string.cpp

粗糙集应用软件

//-------------------------------------------------------------------
// Author........: Aleksander 豩rn
// Date..........:
// Description...:
// Revisions.....:
//===================================================================

#include <stdafx.h> // Precompiled headers.
#include <copyright.h>

#include <kernel/basic/string.h>
#include <kernel/basic/macros.h>

#include <kernel/system/stdlib.h>
#include <kernel/system/stdio.h>
#include <kernel/system/math.h>
#include <kernel/system/iostream.h>
#include <kernel/system/ctype.h>

//-------------------------------------------------------------------
// Static stuff (file scope).
//===================================================================

//-------------------------------------------------------------------
// Method........: StaticCopy
// Author........: Aleksander 豩rn
// Date..........:
// Description...: Copies n bytes and null-terminates.
// Comments......:
// Revisions.....:
//===================================================================

static void
StaticCopy(const char *source, char *destination, int n) {

	if (source == destination) {
    destination[n] = '\0';
		return;
	}

	while (--n >= 0)
		*destination++ = *source++;
	*destination = '\0';

}

//-------------------------------------------------------------------
// Methods for class String.
//===================================================================

//-------------------------------------------------------------------
// Method........: Constructor
// Author........: Aleksander 豩rn
// Date..........:
// Description...:
// Comments......:
// Revisions.....:
//===================================================================

String::String() {
  representation_ = new Representation();
}

//-------------------------------------------------------------------
// Method........: Constructor
// Author........: Aleksander 豩rn
// Date..........:
// Description...:
// Comments......:
// Revisions.....:
//===================================================================

String::String(const char *buffer) {

	// Create a new representation object.
  representation_ = new Representation();

	// Check to avoid trouble.
  if (buffer == NULL)
    buffer = "";

	// Allocate buffer.
	representation_->size_   = strlen(buffer) + 1;
	representation_->buffer_ = new char[representation_->size_];

	// Copy the buffer.
  strcpy(representation_->buffer_, buffer);

}

//-------------------------------------------------------------------
// Method........: Constructor
// Author........: Aleksander 豩rn
// Date..........:
// Description...:
// Comments......:
// Revisions.....:
//===================================================================

String::String(const String &in) {

	// Share the input string's representation object. This makes assignments cheap!
	in.representation_->reference_count_++;
	representation_ = in.representation_;

}

//-------------------------------------------------------------------
// Method........: Constructor
// Author........: Aleksander 豩rn
// Date..........:
// Description...:
// Comments......:
// Revisions.....:
//===================================================================

String::String(char c, int length) {

	if (length < 0)
		length = 0;

	// Create a buffer of the specified length.
  representation_          = new Representation();
  representation_->size_   = length + 1;
  representation_->buffer_ = new char[representation_->size_];

	int i;

	// Fill the buffer with the specified character.
  for (i = 0; i < length; i++)
    representation_->buffer_[i] = c;
  representation_->buffer_[length] = '\0';

}

//-------------------------------------------------------------------
// Method........: Destructor
// Author........: Aleksander 豩rn
// Date..........:
// Description...:
// Comments......:
// Revisions.....:
//===================================================================

String::~String() {

	// Is this the last string using this representation object?
	if (representation_ && --representation_->reference_count_ == 0) {
		delete [] representation_->buffer_;
    delete representation_;
  }

}

//-------------------------------------------------------------------
// Method........: Reserve
// Author........: Aleksander 豩rn
// Date..........: 980703
// Description...: Reserves space so that allocations can be avoided.
// Comments......: Intended for expert use only.
//
//                 Note that the following won't work as intended:
//
//                    String s;
//                    s.Reserve(1000);
//                    s =  "f = ";
//                    s += "(w + x)";
//                    s += "(x + y)";
//                    s += "(y + z)";
//                    ...
//
//                 What happens is that the reserved buffer gets
//                 scrapped in the third line by the assignment
//                 operator '='! To achieve the intended effect of
//                 Reserve, do the following instead:
//
//                    String s;
//                    s.Reserve(1000);
//                    s += "f = ";
//                    s += "(w + x)";
//                    s += "(x + y)";
//                    s += "(y + z)";
//                    ...
//
//                 Consider more optimal reallocation.
// Revisions.....:
//===================================================================

bool
String::Reserve(int length) {

	if (length < 0)
		length = 0;

	if (representation_ == NULL)
		representation_ = new Representation();

	// Already space enough?
	if (representation_->size_ >= length + 1)
		return true;

	// Check current reference count, disconnect if needed.
  if (representation_->reference_count_ > 1) {
    representation_->reference_count_--;
		char *buffer             = representation_->buffer_;
    representation_          = new Representation();
		representation_->size_   = length + 1;
		representation_->buffer_ = new char[representation_->size_];
		strcpy(representation_->buffer_, buffer);
  }
  else {
		representation_->size_   = length + 1;
		char *newbuffer          = new char[representation_->size_];
		if (representation_->buffer_ != NULL) {
			strcpy(newbuffer, representation_->buffer_);
			delete [] representation_->buffer_;
		}
		else {
			strcpy(newbuffer, "");
		}
		representation_->buffer_ = newbuffer;
	}

	return true;

}

//-------------------------------------------------------------------
// Method........: Shrink
// Author........: Aleksander 豩rn
// Date..........: 980703
// Description...:
// Comments......: Intended for expert use only, in conjunction with
//                 the Reserve method.
//
//                 Consider more optimal reallocation.
// Revisions.....:
//===================================================================

bool
String::Shrink() {

	int length = GetLength();

	// Already shrunk to a minimum?
	if (representation_ == NULL || representation_->buffer_ == NULL || representation_->size_ == length + 1)
		return true;

	// Check current reference count, disconnect if needed.
  if (representation_->reference_count_ > 1) {
    representation_->reference_count_--;
		char *buffer             = representation_->buffer_;
    representation_          = new Representation();
		representation_->size_   = length + 1;
		representation_->buffer_ = new char[representation_->size_];
		strcpy(representation_->buffer_, buffer);
  }
  else {
		representation_->size_   = length + 1;
		char *newbuffer          = new char[representation_->size_];
		strcpy(newbuffer, representation_->buffer_);
		delete [] representation_->buffer_;
		representation_->buffer_ = newbuffer;
	}

	return true;

}

//-------------------------------------------------------------------
// Method........: operator =
// Author........: Aleksander 豩rn
// Date..........:
// Description...:
// Comments......:
// Revisions.....: A