    typedef char *iterator;

    /** @brief Return an iterator for the first character in the StringAccum.
     *
     * StringAccum iterators are simply pointers into string data, so they are
     * quite efficient.  @sa StringAccum::data */
    inline const_iterator begin() const {
	return reinterpret_cast<char *>(_s);
    }

    /** @overload */
    inline iterator begin() {
	return reinterpret_cast<char *>(_s);
    }

    /** @brief Return an iterator for the end of the StringAccum.
     *
     * The return value points one character beyond the last character in the
     * StringAccum. */
    inline StringAccum::const_iterator end() const {
	return reinterpret_cast<char *>(_s + _len);
    }

    /** @overload */
    inline iterator end() {
	return reinterpret_cast<char *>(_s + _len);
    }


    typedef int (StringAccum::*unspecified_bool_type)() const;

    /** @brief Return true iff the StringAccum contains characters.
     *
     * Returns false for empty and out-of-memory StringAccums. */
    operator unspecified_bool_type() const {
	return _len != 0 ? &StringAccum::capacity : 0;
    }

    /** @brief Return true iff the StringAccum does not contain characters.
     *
     * Returns true for empty and out-of-memory StringAccums. */
    bool operator!() const {
	return _len == 0;
    }

    /** @brief Return true iff the StringAccum is out-of-memory. */
    bool out_of_memory() const {
	return _cap < 0;
    }


    /** @brief Null-terminate this StringAccum and return its data.
     *
     * Note that the null character does not contribute to the StringAccum's
     * length(), and later append() and similar operations can overwrite it.
     * If appending the null character fails, the StringAccum becomes
     * out-of-memory and the returned value is a null string. */
    const char *c_str();


    /** @brief Return the <a>i</a>th character in the string.
     * @param i character index
     * @pre 0 <= @a i < length() */
    char operator[](int i) const {
	assert((unsigned) i < (unsigned) _len);
	return static_cast<char>(_s[i]);
    }

    /** @brief Return a reference to the <a>i</a>th character in the string.
     * @param i character index
     * @pre 0 <= @a i < length() */
    char &operator[](int i) {
	assert((unsigned) i < (unsigned) _len);
	return reinterpret_cast<char &>(_s[i]);
    }

    /** @brief Return the first character in the string.
     * @pre length() > 0 */
    char front() const {
	assert(_len > 0);
	return static_cast<char>(_s[0]);
    }

    /** @brief Return a reference to the first character in the string.
     * @pre length() > 0 */
    char &front() {
	assert(_len > 0);
	return reinterpret_cast<char &>(_s[0]);
    }

    /** @brief Return the last character in the string.
     * @pre length() > 0 */
    char back() const {
	assert(_len > 0);
	return static_cast<char>(_s[_len - 1]);
    }

    /** @brief Return a reference to the last character in the string.
     * @pre length() > 0 */
    char &back() {
	assert(_len > 0);
	return reinterpret_cast<char &>(_s[_len - 1]);
    }


    /** @brief Clear the StringAccum's comments.
     *
     * All characters in the StringAccum are erased.  Also resets the
     * StringAccum's out-of-memory status. */
    inline void clear() {
	if (_cap < 0) {
	    _cap = 0;
	    _s = 0;
	}
	_len = 0;
    }


    /** @brief Reserve space for at least @a n characters.
     * @return a pointer to at least @a n characters, or null if allocation
     * fails
     * @pre @a n >= 0
     *
     * reserve() does not change the string's length(), only its capacity().
     * In a frequent usage pattern, code calls reserve(), passing an upper
     * bound on the characters that could be written by a series of
     * operations.  After writing into the returned buffer, adjust_length() is
     * called to account for the number of characters actually written.
     *
     * On failure, null is returned and errno is set to ENOMEM. */
    inline char *reserve(int n) {
	assert(n >= 0);
	if (_len + n <= _cap)
	    return reinterpret_cast<char *>(_s + _len);
	else
	    return grow(_len + n);
    }

    /** @brief Set the StringAccum's length to @a len.
     * @param len new length in characters
     * @pre 0 <= @a len <= capacity()
     * @sa adjust_length */
    inline void set_length(int len) {
	assert(len >= 0 && _len <= _cap);
	_len = len;
    }

    /** @brief Set the StringAccum's length to @a len.
     * @pre @a len >= 0
     * @return 0 on success, -ENOMEM on failure */
    int resize(int len);

    /** @brief Adjust the StringAccum's length.
     * @param delta  length adjustment
     * @pre If @a delta > 0, then length() + @a delta <= capacity().
     *      If @a delta < 0, then length() + delta >= 0.
     *
     * The StringAccum's length after adjust_length(@a delta) equals its old
     * length plus @a delta.  Generally adjust_length() is used after a call
     * to reserve().  @sa set_length */
    inline void adjust_length(int delta) {
	assert(_len + delta >= 0 && _len + delta <= _cap);
	_len += delta;
    }

