private static bool Match <T>(
int increment,
T[] sequence,
SkippingGlyphIterator iterator,
Func <T, GlyphShapingData, bool> condition,
Span <int> matches)
{
ushort position = iterator.Index;
ushort offset = iterator.Increment(increment);
IGlyphShapingCollection collection = iterator.Collection;
int i = 0;
while (i < sequence.Length && i < MaxContextLength && offset < collection.Count)
{
if (!condition(sequence[i], collection.GetGlyphShapingData(offset)))
{
break;
}
if (matches.Length == MaxContextLength)
{
matches[i] = iterator.Index;
}
i++;
offset = iterator.Next();
}
iterator.Index = position;
return(i == sequence.Length);
}
public static bool ApplyChainedClassSequenceRule(
SkippingGlyphIterator iterator,
ChainedClassSequenceRuleTable rule,
ClassDefinitionTable inputClassDefinitionTable,
ClassDefinitionTable backtrackClassDefinitionTable,
ClassDefinitionTable lookaheadClassDefinitionTable)
{
if (rule.BacktrackSequence.Length > 0 &&
!MatchClassSequence(iterator, -rule.BacktrackSequence.Length, rule.BacktrackSequence, backtrackClassDefinitionTable))
{
return(false);
}
if (rule.InputSequence.Length > 0 &&
!MatchClassSequence(iterator, 1, rule.InputSequence, inputClassDefinitionTable))
{
return(false);
}
if (rule.LookaheadSequence.Length > 0 &&
!MatchClassSequence(iterator, 1 + rule.InputSequence.Length, rule.LookaheadSequence, lookaheadClassDefinitionTable))
{
return(false);
}
return(true);
}
public static bool MatchSequence(SkippingGlyphIterator iterator, int increment, ushort[] sequence)
=> Match(
increment,
sequence,
iterator,
(component, data) => component == data.GlyphIds[0],
default);
public static bool MatchCoverageSequence(
SkippingGlyphIterator iterator,
CoverageTable[] coverageTable,
int increment)
=> Match(
increment,
coverageTable,
iterator,
(component, data) => component.CoverageIndexOf(data.GlyphIds[0]) >= 0,
default);
public static bool MatchClassSequence(
SkippingGlyphIterator iterator,
int increment,
ushort[] sequence,
ClassDefinitionTable classDefinitionTable)
=> Match(
increment,
sequence,
iterator,
(component, data) => component == classDefinitionTable.ClassIndexOf(data.GlyphIds[0]),
default);
public static bool MatchInputSequence(SkippingGlyphIterator iterator, Tag feature, ushort increment, ushort[] sequence, Span <int> matches)
=> Match(
increment,
sequence,
iterator,
(component, data) =>
{
if (!ContainsFeatureTag(data.Features, feature))
{
return(false);
}
return(component == data.GlyphIds[0]);
},
matches);
public static bool ApplyChainedSequenceRule(SkippingGlyphIterator iterator, ChainedSequenceRuleTable rule)
{
if (rule.BacktrackSequence.Length > 0 &&
!MatchSequence(iterator, -rule.BacktrackSequence.Length, rule.BacktrackSequence))
{
return(false);
}
if (rule.InputSequence.Length > 0 &&
!MatchSequence(iterator, 1, rule.InputSequence))
{
return(false);
}
if (rule.LookaheadSequence.Length > 0 &&
!MatchSequence(iterator, 1 + rule.InputSequence.Length, rule.LookaheadSequence))
{
return(false);
}
return(true);
}