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/*
* Copyright (C) 2010 Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef PODInterval_h
#define PODInterval_h
#ifndef NDEBUG
#include <wtf/text/StringBuilder.h>
#endif
namespace WebCore {
// Class representing a closed interval which can hold an arbitrary
// Plain Old Datatype (POD) as its endpoints and a piece of user
// data. An important characteristic for the algorithms we use is that
// if two intervals have identical endpoints but different user data,
// they are not considered to be equal. This situation can arise when
// representing the vertical extents of bounding boxes of overlapping
// triangles, where the pointer to the triangle is the user data of
// the interval.
//
// *Note* that the destructors of type T and UserData will *not* be
// called by this class. They must not allocate any memory that is
// required to be cleaned up in their destructors.
//
// The following constructors and operators must be implemented on
// type T:
//
// - Copy constructor (if user data is desired)
// - operator<
// - operator==
// - operator=
//
// If the UserData type is specified, it must support a copy
// constructor and assignment operator.
//
// In debug mode, printing of intervals and the data they contain is
// enabled. This requires the following template specializations to be
// available:
//
// template<> struct WebCore::ValueToString<T> {
// static String string(const T& t);
// };
// template<> struct WebCore::ValueToString<UserData> {
// static String string(const UserData& t);
// };
//
// Note that this class requires a copy constructor and assignment
// operator in order to be stored in the red-black tree.
#ifndef NDEBUG
template<class T>
struct ValueToString;
#endif
template<class T, class UserData = void*>
class PODInterval {
public:
// Constructor from endpoints. This constructor only works when the
// UserData type is a pointer or other type which can be initialized
// with 0.
PODInterval(const T& low, const T& high)
: m_low(low)
, m_high(high)
, m_data(0)
, m_maxHigh(high)
{
}
// Constructor from two endpoints plus explicit user data.
PODInterval(const T& low, const T& high, const UserData data)
: m_low(low)
, m_high(high)
, m_data(data)
, m_maxHigh(high)
{
}
const T& low() const { return m_low; }
const T& high() const { return m_high; }
const UserData& data() const { return m_data; }
bool overlaps(const T& low, const T& high) const
{
if (this->high() < low)
return false;
if (high < this->low())
return false;
return true;
}
bool overlaps(const PODInterval& other) const
{
return overlaps(other.low(), other.high());
}
// Returns true if this interval is "less" than the other. The
// comparison is performed on the low endpoints of the intervals.
bool operator<(const PODInterval& other) const
{
return low() < other.low();
}
// Returns true if this interval is strictly equal to the other,
// including comparison of the user data.
bool operator==(const PODInterval& other) const
{
return (low() == other.low()
&& high() == other.high()
&& data() == other.data());
}
const T& maxHigh() const { return m_maxHigh; }
void setMaxHigh(const T& maxHigh) { m_maxHigh = maxHigh; }
#ifndef NDEBUG
// Support for printing PODIntervals.
String toString() const
{
StringBuilder builder;
builder.append("[PODInterval (");
builder.append(ValueToString<T>::string(low()));
builder.append(", ");
builder.append(ValueToString<T>::string(high()));
builder.append("), data=");
builder.append(ValueToString<UserData>::string(data()));
builder.append(", maxHigh=");
builder.append(ValueToString<T>::string(maxHigh()));
builder.append("]");
return builder.toString();
}
#endif
private:
T m_low;
T m_high;
UserData m_data;
T m_maxHigh;
};
} // namespace WebCore
#endif // PODInterval_h
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