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Small algorithm improvements to avoid allocations

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TL depends on cppcoro now
This commit is contained in:
jeanlemotan
2024-07-03 16:14:16 +02:00
parent c898a3b653
commit b307f44333
3 changed files with 55 additions and 92 deletions
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include/tl/algorithm/string.h
+52 -90
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@@ -105,49 +105,7 @@ inline void to_upper_ascii(string& str) noexcept
}
template <class String>
tl::vector<String> split_on_any(const String& str, const char* separators, empty_token_policy token_policy = empty_token_policy::discard) noexcept
{
return split_on_any(str, String(separators), token_policy);
}
template <class String, class Delim>
tl::vector<String> split_on_any(const String& str, const Delim& separators, empty_token_policy token_policy = empty_token_policy::discard) noexcept
{
tl::vector<String> dst;
dst.reserve(32);
split_on_any(str,
separators,
[&dst](const String& token)
{
dst.push_back(token);
},
token_policy);
return dst;
}
template <class String, class Delim>
tl::vector<String> split_on_all(const String& str, const Delim& separator, empty_token_policy token_policy = empty_token_policy::discard) noexcept
{
tl::vector<String> dst;
dst.reserve(32);
split_on_all(str,
separator,
[&dst](const String& token)
{
dst.push_back(token);
},
token_policy);
return dst;
}
template <class String, class Func>
void split_on_any(const String& str, const char* delimiters, const Func& functor, empty_token_policy token_policy = empty_token_policy::discard) noexcept
{
return split_on_any(str, String(delimiters), functor, token_policy);
}
template <class String, class Func>
void split_on_any(const String& str, char delimiter, const Func& functor, empty_token_policy token_policy = empty_token_policy::discard) noexcept
cppcoro::generator<const String&> split_on_any(const String& str, char sep, empty_token_policy token_policy = empty_token_policy::discard) noexcept
{
String token;
const char* cstr = str.data();
@@ -155,35 +113,39 @@ void split_on_any(const String& str, char delimiter, const Func& functor, empty_
const size_t endOffset = str.size();
while (offset <= endOffset)
{
const char* nextCstr = static_cast<const char*>(::memchr(cstr + offset, delimiter, endOffset - offset));
const char* nextCstr = static_cast<const char*>(::memchr(cstr + offset, sep, endOffset - offset));
const size_t nextOffset = nextCstr ? nextCstr - cstr : endOffset;
if (offset < nextOffset || token_policy == empty_token_policy::keep)
{
token.clear();
token.append(cstr + offset, cstr + nextOffset);
functor(token);
co_yield token;
}
offset = nextOffset + 1;
}
}
template <class String, class Delim, class Func>
void split_on_any(const String& str, const Delim& delimiters, const Func& functor, empty_token_policy token_policy = empty_token_policy::discard) noexcept
template <class String>
cppcoro::generator<const String&> split_on_any(const String& str, tl::string_view sep, empty_token_policy token_policy = empty_token_policy::discard) noexcept
{
const size_t k_delims_size = delimiters.size();
if (k_delims_size == 1)
return split_on_any(str, delimiters[0], functor, token_policy);
if (k_delims_size == 0)
const size_t sep_size = sep.size();
if (sep_size == 1)
{
TL_PLAIN_FAIL("'delimiters' cannot be empty");
return;
for (auto const& s: split_on_any(str, sep[0], token_policy))
co_yield s;
co_return;
}
if (sep_size == 0)
{
TL_PLAIN_FAIL("'sep' cannot be empty");
co_return;
}
String token;
const char* cstr = str.data();
const char* delimsStr = delimiters.data();
const char* sepStr = sep.data();
size_t offset = 0;
const size_t endOffset = str.size();
while (offset <= endOffset)
@@ -191,7 +153,7 @@ void split_on_any(const String& str, const Delim& delimiters, const Func& functo
size_t nextOffset = offset;
for (; nextOffset < endOffset; ++nextOffset)
{
if (::memchr(delimsStr, cstr[nextOffset], k_delims_size) != nullptr)
if (::memchr(sepStr, cstr[nextOffset], sep_size) != nullptr)
break;
}
@@ -199,47 +161,47 @@ void split_on_any(const String& str, const Delim& delimiters, const Func& functo
{
token.clear();
token.append(cstr + offset, cstr + nextOffset);
functor(token);
co_yield token;
}
offset = nextOffset + 1;
}
}
template <class String, class Delim, class Func>
void split_on_all(const String& str, const Delim& sep, const Func& functor, empty_token_policy token_policy = empty_token_policy::discard) noexcept
template <class String>
