2 * Copyright 2013 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 #ifndef FOLLY_FORMAT_H_
18 #error This file may only be included from Format.h.
21 #include "folly/Traits.h"
27 extern const char formatHexUpper[256][2];
28 extern const char formatHexLower[256][2];
29 extern const char formatOctal[512][3];
30 extern const char formatBinary[256][8];
32 const size_t kMaxHexLength = 2 * sizeof(uintmax_t);
33 const size_t kMaxOctalLength = 3 * sizeof(uintmax_t);
34 const size_t kMaxBinaryLength = 8 * sizeof(uintmax_t);
37 * Convert an unsigned to hex, using repr (which maps from each possible
38 * 2-hex-bytes value to the 2-character representation).
40 * Just like folly::detail::uintToBuffer in Conv.h, writes at the *end* of
41 * the supplied buffer and returns the offset of the beginning of the string
42 * from the start of the buffer. The formatted string will be in range
43 * [buf+begin, buf+bufLen).
46 size_t uintToHex(char* buffer, size_t bufLen, Uint v,
47 const char (&repr)[256][2]) {
48 // 'v >>= 7, v >>= 1' is no more than a work around to get rid of shift size
49 // warning when Uint = uint8_t (it's false as v >= 256 implies sizeof(v) > 1).
50 for (; !less_than<unsigned, 256>(v); v >>= 7, v >>= 1) {
53 buffer[bufLen] = repr[b][0];
54 buffer[bufLen + 1] = repr[b][1];
56 buffer[--bufLen] = repr[v][1];
58 buffer[--bufLen] = repr[v][0];
64 * Convert an unsigned to hex, using lower-case letters for the digits
65 * above 9. See the comments for uintToHex.
68 inline size_t uintToHexLower(char* buffer, size_t bufLen, Uint v) {
69 return uintToHex(buffer, bufLen, v, formatHexLower);
73 * Convert an unsigned to hex, using upper-case letters for the digits
74 * above 9. See the comments for uintToHex.
77 inline size_t uintToHexUpper(char* buffer, size_t bufLen, Uint v) {
78 return uintToHex(buffer, bufLen, v, formatHexUpper);
82 * Convert an unsigned to octal.
84 * Just like folly::detail::uintToBuffer in Conv.h, writes at the *end* of
85 * the supplied buffer and returns the offset of the beginning of the string
86 * from the start of the buffer. The formatted string will be in range
87 * [buf+begin, buf+bufLen).
90 size_t uintToOctal(char* buffer, size_t bufLen, Uint v) {
91 auto& repr = formatOctal;
92 // 'v >>= 7, v >>= 2' is no more than a work around to get rid of shift size
93 // warning when Uint = uint8_t (it's false as v >= 512 implies sizeof(v) > 1).
94 for (; !less_than<unsigned, 512>(v); v >>= 7, v >>= 2) {
97 buffer[bufLen] = repr[b][0];
98 buffer[bufLen + 1] = repr[b][1];
99 buffer[bufLen + 2] = repr[b][2];
101 buffer[--bufLen] = repr[v][2];
103 buffer[--bufLen] = repr[v][1];
106 buffer[--bufLen] = repr[v][0];
112 * Convert an unsigned to binary.
114 * Just like folly::detail::uintToBuffer in Conv.h, writes at the *end* of
115 * the supplied buffer and returns the offset of the beginning of the string
116 * from the start of the buffer. The formatted string will be in range
117 * [buf+begin, buf+bufLen).
