// StringBuilder.C
//
// Written 19 Feb 1996 by Max Hailperin <max@gac.edu>.
//
// Implementation of a class for incrementally building up strings
//  without knowing in advance their final size -- see StringBuilder.h
//
// The implementation techinique used is a "dynamically growing" array
// where the "growth" really consists of copying the array into twice
// as big a one when it is outgrown.

#include "StringBuilder.h"

class StringBuilderRep{
public:
  char *buf;
  int size;
  int nextFree;
  void reset();
};

static const int initialSize = 20;  // non-critical, seems reasonable

void StringBuilderRep::reset(){
  size = initialSize;
  buf = new char[size];
  nextFree = 0;
}

StringBuilder::StringBuilder(){
  rep = new StringBuilderRep;
  rep->reset();
}

StringBuilder::~StringBuilder(){
  delete [] rep->buf;
  delete rep;
}

void StringBuilder::add(char c){
  if(rep->nextFree == rep->size){
    char *oldBuf = rep->buf;
    rep->size *= 2;
    rep->buf = new char[rep->size];
    for(int i = 0; i < rep->nextFree; i++)
      rep->buf[i] = oldBuf[i];
    delete [] oldBuf;
  }
  rep->buf[rep->nextFree++] = c;
}

char * StringBuilder::string(){
  add('\0');
  char *s = rep->buf;
  rep->reset();
  return s;
}