tvl-depot/absl/strings/numbers.h
Abseil Team 7aacab8ae0 - e2f6b8ac647271815b4fed2991f405524dd762c3 Release cctz microbenchmarks. by Alex Strelnikov <strel@google.com>
- 924ba2a3f9fca695d73c6bf491d20669e2b96b8e Changed RawPtr to use std::addressof() instead of operato... by Abseil Team <absl-team@google.com>
  - e8cf67f9fa74d4c5632da35547025ad2301c6819 Import of CCTZ from GitHub. by Alex Strelnikov <strel@google.com>
  - 2ece8a96611afcddd7b91e0197dadb896248250c Abandon ".inc" files in favor of ".h" headers. by Jorg Brown <jorg@google.com>
  - 37f5ed5da4058f90fb3e6a2733fce5b1fd0aaedf Add exception safety tests for absl::optional<T> by Abseil Team <absl-team@google.com>
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  - 93e5b134607a554993387ad913e6c1621606004b Release Charmap microbenchmark. by Alex Strelnikov <strel@google.com>
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  - 250f51839ed26dd1e6b658d35aa291413e5f4825 Internal change by Greg Falcon <gfalcon@google.com>
  - ce34900fa3d1a95a8446bc943cdd801fac95be25 Improve compatibility of cctz cc_test targets for portabl... by Shaindel Schwartz <shaindel@google.com>
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  - dfcd4e455923703c1a1dcd523c5f915f7990fa2a Accept strings with custom allocators as arguments to abs... by Greg Falcon <gfalcon@google.com>
  - 2946b41ed3d5b8b5a8dc11182e443cf1ab6e3bde Link against benchmark_main instead of using BENCHMARK_MA... by Alex Strelnikov <strel@google.com>
  - f09de9e03bf8edd363069c4b352d8009423f531c Adds link to doc about the formats allowed by SimpleAtof(... by Greg Miller <jgm@google.com>
  - 59b0977e7a308e0800277886cf60226b2cc426a1 Simplify the HideMask() calculation so that it doesn't us... by Jorg Brown <jorg@google.com>

GitOrigin-RevId: e2f6b8ac647271815b4fed2991f405524dd762c3
Change-Id: Ib9c8547ed7fe217fad6cb3ab1362e96181aa5cfa
2018-05-31 15:58:36 -04:00

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7.4 KiB
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//
// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// -----------------------------------------------------------------------------
// File: numbers.h
// -----------------------------------------------------------------------------
//
// This package contains functions for converting strings to numbers. For
// converting numbers to strings, use `StrCat()` or `StrAppend()` in str_cat.h,
// which automatically detect and convert most number values appropriately.
#ifndef ABSL_STRINGS_NUMBERS_H_
#define ABSL_STRINGS_NUMBERS_H_
#include <cstddef>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <limits>
#include <string>
#include <type_traits>
#include "absl/base/macros.h"
#include "absl/base/port.h"
#include "absl/numeric/int128.h"
#include "absl/strings/string_view.h"
namespace absl {
// SimpleAtoi()
//
// Converts the given std::string into an integer value, returning `true` if
// successful. The std::string must reflect a base-10 integer (optionally followed or
// preceded by ASCII whitespace) whose value falls within the range of the
// integer type,
template <typename int_type>
ABSL_MUST_USE_RESULT bool SimpleAtoi(absl::string_view s, int_type* out);
// SimpleAtof()
//
// Converts the given std::string (optionally followed or preceded by ASCII
// whitespace) into a float, which may be rounded on overflow or underflow.
// See http://en.cppreference.com/w/c/std::string/byte/strtof for details about the
// allowed formats for `str`.
ABSL_MUST_USE_RESULT bool SimpleAtof(absl::string_view str, float* value);
// SimpleAtod()
//
// Converts the given std::string (optionally followed or preceded by ASCII
// whitespace) into a double, which may be rounded on overflow or underflow.
// See http://en.cppreference.com/w/c/std::string/byte/strtof for details about the
// allowed formats for `str`.
ABSL_MUST_USE_RESULT bool SimpleAtod(absl::string_view str, double* value);
// SimpleAtob()
//
// Converts the given std::string into a boolean, returning `true` if successful.
// The following case-insensitive strings are interpreted as boolean `true`:
// "true", "t", "yes", "y", "1". The following case-insensitive strings
// are interpreted as boolean `false`: "false", "f", "no", "n", "0".