    /** @brief Reserve space and adjust length in one operation.
     * @param nadjust number of characters to reserve and adjust length
     * @param nreserve additional characters to reserve
     * @pre @a nadjust >= 0 and @a nreserve >= 0
     *
     * This operation combines the effects of reserve(@a nadjust + @a
     * nreserve) and adjust_length(@a nadjust).  Returns the result of the
     * reserve() call. */
    inline char *extend(int nadjust, int nreserve = 0) {
	assert(nadjust >= 0 && nreserve >= 0);
	if (_len + nadjust + nreserve <= _cap) {
	    char *x = reinterpret_cast<char *>(_s + _len);
	    _len += nadjust;
	    return x;
	} else
	    return hard_extend(nadjust, nreserve);
    }


    /** @brief Remove characters from the end of the StringAccum.
     * @param n number of characters to remove
     * @pre @a n >= 0 and @a n <= length()
     *
     * Same as adjust_length(-@a n). */
    inline void pop_back(int n = 1) {
	assert(n >= 0 && _len >= n);
	_len -= n;
    }


    /** @brief Append character @a c to the StringAccum.
     * @param c character to append */
    inline void append(char c) {
	if (_len < _cap || grow(_len))
	    _s[_len++] = c;
    }
    /** @overload */
    inline void append(unsigned char c) {
	append(static_cast<char>(c));
    }

    /** @brief Append @a len copies of character @a c to the StringAccum. */
    void append_fill(int c, int len);

    /** @brief Append the UTF-8 encoding of Unicode character @a ch. */
    inline void append_utf8(unsigned ch) {
	if (ch < 0x80)
	    append((unsigned char) ch);
	else
	    append_utf8_hard(ch);
    }

    /** @brief Append the null-terminated C string @a s to this StringAccum.
     * @param s data to append */
    void append(const char *s);
    /** @brief Append the first @a len characters of @a s to this StringAccum.
     * @param s data to append
     * @param len length of data
     * @pre @a len >= 0 */
    inline void append(const char *s, int len);
    /** @overload */
    inline void append(const unsigned char *s, int len);

    /** @brief Append the data from @a begin to @a end to the end of this
     * StringAccum.
     *
     * Does nothing if @a begin >= @a end. */
    inline void append(const char *begin, const char *end);
    /** @overload */
    inline void append(const unsigned char *begin, const unsigned char *end);

    // word joining
    void append_break_lines(const String &text, int linelen, const String &leftmargin = String());

    /** @brief Append result of snprintf() to this StringAccum.
     * @param n maximum number of characters to print
     * @param format format argument to snprintf()
     *
     * The terminating null character is not appended to the string.
     *
     * @note The safe vsnprintf() variant is called if it exists.  It does in
     * the Linux kernel, and on modern Unix variants.  However, if it does not
     * exist on your machine, then this function is actually unsafe, and you
     * should make sure that the printf() invocation represented by your
     * arguments will never write more than @a n characters, not including the
     * terminating null. */
    StringAccum &snprintf(int n, const char *format, ...) LCDF_SNPRINTF_ATTR;


    /** @brief Return a String object with this StringAccum's contents.
     *
     * This operation donates the StringAccum's memory to the returned String.
     * After a call to take_string(), the StringAccum object becomes empty,
     * and any future append() operations may cause memory allocations.  If
     * the StringAccum is out-of-memory, the returned String is also
     * out-of-memory, but the StringAccum's out-of-memory state is reset. */
    String take_string();


    /** @brief Assign this StringAccum to @a x. */
    StringAccum &operator=(const StringAccum &x) {
	if (&x != this) {
	    if (out_of_memory())
		_s = 0, _cap = 0;
	    _len = 0;
	    append(x.data(), x.length());
	}
	return *this;
    }

    /** @brief Swap this StringAccum's contents with @a x. */
    void swap(StringAccum &x);

    // see also operator<< declarations below

  private:

    enum {
	MEMO_SPACE = String::MEMO_SPACE
    };

    unsigned char *_s;
    int _len;
    int _cap;

    char *grow(int);
    void assign_out_of_memory();

    char *hard_extend(int nadjust, int nreserve);
    void hard_append(const char *s, int len);
    void append_utf8_hard(unsigned ch);

    friend StringAccum &operator<<(StringAccum &sa, const char *s);
    friend StringAccum &operator<<(StringAccum &sa, const String &str);
#if HAVE_PERMSTRING
    friend StringAccum &operator<<(StringAccum &sa, PermString s);
#endif

