/// <summary>
/// Is the letter at provided index a leading letter?
/// </summary>
/// <returns><see langword="true" /> if the letter is a leading letter</returns>
private static bool IsLeadingLetter(FastStringBuilder letters, int index)
{
var currentIndexLetter = letters.Get(index);
char previousIndexLetter = default;
if (index != 0)
previousIndexLetter = letters.Get(index - 1);
char nextIndexLetter = default;
if (index < letters.Length - 1)
nextIndexLetter = letters.Get(index + 1);
bool isPreviousLetterNonConnectable = index == 0 ||
!TextUtils.IsRTLCharacter(previousIndexLetter) ||
previousIndexLetter == (int)GeneralLetters.Alef ||
previousIndexLetter == (int)GeneralLetters.Dal ||
previousIndexLetter == (int)GeneralLetters.Thal ||
previousIndexLetter == (int)GeneralLetters.Ra2 ||
previousIndexLetter == (int)GeneralLetters.Zeen ||
previousIndexLetter == (int)GeneralLetters.PersianZe ||
previousIndexLetter == (int)GeneralLetters.Waw ||
previousIndexLetter == (int)GeneralLetters.AlefMad ||
previousIndexLetter ==
(int)GeneralLetters.AlefHamza ||
previousIndexLetter ==
(int)GeneralLetters.Hamza ||
previousIndexLetter ==
(int)GeneralLetters.AlefMaksoor ||
previousIndexLetter ==
(int)GeneralLetters.ZeroWidthNoJoiner ||
previousIndexLetter ==
(int)GeneralLetters.WawHamza ||
previousIndexLetter ==
(int)IsolatedLetters.Alef ||
previousIndexLetter == (int)IsolatedLetters.Dal ||
previousIndexLetter ==
(int)IsolatedLetters.Thal ||
previousIndexLetter == (int)IsolatedLetters.Ra2 ||
previousIndexLetter ==
(int)IsolatedLetters.Zeen ||
previousIndexLetter ==
(int)IsolatedLetters.PersianZe ||
previousIndexLetter == (int)IsolatedLetters.Waw ||
previousIndexLetter ==
(int)IsolatedLetters.AlefMad ||
previousIndexLetter ==
(int)IsolatedLetters.AlefHamza ||
previousIndexLetter ==
(int)IsolatedLetters.Hamza ||
previousIndexLetter ==
(int)IsolatedLetters.AlefMaksoor;
bool canThisLetterBeLeading = currentIndexLetter != ' ' &&
currentIndexLetter != (int)GeneralLetters.Dal &&
currentIndexLetter != (int)GeneralLetters.Thal &&
currentIndexLetter != (int)GeneralLetters.Ra2 &&
currentIndexLetter != (int)GeneralLetters.Zeen &&
currentIndexLetter != (int)GeneralLetters.PersianZe &&
currentIndexLetter != (int)GeneralLetters.Alef &&
currentIndexLetter != (int)GeneralLetters.AlefHamza &&
currentIndexLetter != (int)GeneralLetters.AlefMaksoor &&
currentIndexLetter != (int)GeneralLetters.AlefMad &&
currentIndexLetter != (int)GeneralLetters.WawHamza &&
currentIndexLetter != (int)GeneralLetters.Waw &&
currentIndexLetter !=
(int)GeneralLetters.ZeroWidthNoJoiner &&
currentIndexLetter != (int)GeneralLetters.Hamza;
bool isNextLetterConnectable = index < letters.Length - 1 &&
TextUtils.IsRTLCharacter(nextIndexLetter) &&
nextIndexLetter != (int)GeneralLetters.Hamza &&
nextIndexLetter !=
(int)GeneralLetters.ZeroWidthNoJoiner;
return isPreviousLetterNonConnectable &&
canThisLetterBeLeading &&
isNextLetterConnectable;
}
/// <summary>
/// Is the letter at provided index a middle letter?