ABSL_MUST_USE_RESULT bool SimpleAtob(absl::string_view str, bool* value);
} // namespace absl
// End of public API. Implementation details follow.
namespace absl {
namespace numbers_internal {
// safe_strto?() functions for implementing SimpleAtoi()
bool safe_strto32_base(absl::string_view text, int32_t* value, int base);
bool safe_strto64_base(absl::string_view text, int64_t* value, int base);
bool safe_strtou32_base(absl::string_view text, uint32_t* value, int base);
bool safe_strtou64_base(absl::string_view text, uint64_t* value, int base);
static const int kFastToBufferSize = 32;
static const int kSixDigitsToBufferSize = 16;
// Helper function for fast formatting of floating-point values.
// The result is the same as printf's "%g", a.k.a. "%.6g"; that is, six
// significant digits are returned, trailing zeros are removed, and numbers
// outside the range 0.0001-999999 are output using scientific notation
// (1.23456e+06). This routine is heavily optimized.
// Required buffer size is `kSixDigitsToBufferSize`.
size_t SixDigitsToBuffer(double d, char* buffer);
// These functions are intended for speed. All functions take an output buffer
// as an argument and return a pointer to the last byte they wrote, which is the
// terminating '\0'. At most `kFastToBufferSize` bytes are written.
char* FastIntToBuffer(int32_t, char*);
char* FastIntToBuffer(uint32_t, char*);
char* FastIntToBuffer(int64_t, char*);
char* FastIntToBuffer(uint64_t, char*);
// For enums and integer types that are not an exact match for the types above,
// use templates to call the appropriate one of the four overloads above.
template <typename int_type>
char* FastIntToBuffer(int_type i, char* buffer) {
static_assert(sizeof(i) <= 64 / 8,
"FastIntToBuffer works only with 64-bit-or-less integers.");
// TODO(jorg): This signed-ness check is used because it works correctly
// with enums, and it also serves to check that int_type is not a pointer.
// If one day something like std::is_signed<enum E> works, switch to it.
if (static_cast<int_type>(1) - 2 < 0) { // Signed
if (sizeof(i) > 32 / 8) { // 33-bit to 64-bit
return FastIntToBuffer(static_cast<int64_t>(i), buffer);
} else { // 32-bit or less
return FastIntToBuffer(static_cast<int32_t>(i), buffer);
}
} else { // Unsigned
if (sizeof(i) > 32 / 8) { // 33-bit to 64-bit
return FastIntToBuffer(static_cast<uint64_t>(i), buffer);
} else { // 32-bit or less
return FastIntToBuffer(static_cast<uint32_t>(i), buffer);
}
}
}
// Implementation of SimpleAtoi, generalized to support arbitrary base (used
// with base different from 10 elsewhere in Abseil implementation).
template <typename int_type>
ABSL_MUST_USE_RESULT bool safe_strtoi_base(absl::string_view s, int_type* out,
int base) {
static_assert(sizeof(*out) == 4 || sizeof(*out) == 8,
"SimpleAtoi works only with 32-bit or 64-bit integers.");
static_assert(!std::is_floating_point<int_type>::value,
"Use SimpleAtof or SimpleAtod instead.");
bool parsed;
// TODO(jorg): This signed-ness check is used because it works correctly
// with enums, and it also serves to check that int_type is not a pointer.
// If one day something like std::is_signed<enum E> works, switch to it.
if (static_cast<int_type>(1) - 2 < 0) { // Signed
if (sizeof(*out) == 64 / 8) { // 64-bit
int64_t val;
parsed = numbers_internal::safe_strto64_base(s, &val, base);
*out = static_cast<int_type>(val);
} else { // 32-bit
int32_t val;
parsed = numbers_internal::safe_strto32_base(s, &val, base);
*out = static_cast<int_type>(val);
}
} else { // Unsigned
if (sizeof(*out) == 64 / 8) { // 64-bit
uint64_t val;
parsed = numbers_internal::safe_strtou64_base(s, &val, base);
*out = static_cast<int_type>(val);
} else { // 32-bit
uint32_t val;
parsed = numbers_internal::safe_strtou32_base(s, &val, base);
*out = static_cast<int_type>(val);
}
}
return parsed;
}
} // namespace numbers_internal
// SimpleAtoi()
//
// Converts a std::string to an integer, using `safe_strto?()` functions for actual
// parsing, returning `true` if successful. The `safe_strto?()` functions apply
// strict checking; the std::string must be a base-10 integer, optionally followed or
// preceded by ASCII whitespace, with a value in the range of the corresponding
// integer type.
template <typename int_type>
ABSL_MUST_USE_RESULT bool SimpleAtoi(absl::string_view s, int_type* out) {
return numbers_internal::safe_strtoi_base(s, out, 10);
}
} // namespace absl
#endif // ABSL_STRINGS_NUMBERS_H_