fstring.hpp

/** Fast String - Voice Technology
 * Simple char[] substitute with faster appender.
 * Fernando Gregianin Testa <testa@voicetechnology.com.br>
 * v0.1 - Usando no provider v2. 2007-02-22
 */
 
#ifndef FSTRING_
#define FSTRING_
 
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <stdio.h>
 
#define DEFAULT_FSTRING_capacity 256
 
#define mymin(x,y) x<y?x:y
 
 
/** Fast string, use as a replacement to char* in your program.
 * It performs faster than stl string and libc, when appending.
 * It does not have the automagically growing feature, unless you explicitly calls append_growing()
 * and this issue is by desing!
 */
class fstring
{
  //! pointer to the internal buffer
  char * _buffer;
  //! integer to store the total buffer capacity
  int _capacity;
  //! integer to store the current end position, the "null character"
  int _endpos;
  //! the blocksize to grow the buffer, when needed.
  int _blocksize;
  
  //! Grows the internal buffer one blocksize.
  void grow()
  {
    char*newbuffer = (char*) malloc(_capacity+_blocksize);
    for(int i=0;i<_capacity;i++)
      newbuffer[i] = _buffer[i];
    free(_buffer);
    _buffer = newbuffer;
    _capacity += _blocksize;
  }
 
public:
 
  /* copy from other string
  void copy(char*src,int size)
  {
    int tc = mymin(size, _capacity);
    for(int i=0;i<tc;i++)
      _buffer[i] = src[i];
  }
*/
  /** Copy up to null char, or _capacity reached.
   *
  void copy(char*src)
  {
    char*s=src;
    for(_endpos=0 ; _endpos<_capacity && *s!=0 ; _endpos++, s++)
      dest[_endpos] = *s;
  }
  */
  
  /** Returns the lenght of a char, i.e., finds the null char on it.
   */
  static int mystrlen(const char * what)
  {
    int len=0;
    while (0!=what[len]) len++;
    return len;
  }
 
  /** Constructs the string with a default capacity
   */
  fstring() {
    _capacity = DEFAULT_FSTRING_capacity;
    _blocksize = DEFAULT_FSTRING_capacity/2;
    _buffer = (char*) malloc(_capacity);
    _buffer[0] = 0;
    _endpos = 0;
  }
  
  /** Constructs the string with the specified capacity
   */
  fstring(int size) {
    if (size<32) size = 32;
    _capacity = size;
    _blocksize = size/2;
    _buffer = (char*) malloc(_capacity);
    *_buffer = 0;
    _endpos = 0;
  }
  
  /** constructs a fstring with a initial buffer.
   */
  fstring(const char *buffer) {
    int size = mystrlen(buffer)+1;
    _blocksize= DEFAULT_FSTRING_capacity/2;
    _capacity = size + _blocksize;
    _buffer = (char*) malloc(_capacity);
//    append(buffer);
    for(_endpos=0;_endpos<_capacity && buffer[_endpos]!=0;_endpos++)
      _buffer[_endpos]=buffer[_endpos];
    _buffer[_endpos]=0;
  }
  
  /** Copy constructor, creates a clone of provided fstring.
   */
  fstring(fstring& x) {
    clone(x);
  }
  
  /** The destructor frees the buffer, since it is our responsibility.
   */
  ~fstring() {
    if (_buffer) free(_buffer);
  }
  
  /** Returns the internal buffer
   */
  char* c_str() {
    return _buffer;
  }
  
  /** Appends data at the end of buffer
   */
  fstring& append(const char*what)  
  {
    char*w=(char*)what;
    for(;;)
    {
      _buffer[_endpos] = *w;
      if (0 == *w || _endpos == _capacity) break;
      w++; _endpos++;
    }
    return *this;
  }
 
  /** Appends data to the buffer and grows the buffer if needed
   */
  fstring& append_growing(const char*what)
  {
    char*w=(char*)what;
    for(;;)
    {
      _buffer[_endpos] = *w;
      if (0 == *w ) break;
      if (_endpos == _capacity-1 ) grow();
      w++; _endpos++;
    }
    return *this;
  }
 
  /** reset the buffer
   */
  fstring& clear() {
    _buffer[0]=0;
    _endpos=0;
    return *this;
  }
 
  fstring& operator=(fstring& x) {
    return clone(x);
  }
 
  fstring& operator=(char*what)
  {
    _endpos=0;
    return append(what);
  }
  
  fstring& operator=(const char*what)
  {
    _endpos=0;
    return append(what);
  }
      
  fstring& operator+=(fstring& what)   {     return (*this += what.c_str());   }
 
  fstring& operator+=(const char*what) { return append(what); }
  
  operator const char *() { return _buffer; }
  
  fstring& operator+=(const char what)
  {
    if (_endpos == _capacity) return *this;
    _buffer[_endpos] = what;
    _endpos++;
  }
 
  int lenght() {     return _endpos;   }
  int size() {         return _endpos;   }
  bool isfull() {     return _endpos == _capacity;   }
  
  /** Returns the remaining space in buffer */
  int remaining() {     return _capacity-_endpos;   }
 
  fstring& format(const char * fmt,...)
  {
        va_list ap;
        va_start ( ap, fmt );
        vsprintf(_buffer, fmt, ap);
        va_end(ap);
    update_endpos();
    return *this;
  }
  
  fstring& clone(fstring&x)
  {
    _capacity = x._capacity;
    _blocksize = x._blocksize;
    _endpos = x._endpos;
    _buffer = (char*)malloc(_capacity);
    for(int i=0;i<_capacity;i++)
      _buffer[i] = x._buffer[i];
    return *this;
  }
  
  const char operator[](int c)
  {
    if(c > _endpos) return 0;
    return _buffer[c];
  }
  
  /** Returns the internal string capacity */  
  int capacity()
  { return _capacity; }
 
  /** This is a sort of "correct the size" function.
   * Users shouldn't use it. */
  void update_endpos()
  {
    for(int i=0;i<_capacity;i++)
      if (0 == _buffer[i])
      { _endpos = i; break; }
  }
};
 
#endif /*FSTRING_*/