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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 INC. 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 INC. 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 TextPosition_h
#define TextPosition_h
#include <wtf/Assertions.h>
namespace WTF {
/*
* Text Position
*
* TextPosition structure specifies coordinates within an text resource. It is used mostly
* for saving script source position.
*
* Later TextPosition0 and TextPosition1 and both number types can be merged together quite easily.
*
* 0-based and 1-based
*
* Line and column numbers could be interpreted as zero-based or 1-based. Since
* both practices coexist in WebKit source base, 'int' type should be replaced with
* a dedicated wrapper types, so that compiler helped us with this ambiguity.
*
* Here we introduce 2 types of numbers: ZeroBasedNumber and OneBasedNumber and
* 2 corresponding types of TextPosition structure. While only one type ought to be enough,
* this is done to keep transition to the new types as transparent as possible:
* e.g. in areas where 0-based integers are used, TextPosition0 should be introduced. This
* way all changes will remain trackable.
*
* Later both number types can be merged in one type quite easily.
*
* For type safety and for the future type merge it is important that all operations in API
* that accept or return integer have a name explicitly defining base of integer. For this reason
* int-receiving constructors are hidden from API.
*/
template<typename NUMBER>
class TextPosition {
public:
TextPosition(NUMBER line, NUMBER column)
: m_line(line)
, m_column(column)
{
}
TextPosition() {}
bool operator==(const TextPosition& other) { return m_line == other.m_line && m_column == other.m_column; }
bool operator!=(const TextPosition& other) { return !((*this) == other); }
// A 'minimum' value of position, used as a default value.
static TextPosition<NUMBER> minimumPosition() { return TextPosition<NUMBER>(NUMBER::base(), NUMBER::base()); }
// A value with line value less than a minimum; used as an impossible position.
static TextPosition<NUMBER> belowRangePosition() { return TextPosition<NUMBER>(NUMBER::belowBase(), NUMBER::belowBase()); }
NUMBER m_line;
NUMBER m_column;
};
class OneBasedNumber;
// An int wrapper that always reminds you that the number should be 0-based
class ZeroBasedNumber {
public:
static ZeroBasedNumber fromZeroBasedInt(int zeroBasedInt) { return ZeroBasedNumber(zeroBasedInt); }
ZeroBasedNumber() {}
int zeroBasedInt() const { return m_value; }
int convertAsOneBasedInt() const { return m_value + 1; }
OneBasedNumber convertToOneBased() const;
bool operator==(ZeroBasedNumber other) { return m_value == other.m_value; }
bool operator!=(ZeroBasedNumber other) { return !((*this) == other); }
static ZeroBasedNumber base() { return 0; }
static ZeroBasedNumber belowBase() { return -1; }
private:
ZeroBasedNumber(int value) : m_value(value) {}
int m_value;
};
// An int wrapper that always reminds you that the number should be 1-based
class OneBasedNumber {
public:
static OneBasedNumber fromOneBasedInt(int oneBasedInt) { return OneBasedNumber(oneBasedInt); }
OneBasedNumber() {}
int oneBasedInt() const { return m_value; }
int convertAsZeroBasedInt() const { return m_value - 1; }
ZeroBasedNumber convertToZeroBased() const { return ZeroBasedNumber::fromZeroBasedInt(m_value - 1); }
bool operator==(OneBasedNumber other) { return m_value == other.m_value; }
bool operator!=(OneBasedNumber other) { return !((*this) == other); }
static OneBasedNumber base() { return 1; }
static OneBasedNumber belowBase() { return 0; }
private:
OneBasedNumber(int value) : m_value(value) {}
int m_value;
};
typedef TextPosition<ZeroBasedNumber> TextPosition0;
typedef TextPosition<OneBasedNumber> TextPosition1;
inline TextPosition0 toZeroBasedTextPosition(const TextPosition1& position)
{
return TextPosition0(position.m_line.convertToZeroBased(), position.m_column.convertToZeroBased());
}
inline TextPosition1 toOneBasedTextPosition(const TextPosition0& position)
{
return TextPosition1(position.m_line.convertToOneBased(), position.m_column.convertToOneBased());
}
inline OneBasedNumber ZeroBasedNumber::convertToOneBased() const
{
return OneBasedNumber::fromOneBasedInt(m_value + 1);
}
}
using WTF::TextPosition0;
using WTF::TextPosition1;
#endif // TextPosition_h
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