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Avoid string copy and std::list penalty in strings::Format.

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This commit is contained in:
vng 2012-06-29 18:16:59 -07:00 • committed by Alex Zolotarev
parent 117222c206
commit e98923322e
2 changed files with 31 additions and 49 deletions
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30
base/string_format.cpp
View file

@ -1,25 +1,27 @@
#include "string_format.hpp"
#include "logging.hpp"
#include "../std/list.hpp"
namespace strings
{
string const FormatImpl(string const & s, list<string> const & l)
string const FormatImpl(string const & s, string arr[], size_t count)
{
size_t offs = 0;
list<size_t> fieldOffs;
string temp = s;
string res = s;
while (true)
{
offs = temp.find("%", offs);
offs = res.find("%", offs);
if (offs == string::npos)
break;
else
{
if ((offs != 0) && (temp[offs - 1] == '\\'))
if ((offs != 0) && (res[offs - 1] == '\\'))
{
temp = temp.erase(offs - 1, 1);
res = res.erase(offs - 1, 1);
--offs;
}
else
@ -30,18 +32,14 @@ namespace strings
}
offs = 0;
size_t i = 0;
string res = temp;
list<size_t>::const_iterator offsIt;
list<string>::const_iterator strIt;
for (offsIt = fieldOffs.begin(), strIt = l.begin();
(offsIt != fieldOffs.end()) && (strIt != l.end());
++offsIt, ++strIt)
for (list<size_t>::const_iterator offsIt = fieldOffs.begin();
(offsIt != fieldOffs.end()) && (i < count);
++offsIt, ++i)
{
res.replace(*offsIt + offs, 1, *strIt);
offs += strIt->size() - 1;
res.replace(*offsIt + offs, 1, arr[i]);
offs += (arr[i].size() - 1);
}
return res;

50
base/string_format.hpp
View file

@ -1,73 +1,57 @@
#pragma once
#include "base.hpp"
#include "macros.hpp"
#include "../std/string.hpp"
#include "../std/sstream.hpp"
#include "../std/list.hpp"
namespace strings
{
template <typename T>
string ToString(T t)
string ToString(T const & t)
{
// May be we should use DebugPrint here. Not sure.
ostringstream out;
out << t;
return out.str();
}
string const FormatImpl(string const & s, list<string> const & l);
string const FormatImpl(string const & s, string arr[], size_t count);
template <typename T1>
string const Format(string const & s, T1 const & t1)
{
list<string> l;
l.push_back(ToString(t1));
return FormatImpl(s, l);
string arr[] = { ToString(t1) };
return FormatImpl(s, arr, ARRAY_SIZE(arr));
}
template <typename T1, typename T2>
string const Format(string const & s, T1 const & t1, T2 const & t2)
{
list<string> l;
l.push_back(ToString(t1));
l.push_back(ToString(t2));
return FormatImpl(s, l);
string arr[] = { ToString(t1), ToString(t2) };
return FormatImpl(s, arr, ARRAY_SIZE(arr));
}
template <typename T1, typename T2, typename T3>
string const Format(string const & s, T1 const & t1, T2 const & t2, T3 const & t3)
{
list<string> l;
l.push_back(ToString(t1));
l.push_back(ToString(t2));
l.push_back(ToString(t3));
return FormatImpl(s, l);
string arr[] = { ToString(t1), ToString(t2), ToString(t3) };
return FormatImpl(s, arr, ARRAY_SIZE(arr));
}
template <typename T1, typename T2, typename T3, typename T4>
string const Format(string const & s, T1 const & t1, T2 const & t2, T3 const & t3, T4 const & t4)
{
list<string> l;
l.push_back(ToString(t1));
l.push_back(ToString(t2));
l.push_back(ToString(t3));
l.push_back(ToString(t4));
return FormatImpl(s, l);
string arr[] = { ToString(t1), ToString(t2), ToString(t3), ToString(t4) };
return FormatImpl(s, arr, ARRAY_SIZE(arr));
}
template <typename T1, typename T2, typename T3, typename T4, typename T5>
string const Format(string const & s, T1 const & t1, T2 const & t2, T3 const & t3, T4 const & t4, T5 const & t5)
{
list<string> l;
l.push_back(ToString(t1));
l.push_back(ToString(t2));
l.push_back(ToString(t3));
l.push_back(ToString(t4));
l.push_back(ToString(t5));
return FormatImpl(s, l);
string arr[] = { ToString(t1), ToString(t2), ToString(t3), ToString(t4), ToString(t5) };
return FormatImpl(s, arr, ARRAY_SIZE(arr));
}
}