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.
- */
+// An abstract number of element in a sequence. The sequence has a first element.
+// This type should be used instead of integer because 2 contradicting traditions can
+// call a first element '0' or '1' which makes integer type ambiguous.
+class OrdinalNumber {
+public:
+ static OrdinalNumber fromZeroBasedInt(int zeroBasedInt) { return OrdinalNumber(zeroBasedInt); }
+ static OrdinalNumber fromOneBasedInt(int oneBasedInt) { return OrdinalNumber(oneBasedInt - 1); }
+ OrdinalNumber() { }
+
+ int zeroBasedInt() const { return m_zeroBasedValue; }
+ int oneBasedInt() const { return m_zeroBasedValue + 1; }
-template<typename T>
+ bool operator==(OrdinalNumber other) { return m_zeroBasedValue == other.m_zeroBasedValue; }
+ bool operator!=(OrdinalNumber other) { return !((*this) == other); }
+
+ static OrdinalNumber first() { return OrdinalNumber(0); }
+ static OrdinalNumber beforeFirst() { return OrdinalNumber(-1); }
+
+private:
+ OrdinalNumber(int zeroBasedInt) : m_zeroBasedValue(zeroBasedInt) { }
+ int m_zeroBasedValue;
+};
+
+
+// TextPosition structure specifies coordinates within an text resource. It is used mostly
+// for saving script source position.
class TextPosition {
public:
- TextPosition(T line, T column)
+ TextPosition(OrdinalNumber line, OrdinalNumber column)
: m_line(line)
, m_column(column)
{
}
- TextPosition() {}
+ 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<T> minimumPosition() { return TextPosition<T>(T::base(), T::base()); }
+ static TextPosition minimumPosition() { return TextPosition(OrdinalNumber::first(), OrdinalNumber::first()); }
// A value with line value less than a minimum; used as an impossible position.
- static TextPosition<T> belowRangePosition() { return TextPosition<T>(T::belowBase(), T::belowBase()); }
+ static TextPosition belowRangePosition() { return TextPosition(OrdinalNumber::beforeFirst(), OrdinalNumber::beforeFirst()); }
- T m_line;
- T m_column;
+ OrdinalNumber m_line;
+ OrdinalNumber 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::OrdinalNumber;
-using WTF::TextPosition0;
-using WTF::TextPosition1;
+using WTF::TextPosition;
#endif // TextPosition_h
projects / vuplus_webkit / blobdiff