428 lines
12 KiB
C++
428 lines
12 KiB
C++
/*
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* Copyright 2012-present Facebook, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <folly/Format.h>
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#include <folly/ConstexprMath.h>
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#include <folly/CppAttributes.h>
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#include <folly/container/Array.h>
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#include <double-conversion/double-conversion.h>
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namespace folly {
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namespace detail {
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// ctor for items in the align table
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struct format_table_align_make_item {
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static constexpr std::size_t size = 256;
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constexpr FormatArg::Align operator()(std::size_t index) const {
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// clang-format off
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return
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index == '<' ? FormatArg::Align::LEFT:
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index == '>' ? FormatArg::Align::RIGHT :
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index == '=' ? FormatArg::Align::PAD_AFTER_SIGN :
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index == '^' ? FormatArg::Align::CENTER :
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FormatArg::Align::INVALID;
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// clang-format on
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}
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};
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// ctor for items in the conv tables for representing parts of nonnegative
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// integers into ascii digits of length Size, over a given base Base
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template <std::size_t Base, std::size_t Size, bool Upper = false>
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struct format_table_conv_make_item {
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static_assert(Base <= 36, "Base is unrepresentable");
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struct make_item {
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std::size_t index{};
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constexpr explicit make_item(std::size_t index_) : index(index_) {} // gcc49
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constexpr char alpha(std::size_t ord) const {
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return ord < 10 ? '0' + ord : (Upper ? 'A' : 'a') + (ord - 10);
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}
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constexpr char operator()(std::size_t offset) const {
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return alpha(index / constexpr_pow(Base, Size - offset - 1) % Base);
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}
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};
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constexpr std::array<char, Size> operator()(std::size_t index) const {
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return make_array_with<Size>(make_item{index});
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}
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};
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// ctor for items in the sign table
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struct format_table_sign_make_item {
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static constexpr std::size_t size = 256;
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constexpr FormatArg::Sign operator()(std::size_t index) const {
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// clang-format off
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return
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index == '+' ? FormatArg::Sign::PLUS_OR_MINUS :
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index == '-' ? FormatArg::Sign::MINUS :
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index == ' ' ? FormatArg::Sign::SPACE_OR_MINUS :
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FormatArg::Sign::INVALID;
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// clang-format on
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}
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};
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// the tables
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FOLLY_STORAGE_CONSTEXPR auto formatAlignTable =
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make_array_with<256>(format_table_align_make_item{});
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FOLLY_STORAGE_CONSTEXPR auto formatSignTable =
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make_array_with<256>(format_table_sign_make_item{});
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FOLLY_STORAGE_CONSTEXPR decltype(formatHexLower) formatHexLower =
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make_array_with<256>(format_table_conv_make_item<16, 2, false>{});
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FOLLY_STORAGE_CONSTEXPR decltype(formatHexUpper) formatHexUpper =
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make_array_with<256>(format_table_conv_make_item<16, 2, true>{});
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FOLLY_STORAGE_CONSTEXPR decltype(formatOctal) formatOctal =
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make_array_with<512>(format_table_conv_make_item<8, 3>{});
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FOLLY_STORAGE_CONSTEXPR decltype(formatBinary) formatBinary =
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make_array_with<256>(format_table_conv_make_item<2, 8>{});
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} // namespace detail
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using namespace folly::detail;
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void FormatValue<double>::formatHelper(
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fbstring& piece,
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int& prefixLen,
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FormatArg& arg) const {
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using ::double_conversion::DoubleToStringConverter;
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using ::double_conversion::StringBuilder;
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arg.validate(FormatArg::Type::FLOAT);
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if (arg.presentation == FormatArg::kDefaultPresentation) {
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arg.presentation = 'g';
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}
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const char* infinitySymbol = isupper(arg.presentation) ? "INF" : "inf";
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const char* nanSymbol = isupper(arg.presentation) ? "NAN" : "nan";
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char exponentSymbol = isupper(arg.presentation) ? 'E' : 'e';
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if (arg.precision == FormatArg::kDefaultPrecision) {
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arg.precision = 6;
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}
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// 2+: for null terminator and optional sign shenanigans.
