static void diffRecursively (TextDiff& td, const StringRegion& a, const StringRegion& b)
{
int indexA, indexB;
const int len = findLongestCommonSubstring (a.text, a.length,
b.text, b.length,
indexA, indexB);
if (len >= minLengthToMatch)
{
if (indexA > 0 && indexB > 0)
diffSkippingCommonStart (td, StringRegion (a.text, a.start, indexA),
StringRegion (b.text, b.start, indexB));
else if (indexA > 0)
addDeletion (td, b.start, indexA);
else if (indexB > 0)
addInsertion (td, b.text, b.start, indexB);
diffRecursively (td, StringRegion (a.text + indexA + len, a.start + indexA + len, a.length - indexA - len),
StringRegion (b.text + indexB + len, b.start + indexB + len, b.length - indexB - len));
}
else
{
if (a.length > 0) addDeletion (td, b.start, a.length);
if (b.length > 0) addInsertion (td, b.text, b.start, b.length);
}
}
static int findLongestCommonSubstring (String::CharPointerType a, const int lenA, int& indexInA,
String::CharPointerType b, const int lenB, int& indexInB) noexcept
{
if (lenA == 0 || lenB == 0)
return 0;
if (lenA * lenB > maxComplexity)
return findCommonSuffix (a, lenA, indexInA,
b, lenB, indexInB);
const size_t scratchSpace = sizeof (int) * (2 + 2 * (size_t) lenB);
if (scratchSpace < 4096)
{
int* scratch = (int*) alloca (scratchSpace);
return findLongestCommonSubstring (a, lenA, indexInA, b, lenB, indexInB, scratchSpace, scratch);
}
HeapBlock<int> scratch (scratchSpace);
return findLongestCommonSubstring (a, lenA, indexInA, b, lenB, indexInB, scratchSpace, scratch);
}