119 template <class Uint>
120 size_t uintToBinary(char* buffer, size_t bufLen, Uint v) {
121 auto& repr = formatBinary;
123 buffer[--bufLen] = '0';
126 for (; v; v >>= 7, v >>= 1) {
129 memcpy(buffer + bufLen, &(repr[b][0]), 8);
131 while (buffer[bufLen] == '0') {
137 } // namespace detail
140 template <bool containerMode, class... Args>
141 Formatter<containerMode, Args...>::Formatter(StringPiece str, Args&&... args)
143 values_(FormatValue<typename std::decay<Args>::type>(
144 std::forward<Args>(args))...) {
145 static_assert(!containerMode || sizeof...(Args) == 1,
146 "Exactly one argument required in container mode");
149 template <bool containerMode, class... Args>
150 template <class Output>
151 void Formatter<containerMode, Args...>::operator()(Output& out) const {
152 auto p = str_.begin();
153 auto end = str_.end();
155 // Copy raw string (without format specifiers) to output;
156 // not as simple as we'd like, as we still need to translate "}}" to "}"
157 // and throw if we see any lone "}"
158 auto outputString = [&out] (StringPiece s) {
162 auto q = static_cast<const char*>(memchr(p, '}', end - p));
164 out(StringPiece(p, end));
168 out(StringPiece(p, q));
171 if (p == end || *p != '}') {
172 throw std::invalid_argument(
173 "folly::format: single '}' in format string");
180 bool hasDefaultArgIndex = false;
181 bool hasExplicitArgIndex = false;
183 auto q = static_cast<const char*>(memchr(p, '{', end - p));
185 outputString(StringPiece(p, end));
188 outputString(StringPiece(p, q));
192 throw std::invalid_argument(
193 "folly::format: '}' at end of format string");
198 out(StringPiece(p, 1));
204 q = static_cast<const char*>(memchr(p, '}', end - p));
206 throw std::invalid_argument("folly::format: missing ending '}'");
208 FormatArg arg(StringPiece(p, q));
212 auto piece = arg.splitKey<true>(); // empty key component is okay
213 if (containerMode) { // static
215 arg.setNextIntKey(nextArg++);
216 hasDefaultArgIndex = true;
218 arg.setNextKey(piece);
219 hasExplicitArgIndex = true;
223 argIndex = nextArg++;
224 hasDefaultArgIndex = true;
227 argIndex = to<int>(piece);
228 } catch (const std::out_of_range& e) {
229 arg.error("argument index must be integer");
231 arg.enforce(argIndex >= 0, "argument index must be non-negative");
232 hasExplicitArgIndex = true;
236 if (hasDefaultArgIndex && hasExplicitArgIndex) {
237 throw std::invalid_argument(
238 "folly::format: may not have both default and explicit arg indexes");
241 doFormat(argIndex, arg, out);
245 namespace format_value {
247 template <class FormatCallback>
248 void formatString(StringPiece val, FormatArg& arg, FormatCallback& cb) {
249 if (arg.precision != FormatArg::kDefaultPrecision &&
250 val.size() > arg.precision) {
251 val.reset(val.data(), arg.precision);
254 constexpr int padBufSize = 128;
255 char padBuf[padBufSize];
257 // Output padding, no more than padBufSize at once
258 auto pad = [&padBuf, &cb, padBufSize] (int chars) {
260 int n = std::min(chars, padBufSize);
261 cb(StringPiece(padBuf, n));
266 int padRemaining = 0;
267 if (arg.width != FormatArg::kDefaultWidth && val.size() < arg.width) {
268 char fill = arg.fill == FormatArg::kDefaultFill ? ' ' : arg.fill;
269 int padChars = arg.width - val.size();
270 memset(padBuf, fill, std::min(padBufSize, padChars));
273 case FormatArg::Align::DEFAULT:
274 case FormatArg::Align::LEFT:
275 padRemaining = padChars;
277 case FormatArg::Align::CENTER:
279 padRemaining = padChars - padChars / 2;
281 case FormatArg::Align::RIGHT:
282 case FormatArg::Align::PAD_AFTER_SIGN:
298 template <class FormatCallback>