cppcoro::generator<const String&> split_on_all(const String& str, tl::string_view sep, empty_token_policy token_policy = empty_token_policy::discard) noexcept
{
String separator(sep);
if (separator.empty())
if (sep.empty())
{
TL_PLAIN_FAIL("'delimiters' cannot be empty");
return;
TL_PLAIN_FAIL("'sep' cannot be empty");
co_return;
}
size_t p0 = 0;
size_t p1 = 0;
const String empty_token;
String token;
while ((p1 = str.find(separator, p0)) != String::npos)
while ((p1 = str.find(sep, p0)) != String::npos)
{
if (p1 > p0)
{
token.clear();
token.append(str, p0, p1 - p0);
functor(token);
co_yield token;
}
else if (token_policy == empty_token_policy::keep)
functor(String{});
co_yield empty_token;
p0 = p1 + separator.size();
p0 = p1 + sep.size();
}
if (str.size() > p0)
{
token.clear();
token.append(str, p0, String::npos);
functor(token);
co_yield token;
}
else if (token_policy == empty_token_policy::keep)
functor(String{});
co_yield empty_token;
}
template <class String>
@@ -541,13 +503,13 @@ size_t replace_first(const string& text, const string& target, const string& rep
namespace detail
{
template <class Container, class String>
String join_worker(const Container& container, const String& delimiter) noexcept
String join_worker(const Container& container, const String& sep) noexcept
{
String dst;
//reserve some space based on some heuristics:
// We'll have size - 1 delimiters
// We'll have size - 1 seps
// And an average string size of 2 chars. The small choice is made to help with the small string case only where the allocator overhead is significant.
dst.reserve((delimiter.size() + 2) * container.size());
dst.reserve((sep.size() + 2) * container.size());
auto end = std::end(container);
auto it = std::begin(container);
@@ -558,19 +520,19 @@ String join_worker(const Container& container, const String& delimiter) noexcept
if (it == end)
break;
dst += delimiter;
dst += sep;
}
return dst;
}
template <class Container>
string join_worker(const Container& container, const string& delimiter) noexcept
string join_worker(const Container& container, const string& sep) noexcept
{
eastl::string buffer;
//reserve some space based on some heuristics:
// We'll have size - 1 delimiters
// We'll have size - 1 seps
// And an average string size of 2 chars. The small choice is made to help with the small string case only where the allocator overhead is significant.
buffer.reserve((delimiter.size() + 2) * container.size());
buffer.reserve((sep.size() + 2) * container.size());
auto end = std::end(container);
auto it = std::begin(container);
@@ -582,41 +544,41 @@ string join_worker(const Container& container, const string& delimiter) noexcept
if (it == end)
break;
buffer.append(delimiter.data(), delimiter.size());
buffer.append(sep.data(), sep.size());
}
return string(buffer);
}
//joiner used when the Delim and String are of the same type
template <class Container, class Delim, class String>
//joiner used when the Sep and String are of the same type
template <class Container, class Sep, class String>
std::enable_if_t<
std::is_same_v<
std::remove_const_t<std::remove_reference_t<String>>,
std::remove_const_t<std::remove_reference_t<Delim>>>,
String> join(const Container& container, const Delim& delimiter) noexcept
std::remove_const_t<std::remove_reference_t<Sep>>>,
String> join(const Container& container, const Sep& sep) noexcept
{
return join_worker(container, delimiter);
return join_worker(container, sep);
}
//joiner used when the Delim and String are different types
template <class Container, class Delim, class String>
//joiner used when the Sep and String are different types
template <class Container, class Sep, class String>
std::enable_if_t<
!std::is_same_v<
std::remove_const_t<std::remove_reference_t<String>>,
std::remove_const_t<std::remove_reference_t<Delim>>>,
String> join(const Container& container, const Delim& delimiter) noexcept
std::remove_const_t<std::remove_reference_t<Sep>>>,
String> join(const Container& container, const Sep& sep) noexcept
{
return join_worker(container, String(delimiter));
return join_worker(container, String(sep));
}
} //namespace detail
template <class Container, class Delim, class String>
String join(const Container& container, const Delim& delimiter) noexcept
template <class Container, class Sep, class String>
String join(const Container& container, const Sep& sep) noexcept
{
if (container.empty())
return String();
return detail::join<Container, Delim, String>(container, delimiter);
return detail::join<Container, Sep, String>(container, sep);
}
}
}