aboutsummaryrefslogtreecommitdiff
path: root/absl/algorithm/container.h
diff options
context:
space:
mode:
Diffstat (limited to 'absl/algorithm/container.h')
-rw-r--r--absl/algorithm/container.h133
1 files changed, 60 insertions, 73 deletions
diff --git a/absl/algorithm/container.h b/absl/algorithm/container.h
index c7782d4f..c7bafae1 100644
--- a/absl/algorithm/container.h
+++ b/absl/algorithm/container.h
@@ -52,6 +52,7 @@
#include "absl/algorithm/algorithm.h"
#include "absl/base/macros.h"
+#include "absl/base/nullability.h"
#include "absl/meta/type_traits.h"
namespace absl {
@@ -116,18 +117,6 @@ template <class Key, class Hash, class KeyEqual, class Allocator>
struct IsUnorderedContainer<std::unordered_set<Key, Hash, KeyEqual, Allocator>>
: std::true_type {};
-// container_algorithm_internal::c_size. It is meant for internal use only.
-
-template <class C>
-auto c_size(C& c) -> decltype(c.size()) {
- return c.size();
-}
-
-template <class T, std::size_t N>
-constexpr std::size_t c_size(T (&)[N]) {
- return N;
-}
-
} // namespace container_algorithm_internal
// PUBLIC API
@@ -348,20 +337,10 @@ container_algorithm_internal::ContainerDifferenceType<const C> c_count_if(
template <typename C1, typename C2>
container_algorithm_internal::ContainerIterPairType<C1, C2> c_mismatch(C1& c1,
C2& c2) {
- auto first1 = container_algorithm_internal::c_begin(c1);
- auto last1 = container_algorithm_internal::c_end(c1);
- auto first2 = container_algorithm_internal::c_begin(c2);
- auto last2 = container_algorithm_internal::c_end(c2);
-
- for (; first1 != last1 && first2 != last2; ++first1, (void)++first2) {
- // Negates equality because Cpp17EqualityComparable doesn't require clients
- // to overload both `operator==` and `operator!=`.
- if (!(*first1 == *first2)) {
- break;
- }
- }
-
- return std::make_pair(first1, first2);
+ return std::mismatch(container_algorithm_internal::c_begin(c1),
+ container_algorithm_internal::c_end(c1),
+ container_algorithm_internal::c_begin(c2),
+ container_algorithm_internal::c_end(c2));
}
// Overload of c_mismatch() for using a predicate evaluation other than `==` as
@@ -370,56 +349,33 @@ container_algorithm_internal::ContainerIterPairType<C1, C2> c_mismatch(C1& c1,
template <typename C1, typename C2, typename BinaryPredicate>
container_algorithm_internal::ContainerIterPairType<C1, C2> c_mismatch(
C1& c1, C2& c2, BinaryPredicate pred) {
- auto first1 = container_algorithm_internal::c_begin(c1);
- auto last1 = container_algorithm_internal::c_end(c1);
- auto first2 = container_algorithm_internal::c_begin(c2);
- auto last2 = container_algorithm_internal::c_end(c2);
-
- for (; first1 != last1 && first2 != last2; ++first1, (void)++first2) {
- if (!pred(*first1, *first2)) {
- break;
- }
- }
-
- return std::make_pair(first1, first2);
+ return std::mismatch(container_algorithm_internal::c_begin(c1),
+ container_algorithm_internal::c_end(c1),
+ container_algorithm_internal::c_begin(c2),
+ container_algorithm_internal::c_end(c2), pred);
}
// c_equal()
//
// Container-based version of the <algorithm> `std::equal()` function to
// test whether two containers are equal.
-//
-// NOTE: the semantics of c_equal() are slightly different than those of
-// equal(): while the latter iterates over the second container only up to the
-// size of the first container, c_equal() also checks whether the container
-// sizes are equal. This better matches expectations about c_equal() based on
-// its signature.
-//
-// Example:
-// vector v1 = <1, 2, 3>;
-// vector v2 = <1, 2, 3, 4>;
-// equal(std::begin(v1), std::end(v1), std::begin(v2)) returns true
-// c_equal(v1, v2) returns false
-
template <typename C1, typename C2>
bool c_equal(const C1& c1, const C2& c2) {
- return ((container_algorithm_internal::c_size(c1) ==
- container_algorithm_internal::c_size(c2)) &&
- std::equal(container_algorithm_internal::c_begin(c1),
- container_algorithm_internal::c_end(c1),
- container_algorithm_internal::c_begin(c2)));
+ return std::equal(container_algorithm_internal::c_begin(c1),
+ container_algorithm_internal::c_end(c1),
+ container_algorithm_internal::c_begin(c2),
+ container_algorithm_internal::c_end(c2));
}
// Overload of c_equal() for using a predicate evaluation other than `==` as
// the function's test condition.
