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Avoid extra copy

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This commit is contained in:
Victor Zverovich
2018-10-17 08:19:46 -07:00
parent 98f1c1fe87
commit e8efdef8de
3 changed files with 14 additions and 15 deletions
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14
include/fmt/format.h
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@@ -299,10 +299,10 @@ struct grisu2_specs {
// https://www.cs.tufts.edu/~nr/cs257/archive/florian-loitsch/printf.pdf
template <typename Double>
FMT_API typename std::enable_if<sizeof(Double) == sizeof(uint64_t), bool>::type
grisu2_format(Double value, char *buffer, size_t &size, grisu2_specs);
grisu2_format(Double value, buffer &buf, grisu2_specs);
template <typename Double>
inline typename std::enable_if<sizeof(Double) != sizeof(uint64_t), bool>::type
grisu2_format(Double, char *, size_t &, grisu2_specs) { return false; }
grisu2_format(Double, buffer &, grisu2_specs) { return false; }
template <typename Allocator>
typename Allocator::value_type *allocate(Allocator& alloc, std::size_t n) {
@@ -2862,22 +2862,16 @@ void basic_writer<Range>::write_double(T value, const format_specs &spec) {
bool use_grisu = internal::use_grisu() && sizeof(T) <= sizeof(double) &&
type != 'a' && type != 'A';
if (use_grisu) {
char buf[100]; // TODO: correct buffer size
size_t size = 0;
auto gs = internal::grisu2_specs();
gs.type = type;
gs.precision = spec.precision();
gs.flags = spec.flags_;
use_grisu = internal::grisu2_format(
static_cast<double>(value), buf, size, gs);
if (use_grisu) {
FMT_ASSERT(size <= 100, "buffer overflow");
buffer.append(buf, buf + size); // TODO: avoid extra copy
}
use_grisu = internal::grisu2_format(static_cast<double>(value), buffer, gs);
}
if (!use_grisu) {
format_specs normalized_spec(spec);
normalized_spec.type_ = handler.type;
buffer.clear();
write_double_sprintf(value, normalized_spec, buffer);
}
size_t n = buffer.size();