spiralindex< T > Class Template Reference

Spiral about a rectangular matrix, travelling to every point. More...

#include <spiralindex.h>

Collaboration diagram for spiralindex< T >:

List of all members.

Public Member Functions
	spiralindex (T const _rows, T const _columns, boolc anticlockwise=true)
	Define a 2D matrix.
void	reset ()
	Reset the iterator.
boolc	operator! () const
	Is the iterator valid?
void	operator++ ()
	Increment the iterator.
void	pos (T &row, T &col) const
	The current position as a 2D indexed point.
void	pos (T &k2) const
	The current position as an index from the start.
boolc	valid (point2< T > const &p) const
	Is the point within the matrix?
void	indexsequence (T *seq)
	Write the 2D matrix in one go.
Public Attributes
T const	rows
	The number of rows.
T const	columns
	The number of columns.
point2< T >	di [4]
	The four ordered directions.
uint	direction
	Index to the current direction.

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Detailed Description

template<typename T = int>
class spiralindex< T >

Spiral about a rectangular matrix, travelling to every point.

The start is top left. Choose to traverse in either an anticlockwise or clockwise direction. The matrix coordinate system's meaning is preserved so increasing terms go down in the negative y-axis direction.

To reverse the spiral so it travels from the inside out, generate the iteration sequence using indexsequence(T*) and then reverse it.

Definition at line 22 of file spiralindex.h.

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Constructor & Destructor Documentation

template<typename T >

spiralindex< T >::spiralindex	(	T const	_rows,
		T const	_columns,
		boolc	anticlockwise = true
	)			[inline]

Define a 2D matrix.

Definition at line 261 of file spiralindex.h.

  : count(0), countend(_rows*_columns), current(0,0), 
    rows(_rows), columns(_columns)
{
  assert(rows>0);
  assert(columns>0);

  if (anticlockwise)
    directionanticlockwise();
  else
    directionclockwise();
}

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Member Function Documentation

template<typename T >

void spiralindex< T >::indexsequence

(

T *

seq

)

[inline]

Write the 2D matrix in one go.

seq is a M by N matrix.

Definition at line 231 of file spiralindex.h.

References spiralindex< T >::operator!(), spiralindex< T >::operator++(), spiralindex< T >::pos(), and spiralindex< T >::reset().

Referenced by spiralindex3D< T >::spiralindex3D().

{
  //T k2;
  for ( reset(); operator !(); operator++() )
  {
    pos(*seq);
    ++seq;
  }
}

template<typename T = int>

boolc spiralindex< T >::operator!

(

)

const [inline]

Is the iterator valid?

Definition at line 64 of file spiralindex.h.

Referenced by spiralindex< T >::indexsequence().

    { return count < countend; }

template<typename T >

void spiralindex< T >::operator++

(

)

[inline]

Increment the iterator.

Definition at line 321 of file spiralindex.h.

References spiralindex< T >::di, spiralindex< T >::direction, and spiralindex< T >::valid().

Referenced by spiralindex< T >::indexsequence().

{
  ++count;

  point2<T> c2 = current + di[direction];
  if (valid(c2)==false)
  {
    if (c2==start)
    {
      ++direction;
      direction %= 4;

      current += di[direction];
      start = current;

      ++xrange.x;
      --xrange.y;
      ++yrange.x;
      --yrange.y;
    }
    else
    {
      ++direction;
      direction %= 4;

      //start = current;
      current += di[direction];
    }
  }
  else
    current = c2;
}

template<typename T = int>

void spiralindex< T >::pos

(

T &

k2

)

const [inline]

The current position as an index from the start.

Definition at line 72 of file spiralindex.h.

References spiralindex< T >::columns.

    { k2 = current.x*columns+current.y; }

template<typename T = int>

void spiralindex< T >::pos	(	T &	row,
		T &	col
	)			const [inline]

The current position as a 2D indexed point.

Definition at line 69 of file spiralindex.h.

Referenced by spiralindex< T >::indexsequence(), spiralindextest::test01(), and spiralindextest::test02().

    { row=current.x; col=current.y; }

template<typename T >

void spiralindex< T >::reset

(

)

[inline]

Reset the iterator.

Definition at line 303 of file spiralindex.h.

References spiralindex< T >::columns, spiralindex< T >::direction, and spiralindex< T >::rows.

Referenced by spiralindex< T >::indexsequence(), spiralindextest::test01(), and spiralindextest::test02().

{
  current.x = 0;
  current.y = 0;
  count = 0;

  direction=0;

  start.x = 0;
  start.y = 0;

  xrange.x = 0;
  xrange.y = columns-1;
  yrange.x = 0;
  yrange.y = rows-1;
}

template<typename T >

boolc spiralindex< T >::valid

(

point2< T > const &

p

)

const [inline]

Is the point within the matrix?

Definition at line 279 of file spiralindex.h.

References point2< T >::x, and point2< T >::y.

Referenced by spiralindex< T >::operator++().

{
  if (p.x==start.x)
  {
    if (p.y==start.y)
      return false;
  }

  if (p.x<yrange.x)
    return false;

  if (p.y<xrange.x)
    return false;

  if (p.x>yrange.y)
    return false;

  if (p.y>xrange.y)
    return false;

  return true;
}

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Member Data Documentation

template<typename T = int>

T const spiralindex< T >::columns

The number of columns.

Definition at line 47 of file spiralindex.h.

Referenced by spiralindex< T >::pos(), and spiralindex< T >::reset().

template<typename T = int>

point2<T> spiralindex< T >::di[4]

The four ordered directions.

Definition at line 49 of file spiralindex.h.

Referenced by spiralindex< T >::operator++().

template<typename T = int>

uint spiralindex< T >::direction

Index to the current direction.

Definition at line 51 of file spiralindex.h.

Referenced by spiralindex< T >::operator++(), and spiralindex< T >::reset().

template<typename T = int>

T const spiralindex< T >::rows

The number of rows.

Definition at line 45 of file spiralindex.h.

Referenced by spiralindex< T >::reset().

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The documentation for this class was generated from the following file:

• sortsimple/spiralindex.h