mirror of
https://github.com/ecency/ecency-mobile.git
synced 2024-12-23 13:22:02 +03:00
64 lines
1.9 KiB
C++
64 lines
1.9 KiB
C++
/*
|
|
* Copyright 2016 Facebook, Inc.
|
|
*
|
|
* 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.
|
|
*/
|
|
|
|
#pragma once
|
|
|
|
#include <type_traits>
|
|
|
|
namespace folly { namespace detail {
|
|
|
|
// Shortcut, so we don't have to use enable_if everywhere
|
|
struct FormatTraitsBase {
|
|
typedef void enabled;
|
|
};
|
|
|
|
// Traits that define enabled, value_type, and at() for anything
|
|
// indexable with integral keys: pointers, arrays, vectors, and maps
|
|
// with integral keys
|
|
template <class T, class Enable = void> struct IndexableTraits;
|
|
|
|
// Base class for sequences (vectors, deques)
|
|
template <class C>
|
|
struct IndexableTraitsSeq : public FormatTraitsBase {
|
|
typedef C container_type;
|
|
typedef typename C::value_type value_type;
|
|
|
|
static const value_type& at(const C& c, int idx) {
|
|
return c.at(idx);
|
|
}
|
|
|
|
static const value_type& at(const C& c, int idx, const value_type& dflt) {
|
|
return (idx >= 0 && size_t(idx) < c.size()) ? c.at(idx) : dflt;
|
|
}
|
|
};
|
|
|
|
// Base class for associative types (maps)
|
|
template <class C>
|
|
struct IndexableTraitsAssoc : public FormatTraitsBase {
|
|
typedef typename C::value_type::second_type value_type;
|
|
|
|
static const value_type& at(const C& c, int idx) {
|
|
return c.at(static_cast<typename C::key_type>(idx));
|
|
}
|
|
|
|
static const value_type& at(const C& c, int idx, const value_type& dflt) {
|
|
auto pos = c.find(static_cast<typename C::key_type>(idx));
|
|
return pos != c.end() ? pos->second : dflt;
|
|
}
|
|
};
|
|
|
|
}} // namespaces
|