299 void formatNumber(StringPiece val, int prefixLen, FormatArg& arg,
300 FormatCallback& cb) {
301 // precision means something different for numbers
302 arg.precision = FormatArg::kDefaultPrecision;
303 if (arg.align == FormatArg::Align::DEFAULT) {
304 arg.align = FormatArg::Align::RIGHT;
305 } else if (prefixLen && arg.align == FormatArg::Align::PAD_AFTER_SIGN) {
306 // Split off the prefix, then do any padding if necessary
307 cb(val.subpiece(0, prefixLen));
308 val.advance(prefixLen);
309 arg.width = std::max(arg.width - prefixLen, 0);
311 format_value::formatString(val, arg, cb);
314 template <class FormatCallback, bool containerMode, class... Args>
315 void formatFormatter(const Formatter<containerMode, Args...>& formatter,
317 FormatCallback& cb) {
318 if (arg.width == FormatArg::kDefaultWidth &&
319 arg.precision == FormatArg::kDefaultPrecision) {
322 } else if (arg.align != FormatArg::Align::LEFT &&
323 arg.align != FormatArg::Align::DEFAULT) {
324 // We can only avoid creating a temporary string if we align left,
325 // as we'd need to know the size beforehand otherwise
326 format_value::formatString(formatter.fbstr(), arg, cb);
328 auto fn = [&arg, &cb] (StringPiece sp) mutable {
329 int sz = static_cast<int>(sp.size());
330 if (arg.precision != FormatArg::kDefaultPrecision) {
331 sz = std::min(arg.precision, sz);
332 sp.reset(sp.data(), sz);
337 if (arg.width != FormatArg::kDefaultWidth) {
338 arg.width = std::max(arg.width - sz, 0);
343 if (arg.width != FormatArg::kDefaultWidth && arg.width != 0) {
344 // Rely on formatString to do appropriate padding
345 format_value::formatString(StringPiece(), arg, cb);
350 } // namespace format_value
352 // Definitions for default FormatValue classes
354 // Integral types (except bool)
357 T, typename std::enable_if<
358 std::is_integral<T>::value &&
359 !std::is_same<T, bool>::value>::type>
362 explicit FormatValue(T val) : val_(val) { }
363 template <class FormatCallback>
364 void format(FormatArg& arg, FormatCallback& cb) const {
365 arg.validate(FormatArg::Type::INTEGER);
369 template <class FormatCallback>
370 void doFormat(FormatArg& arg, FormatCallback& cb) const {
371 char presentation = arg.presentation;
372 if (presentation == FormatArg::kDefaultPresentation) {
373 presentation = std::is_same<T, char>::value ? 'c' : 'd';
376 // Do all work as unsigned, we'll add the prefix ('0' or '0x' if necessary)
377 // and sign ourselves.
378 typedef typename std::make_unsigned<T>::type UT;
381 if (std::is_signed<T>::value) {
382 if (folly::is_negative(val_)) {
383 uval = static_cast<UT>(-val_);
386 uval = static_cast<UT>(val_);
388 case FormatArg::Sign::PLUS_OR_MINUS:
391 case FormatArg::Sign::SPACE_OR_MINUS:
403 arg.enforce(arg.sign == FormatArg::Sign::DEFAULT,
404 "sign specifications not allowed for unsigned values");
408 // #x: 0x prefix + 16 bytes = 18 bytes
409 // #o: 0 prefix + 22 bytes = 23 bytes
410 // #b: 0b prefix + 64 bytes = 65 bytes
411 // ,d: 26 bytes (including thousands separators!)
413 // + 3 for sign and prefix shenanigans (see below)
414 constexpr size_t valBufSize = 69;
415 char valBuf[valBufSize];
416 char* valBufBegin = nullptr;
417 char* valBufEnd = nullptr;
420 auto useSprintf = [&] (const char* format) mutable {
421 valBufBegin = valBuf + 3; // room for sign and base prefix
422 valBufEnd = valBufBegin + sprintf(valBufBegin, format,
423 static_cast<uintmax_t>(uval));
428 switch (presentation) {
429 case 'n': // TODO(tudorb): locale awareness?
431 arg.enforce(!arg.basePrefix,
432 "base prefix not allowed with '", presentation,
434 if (arg.thousandsSeparator) {
437 // Use uintToBuffer, faster than sprintf
