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Improve string fast loop

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This commit is contained in:
Vinnie Falco
2019-11-01 10:58:47 -07:00
parent 485aa70367
commit 3150db1069
3 changed files with 44 additions and 114 deletions
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114
include/boost/json/impl/serializer.ipp
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@@ -338,7 +338,7 @@ loop_str:
*p++ = '\"';
stack_.front().st = state::str2;
BOOST_FALLTHROUGH;
#if 1
case state::str2:
{
auto s = str_.data();
@@ -356,16 +356,19 @@ loop_str:
break;
// fast loop
char const* ss = s;
while(s < sn)
{
auto const ch = *s++;
auto const c = esc[static_cast<
unsigned char>(ch)];
if(! c)
{
*p++ = ch;
continue;
}
auto const n = (s - ss) - 1;
std::memcpy(p, ss, n);
ss = s;
p += n;
*p++ = ch;
*p++ = '\\';
*p++ = c;
if(c != 'u')
@@ -377,6 +380,9 @@ loop_str:
*p++ = hex[static_cast<
unsigned char>(ch) & 15];
}
auto const n = s - ss;
std::memcpy(p, ss, n);
p += n;
}
while(p < p1 && s < s1)
{
@@ -442,106 +448,6 @@ loop_str:
state::str3;
BOOST_FALLTHROUGH;
}
#else
case state::str2:
{
auto s = str_.data();
auto const s1 =
s + str_.size();
if(static_cast<unsigned long>(
p1 - p) >= 6 * str_.size())
{
// fast loop
while(s < s1)
{
auto const ch = *s++;
auto const c = esc[static_cast<
unsigned char>(ch)];
if(! c)
{
*p++ = ch;
continue;
}
*p++ = '\\';
*p++ = c;
if(c != 'u')
continue;
*p++ = '0';
*p++ = '0';
*p++ = hex[static_cast<
unsigned char>(ch) >> 4];
*p++ = hex[static_cast<
unsigned char>(ch) & 15];
}
}
else
{
while(p < p1 && s < s1)
{
auto const ch = *s++;
auto const c = esc[static_cast<
unsigned char>(ch)];
if(! c)
{
*p++ = ch;
continue;
}
if(c != 'u')
{
if(p + 2 <= p1)
{
*p++ = '\\';
*p++ = c;
continue;
}
buf_[1] = '\\';
buf_[0] = c;
nbuf_ = 2;
str_ = str_.substr(
s - str_.data());
stack_.front().st =
state::str4;
goto loop;
}
if(p + 6 <= p1)
{
*p++ = '\\';
*p++ = 'u';
*p++ = '0';
*p++ = '0';
*p++ = hex[static_cast<
unsigned char>(ch) >> 4];
*p++ = hex[static_cast<
unsigned char>(ch) & 15];
continue;
}
buf_[5] = '\\';
buf_[4] = 'u';
buf_[3] = '0';
buf_[2] = '0';
buf_[1] = hex[static_cast<
unsigned char>(ch) >> 4];
buf_[0] = hex[static_cast<
unsigned char>(ch) & 15];
nbuf_ = 6;
str_ = str_.substr(
s - str_.data());
stack_.front().st =
state::str4;
goto loop;
}
}
if(s < s1)
{
str_ = str_.substr(
s - str_.data());
goto finish;
}
stack_.front().st =
state::str3;
BOOST_FALLTHROUGH;
}
#endif
case state::str3:
if(p >= p1)