template <typename C1, typename C2, typename BinaryPredicate>
bool c_equal(const C1& c1, const C2& c2, BinaryPredicate&& pred) {
- return ((container_algorithm_internal::c_size(c1) ==
- container_algorithm_internal::c_size(c2)) &&
- std::equal(container_algorithm_internal::c_begin(c1),
- container_algorithm_internal::c_end(c1),
- container_algorithm_internal::c_begin(c2),
- std::forward<BinaryPredicate>(pred)));
+ return std::equal(container_algorithm_internal::c_begin(c1),
+ container_algorithm_internal::c_end(c1),
+ container_algorithm_internal::c_begin(c2),
+ container_algorithm_internal::c_end(c2),
+ std::forward<BinaryPredicate>(pred));
}
// c_is_permutation()
@@ -428,20 +384,20 @@ bool c_equal(const C1& c1, const C2& c2, BinaryPredicate&& pred) {
// to test whether a container is a permutation of another.
template <typename C1, typename C2>
bool c_is_permutation(const C1& c1, const C2& c2) {
- using std::begin;
- using std::end;
- return c1.size() == c2.size() &&
- std::is_permutation(begin(c1), end(c1), begin(c2));
+ return std::is_permutation(container_algorithm_internal::c_begin(c1),
+ container_algorithm_internal::c_end(c1),
+ container_algorithm_internal::c_begin(c2),
+ container_algorithm_internal::c_end(c2));
}
// Overload of c_is_permutation() for using a predicate evaluation other than
// `==` as the function's test condition.
template <typename C1, typename C2, typename BinaryPredicate>
bool c_is_permutation(const C1& c1, const C2& c2, BinaryPredicate&& pred) {
- using std::begin;
- using std::end;
- return c1.size() == c2.size() &&
- std::is_permutation(begin(c1), end(c1), begin(c2),
+ return std::is_permutation(container_algorithm_internal::c_begin(c1),
+ container_algorithm_internal::c_end(c1),
+ container_algorithm_internal::c_begin(c2),
+ container_algorithm_internal::c_end(c2),
std::forward<BinaryPredicate>(pred));
}
@@ -818,6 +774,36 @@ void c_shuffle(RandomAccessContainer& c, UniformRandomBitGenerator&& gen) {
std::forward<UniformRandomBitGenerator>(gen));
}
+// c_sample()
+//
+// Container-based version of the <algorithm> `std::sample()` function to
+// randomly sample elements from the container without replacement using a
+// `gen()` uniform random number generator and write them to an iterator range.
+template <typename C, typename OutputIterator, typename Distance,
+ typename UniformRandomBitGenerator>
+OutputIterator c_sample(const C& c, OutputIterator result, Distance n,
+ UniformRandomBitGenerator&& gen) {
+#if defined(__cpp_lib_sample) && __cpp_lib_sample >= 201603L
+ return std::sample(container_algorithm_internal::c_begin(c),
+ container_algorithm_internal::c_end(c), result, n,
+ std::forward<UniformRandomBitGenerator>(gen));
+#else
+ // Fall back to a stable selection-sampling implementation.
+ auto first = container_algorithm_internal::c_begin(c);
+ Distance unsampled_elements = c_distance(c);
+ n = (std::min)(n, unsampled_elements);
+ for (; n != 0; ++first) {
+ Distance r =
+ std::uniform_int_distribution<Distance>(0, --unsampled_elements)(gen);
+ if (r < n) {
+ *result++ = *first;
+ --n;
+ }
+ }
+ return result;
+#endif
+}
+
//------------------------------------------------------------------------------
// <algorithm> Partition functions
//------------------------------------------------------------------------------
@@ -1131,7 +1117,7 @@ c_equal_range(Sequence& sequence, const T& value, LessThan&& comp) {
// to test if any element in the sorted container contains a value equivalent to
// 'value'.
template <typename Sequence, typename T>
-bool c_binary_search(Sequence&& sequence, const T& value) {
+bool c_binary_search(const Sequence& sequence, const T& value) {
return std::binary_search(container_algorithm_internal::c_begin(sequence),
container_algorithm_internal::c_end(sequence),
value);
@@ -1140,7 +1126,8 @@ bool c_binary_search(Sequence&& sequence, const T& value) {
// Overload of c_binary_search() for performing a `comp` comparison other than
// the default `operator<`.
template <typename Sequence, typename T, typename LessThan>
-bool c_binary_search(Sequence&& sequence, const T& value, LessThan&& comp) {
+bool c_binary_search(const Sequence& sequence, const T& value,
+ LessThan&& comp) {
return std::binary_search(container_algorithm_internal::c_begin(sequence),
container_algorithm_internal::c_end(sequence),
value, std::forward<LessThan>(comp));
@@ -1656,7 +1643,7 @@ bool c_prev_permutation(C& c, LessThan&& comp) {
//
// Container-based version of the <numeric> `std::iota()` function
// to compute successive values of `value`, as if incremented with `++value`
-// after each element is written. and write them to the container.
+// after each element is written, and write them to the container.
template <typename Sequence, typename T>
void c_iota(Sequence& sequence, const T& value) {
std::iota(container_algorithm_internal::c_begin(sequence),
generated by cgit v1.2.3 (git 2.25.1) at 2024-05-28 11:35:05 +0000