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constexpr int bufLen = 2 +
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constexpr_max(2 + DoubleToStringConverter::kMaxFixedDigitsBeforePoint +
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DoubleToStringConverter::kMaxFixedDigitsAfterPoint,
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constexpr_max(
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8 + DoubleToStringConverter::kMaxExponentialDigits,
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7 + DoubleToStringConverter::kMaxPrecisionDigits));
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char buf[bufLen];
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StringBuilder builder(buf + 1, bufLen - 1);
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char plusSign;
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switch (arg.sign) {
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case FormatArg::Sign::PLUS_OR_MINUS:
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plusSign = '+';
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break;
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case FormatArg::Sign::SPACE_OR_MINUS:
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plusSign = ' ';
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break;
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default:
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plusSign = '\0';
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break;
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};
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auto flags = DoubleToStringConverter::EMIT_POSITIVE_EXPONENT_SIGN |
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(arg.trailingDot ? DoubleToStringConverter::EMIT_TRAILING_DECIMAL_POINT
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: 0);
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double val = val_;
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switch (arg.presentation) {
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case '%':
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val *= 100;
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FOLLY_FALLTHROUGH;
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case 'f':
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case 'F': {
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if (arg.precision > DoubleToStringConverter::kMaxFixedDigitsAfterPoint) {
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arg.precision = DoubleToStringConverter::kMaxFixedDigitsAfterPoint;
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}
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DoubleToStringConverter conv(
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flags,
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infinitySymbol,
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nanSymbol,
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exponentSymbol,
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-4,
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arg.precision,
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0,
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0);
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arg.enforce(
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conv.ToFixed(val, arg.precision, &builder),
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"fixed double conversion failed");
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break;
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}
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case 'e':
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case 'E': {
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if (arg.precision > DoubleToStringConverter::kMaxExponentialDigits) {
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arg.precision = DoubleToStringConverter::kMaxExponentialDigits;
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}
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DoubleToStringConverter conv(
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flags,
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infinitySymbol,
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nanSymbol,
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exponentSymbol,
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-4,
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arg.precision,
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0,
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0);
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arg.enforce(conv.ToExponential(val, arg.precision, &builder));
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break;
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}
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case 'n': // should be locale-aware, but isn't
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case 'g':
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case 'G': {
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if (arg.precision < DoubleToStringConverter::kMinPrecisionDigits) {
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arg.precision = DoubleToStringConverter::kMinPrecisionDigits;
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} else if (arg.precision > DoubleToStringConverter::kMaxPrecisionDigits) {
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arg.precision = DoubleToStringConverter::kMaxPrecisionDigits;
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}
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DoubleToStringConverter conv(
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flags,
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infinitySymbol,
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nanSymbol,
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exponentSymbol,
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-4,
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arg.precision,
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0,
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0);
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arg.enforce(conv.ToShortest(val, &builder));
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break;
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}
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default:
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arg.error("invalid specifier '", arg.presentation, "'");
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}
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int len = builder.position();
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builder.Finalize();
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DCHECK_GT(len, 0);
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// Add '+' or ' ' sign if needed
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char* p = buf + 1;
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// anything that's neither negative nor nan
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prefixLen = 0;
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if (plusSign && (*p != '-' && *p != 'n' && *p != 'N')) {
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*--p = plusSign;
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++len;
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prefixLen = 1;
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} else if (*p == '-') {
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prefixLen = 1;
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}
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piece = fbstring(p, size_t(len));
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}
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void FormatArg::initSlow() {
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auto b = fullArgString.begin();
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auto end = fullArgString.end();
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// Parse key
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auto p = static_cast<const char*>(memchr(b, ':', size_t(end - b)));
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if (!p) {
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key_ = StringPiece(b, end);
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return;
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}
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key_ = StringPiece(b, p);
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if (*p == ':') {
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// parse format spec
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if (++p == end) {
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return;
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}
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// fill/align, or just align
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Align a;
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if (p + 1 != end &&
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(a = formatAlignTable[static_cast<unsigned char>(p[1])]) !=
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Align::INVALID) {
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fill = *p;
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align = a;
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p += 2;
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if (p == end) {
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return;
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}
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} else if (
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(a = formatAlignTable[static_cast<unsigned char>(*p)]) !=
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Align::INVALID) {
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align = a;
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if (++p == end) {
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return;
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}
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}
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Sign s;
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unsigned char uSign = static_cast<unsigned char>(*p);
