Language/OS - Multiplatform Resource Library/LANGUAGE OS.iso/cpp_libs/utility.lha/utility/strings.C

C/C++ Source or Header | 1993-08-08 | 5KB | 279 lines

// $Id: strings.C,v 1.4 92/01/09 11:26:01 dag Exp $
//
// NOTE: internal_buffer_size > 1 required by operator = (char).


#include <defs.H>
#include <strings.H>
#include <ctype.h>
#include <iostream.h>


// Set DO_STAT true to collect statistics on string lengths.

#define DO_STAT 0

#if DO_STAT
#include <statcount.H>
static void Count(int sz)
{
  static StatCount cnt("Distribution of string sizes", 0, 64, 4);
  cnt(sz);
}
#else
#define Count(size)
#endif


// The following macros handle allocation of string memory, either with
// the internal buffer of by allocating on the heap.

#define allocate(str, n) str = n <= internal_buffer_size ? buf : new char[n]
#define deallocate(str) if (str != buf) delete [] str


// ----------------------------------------------------------------------------
// Constructors, destructor

String :: String ()
{
  size = internal_buffer_size;
  allocate(str, internal_buffer_size);
Count(size);
  str[0] = '\0';
}


String :: String (const char* s)
{
  if (s == nil)
    s = "";
  size = max(strlen(s)+1, internal_buffer_size);
  allocate(str, size);
Count(size);
  strcpy(str, s);
}


String :: String (const String& s)
{
  size = s.Size();
  allocate(str, size);
Count(size);
  strcpy(str, s.str);
}


String :: ~String()
{
  deallocate(str);
}


// ----------------------------------------------------------------------------
// Assignment, assignment operators

String& String :: operator = (const String& s)
{
  if (&s != this) {        // same object?
    int len = s.Length();
    if (len >= size) {
      size = len + 1;
      deallocate(str);
      allocate(str, size);
Count(size);
    }
    strcpy(str, s.str);
  }
  return *this;
}


String& String :: operator = (const char* s)
// Note: works even if s == this->str, although "strcpy" is not needed.
{
  if (s == nil)
    s = "";

  int len = strlen(s);
  if (len >= size) {
    size = len + 1;
    deallocate(str);
    allocate(str, size);
Count(size);
  }
  strcpy(str, s);

  return *this;
}


String& String :: operator = (char c)
{
  str[0] = c;
  str[1] = '\0';
  return *this;
}


void String :: operator += (const String& s)
{
  unsigned newlen = Length() + s.Length();
  if (newlen < size)
    strcat(str, s.str);
  else {
    size = newlen + internal_buffer_size;
    char* r = new char[size];
Count(size);
    strcpy(r, str);
    strcat(r, s.str);
    deallocate(str);
    str = r;
  }
}


void String :: operator += (char c)
{
  const int chunk_size = internal_buffer_size;

  unsigned oldlength = Length();
  if (oldlength + 1 >= size) {
    size += chunk_size;
    char* r = new char[size];
Count(size);
    strcpy(r, str);
    deallocate(str);
    str = r;
  }
  str[oldlength] = c;
  str[oldlength+1] = '\0';
}


String operator + (const String& s1, const String& s2)
{
  String r = s1;
  r += s2;
  return r;
}


// ----------------------------------------------------------------------------
// Subscripting

char String :: operator () (unsigned i) const
{
  if (i < Length())
    return str[i];
  else
    return '\0';
}


String String :: operator () (unsigned start, unsigned n) const
{
  static char* r = 0;        // temporary storage
  delete r;

  unsigned len = Length();
  if (start >= len)
    return "";
  n = min(n, len-start);

  r = new char[n + 1];
  strncpy(r, str+start, n);
  r[n] = 0;
  return r;
}


// ----------------------------------------------------------------------------
// Comparisons


boolean operator == (const String& s1, const char* s2)
{
  if (s2 == nil)
    s2 = "";
  return s1.str[0] == s2[0] && strcmp(s1.str, s2) == 0;
}


boolean operator == (char* s1, const String& s2)
{
  if (s1 == nil)
    s1 = "";
  return s1[0] == s2.str[0] && strcmp(s1, s2.str) == 0;
}


// ----------------------------------------------------------------------------
// Misc. utility functions


char* String :: Copy() const
{
  char* s = new char[Length() + 1];
  strcpy(s, str);
  return s;
}


String String :: upper() const
{
  String t = *this;
  register char* p = &t.str[t.Length()];
  while (--p >= t.str)
    if (islower(*p)) *p = toupper(*p);
  return t;
}


String String :: lower() const
{
  String t = *this;
  register char* p = &t.str[t.Length()];
  while (--p >= t.str)
    if (isupper(*p)) *p = tolower(*p);
  return t;
}


unsigned String :: Hashval() const
{
  register char* p = str;
  register unsigned h = 0;
  while (*p != 0)
    h += unsigned(*(p++));
  return h;
}


// ----------------------------------------------------------------------------
// Input/output on streams

ostream& operator << (ostream& o, const String& s)
{
  o << s.str;
  return o;
}


istream& operator >> (istream& i, String& s)
{
  char c;
  s = "";

  while (i.get(c) && isspace(c)) // skip to next word
    ;
  if (i) {            // read a word
    do
      s += c;
    while (i.get(c) && !isspace(c));
    if (i)
      i.putback(c);
  }
  return i;
}