The problem:
Here's a new idea for implementing the seuqnce class from Section 3.2. Instead of the items being stored on a linked list they will be stored using two stacks as private member variables with the following:
1. The bottom of the first stack is the beginning of the sequence.
2. The elements of the sequence continue up to the top of the first stack.
3. The next element of the sequence is then the top of the second stack.
4. And the elements of the sequence is then the top of the sequence then continues down to the bottom of the second sequence (which is the end of the sequence)
5. If there is a current element, then that element is at the top of the first stack.
You should delete the CAPACITY constant, but don't change any of the prototypes for any of the public member functions.
All of the public member functions should take constant time with one exception.
Note: If you use a correctly written stack class for your two private member variables, then you do not need to write your own assignment operator, copy constructor, or destructor. The reason for this is that C++ provides automatic versions of all three of these items, and the automatic versions call the respective functions for each of the member vari- ables of the new class.
sequence4.h
#ifndef _STACK_SEQUENCE_H_
#define _STACK_SAVITCH_SEQUENCE_H_
#include // Provides size_t
#include
namespace stack_sequence_4
{
template
class sequence
{
public:
// TYPEDEFS and MEMBER CONSTANTS
typedef std::size_t size_type;
// CONSTRUCTOR
sequence( );
// MODIFICATION MEMBER FUNCTIONS
void start( );
void advance( );
void insert(const T& entry);
void attach(const T& entry);
void remove_current( );
// CONSTANT MEMBER FUNCTIONS
size_type size( ) const;
bool is_item( ) const;
T current( ) const;
private:
std::stack first;
std::stack second;
};
}
sequence_exam4.cpp
#include // Provides cout.
#include // Provides size_t.
#include "sequence4.h" // Provides the sequence class with double items.
using namespace std;
using namespace stack_sequence_4;
// Descriptions and points for each of the tests:
const size_t MANY_TESTS = 3;
const int POINTS[MANY_TESTS+1] = {
100, // Total points for all tests.
50, // Test 1 points
25, // Test 2 points
25 // Test 3 points
};
const char DESCRIPTION[MANY_TESTS+1][256] = {
"tests for Chapter 3 sequence Class",
"Testing insert, attach, and the constant member functions",
"Testing situations where the cursor goes off the sequence",
"Testing remove_current"
};
// **************************************************************************
// bool test_basic(const sequence& test, size_t s, bool has_cursor)
// Postcondition: A return value of true indicates:
// a. test.size() is s, and
// b. test.is_item() is has_cursor.
// Otherwise the return value is false.
// In either case, a description of the test result is printed to cout.
// **************************************************************************
bool test_basic(const sequence& test, size_t s, bool has_cursor)
{
bool answer;
cout << "Testing that size() returns " << s << " ... ";
cout.flush( );
answer = (test.size( ) == s);
cout << (answer ? "Passed." : "Failed.") << endl;
if (answer)
{
cout << "Testing that is_item() returns ";
cout << (has_cursor ? "true" : "false") << " ... ";
cout.flush( );
answer = (test.is_item( ) == has_cursor);
cout << (answer ? "Passed." : "Failed.") << endl;
}
return answer;
}
// **************************************************************************
// bool test_items(sequence& test, size_t s, size_t i, double items[])
// The function determines if the test sequence has the correct items
// Precondition: The size of the items array is at least s.
// Postcondition: A return value of true indicates that test.current()
// is equal to items[i], and after test.advance() the result of
// test.current() is items[i+1], and so on through items[s-1].
// At this point, one more advance takes the cursor off the sequence.
// If any of this fails, the return value is false.
// NOTE: The test sequence has been changed by advancing its cursor.
