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⚡ micro-optimizations for dump()

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All ‘<<‘ calls have been replaced by write()/put() calls. The
indentation strings needs not to be resized. Cachegrind measures 1%
performance improvement.
This commit is contained in:
Niels Lohmann 2017-02-27 01:22:24 +01:00
parent b1441f3485
commit 0f04e42dd5
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GPG key ID: 7F3CEA63AE251B69
2 changed files with 132 additions and 52 deletions
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92
src/json.hpp
View file

@ -8420,47 +8420,69 @@ class basic_json
{ {
if (m_value.object->empty()) if (m_value.object->empty())
{ {
o << "{}"; o.write("{}", 2);
return; return;
} }
if (pretty_print) if (pretty_print)
{ {
o << "{\n"; o.write("{\n", 2);
// variable to hold indentation for recursive calls // variable to hold indentation for recursive calls
const auto new_indent = current_indent + indent_step; const auto new_indent = current_indent + indent_step;
string_t indent_string = string_t(new_indent, ' '); string_t indent_string = string_t(new_indent, ' ');
// first n-1 elements
auto i = m_value.object->cbegin(); auto i = m_value.object->cbegin();
for (size_t cnt = 0; cnt < m_value.object->size() - 1; ++cnt, ++i) for (size_t cnt = 0; cnt < m_value.object->size() - 1; ++cnt, ++i)
{ {
o << indent_string << '\"' << escape_string(i->first) << "\": "; o.write(indent_string.c_str(), new_indent);
o.put('\"');
const auto s = escape_string(i->first);
o.write(s.c_str(), static_cast<std::streamsize>(s.size()));
o.write("\": ", 3);
i->second.dump(o, true, indent_step, new_indent); i->second.dump(o, true, indent_step, new_indent);
o << ",\n"; o.write(",\n", 2);
} }
o << indent_string << '\"' << escape_string(i->first) << "\": "; // last element
assert(i != m_value.object->cend());
o.write(indent_string.c_str(), new_indent);
o.put('\"');
const auto s = escape_string(i->first);
o.write(s.c_str(), static_cast<std::streamsize>(s.size()));
o.write("\": ", 3);
i->second.dump(o, true, indent_step, new_indent); i->second.dump(o, true, indent_step, new_indent);
indent_string.resize(current_indent); o.put('\n');
o << '\n' << indent_string << '}'; o.write(indent_string.c_str(), current_indent);
o.put('}');
} }
else else
{ {
o << '{'; o.put('{');
// first n-1 elements
auto i = m_value.object->cbegin(); auto i = m_value.object->cbegin();
for (size_t cnt = 0; cnt < m_value.object->size() - 1; ++cnt, ++i) for (size_t cnt = 0; cnt < m_value.object->size() - 1; ++cnt, ++i)
{ {
o << '\"' << escape_string(i->first) << "\":"; o.put('\"');
const auto s = escape_string(i->first);
o.write(s.c_str(), static_cast<std::streamsize>(s.size()));
o.write("\":", 2);
i->second.dump(o, false, indent_step, current_indent); i->second.dump(o, false, indent_step, current_indent);
o << ','; o.put(',');
} }
o << '\"' << escape_string(i->first) << "\":"; // last element
assert(i != m_value.object->cend());
o.put('\"');
const auto s = escape_string(i->first);
o.write(s.c_str(), static_cast<std::streamsize>(s.size()));
o.write("\":", 2);
i->second.dump(o, false, indent_step, current_indent); i->second.dump(o, false, indent_step, current_indent);
o << '}';
o.put('}');
} }
return; return;
@ -8470,43 +8492,51 @@ class basic_json
{ {
if (m_value.array->empty()) if (m_value.array->empty())
{ {
o << "[]"; o.write("[]", 2);
return; return;
} }
if (pretty_print) if (pretty_print)
{ {
o << "[\n"; o.write("[\n", 2);
// variable to hold indentation for recursive calls // variable to hold indentation for recursive calls
const auto new_indent = current_indent + indent_step; const auto new_indent = current_indent + indent_step;
string_t indent_string = string_t(new_indent, ' '); string_t indent_string = string_t(new_indent, ' ');
