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tag/FixString: add optimistic quick check

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Optimizes a few nanoseconds from the common code path.
This commit is contained in:
Max Kellermann 2020-04-24 15:40:51 +02:00
parent cc72ceb368
commit 8a28f7b0a1
1 changed files with 15 additions and 0 deletions
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15
src/tag/FixString.cxx
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@ -24,6 +24,7 @@
#include "util/StringView.hxx" #include "util/StringView.hxx"
#include "util/UTF8.hxx" #include "util/UTF8.hxx"
#include <algorithm>
#include <cassert> #include <cassert>
#include <stdlib.h> #include <stdlib.h>
@ -115,9 +116,23 @@ clear_non_printable(StringView src)
return { dest, src.size }; return { dest, src.size };
} }
gcc_pure
static bool
IsSafe(StringView s) noexcept
{
return std::all_of(s.begin(), s.end(),
[](char ch){
return IsASCII(ch) && IsPrintableASCII(ch);
});
}
WritableBuffer<char> WritableBuffer<char>
FixTagString(StringView p) FixTagString(StringView p)
{ {
if (IsSafe(p))
/* optimistic optimization for the common case */
return nullptr;
auto utf8 = fix_utf8(p); auto utf8 = fix_utf8(p);
if (!utf8.IsNull()) if (!utf8.IsNull())
p = {utf8.data, utf8.size}; p = {utf8.data, utf8.size};