// **************************************************************************
bool test_items(sequence& test, size_t s, size_t i, double items[])
{
bool answer = true;
cout << "The cursor should be at item [" << i << "]" << " of the sequencen";
cout << "(counting the first item as [0]). I will advance the cursorn";
cout << "to the end of the sequence, checking that each item is correct...";
cout.flush( );
while ((i < s) && test.is_item( ) && (test.current( ) == items[i]))
{
i++;
test.advance( );
}
if ((i != s) && !test.is_item( ))
{ // The test.is_item( ) function returns false too soon.
cout << "n Cursor fell off the sequence too soon." << endl;
answer = false;
}
else if (i != s)
{ // The test.current( ) function returned a wrong value.
cout << "n The item [" << i << "] should be " << items[i] << ",n";
cout << " but it was " << test.current( ) << " instead.n";
answer = false;
}
else if (test.is_item( ))
{ // The test.is_item( ) function returns true after moving off the sequence.
cout << "n The cursor was moved off the sequence,";
cout << " but is_item still returns true." << endl;
answer = false;
}
cout << (answer ? "Passed." : "Failed.") << endl;
return answer;
}
// **************************************************************************
// bool correct(sequence test, size_t s, size_t cursor_spot, double items[])
// This function determines if the sequence (test) is "correct" according to
// these requirements:
// a. it has exactly s items.
// b. the items (starting at the front) are equal to
// double[0] ... double[size-1]
// c. if cursor_spot < size, then test's cursor must be at
// the location given by cursor_spot.
// d. if cursor_spot >= size, then test must not have a cursor.
// NOTE: The function also moves the cursor off the sequence.
// **************************************************************************
bool correct(sequence& test, size_t size, size_t cursor_spot, double items[])
{
bool has_cursor = (cursor_spot < size);
// Check the sequence's size and whether it has a cursor.
if (!test_basic(test, size, has_cursor))
{
cout << "Basic test of size() or is_item() failed." << endl << endl;
return false;
}
// If there is a cursor, check the items from cursor to end of the sequence.
if (has_cursor && !test_items(test, size, cursor_spot, items))
{
cout << "Test of the sequence's items failed." << endl << endl;
return false;
}
// Restart the cursor at the front of the sequence and test items again.
cout << "I'll call start() and look at the items one more time..." << endl;
test.start( );
if (has_cursor && !test_items(test, size, 0, items))
{
cout << "Test of the sequence's items failed." << endl << endl;
return false;
}
// If the code reaches here, then all tests have been passed.
cout << "All tests passed for this sequence." << endl << endl;
return true;
}
// **************************************************************************
// int test1( )
// Performs some basic tests of insert, attach, and the constant member
// functions. Returns POINTS[1] if the tests are passed. Otherwise returns 0.
// **************************************************************************
int test1( )
{
sequence empty; // An empty sequence
sequence test; // A sequence to add items to
double items1[4] = { 5, 10, 20, 30 }; // These 4 items are put in a sequence
double items2[4] = { 10, 15, 20, 30 }; // These are put in another sequence
// Test that the empty sequence is really empty
cout << "Starting with an empty sequence." << endl;
if (!correct(empty, 0, 0, items1)) return 0;
// Test the attach function to add something to an empty sequence
cout << "I am now using attach to put 10 into an empty sequence." << endl;
test.attach(10);
if (!correct(test, 1, 0, items2)) return 0;
// Test the insert function to add something to an empty sequence
cout << "I am now using insert to put 10 into an empty sequence." << endl;
test = empty;
test.insert(10);
if (!correct(test, 1, 0, items2)) return 0;
// Test the insert function to add an item at the front of a sequence
cout << "I am now using attach to put 10,20,30 in an empty sequence.n";
cout << "Then I move the cursor to the start and insert 5." << endl;
test = empty;
test.attach(10);
test.attach(20);
test.attach(30);
test.start( );
test.insert(5);
if (!correct(test, 4, 0, items1)) return 0;
// Test the insert function to add an item in the middle of a sequence
cout << "I am now using attach to put 10,20,30 in an empty sequence.n";
cout << "Then I move the cursor to the start, advance once, ";
cout << "and insert 15." << endl;
test = empty;
test.attach(10);
test.attach(20);
test.attach(30);
test.start( );
test.advance( );
test.insert(15);
if (!correct(test, 4, 1, items2)) return 0;
// Test the attach function to add an item in the middle of a sequence
cout << "I am now using attach to put 10,20,30 in an empty sequence.n";
cout << "Then I move the cursor to the start and attach 15 ";
cout << "after the 10." << endl;
test = empty;
test.attach(10);
test.attach(20);
test.attach(30);
test.start( );
test.attach(15);
if (!correct(test, 4, 1, items2)) return 0;
// All tests have been passed
cout << "All tests of this first function have been passed." << endl;
return POINTS[1];
}
// **************************************************************************
// int test2( )
// Performs a test to ensure that the cursor can correctly be run off the end
// of the sequence. Also tests that attach/insert work correctly when there is
// no cursor. Returns POINTS[2] if the tests are passed. Otherwise returns 0.