// first n-1 elements
for (auto i = m_value.array->cbegin(); i != m_value.array->cend() - 1; ++i) for (auto i = m_value.array->cbegin(); i != m_value.array->cend() - 1; ++i)
{ {
o << indent_string; o.write(indent_string.c_str(), new_indent);
i->dump(o, true, indent_step, new_indent); i->dump(o, true, indent_step, new_indent);
o << ",\n"; o.write(",\n", 2);
} }
o << indent_string; // last element
assert(not m_value.array->empty()); assert(not m_value.array->empty());
o.write(indent_string.c_str(), new_indent);
m_value.array->back().dump(o, true, indent_step, new_indent); m_value.array->back().dump(o, true, indent_step, new_indent);
indent_string.resize(current_indent); o.put('\n');
o << '\n' << indent_string << ']'; o.write(indent_string.c_str(), current_indent);
o.put(']');
} }
else else
{ {
o << '['; o.put('[');
// first n-1 elements
for (auto i = m_value.array->cbegin(); i != m_value.array->cend() - 1; ++i) for (auto i = m_value.array->cbegin(); i != m_value.array->cend() - 1; ++i)
{ {
i->dump(o, false, indent_step, current_indent); i->dump(o, false, indent_step, current_indent);
o << ','; o.put(',');
} }
// last element
assert(not m_value.array->empty()); assert(not m_value.array->empty());
m_value.array->back().dump(o, false, indent_step, current_indent); m_value.array->back().dump(o, false, indent_step, current_indent);
o << ']';
o.put(']');
} }
return; return;
@ -8514,13 +8544,23 @@ class basic_json
case value_t::string: case value_t::string:
{ {
o << '\"' << escape_string(*m_value.string) << '\"'; o.put('\"');
const auto s = escape_string(*m_value.string);
o.write(s.c_str(), static_cast<std::streamsize>(s.size()));
o.put('\"');
return; return;
} }
case value_t::boolean: case value_t::boolean:
{ {
o << (m_value.boolean ? "true" : "false"); if (m_value.boolean)
{
o.write("true", 4);
}
else
{
o.write("false", 5);
}
return; return;
} }
@ -8544,13 +8584,13 @@ class basic_json
case value_t::discarded: case value_t::discarded:
{ {
o << "<discarded>"; o.write("<discarded>", 11);
return; return;
} }
case value_t::null: case value_t::null:
{ {
o << "null"; o.write("null", 4);
return; return;
} }
} }

92
src/json.hpp.re2c
View file

@ -8420,47 +8420,69 @@ class basic_json
{ {
if (m_value.object->empty()) if (m_value.object->empty())
{ {
o << "{}"; o.write("{}", 2);
return; return;
} }
if (pretty_print) if (pretty_print)
{ {
o << "{\n"; o.write("{\n", 2);
// variable to hold indentation for recursive calls // variable to hold indentation for recursive calls
const auto new_indent = current_indent + indent_step; const auto new_indent = current_indent + indent_step;
string_t indent_string = string_t(new_indent, ' '); string_t indent_string = string_t(new_indent, ' ');
// first n-1 elements
auto i = m_value.object->cbegin(); auto i = m_value.object->cbegin();
for (size_t cnt = 0; cnt < m_value.object->size() - 1; ++cnt, ++i) for (size_t cnt = 0; cnt < m_value.object->size() - 1; ++cnt, ++i)
{ {
o << indent_string << '\"' << escape_string(i->first) << "\": "; o.write(indent_string.c_str(), new_indent);
o.put('\"');
const auto s = escape_string(i->first);
o.write(s.c_str(), static_cast<std::streamsize>(s.size()));
o.write("\": ", 3);
i->second.dump(o, true, indent_step, new_indent); i->second.dump(o, true, indent_step, new_indent);
o << ",\n"; o.write(",\n", 2);
} }
o << indent_string << '\"' << escape_string(i->first) << "\": "; // last element
assert(i != m_value.object->cend());
o.write(indent_string.c_str(), new_indent);
o.put('\"');
const auto s = escape_string(i->first);
o.write(s.c_str(), static_cast<std::streamsize>(s.size()));
o.write("\": ", 3);
i->second.dump(o, true, indent_step, new_indent); i->second.dump(o, true, indent_step, new_indent);