};

inline StringAccum &operator<<(StringAccum &, char);
inline StringAccum &operator<<(StringAccum &, unsigned char);
inline StringAccum &operator<<(StringAccum &, const char *);
inline StringAccum &operator<<(StringAccum &, const String &);
inline StringAccum &operator<<(StringAccum &, const StringAccum &);
#ifdef HAVE_PERMSTRING
inline StringAccum &operator<<(StringAccum &, PermString);
#endif

inline StringAccum &operator<<(StringAccum &, bool);
inline StringAccum &operator<<(StringAccum &, short);
inline StringAccum &operator<<(StringAccum &, unsigned short);
inline StringAccum &operator<<(StringAccum &, int);
inline StringAccum &operator<<(StringAccum &, unsigned);
StringAccum &operator<<(StringAccum &, long);
StringAccum &operator<<(StringAccum &, unsigned long);
StringAccum &operator<<(StringAccum &, double);


inline
StringAccum::StringAccum(int capacity)
    : _len(0)
{
    assert(capacity >= 0);
    if (capacity
	&& (_s = new unsigned char[capacity + MEMO_SPACE])) {
	_s += MEMO_SPACE;
	_cap = capacity;
    } else {
	_s = 0;
	_cap = 0;
    }
}

inline void StringAccum::append(const char *s, int len) {
    assert(len >= 0);
    if (_len + len <= _cap) {
	memcpy(_s + _len, s, len);
	_len += len;
    } else
	hard_append(s, len);
}

inline void StringAccum::append(const unsigned char *s, int len) {
    append(reinterpret_cast<const char *>(s), len);
}

inline void StringAccum::append(const char *begin, const char *end) {
    if (begin < end)
	append(begin, end - begin);
}

inline void StringAccum::append(const unsigned char *begin, const unsigned char *end) {
    if (begin < end)
	append(begin, end - begin);
}

/** @relates StringAccum
    @brief Append character @a c to StringAccum @a sa.
    @return @a sa
    @note Same as @a sa.append(@a c). */
inline StringAccum &
operator<<(StringAccum &sa, char c)
{
    sa.append(c);
    return sa;
}

/** @relates StringAccum
    @brief Append character @a c to StringAccum @a sa.
    @return @a sa
    @note Same as @a sa.append(@a c). */
inline StringAccum &
operator<<(StringAccum &sa, unsigned char c)
{
    sa.append(c);
    return sa;
}

/** @relates StringAccum
    @brief Append null-terminated C string @a cstr to StringAccum @a sa.
    @return @a sa
    @note Same as @a sa.append(@a cstr). */
inline StringAccum &
operator<<(StringAccum &sa, const char *cstr)
{
    sa.append(cstr);
    return sa;
}

/** @relates StringAccum
    @brief Append "true" or "false" to @a sa, depending on @a b.
    @return @a sa */
inline StringAccum &
operator<<(StringAccum &sa, bool b)
{
    static const char truefalse[] = "truefalse";
    if (b)
	sa.append(truefalse, 4);
    else
	sa.append(truefalse + 4, 5);
    return sa;
}

/** @relates StringAccum
    @brief Append decimal representation of @a i to @a sa.
    @return @a sa */
inline StringAccum &
operator<<(StringAccum &sa, short i)
{
    return sa << static_cast<long>(i);
}

/** @relates StringAccum
    @brief Append decimal representation of @a u to @a sa.
    @return @a sa */
inline StringAccum &
operator<<(StringAccum &sa, unsigned short u)
{
    return sa << static_cast<unsigned long>(u);
}

/** @relates StringAccum
    @brief Append decimal representation of @a i to @a sa.
    @return @a sa */
inline StringAccum &
operator<<(StringAccum &sa, int i)
{
    return sa << static_cast<long>(i);
}

/** @relates StringAccum
    @brief Append decimal representation of @a u to @a sa.
    @return @a sa */
inline StringAccum &
operator<<(StringAccum &sa, unsigned u)
{
    return sa << static_cast<unsigned long>(u);
}

/** @relates StringAccum
    @brief Append the contents of @a str to @a sa.
    @return @a sa */
inline StringAccum &
operator<<(StringAccum &sa, const String &str)
{
    if (!str.out_of_memory())
	sa.hard_append(str.begin(), str.length());
    else
	sa.assign_out_of_memory();
    return sa;
}

#ifdef HAVE_PERMSTRING
inline StringAccum &
operator<<(StringAccum &sa, PermString s)
{
    sa.append(s.c_str(), s.length());
    return sa;
}
#endif

/** @relates StringAccum
    @brief Append the contents of @a sb to @a sa.
    @return @a sa */
inline StringAccum &
operator<<(StringAccum &sa, const StringAccum &sb)
{
    sa.append(sb.begin(), sb.end());
    return sa;
}

inline bool
operator==(StringAccum &sa, const char *s)
{
    return strcmp(sa.c_str(), s) == 0;
}

inline bool
operator!=(StringAccum &sa, const char *s)
{
    return strcmp(sa.c_str(), s) != 0;
}

#undef LCDF_SNPRINTF_ATTR
#endif