/// <summary>
/// Symmetrical with <see cref="Span(ICharSequence, int, SpanCondition, out int)"/>.
/// Span the trailing substring for which each character c has <paramref name="spanCondition"/>==Contains(c).
/// It must be <paramref name="s"/>.Length >= limit and <paramref name="spanCondition"/>==0 or 1.
/// </summary>
/// <returns>The string index which starts the span (i.e. inclusive).</returns>
public int SpanBack(ICharSequence s, int limit, SpanCondition spanCondition)
{
char c, c2;
if (SpanCondition.NotContained != spanCondition)
{
// span
for (; ;)
{
c = s[--limit];
if (c <= 0xff)
{
if (!latin1Contains[c])
{
break;
}
}
else if (c <= 0x7ff)
{
if ((table7FF[c & 0x3f] & (1 << (c >> 6))) == 0)
{
break;
}
}
else if (c < 0xd800 ||
c < 0xdc00 || 0 == limit || (c2 = s[limit - 1]) < 0xd800 || c2 >= 0xdc00)
{
int lead = c >> 12;
int twoBits = (bmpBlockBits[(c >> 6) & 0x3f] >> lead) & 0x10001;
if (twoBits <= 1)
{
// All 64 code points with the same bits 15..6
// are either in the set or not.
if (twoBits == 0)
{
break;
}
}
else
{
// Look up the code point in its 4k block of code points.
if (!ContainsSlow(c, list4kStarts[lead], list4kStarts[lead + 1]))
{
break;
}
}
}
else
{
// surrogate pair
int supplementary = Character.ToCodePoint(c2, c);
if (!ContainsSlow(supplementary, list4kStarts[0x10], list4kStarts[0x11]))
{
break;
}
--limit;
}
if (0 == limit)
{
return(0);
}
}
}
else
{
// span not
for (; ;)
{
c = s[--limit];
if (c <= 0xff)
{
if (latin1Contains[c])
{
break;
}
}
else if (c <= 0x7ff)
{
if ((table7FF[c & 0x3f] & (1 << (c >> 6))) != 0)
{
break;
}
}
else if (c < 0xd800 ||
c < 0xdc00 || 0 == limit || (c2 = s[limit - 1]) < 0xd800 || c2 >= 0xdc00)
{
int lead = c >> 12;
int twoBits = (bmpBlockBits[(c >> 6) & 0x3f] >> lead) & 0x10001;
if (twoBits <= 1)
{
// All 64 code points with the same bits 15..6
// are either in the set or not.
if (twoBits != 0)
{
break;
}
}
else
{
// Look up the code point in its 4k block of code points.
if (ContainsSlow(c, list4kStarts[lead], list4kStarts[lead + 1]))
{
break;
}
}
}
else
{
// surrogate pair
int supplementary = Character.ToCodePoint(c2, c);
if (ContainsSlow(supplementary, list4kStarts[0x10], list4kStarts[0x11]))
{
break;
}
--limit;
}
if (0 == limit)
{
return(0);
}
}
}
return(limit + 1);
}
/// <summary>
/// Span the initial substring for which each character c has <paramref name="spanCondition"/>==Contains(c).
/// It must be <paramref name="spanCondition"/>==0 or 1.
/// </summary>
/// <param name="s"></param>
/// <param name="start">The start index.</param>
/// <param name="spanCondition"></param>
/// <param name="outCount">If not null: Receives the number of code points in the span.</param>
/// <returns>The limit (exclusive end) of the span.</returns>
/// <remarks>
/// NOTE: to reduce the overhead of function call to Contains(c), it is manually inlined here. Check for
/// sufficient length for trail unit for each surrogate pair. Handle single surrogates as surrogate code points
/// as usual in ICU.
/// </remarks>
public int Span(ICharSequence s, int start, SpanCondition spanCondition,
out int outCount)
{
char c, c2;
int i = start;
int limit = s.Length;
int numSupplementary = 0;
if (SpanCondition.NotContained != spanCondition)
{
// span
while (i < limit)
{
c = s[i];
if (c <= 0xff)
{
if (!latin1Contains[c])
{
break;
}
}
else if (c <= 0x7ff)
{
if ((table7FF[c & 0x3f] & (1 << (c >> 6))) == 0)
{
break;
}
}
else if (c < 0xd800 ||
c >= 0xdc00 || (i + 1) == limit || (c2 = s[i + 1]) < 0xdc00 || c2 >= 0xe000)
{
int lead = c >> 12;
int twoBits = (bmpBlockBits[(c >> 6) & 0x3f] >> lead) & 0x10001;
if (twoBits <= 1)
{
// All 64 code points with the same bits 15..6
// are either in the set or not.
if (twoBits == 0)
{
break;
}
}
else
{
// Look up the code point in its 4k block of code points.
if (!ContainsSlow(c, list4kStarts[lead], list4kStarts[lead + 1]))
{
break;
}
}
}
else
{
// surrogate pair
int supplementary = Character.ToCodePoint(c, c2);
if (!ContainsSlow(supplementary, list4kStarts[0x10], list4kStarts[0x11]))
{
break;
}
++numSupplementary;
++i;
}
++i;
}
}
else
{
// span not
while (i < limit)
{
c = s[i];
if (c <= 0xff)
{
if (latin1Contains[c])
{
break;
}
}
else if (c <= 0x7ff)
{
if ((table7FF[c & 0x3f] & (1 << (c >> 6))) != 0)
{
break;
}
}
else if (c < 0xd800 ||
c >= 0xdc00 || (i + 1) == limit || (c2 = s[i + 1]) < 0xdc00 || c2 >= 0xe000)
{
int lead = c >> 12;
int twoBits = (bmpBlockBits[(c >> 6) & 0x3f] >> lead) & 0x10001;
if (twoBits <= 1)
{
// All 64 code points with the same bits 15..6
// are either in the set or not.
if (twoBits != 0)
{
break;
}
}
else
{
// Look up the code point in its 4k block of code points.
if (ContainsSlow(c, list4kStarts[lead], list4kStarts[lead + 1]))
{
break;
}
}
}
else
{
// surrogate pair
int supplementary = Character.ToCodePoint(c, c2);
if (ContainsSlow(supplementary, list4kStarts[0x10], list4kStarts[0x11]))
{
break;
}
++numSupplementary;
++i;
}
++i;
}
}
int spanLength = i - start;
outCount = spanLength - numSupplementary; // number of code points
return(i);
}