indent_string.resize(current_indent); o.put('\n');
o << '\n' << indent_string << '}'; o.write(indent_string.c_str(), current_indent);
o.put('}');
} }
else else
{ {
o << '{'; o.put('{');
// first n-1 elements
auto i = m_value.object->cbegin(); auto i = m_value.object->cbegin();
for (size_t cnt = 0; cnt < m_value.object->size() - 1; ++cnt, ++i) for (size_t cnt = 0; cnt < m_value.object->size() - 1; ++cnt, ++i)
{ {
o << '\"' << escape_string(i->first) << "\":"; o.put('\"');
const auto s = escape_string(i->first);
o.write(s.c_str(), static_cast<std::streamsize>(s.size()));
o.write("\":", 2);
i->second.dump(o, false, indent_step, current_indent); i->second.dump(o, false, indent_step, current_indent);
o << ','; o.put(',');
} }
o << '\"' << escape_string(i->first) << "\":"; // last element
assert(i != m_value.object->cend());
o.put('\"');
const auto s = escape_string(i->first);
o.write(s.c_str(), static_cast<std::streamsize>(s.size()));
o.write("\":", 2);
i->second.dump(o, false, indent_step, current_indent); i->second.dump(o, false, indent_step, current_indent);
o << '}';
o.put('}');
} }
return; return;
@ -8470,43 +8492,51 @@ class basic_json
{ {
if (m_value.array->empty()) if (m_value.array->empty())
{ {
o << "[]"; o.write("[]", 2);
return; return;
} }
if (pretty_print) if (pretty_print)
{ {
o << "[\n"; o.write("[\n", 2);
// variable to hold indentation for recursive calls // variable to hold indentation for recursive calls
const auto new_indent = current_indent + indent_step; const auto new_indent = current_indent + indent_step;
string_t indent_string = string_t(new_indent, ' '); string_t indent_string = string_t(new_indent, ' ');
// first n-1 elements
for (auto i = m_value.array->cbegin(); i != m_value.array->cend() - 1; ++i) for (auto i = m_value.array->cbegin(); i != m_value.array->cend() - 1; ++i)
{ {
o << indent_string; o.write(indent_string.c_str(), new_indent);
i->dump(o, true, indent_step, new_indent); i->dump(o, true, indent_step, new_indent);
o << ",\n"; o.write(",\n", 2);
} }
o << indent_string; // last element
assert(not m_value.array->empty()); assert(not m_value.array->empty());
o.write(indent_string.c_str(), new_indent);
m_value.array->back().dump(o, true, indent_step, new_indent); m_value.array->back().dump(o, true, indent_step, new_indent);
indent_string.resize(current_indent); o.put('\n');
o << '\n' << indent_string << ']'; o.write(indent_string.c_str(), current_indent);
o.put(']');
} }
else else
{ {
o << '['; o.put('[');
// first n-1 elements
for (auto i = m_value.array->cbegin(); i != m_value.array->cend() - 1; ++i) for (auto i = m_value.array->cbegin(); i != m_value.array->cend() - 1; ++i)
{ {
i->dump(o, false, indent_step, current_indent); i->dump(o, false, indent_step, current_indent);
o << ','; o.put(',');
} }
// last element
assert(not m_value.array->empty()); assert(not m_value.array->empty());
m_value.array->back().dump(o, false, indent_step, current_indent); m_value.array->back().dump(o, false, indent_step, current_indent);
o << ']';
o.put(']');
} }
return; return;
@ -8514,13 +8544,23 @@ class basic_json
case value_t::string: case value_t::string:
{ {
o << '\"' << escape_string(*m_value.string) << '\"'; o.put('\"');
const auto s = escape_string(*m_value.string);
o.write(s.c_str(), static_cast<std::streamsize>(s.size()));
o.put('\"');
return; return;
} }
case value_t::boolean: case value_t::boolean:
{ {
o << (m_value.boolean ? "true" : "false"); if (m_value.boolean)
{
o.write("true", 4);
}
else
{
o.write("false", 5);
}
return; return;
} }
@ -8544,13 +8584,13 @@ class basic_json
case value_t::discarded: case value_t::discarded:
{ {
o << "<discarded>"; o.write("<discarded>", 11);
return; return;
} }
case value_t::null: case value_t::null:
{ {
o << "null"; o.write("null", 4);
return; return;
} }
} }