StarMirror/xlnt
1
0
Fork 0
mirror of https://github.com/tfussell/xlnt.git synced 2024-03-22 13:11:17 +08:00
Code Issues Projects Releases Wiki Activity

Improving the hash function

Browse Source 
Using Szudzik's pairing function (more efficient than the previous approach or Cantor's)
This commit is contained in:
Teebonne 2022-09-10 21:35:48 +01:00 committed by GitHub
parent fbae8cd6c1
commit 48c126cf9c
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 6 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
include/xlnt/cell/cell_reference.hpp
View File

@ -262,11 +262,13 @@ namespace std {
template <>
struct hash<xlnt::cell_reference>
{
size_t operator()(const xlnt::cell_reference &x) const
size_t operator()(const xlnt::cell_reference &x) const // using Szudzik's pairing function
{
static_assert(std::is_same<decltype(x.row()), std::uint32_t>::value, "this hash function expects both row and column to be 32-bit numbers");
static_assert(std::is_same<decltype(x.column_index()), std::uint32_t>::value, "this hash function expects both row and column to be 32-bit numbers");
return hash<std::uint64_t>{}(x.row() | static_cast<std::uint64_t>(x.column_index()) << 32);
if (x.column_index() >= x.row()) {
return hash<size_t>{}(x.column_index() * x.column_index() + x.column_index() + x.row());
} else {
return hash<size_t>{}(x.column_index() + x.row() * x.row());
};
}
};
} // namespace std