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Simplify grisu_writer

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This commit is contained in:
Victor Zverovich 2019-10-21 17:07:45 -07:00
parent 7aa58c30bf
commit b7a157401e
1 changed files with 77 additions and 77 deletions
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118
include/fmt/format.h
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@ -1028,6 +1028,14 @@ using format_specs = basic_format_specs<char>;
namespace internal {
struct gen_digits_params {
int num_digits;
sign_t sign : 3;
bool fixed;
bool upper;
bool trailing_zeros;
};
// Writes the exponent exp in the form "[+-]d{2,3}" to buffer.
template <typename Char, typename It> It write_exponent(int exp, It it) {
FMT_ASSERT(-1000 < exp && exp < 1000, "exponent out of range");
@ -1047,38 +1055,38 @@ template <typename Char, typename It> It write_exponent(int exp, It it) {
return it;
}
struct gen_digits_params {
int num_digits;
sign_t sign : 3;
bool fixed;
bool upper;
bool trailing_zeros;
};
template <typename Char> class grisu_writer {
private:
// The number is given as v = digits_ * pow(10, exp_).
const char* digits_;
int num_digits_;
int exp_;
size_t size_;
gen_digits_params params_;
Char decimal_point_;
// The number is given as v = digits * pow(10, exp).
template <typename Char, typename It>
It grisu_prettify(const char* digits, int size, int exp, It it,
gen_digits_params params, Char decimal_point) {
template <typename It> It grisu_prettify(It it) const {
// pow(10, full_exp - 1) <= v <= pow(10, full_exp).
int full_exp = size + exp;
if (!params.fixed) {
int full_exp = num_digits_ + exp_;
if (!params_.fixed) {
// Insert a decimal point after the first digit and add an exponent.
*it++ = static_cast<Char>(*digits);
if (size > 1) *it++ = decimal_point;
exp += size - 1;
it = copy_str<Char>(digits + 1, digits + size, it);
if (size < params.num_digits)
it = std::fill_n(it, params.num_digits - size, static_cast<Char>('0'));
*it++ = static_cast<Char>(params.upper ? 'E' : 'e');
return write_exponent<Char>(exp, it);
*it++ = static_cast<Char>(*digits_);
if (num_digits_ > 1) *it++ = decimal_point_;
it = copy_str<Char>(digits_ + 1, digits_ + num_digits_, it);
if (num_digits_ < params_.num_digits) {
it = std::fill_n(it, params_.num_digits - num_digits_,
static_cast<Char>('0'));
}
if (size <= full_exp) {
*it++ = static_cast<Char>(params_.upper ? 'E' : 'e');
return write_exponent<Char>(full_exp - 1, it);
}
if (num_digits_ <= full_exp) {
// 1234e7 -> 12340000000[.0+]
it = copy_str<Char>(digits, digits + size, it);
it = std::fill_n(it, full_exp - size, static_cast<Char>('0'));
int num_zeros = (std::max)(params.num_digits - full_exp, 1);
if (params.trailing_zeros) {
*it++ = decimal_point;
it = copy_str<Char>(digits_, digits_ + num_digits_, it);
it = std::fill_n(it, full_exp - num_digits_, static_cast<Char>('0'));
int num_zeros = (std::max)(params_.num_digits - full_exp, 1);
if (params_.trailing_zeros) {
*it++ = decimal_point_;
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
if (num_zeros > 1000)
throw std::runtime_error("fuzz mode - avoiding excessive cpu use");
@ -1087,45 +1095,39 @@ It grisu_prettify(const char* digits, int size, int exp, It it,
}
} else if (full_exp > 0) {
// 1234e-2 -> 12.34[0+]
it = copy_str<Char>(digits, digits + full_exp, it);
if (!params.trailing_zeros) {
it = copy_str<Char>(digits_, digits_ + full_exp, it);
if (!params_.trailing_zeros) {
// Remove trailing zeros.
while (size > full_exp && digits[size - 1] == '0') --size;
if (size != full_exp) *it++ = decimal_point;
return copy_str<Char>(digits + full_exp, digits + size, it);
int num_digits = num_digits_;
while (num_digits > full_exp && digits_[num_digits - 1] == '0')
--num_digits;
if (num_digits != full_exp) *it++ = decimal_point_;
return copy_str<Char>(digits_ + full_exp, digits_ + num_digits, it);
}
*it++ = decimal_point;
it = copy_str<Char>(digits + full_exp, digits + size, it);
if (params.num_digits > size) {
*it++ = decimal_point_;
it = copy_str<Char>(digits_ + full_exp, digits_ + num_digits_, it);
if (params_.num_digits > num_digits_) {
// Add trailing zeros.
int num_zeros = params.num_digits - size;
int num_zeros = params_.num_digits - num_digits_;
it = std::fill_n(it, num_zeros, static_cast<Char>('0'));
}
} else {
// 1234e-6 -> 0.001234
*it++ = static_cast<Char>('0');
int num_zeros = -full_exp;
if (params.num_digits >= 0 && params.num_digits < num_zeros)
num_zeros = params.num_digits;
if (!params.trailing_zeros)
while (size > 0 && digits[size - 1] == '0') --size;
if (num_zeros != 0 || size != 0) {
*it++ = decimal_point;
if (params_.num_digits >= 0 && params_.num_digits < num_zeros)
num_zeros = params_.num_digits;
int num_digits = num_digits_;
if (!params_.trailing_zeros)
while (num_digits > 0 && digits_[num_digits - 1] == '0') --num_digits;
if (num_zeros != 0 || num_digits != 0) {
*it++ = decimal_point_;
it = std::fill_n(it, num_zeros, static_cast<Char>('0'));
it = copy_str<Char>(digits, digits + size, it);
it = copy_str<Char>(digits_, digits_ + num_digits, it);
}
}
return it;
}
template <typename Char> class grisu_writer {
private:
const char* digits_;
int num_digits_;
int exp_;
size_t size_;
gen_digits_params params_;
Char decimal_point_;
}
public:
grisu_writer(const char* digits, int num_digits, int exp,
@ -1138,18 +1140,16 @@ template <typename Char> class grisu_writer {
int full_exp = num_digits + exp - 1;
int precision = params.num_digits > 0 ? params.num_digits : 16;
params_.fixed |= full_exp >= -4 && full_exp < precision;
auto it = grisu_prettify(digits, num_digits, exp, counting_iterator(),
params_, '\0');
size_ = it.count();
size_ = grisu_prettify(counting_iterator()).count();
size_ += params_.sign ? 1 : 0;
}
size_t size() const { return size_ + (params_.sign ? 1 : 0); }
size_t size() const { return size_; }
size_t width() const { return size(); }
template <typename It> void operator()(It&& it) {
if (params_.sign) *it++ = static_cast<Char>(data::signs[params_.sign]);
it =
grisu_prettify(digits_, num_digits_, exp_, it, params_, decimal_point_);
it = grisu_prettify(it);
}
};