chromium/third_party/abseil-cpp/absl/strings/internal/str_format/parser.h

// Copyright 2020 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
//
//      https://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.

#ifndef ABSL_STRINGS_INTERNAL_STR_FORMAT_PARSER_H_
#define ABSL_STRINGS_INTERNAL_STR_FORMAT_PARSER_H_

#include <stddef.h>
#include <stdlib.h>

#include <cassert>
#include <cstring>
#include <initializer_list>
#include <memory>
#include <string>
#include <utility>
#include <vector>

#include "absl/base/config.h"
#include "absl/base/optimization.h"
#include "absl/strings/internal/str_format/checker.h"
#include "absl/strings/internal/str_format/constexpr_parser.h"
#include "absl/strings/internal/str_format/extension.h"
#include "absl/strings/string_view.h"

namespace absl {
ABSL_NAMESPACE_BEGIN
namespace str_format_internal {

std::string LengthModToString(LengthMod v);

const char* ConsumeUnboundConversionNoInline(const char* p, const char* end,
                                             UnboundConversion* conv,
                                             int* next_arg);

// Parse the format string provided in 'src' and pass the identified items into
// 'consumer'.
// Text runs will be passed by calling
//   Consumer::Append(string_view);
// ConversionItems will be passed by calling
//   Consumer::ConvertOne(UnboundConversion, string_view);
// In the case of ConvertOne, the string_view that is passed is the
// portion of the format string corresponding to the conversion, not including
// the leading %. On success, it returns true. On failure, it stops and returns
// false.
template <typename Consumer>
bool ParseFormatString(string_view src, Consumer consumer) { … }

// Always returns true, or fails to compile in a constexpr context if s does not
// point to a constexpr char array.
constexpr bool EnsureConstexpr(string_view s) { … }

class ParsedFormatBase { … };


// A value type representing a preparsed format.  These can be created, copied
// around, and reused to speed up formatting loops.
// The user must specify through the template arguments the conversion
// characters used in the format. This will be checked at compile time.
//
// This class uses Conv enum values to specify each argument.
// This allows for more flexibility as you can specify multiple possible
// conversion characters for each argument.
// ParsedFormat<char...> is a simplified alias for when the user only
// needs to specify a single conversion character for each argument.
//
// Example:
//   // Extended format supports multiple characters per argument:
//   using MyFormat = ExtendedParsedFormat<Conv::d | Conv::x>;
//   MyFormat GetFormat(bool use_hex) {
//     if (use_hex) return MyFormat("foo %x bar");
//     return MyFormat("foo %d bar");
//   }
//   // 'format' can be used with any value that supports 'd' and 'x',
//   // like `int`.
//   auto format = GetFormat(use_hex);
//   value = StringF(format, i);
//
// This class also supports runtime format checking with the ::New() and
// ::NewAllowIgnored() factory functions.
// This is the only API that allows the user to pass a runtime specified format
// string. These factory functions will return NULL if the format does not match
// the conversions requested by the user.
template <FormatConversionCharSet... C>
class ExtendedParsedFormat : public str_format_internal::ParsedFormatBase { … };
}  // namespace str_format_internal
ABSL_NAMESPACE_END
}  // namespace absl

#endif  // ABSL_STRINGS_INTERNAL_STR_FORMAT_PARSER_H_