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epee: speedup word/number matching

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Number matching semantics are slightly changed: since this is used
as a filter to check whether a number is signed and/or floating
point, we can speed this up further. strto* functions are called
afterwards and will error out where necessary. We now also accept
numbers like .4 which were not accepted before.

The strto* calls on a boost::string_ref will not access unallocated
memory since the parsers always stop at the first bad character,
and the original string is zero terminated.

in arbitrary time measurement units for some arbitrary test case:

match_number2: 235 -> 70
match_word2: 330 -> 108
This commit is contained in:
moneromooo-monero 2018-12-26 09:46:41 +00:00
parent 6285c43ffc
commit 21777daf6e
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3 changed files with 173 additions and 45 deletions
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72
contrib/epee/include/storages/parserse_base_utils.h
View file

@ -29,6 +29,7 @@
#pragma once
#include <algorithm>
#include <boost/utility/string_ref.hpp>
namespace epee
{
@ -36,6 +37,40 @@ namespace misc_utils
{
namespace parse
{
// 1: digit
// 2: .eE (floating point)
// 4: alpha
// 8: whitespace
// 16: allowed in float but doesn't necessarily mean it's a float
static const constexpr uint8_t lut[256]={
0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 0, 0, // 16
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 32
8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 16, 0, 16, 18, 0, // 48
17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 0, 0, 0, 0, 0, 0, // 64
0, 4, 4, 4, 4, 22, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, // 80
4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 0, 0, 0, 0, 0, // 96
0, 4, 4, 4, 4, 22, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, // 112
4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 0, 0, 0, 0, 0, // 128
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
};
inline bool isspace(char c)
{
return lut[(uint8_t)c] & 8;
}
inline bool isdigit(char c)
{
return lut[(uint8_t)c] & 1;
}
inline std::string transform_to_escape_sequence(const std::string& src)
{
static const char escaped[] = "\b\f\n\r\t\v\"\\/";
@ -159,25 +194,34 @@ namespace misc_utils
return false;
}
}
inline void match_number2(std::string::const_iterator& star_end_string, std::string::const_iterator buf_end, std::string& val, bool& is_float_val, bool& is_signed_val)
inline void match_number2(std::string::const_iterator& star_end_string, std::string::const_iterator buf_end, boost::string_ref& val, bool& is_float_val, bool& is_signed_val)
{
val.clear();
is_float_val = false;
for(std::string::const_iterator it = star_end_string;it != buf_end;it++)
uint8_t float_flag = 0;
is_signed_val = false;
size_t chars = 0;
std::string::const_iterator it = star_end_string;
if (it != buf_end && *it == '-')
{
if(isdigit(*it) || (it == star_end_string && *it == '-') || (val.size() && *it == '.' ) || (is_float_val && (*it == 'e' || *it == 'E' || *it == '-' || *it == '+' )) )
is_signed_val = true;
++chars;
++it;
}
for(;it != buf_end;it++)
{
const uint8_t flags = lut[(uint8_t)*it];
if (flags & 16)
{
if(!val.size() && *it == '-')
is_signed_val = true;
if(*it == '.' )
is_float_val = true;
val.push_back(*it);
float_flag |= flags;
++chars;
}
else
{
val = boost::string_ref(&*star_end_string, chars);
if(val.size())
{
star_end_string = --it;
is_float_val = !!(float_flag & 2);
return;
}
else
@ -186,7 +230,7 @@ namespace misc_utils
}
ASSERT_MES_AND_THROW("wrong number in json entry: " << std::string(star_end_string, buf_end));
}
inline bool match_number(std::string::const_iterator& star_end_string, std::string::const_iterator buf_end, std::string& val)
inline bool match_number(std::string::const_iterator& star_end_string, std::string::const_iterator buf_end, boost::string_ref& val)
{
try
{
@ -199,15 +243,15 @@ namespace misc_utils
return false;
}
}
inline void match_word2(std::string::const_iterator& star_end_string, std::string::const_iterator buf_end, std::string& val)
inline void match_word2(std::string::const_iterator& star_end_string, std::string::const_iterator buf_end, boost::string_ref& val)
{
val.clear();
for(std::string::const_iterator it = star_end_string;it != buf_end;it++)
{
if(!isalpha(*it))
if (!(lut[(uint8_t)*it] & 4))
{
val.assign(star_end_string, it);
val = boost::string_ref(&*star_end_string, std::distance(star_end_string, it));
if(val.size())
{
star_end_string = --it;
@ -218,7 +262,7 @@ namespace misc_utils
}
ASSERT_MES_AND_THROW("failed to match word number in json entry: " << std::string(star_end_string, buf_end));
}
inline bool match_word(std::string::const_iterator& star_end_string, std::string::const_iterator buf_end, std::string& val)
inline bool match_word(std::string::const_iterator& star_end_string, std::string::const_iterator buf_end, boost::string_ref& val)
{
try
{