// **************************************************************************
int test2( )
{
sequence test;
size_t i;
// Put three items in the sequence
cout << "Using attach to put 20 and 30 in the sequence, and then callingn";
cout << "advance, so that is_item should return false ... ";
cout.flush( );
test.attach(20);
test.attach(30);
test.advance( );
if (test.is_item( ))
{
cout << "failed." << endl;
return 0;
}
cout << "passed." << endl;
// Insert 10 at the front and run the cursor off the end again
cout << "Inserting 10, which should go at the sequence's front." << endl;
cout << "Then calling advance three times to run cursor off the sequence ...";
cout.flush( );
test.insert(10);
test.advance( ); // advance to the 20
test.advance( ); // advance to the 30
test.advance( ); // advance right off the sequence
if (test.is_item( ))
{
cout << " failed." << endl;
return false;
}
cout << " passed." << endl;
/*
// Attach more items until the sequence becomes full.
// Note that the first attach should attach to the end of the sequence.
cout << "Calling attach to put the numbers 40, 50, 60 ...";
cout << test.CAPACITY*10 << " at the sequence's end." << endl;
for (i = 4; i <= test.CAPACITY; i++)
test.attach(i*10);
// Test that the sequence is correctly filled.
cout << "Now I will test that the sequence has 10, 20, 30, ...";
cout << test.CAPACITY*10 << "." << endl;
test.start( );
for (i = 1; i <= test.CAPACITY; i++)
{
if ((!test.is_item( )) || test.current( ) != i*10)
{
cout << " Test failed to find " << i*10 << endl;
return 0;
}
test.advance( );
}
if (test.is_item( ))
{
cout << " There are too many items on the sequence." << endl;
return false;
}
*/
// All tests passed
cout << "All tests of this second function have been passed." << endl;
return POINTS[2];
}
// **************************************************************************
// int test3( )
// Performs basic tests for the remove_current function.
// Returns POINTS[3] if the tests are passed. Returns POINTS[3] / 4 if almost
// all the tests are passed. Otherwise returns 0.
// **************************************************************************
int test3( )
{
// In the next declarations, I am declaring a sequence called test.
// Both before and after the sequence, I declare a small array of characters,
// and I put the character 'x' into each spot of these arrays.
// Later, if I notice that one of the x's has been changed, or if
// I notice an 'x' inside of the sequence, then the most
// likely reason was that one of the sequence's member functions accessed
// the sequence's array outside of its legal indexes.
char prefix[4] = {'x', 'x', 'x', 'x'};
sequence test;
char suffix[4] = {'x', 'x', 'x', 'x'};
// Within this function, I create several different sequences using the
// items in these arrays:
double items1[1] = { 30 };
double items2[2] = { 10, 30 };
double items3[3] = { 10, 20, 30 };
size_t i; // for-loop control variable
char *char_ptr; // Variable to loop at each character in a sequence's memory
// Build a sequence with three items 10, 20, 30, and remove the middle,
// and last and then first.
cout << "Using attach to build a sequence with 10,30." << endl;
test.attach(10);
test.attach(30);
cout << "Insert a 20 before the 30, so entire sequence is 10,20,30." << endl;
test.insert(20);
if (!correct(test, 3, 1, items3)) return 0;
cout << "Remove the 20, so entire sequence is now 10,30." << endl;
test.start( );
test.advance( );
test.remove_current( );
if (!correct(test, 2, 1, items2)) return 0;
cout << "Remove the 30, so entire sequence is now just 10 with no cursor.";
cout << endl;
test.start( );
test.advance( );
test.remove_current( );
if (!correct(test, 1, 1, items2)) return 0;
cout << "Set the cursor to the start and remove the 10." << endl;
test.start( );
test.remove_current( );
if (!correct(test, 0, 0, items2)) return 0;
// Build a sequence with three items 10, 20, 30, and remove the middle,
// and then first and then last.