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if ((s = formatSignTable[uSign]) != Sign::INVALID) {
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sign = s;
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if (++p == end) {
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return;
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}
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}
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if (*p == '#') {
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basePrefix = true;
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if (++p == end) {
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return;
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}
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}
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if (*p == '0') {
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enforce(align == Align::DEFAULT, "alignment specified twice");
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fill = '0';
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align = Align::PAD_AFTER_SIGN;
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if (++p == end) {
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return;
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}
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}
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auto readInt = [&] {
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auto const c = p;
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do {
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++p;
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} while (p != end && *p >= '0' && *p <= '9');
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return to<int>(StringPiece(c, p));
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};
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if (*p == '*') {
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width = kDynamicWidth;
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++p;
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if (p == end) {
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return;
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}
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if (*p >= '0' && *p <= '9') {
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widthIndex = readInt();
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}
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if (p == end) {
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return;
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}
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} else if (*p >= '0' && *p <= '9') {
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width = readInt();
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if (p == end) {
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return;
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}
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}
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if (*p == ',') {
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thousandsSeparator = true;
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if (++p == end) {
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return;
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}
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}
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if (*p == '.') {
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auto d = ++p;
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while (p != end && *p >= '0' && *p <= '9') {
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++p;
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}
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if (p != d) {
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precision = to<int>(StringPiece(d, p));
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if (p != end && *p == '.') {
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trailingDot = true;
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++p;
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}
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} else {
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trailingDot = true;
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}
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if (p == end) {
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return;
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}
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}
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presentation = *p;
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if (++p == end) {
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return;
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}
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}
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error("extra characters in format string");
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}
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void FormatArg::validate(Type type) const {
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enforce(keyEmpty(), "index not allowed");
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switch (type) {
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case Type::INTEGER:
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enforce(
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precision == kDefaultPrecision, "precision not allowed on integers");
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break;
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case Type::FLOAT:
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enforce(
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!basePrefix, "base prefix ('#') specifier only allowed on integers");
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enforce(
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!thousandsSeparator,
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"thousands separator (',') only allowed on integers");
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break;
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case Type::OTHER:
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enforce(
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align != Align::PAD_AFTER_SIGN,
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"'='alignment only allowed on numbers");
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enforce(sign == Sign::DEFAULT, "sign specifier only allowed on numbers");
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enforce(
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!basePrefix, "base prefix ('#') specifier only allowed on integers");
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enforce(
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!thousandsSeparator,
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"thousands separator (',') only allowed on integers");
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break;
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}
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}
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namespace detail {
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void insertThousandsGroupingUnsafe(char* start_buffer, char** end_buffer) {
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uint32_t remaining_digits = uint32_t(*end_buffer - start_buffer);
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uint32_t separator_size = (remaining_digits - 1) / 3;
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uint32_t result_size = remaining_digits + separator_size;
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*end_buffer = *end_buffer + separator_size;
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// get the end of the new string with the separators
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uint32_t buffer_write_index = result_size - 1;
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uint32_t buffer_read_index = remaining_digits - 1;
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start_buffer[buffer_write_index + 1] = 0;
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bool done = false;
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uint32_t next_group_size = 3;
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while (!done) {
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uint32_t current_group_size = std::max<uint32_t>(
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1, std::min<uint32_t>(remaining_digits, next_group_size));
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// write out the current group's digits to the buffer index
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for (uint32_t i = 0; i < current_group_size; i++) {
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start_buffer[buffer_write_index--] = start_buffer[buffer_read_index--];
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}
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// if not finished, write the separator before the next group
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if (buffer_write_index < buffer_write_index + 1) {
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start_buffer[buffer_write_index--] = ',';
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} else {
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done = true;
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}
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remaining_digits -= current_group_size;
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}
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}
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} // namespace detail
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FormatKeyNotFoundException::FormatKeyNotFoundException(StringPiece key)
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: std::out_of_range(kMessagePrefix.str() + key.str()) {}
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constexpr StringPiece const FormatKeyNotFoundException::kMessagePrefix;
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} // namespace folly
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