438 valBufBegin = valBuf + 3;
439 valBufEnd = valBufBegin + uint64ToBufferUnsafe(uval, valBufBegin);
443 arg.enforce(!arg.basePrefix,
444 "base prefix not allowed with '", presentation,
446 arg.enforce(!arg.thousandsSeparator,
447 "thousands separator (',') not allowed with '",
448 presentation, "' specifier");
449 valBufBegin = valBuf + 3;
450 *valBufBegin = static_cast<char>(uval);
451 valBufEnd = valBufBegin + 1;
455 arg.enforce(!arg.thousandsSeparator,
456 "thousands separator (',') not allowed with '",
457 presentation, "' specifier");
458 valBufEnd = valBuf + valBufSize - 1;
459 valBufBegin = valBuf + detail::uintToOctal(valBuf, valBufSize - 1, uval);
460 if (arg.basePrefix) {
461 *--valBufBegin = '0';
466 arg.enforce(!arg.thousandsSeparator,
467 "thousands separator (',') not allowed with '",
468 presentation, "' specifier");
469 valBufEnd = valBuf + valBufSize - 1;
470 valBufBegin = valBuf + detail::uintToHexLower(valBuf, valBufSize - 1,
472 if (arg.basePrefix) {
473 *--valBufBegin = 'x';
474 *--valBufBegin = '0';
479 arg.enforce(!arg.thousandsSeparator,
480 "thousands separator (',') not allowed with '",
481 presentation, "' specifier");
482 valBufEnd = valBuf + valBufSize - 1;
483 valBufBegin = valBuf + detail::uintToHexUpper(valBuf, valBufSize - 1,
485 if (arg.basePrefix) {
486 *--valBufBegin = 'X';
487 *--valBufBegin = '0';
493 arg.enforce(!arg.thousandsSeparator,
494 "thousands separator (',') not allowed with '",
495 presentation, "' specifier");
496 valBufEnd = valBuf + valBufSize - 1;
497 valBufBegin = valBuf + detail::uintToBinary(valBuf, valBufSize - 1,
499 if (arg.basePrefix) {
500 *--valBufBegin = presentation; // 0b or 0B
501 *--valBufBegin = '0';
506 arg.error("invalid specifier '", presentation, "'");
510 *--valBufBegin = sign;
514 format_value::formatNumber(StringPiece(valBufBegin, valBufEnd), prefixLen,
524 class FormatValue<bool> {
526 explicit FormatValue(bool val) : val_(val) { }
528 template <class FormatCallback>
529 void format(FormatArg& arg, FormatCallback& cb) const {
530 if (arg.presentation == FormatArg::kDefaultPresentation) {
531 arg.validate(FormatArg::Type::OTHER);
532 format_value::formatString(val_ ? "true" : "false", arg, cb);
534 FormatValue<int>(val_).format(arg, cb);
544 class FormatValue<double> {
546 explicit FormatValue(double val) : val_(val) { }
548 template <class FormatCallback>
549 void format(FormatArg& arg, FormatCallback& cb) const {
550 using ::double_conversion::DoubleToStringConverter;
551 using ::double_conversion::StringBuilder;
553 arg.validate(FormatArg::Type::FLOAT);
555 if (arg.presentation == FormatArg::kDefaultPresentation) {
556 arg.presentation = 'g';
559 const char* infinitySymbol = isupper(arg.presentation) ? "INF" : "inf";
560 const char* nanSymbol = isupper(arg.presentation) ? "NAN" : "nan";
561 char exponentSymbol = isupper(arg.presentation) ? 'E' : 'e';
563 if (arg.precision == FormatArg::kDefaultPrecision) {
567 // 2+: for null terminator and optional sign shenanigans.
568 char buf[2 + std::max({
569 (2 + DoubleToStringConverter::kMaxFixedDigitsBeforePoint +
570 DoubleToStringConverter::kMaxFixedDigitsAfterPoint),
571 (8 + DoubleToStringConverter::kMaxExponentialDigits),
572 (7 + DoubleToStringConverter::kMaxPrecisionDigits)})];
573 StringBuilder builder(buf + 1, sizeof(buf) - 1);
577 case FormatArg::Sign::PLUS_OR_MINUS:
580 case FormatArg::Sign::SPACE_OR_MINUS:
589 switch (arg.presentation) {
596 DoubleToStringConverter::kMaxFixedDigitsAfterPoint) {
597 arg.precision = DoubleToStringConverter::kMaxFixedDigitsAfterPoint;
599 DoubleToStringConverter conv(