/// </summary>
/// <returns><see langword="true" /> if the letter is a middle letter</returns>
private static bool IsMiddleLetter(FastStringBuilder letters, int index)
{
var currentIndexLetter = letters.Get(index);
char previousIndexLetter = default;
if (index != 0)
previousIndexLetter = letters.Get(index - 1);
char nextIndexLetter = default;
if (index < letters.Length - 1)
nextIndexLetter = letters.Get(index + 1);
bool middleLetterCheck = index != 0 &&
currentIndexLetter != (int)GeneralLetters.Alef &&
currentIndexLetter != (int)GeneralLetters.Dal &&
currentIndexLetter != (int)GeneralLetters.Thal &&
currentIndexLetter != (int)GeneralLetters.Ra2 &&
currentIndexLetter != (int)GeneralLetters.Zeen &&
currentIndexLetter != (int)GeneralLetters.PersianZe &&
currentIndexLetter != (int)GeneralLetters.Waw &&
currentIndexLetter != (int)GeneralLetters.AlefMad &&
currentIndexLetter != (int)GeneralLetters.AlefHamza &&
currentIndexLetter != (int)GeneralLetters.AlefMaksoor &&
currentIndexLetter != (int)GeneralLetters.WawHamza &&
currentIndexLetter != (int)GeneralLetters.ZeroWidthNoJoiner &&
currentIndexLetter != (int)GeneralLetters.Hamza;
bool previousLetterCheck = index != 0 &&
previousIndexLetter != (int)GeneralLetters.Alef &&
previousIndexLetter != (int)GeneralLetters.Dal &&
previousIndexLetter != (int)GeneralLetters.Thal &&
previousIndexLetter != (int)GeneralLetters.Ra2 &&
previousIndexLetter != (int)GeneralLetters.Zeen &&
previousIndexLetter != (int)GeneralLetters.PersianZe &&
previousIndexLetter != (int)GeneralLetters.Waw &&
previousIndexLetter != (int)GeneralLetters.AlefMad &&
previousIndexLetter != (int)GeneralLetters.AlefHamza &&
previousIndexLetter != (int)GeneralLetters.AlefMaksoor &&
previousIndexLetter != (int)GeneralLetters.WawHamza &&
previousIndexLetter != (int)GeneralLetters.Hamza &&
previousIndexLetter !=
(int)GeneralLetters.ZeroWidthNoJoiner &&
previousIndexLetter != (int)IsolatedLetters.Alef &&
previousIndexLetter != (int)IsolatedLetters.Dal &&
previousIndexLetter != (int)IsolatedLetters.Thal &&
previousIndexLetter != (int)IsolatedLetters.Ra2 &&
previousIndexLetter != (int)IsolatedLetters.Zeen &&
previousIndexLetter != (int)IsolatedLetters.PersianZe &&
previousIndexLetter != (int)IsolatedLetters.Waw &&
previousIndexLetter != (int)IsolatedLetters.AlefMad &&
previousIndexLetter != (int)IsolatedLetters.AlefHamza &&
previousIndexLetter != (int)IsolatedLetters.AlefMaksoor &&
previousIndexLetter != (int)IsolatedLetters.WawHamza &&
previousIndexLetter != (int)IsolatedLetters.Hamza &&
TextUtils.IsRTLCharacter(previousIndexLetter);
bool nextLetterCheck = index < letters.Length - 1 &&
TextUtils.IsRTLCharacter(nextIndexLetter) &&
nextIndexLetter != (int)GeneralLetters.ZeroWidthNoJoiner &&
nextIndexLetter != (int)GeneralLetters.Hamza &&
nextIndexLetter != (int)IsolatedLetters.Hamza;
return nextLetterCheck && previousLetterCheck && middleLetterCheck;
}
public static void FindTag(
FastStringBuilder str,
int start,
out Tag tag)
{
for (int i = start; i < str.Length;)
{
if (str.Get(i) != '<')
{
i++;
continue;
}
bool calculateHashCode = true;
tag.HashCode = 0;
for (int j = i + 1; j < str.Length; j++)
{
int jChar = str.Get(j);
if (calculateHashCode)
{
if (Char32Utils.IsLetter(jChar))
{
unchecked
{
if (tag.HashCode == 0)
{
tag.HashCode = jChar.GetHashCode();
}
else
{
tag.HashCode = (tag.HashCode * 397) ^ jChar.GetHashCode();
}
}
}
else if (tag.HashCode != 0)
{
// We have computed the hash code. Now we reached a non letter character. We need to stop
calculateHashCode = false;
}
}
// Rich text tag cannot contain < or start with space
if ((j == i + 1 && jChar == ' ') || jChar == '<')
{
break;
}
if (jChar == '>')
{
// Check if the tag is closing, opening or self contained
tag.Start = i;
tag.End = j;
if (str.Get(j - 1) == '/')
{
// This is self contained.
tag.Type = TagType.SelfContained;
}
else if (str.Get(i + 1) == '/')
{
// This is closing
tag.Type = TagType.Closing;
}
else
{
tag.Type = TagType.Opening;
}
return;
}
}
i++;
}
tag.Start = 0;
tag.End = 0;
tag.Type = TagType.None;
tag.HashCode = 0;
}