cout << "Using attach to build another sequence with 10,30." << endl;
test.attach(10);
test.attach(30);
cout << "Insert a 20 before the 30, so entire sequence is 10,20,30." << endl;
test.insert(20);
if (!correct(test, 3, 1, items3)) return 0;
cout << "Remove the 20, so entire sequence is now 10,30." << endl;
test.start( );
test.advance( );
test.remove_current( );
if (!correct(test, 2, 1, items2)) return 0;
cout << "Set the cursor to the start and remove the 10," << endl;
cout << "so the sequence should now contain just 30." << endl;
test.start( );
test.remove_current( );
if (!correct(test, 1, 0, items1)) return 0;
cout << "Remove the 30 from the sequence, resulting in an empty sequence." << endl;
test.start( );
test.remove_current( );
if (!correct(test, 0, 0, items1)) return 0;
// Build a sequence with three items 10, 20, 30, and remove the first.
cout << "Build a new sequence by inserting 30, 10, 20 (so the sequencen";
cout << "is 20, then 10, then 30). Then remove the 20." << endl;
test.insert(30);
test.insert(10);
test.insert(20);
test.remove_current( );
if (!correct(test, 2, 0, items2)) return 0;
test.start( );
test.remove_current( );
test.remove_current( );
/*
// Just for fun, fill up the sequence, and empty it!
cout << "Just for fun, I'll empty the sequence then fill it up, thenn";
cout << "empty it again. During this process, I'll try to determinen";
cout << "whether any of the sequence's member functions access then";
cout << "array outside of its legal indexes." << endl;
for (i = 0; i < test.CAPACITY; i++)
test.insert(0);
for (i = 0; i < test.CAPACITY; i++)
test.remove_current( );
// Make sure that the character 'x' didn't somehow get into the sequence,
// as that would indicate that the sequence member functions are
// copying data from before or after the sequence into the sequence.
char_ptr = (char *) &test;
for (i = 0; i < sizeof(sequence); i++)
if (char_ptr[i] == 'x')
{
cout << "Illegal array access detected." << endl;
return POINTS[3] / 4;
}
*/
// Make sure that the prefix and suffix arrays still have four
// x's each. Otherwise one of the sequence operations wrote outside of
// the legal boundaries of its array.
for (i = 0; i < 4; i++)
if ((suffix[i] != 'x') || (prefix[i] != 'x'))
{
cout << "Illegal array access detected." << endl;
return POINTS[3] / 4;
}
// All tests passed
cout << "All tests of this third function have been passed." << endl;
return POINTS[3];
}
int run_a_test(int number, const char message[], int test_function( ), int max)
{
int result;
cout << endl << "START OF TEST " << number << ":" << endl;
cout << message << " (" << max << " points)." << endl;
result = test_function( );
if (result > 0)
{
cout << "Test " << number << " got " << result << " points";
cout << " out of a possible " << max << "." << endl;
}
else
cout << "Test " << number << " failed." << endl;
cout << "END OF TEST " << number << "." << endl << endl;
return result;
}
// **************************************************************************
// int main( )
// The main program calls all tests and prints the sum of all points
// earned from the tests.
// **************************************************************************
int main( )
{
int sum = 0;
cout << "Running " << DESCRIPTION[0] << endl;
sum += run_a_test(1, DESCRIPTION[1], test1, POINTS[1]);
sum += run_a_test(2, DESCRIPTION[2], test2, POINTS[2]);
sum += run_a_test(3, DESCRIPTION[3], test3, POINTS[3]);
cout << "If you submit the Chapter 3 sequence to Dora now, you will haven";
cout << sum << " points out of the " << POINTS[0];
cout << " points from this test program.n";
return EXIT_SUCCESS;
}