600 DoubleToStringConverter::EMIT_POSITIVE_EXPONENT_SIGN,
606 arg.enforce(conv.ToFixed(val, arg.precision, &builder),
607 "fixed double conversion failed");
613 if (arg.precision > DoubleToStringConverter::kMaxExponentialDigits) {
614 arg.precision = DoubleToStringConverter::kMaxExponentialDigits;
617 DoubleToStringConverter conv(
618 DoubleToStringConverter::EMIT_POSITIVE_EXPONENT_SIGN,
624 CHECK(conv.ToExponential(val, arg.precision, &builder));
627 case 'n': // should be locale-aware, but isn't
631 if (arg.precision < DoubleToStringConverter::kMinPrecisionDigits) {
632 arg.precision = DoubleToStringConverter::kMinPrecisionDigits;
633 } else if (arg.precision >
634 DoubleToStringConverter::kMaxPrecisionDigits) {
635 arg.precision = DoubleToStringConverter::kMaxPrecisionDigits;
637 DoubleToStringConverter conv(
638 DoubleToStringConverter::EMIT_POSITIVE_EXPONENT_SIGN,
644 CHECK(conv.ToShortest(val, &builder));
648 arg.error("invalid specifier '", arg.presentation, "'");
651 int len = builder.position();
655 // Add '+' or ' ' sign if needed
657 // anything that's neither negative nor nan
659 if (plusSign && (*p != '-' && *p != 'n' && *p != 'N')) {
663 } else if (*p == '-') {
667 format_value::formatNumber(StringPiece(p, len), prefixLen, arg, cb);
674 // float (defer to double)
676 class FormatValue<float> {
678 explicit FormatValue(float val) : val_(val) { }
680 template <class FormatCallback>
681 void format(FormatArg& arg, FormatCallback& cb) const {
682 FormatValue<double>(val_).format(arg, cb);
689 // Sring-y types (implicitly convertible to StringPiece, except char*)
692 T, typename std::enable_if<
693 (!std::is_pointer<T>::value ||
694 !std::is_same<char, typename std::decay<
695 typename std::remove_pointer<T>::type>::type>::value) &&
696 std::is_convertible<T, StringPiece>::value>::type>
699 explicit FormatValue(StringPiece val) : val_(val) { }
701 template <class FormatCallback>
702 void format(FormatArg& arg, FormatCallback& cb) const {
703 if (arg.keyEmpty()) {
704 arg.validate(FormatArg::Type::OTHER);
705 arg.enforce(arg.presentation == FormatArg::kDefaultPresentation ||
706 arg.presentation == 's',
707 "invalid specifier '", arg.presentation, "'");
708 format_value::formatString(val_, arg, cb);
710 FormatValue<char>(val_.at(arg.splitIntKey())).format(arg, cb);
720 class FormatValue<std::nullptr_t> {
722 explicit FormatValue(std::nullptr_t) { }
724 template <class FormatCallback>
725 void format(FormatArg& arg, FormatCallback& cb) const {
726 arg.validate(FormatArg::Type::OTHER);
727 arg.enforce(arg.presentation == FormatArg::kDefaultPresentation,
728 "invalid specifier '", arg.presentation, "'");
729 format_value::formatString("(null)", arg, cb);
733 // Partial specialization of FormatValue for char*
737 typename std::enable_if<
738 std::is_same<char, typename std::decay<T>::type>::value>::type>
741 explicit FormatValue(T* val) : val_(val) { }
743 template <class FormatCallback>
744 void format(FormatArg& arg, FormatCallback& cb) const {
745 if (arg.keyEmpty()) {
747 FormatValue<std::nullptr_t>(nullptr).format(arg, cb);
749 FormatValue<StringPiece>(val_).format(arg, cb);
752 FormatValue<typename std::decay<T>::type>(
753 val_[arg.splitIntKey()]).format(arg, cb);
761 // Partial specialization of FormatValue for void*
765 typename std::enable_if<
766 std::is_same<void, typename std::decay<T>::type>::value>::type>
769 explicit FormatValue(T* val) : val_(val) { }
771 template <class FormatCallback>
772 void format(FormatArg& arg, FormatCallback& cb) const {
774 FormatValue<std::nullptr_t>(nullptr).format(arg, cb);
776 // Print as a pointer, in hex.
