mirror of
https://github.com/aykhans/AzSuicideDataVisualization.git
synced 2025-04-22 18:32:15 +00:00
156 lines
4.7 KiB
C++
156 lines
4.7 KiB
C++
// Licensed to the Apache Software Foundation (ASF) under one
|
|
// or more contributor license agreements. See the NOTICE file
|
|
// distributed with this work for additional information
|
|
// regarding copyright ownership. The ASF licenses this file
|
|
// to you 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 <cstddef>
|
|
#include <cstdint>
|
|
#include <iterator>
|
|
#include <numeric>
|
|
#include <utility>
|
|
#include <vector>
|
|
|
|
namespace arrow {
|
|
namespace internal {
|
|
|
|
/// Create a vector containing the values from start up to stop
|
|
template <typename T>
|
|
std::vector<T> Iota(T start, T stop) {
|
|
if (start > stop) {
|
|
return {};
|
|
}
|
|
std::vector<T> result(static_cast<size_t>(stop - start));
|
|
std::iota(result.begin(), result.end(), start);
|
|
return result;
|
|
}
|
|
|
|
/// Create a vector containing the values from 0 up to length
|
|
template <typename T>
|
|
std::vector<T> Iota(T length) {
|
|
return Iota(static_cast<T>(0), length);
|
|
}
|
|
|
|
/// Create a range from a callable which takes a single index parameter
|
|
/// and returns the value of iterator on each call and a length.
|
|
/// Only iterators obtained from the same range should be compared, the
|
|
/// behaviour generally similar to other STL containers.
|
|
template <typename Generator>
|
|
class LazyRange {
|
|
private:
|
|
// callable which generates the values
|
|
// has to be defined at the beginning of the class for type deduction
|
|
const Generator gen_;
|
|
// the length of the range
|
|
int64_t length_;
|
|
#ifdef _MSC_VER
|
|
// workaround to VS2010 not supporting decltype properly
|
|
// see https://stackoverflow.com/questions/21782846/decltype-for-class-member-function
|
|
static Generator gen_static_;
|
|
#endif
|
|
|
|
public:
|
|
#ifdef _MSC_VER
|
|
using return_type = decltype(gen_static_(0));
|
|
#else
|
|
using return_type = decltype(gen_(0));
|
|
#endif
|
|
|
|
/// Construct a new range from a callable and length
|
|
LazyRange(Generator gen, int64_t length) : gen_(gen), length_(length) {}
|
|
|
|
// Class of the dependent iterator, created implicitly by begin and end
|
|
class RangeIter {
|
|
public:
|
|
using difference_type = int64_t;
|
|
using value_type = return_type;
|
|
using reference = const value_type&;
|
|
using pointer = const value_type*;
|
|
using iterator_category = std::forward_iterator_tag;
|
|
|
|
#ifdef _MSC_VER
|
|
// msvc complains about unchecked iterators,
|
|
// see https://stackoverflow.com/questions/21655496/error-c4996-checked-iterators
|
|
using _Unchecked_type = typename LazyRange<Generator>::RangeIter;
|
|
#endif
|
|
|
|
RangeIter() = delete;
|
|
RangeIter(const RangeIter& other) = default;
|
|
RangeIter& operator=(const RangeIter& other) = default;
|
|
|
|
RangeIter(const LazyRange<Generator>& range, int64_t index)
|
|
: range_(&range), index_(index) {}
|
|
|
|
const return_type operator*() const { return range_->gen_(index_); }
|
|
|
|
RangeIter operator+(difference_type length) const {
|
|
return RangeIter(*range_, index_ + length);
|
|
}
|
|
|
|
// pre-increment
|
|
RangeIter& operator++() {
|
|
++index_;
|
|
return *this;
|
|
}
|
|
|
|
// post-increment
|
|
RangeIter operator++(int) {
|
|
auto copy = RangeIter(*this);
|
|
++index_;
|
|
return copy;
|
|
}
|
|
|
|
bool operator==(const typename LazyRange<Generator>::RangeIter& other) const {
|
|
return this->index_ == other.index_ && this->range_ == other.range_;
|
|
}
|
|
|
|
bool operator!=(const typename LazyRange<Generator>::RangeIter& other) const {
|
|
return this->index_ != other.index_ || this->range_ != other.range_;
|
|
}
|
|
|
|
int64_t operator-(const typename LazyRange<Generator>::RangeIter& other) const {
|
|
return this->index_ - other.index_;
|
|
}
|
|
|
|
bool operator<(const typename LazyRange<Generator>::RangeIter& other) const {
|
|
return this->index_ < other.index_;
|
|
}
|
|
|
|
private:
|
|
// parent range reference
|
|
const LazyRange* range_;
|
|
// current index
|
|
int64_t index_;
|
|
};
|
|
|
|
friend class RangeIter;
|
|
|
|
// Create a new begin const iterator
|
|
RangeIter begin() { return RangeIter(*this, 0); }
|
|
|
|
// Create a new end const iterator
|
|
RangeIter end() { return RangeIter(*this, length_); }
|
|
};
|
|
|
|
/// Helper function to create a lazy range from a callable (e.g. lambda) and length
|
|
template <typename Generator>
|
|
LazyRange<Generator> MakeLazyRange(Generator&& gen, int64_t length) {
|
|
return LazyRange<Generator>(std::forward<Generator>(gen), length);
|
|
}
|
|
|
|
} // namespace internal
|
|
} // namespace arrow
|