777 arg.validate(FormatArg::Type::OTHER);
778 arg.enforce(arg.presentation == FormatArg::kDefaultPresentation,
779 "invalid specifier '", arg.presentation, "'");
780 arg.basePrefix = true;
781 arg.presentation = 'x';
782 if (arg.align == FormatArg::Align::DEFAULT) {
783 arg.align = FormatArg::Align::LEFT;
785 FormatValue<uintptr_t>(
786 reinterpret_cast<uintptr_t>(val_)).doFormat(arg, cb);
794 template <class T, class = void>
795 class TryFormatValue {
797 template <class FormatCallback>
798 static void formatOrFail(T& value, FormatArg& arg, FormatCallback& cb) {
799 arg.error("No formatter available for this type");
804 class TryFormatValue<
806 typename std::enable_if<
807 0 < sizeof(FormatValue<typename std::decay<T>::type>)>::type>
810 template <class FormatCallback>
811 static void formatOrFail(T& value, FormatArg& arg, FormatCallback& cb) {
812 FormatValue<typename std::decay<T>::type>(value).format(arg, cb);
816 // Partial specialization of FormatValue for other pointers
820 typename std::enable_if<
821 !std::is_same<char, typename std::decay<T>::type>::value &&
822 !std::is_same<void, typename std::decay<T>::type>::value>::type>
825 explicit FormatValue(T* val) : val_(val) { }
827 template <class FormatCallback>
828 void format(FormatArg& arg, FormatCallback& cb) const {
829 if (arg.keyEmpty()) {
830 FormatValue<void*>((void*)val_).format(arg, cb);
832 TryFormatValue<T>::formatOrFail(val_[arg.splitIntKey()], arg, cb);
841 // Shortcut, so we don't have to use enable_if everywhere
842 struct FormatTraitsBase {
843 typedef void enabled;
846 // Traits that define enabled, value_type, and at() for anything
847 // indexable with integral keys: pointers, arrays, vectors, and maps
848 // with integral keys
849 template <class T, class Enable=void> struct IndexableTraits;
851 // Base class for sequences (vectors, deques)
853 struct IndexableTraitsSeq : public FormatTraitsBase {
854 typedef C container_type;
855 typedef typename C::value_type value_type;
856 static const value_type& at(const C& c, int idx) {
861 // Base class for associative types (maps)
863 struct IndexableTraitsAssoc : public FormatTraitsBase {
864 typedef typename C::value_type::second_type value_type;
865 static const value_type& at(const C& c, int idx) {
866 return c.at(static_cast<typename C::key_type>(idx));
871 template <class T, size_t N>
872 struct IndexableTraits<std::array<T, N>>
873 : public IndexableTraitsSeq<std::array<T, N>> {
877 template <class T, class A>
878 struct IndexableTraits<std::vector<T, A>>
879 : public IndexableTraitsSeq<std::vector<T, A>> {
883 template <class T, class A>
884 struct IndexableTraits<std::deque<T, A>>
885 : public IndexableTraitsSeq<std::deque<T, A>> {
889 template <class T, class A>
890 struct IndexableTraits<fbvector<T, A>>
891 : public IndexableTraitsSeq<fbvector<T, A>> {
895 template <class T, size_t M, class A, class B, class C>
896 struct IndexableTraits<small_vector<T, M, A, B, C>>
897 : public IndexableTraitsSeq<small_vector<T, M, A, B, C>> {
900 // std::map with integral keys
901 template <class K, class T, class C, class A>
902 struct IndexableTraits<
903 std::map<K, T, C, A>,
904 typename std::enable_if<std::is_integral<K>::value>::type>
905 : public IndexableTraitsAssoc<std::map<K, T, C, A>> {
908 // std::unordered_map with integral keys
909 template <class K, class T, class H, class E, class A>
910 struct IndexableTraits<
911 std::unordered_map<K, T, H, E, A>,
912 typename std::enable_if<std::is_integral<K>::value>::type>
913 : public IndexableTraitsAssoc<std::unordered_map<K, T, H, E, A>> {
916 } // namespace detail
918 // Partial specialization of FormatValue for integer-indexable containers
922 typename detail::IndexableTraits<T>::enabled> {
924 explicit FormatValue(const T& val) : val_(val) { }
926 template <class FormatCallback>
927 void format(FormatArg& arg, FormatCallback& cb) const {
928 FormatValue<typename std::decay<
929 typename detail::IndexableTraits<T>::value_type>::type>(
930 detail::IndexableTraits<T>::at(
931 val_, arg.splitIntKey())).format(arg, cb);
940 // Define enabled, key_type, convert from StringPiece to the key types
942 template <class T> struct KeyFromStringPiece;
946 struct KeyFromStringPiece<std::string> : public FormatTraitsBase {
947 typedef std::string key_type;
948 static std::string convert(StringPiece s) {
951 typedef void enabled;
956 struct KeyFromStringPiece<fbstring> : public FormatTraitsBase {
957 typedef fbstring key_type;
958 static fbstring convert(StringPiece s) {
959 return s.toFbstring();
965 struct KeyFromStringPiece<StringPiece> : public FormatTraitsBase {
966 typedef StringPiece key_type;
967 static StringPiece convert(StringPiece s) {
972 // Base class for associative types keyed by strings
973 template <class T> struct KeyableTraitsAssoc : public FormatTraitsBase {
974 typedef typename T::key_type key_type;
975 typedef typename T::value_type::second_type value_type;
976 static const value_type& at(const T& map, StringPiece key) {
977 return map.at(KeyFromStringPiece<key_type>::convert(key));
981 // Define enabled, key_type, value_type, at() for supported string-keyed
983 template <class T, class Enabled=void> struct KeyableTraits;
985 // std::map with string key
986 template <class K, class T, class C, class A>
987 struct KeyableTraits<
988 std::map<K, T, C, A>,
989 typename KeyFromStringPiece<K>::enabled>
990 : public KeyableTraitsAssoc<std::map<K, T, C, A>> {
993 // std::unordered_map with string key
994 template <class K, class T, class H, class E, class A>
995 struct KeyableTraits<
996 std::unordered_map<K, T, H, E, A>,
997 typename KeyFromStringPiece<K>::enabled>
998 : public KeyableTraitsAssoc<std::unordered_map<K, T, H, E, A>> {
1001 } // namespace detail
1003 // Partial specialization of FormatValue for string-keyed containers
1007 typename detail::KeyableTraits<T>::enabled> {
1009 explicit FormatValue(const T& val) : val_(val) { }
1011 template <class FormatCallback>
1012 void format(FormatArg& arg, FormatCallback& cb) const {
1013 FormatValue<typename std::decay<
1014 typename detail::KeyableTraits<T>::value_type>::type>(
1015 detail::KeyableTraits<T>::at(
1016 val_, arg.splitKey())).format(arg, cb);
1023 // Partial specialization of FormatValue for pairs
1024 template <class A, class B>
1025 class FormatValue<std::pair<A, B>> {
1027 explicit FormatValue(const std::pair<A, B>& val) : val_(val) { }
1029 template <class FormatCallback>
1030 void format(FormatArg& arg, FormatCallback& cb) const {
1031 int key = arg.splitIntKey();
1034 FormatValue<typename std::decay<A>::type>(val_.first).format(arg, cb);
1037 FormatValue<typename std::decay<B>::type>(val_.second).format(arg, cb);
1040 arg.error("invalid index for pair");
1045 const std::pair<A, B>& val_;
1048 // Partial specialization of FormatValue for tuples
1049 template <class... Args>
1050 class FormatValue<std::tuple<Args...>> {
1051 typedef std::tuple<Args...> Tuple;
1053 explicit FormatValue(const Tuple& val) : val_(val) { }
1055 template <class FormatCallback>
1056 void format(FormatArg& arg, FormatCallback& cb) const {
1057 int key = arg.splitIntKey();
1058 arg.enforce(key >= 0, "tuple index must be non-negative");
1059 doFormat(key, arg, cb);
1063 static constexpr size_t valueCount = std::tuple_size<Tuple>::value;
1065 template <size_t K, class Callback>
1066 typename std::enable_if<K == valueCount>::type
1067 doFormatFrom(size_t i, FormatArg& arg, Callback& cb) const {
1068 arg.enforce("tuple index out of range, max=", i);
1071 template <size_t K, class Callback>
1072 typename std::enable_if<(K < valueCount)>::type
1073 doFormatFrom(size_t i, FormatArg& arg, Callback& cb) const {
1075 FormatValue<typename std::decay<
1076 typename std::tuple_element<K, Tuple>::type>::type>(
1077 std::get<K>(val_)).format(arg, cb);
1079 doFormatFrom<K+1>(i, arg, cb);
1083 template <class Callback>
1084 void doFormat(size_t i, FormatArg& arg, Callback& cb) const {
1085 return doFormatFrom<0>(i, arg, cb);
1091 // Partial specialization of FormatValue for nested Formatters
1092 template <bool containerMode, class... Args>
1093 class FormatValue<Formatter<containerMode, Args...>, void> {
1094 typedef Formatter<containerMode, Args...> FormatterValue;
1096 explicit FormatValue(const FormatterValue& f) : f_(f) { }
1098 template <class FormatCallback>
1099 void format(FormatArg& arg, FormatCallback& cb) const {
1100 format_value::formatFormatter(f_, arg, cb);
1103 const FormatterValue& f_;
1107 * Formatter objects can be appended to strings, and therefore they're
1108 * compatible with folly::toAppend and folly::to.
1110 template <class Tgt, bool containerMode, class... Args>
1111 typename std::enable_if<
1112 detail::IsSomeString<Tgt>::value>::type
1113 toAppend(const Formatter<containerMode, Args...>& value, Tgt * result) {
1114 value.appendTo(*result);
1117 } // namespace folly