summaryrefslogtreecommitdiffstats
path: root/dom/quota/Flatten.h
diff options
context:
space:
mode:
authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 00:47:55 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 00:47:55 +0000
commit26a029d407be480d791972afb5975cf62c9360a6 (patch)
treef435a8308119effd964b339f76abb83a57c29483 /dom/quota/Flatten.h
parentInitial commit. (diff)
downloadfirefox-26a029d407be480d791972afb5975cf62c9360a6.tar.xz
firefox-26a029d407be480d791972afb5975cf62c9360a6.zip
Adding upstream version 124.0.1.upstream/124.0.1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'dom/quota/Flatten.h')
-rw-r--r--dom/quota/Flatten.h118
1 files changed, 118 insertions, 0 deletions
diff --git a/dom/quota/Flatten.h b/dom/quota/Flatten.h
new file mode 100644
index 0000000000..2eb29c6010
--- /dev/null
+++ b/dom/quota/Flatten.h
@@ -0,0 +1,118 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef DOM_QUOTA_FLATTEN_H_
+#define DOM_QUOTA_FLATTEN_H_
+
+#include <iterator>
+#include <type_traits>
+#include <utility>
+
+// XXX This should be moved to MFBT.
+
+namespace mozilla::dom::quota {
+
+namespace detail {
+
+using std::begin;
+using std::end;
+
+template <typename T, typename NestedRange>
+auto Flatten(NestedRange&& aRange) -> std::enable_if_t<
+ std::is_same_v<T, std::decay_t<typename decltype(begin(
+ std::declval<const NestedRange&>()))::value_type>>,
+ std::conditional_t<std::is_rvalue_reference_v<NestedRange>,
+ std::decay_t<NestedRange>, NestedRange>> {
+ return std::forward<NestedRange>(aRange);
+}
+
+template <typename T, typename NestedRange>
+struct FlatIter {
+ using OuterIterator =
+ decltype(begin(std::declval<const std::decay_t<NestedRange>&>()));
+ using InnerIterator =
+ decltype(begin(*begin(std::declval<const std::decay_t<NestedRange>&>())));
+
+ explicit FlatIter(const NestedRange& aRange, OuterIterator aIter)
+ : mOuterIter{std::move(aIter)}, mOuterEnd{end(aRange)} {
+ InitInner();
+ }
+
+ const T& operator*() const { return *mInnerIter; }
+
+ FlatIter& operator++() {
+ ++mInnerIter;
+ if (mInnerIter == mInnerEnd) {
+ ++mOuterIter;
+ InitInner();
+ }
+ return *this;
+ }
+
+ bool operator!=(const FlatIter& aOther) const {
+ return mOuterIter != aOther.mOuterIter ||
+ (mOuterIter != mOuterEnd && mInnerIter != aOther.mInnerIter);
+ }
+
+ private:
+ void InitInner() {
+ while (mOuterIter != mOuterEnd) {
+ const typename OuterIterator::value_type& innerRange = *mOuterIter;
+
+ mInnerIter = begin(innerRange);
+ mInnerEnd = end(innerRange);
+
+ if (mInnerIter != mInnerEnd) {
+ break;
+ }
+
+ ++mOuterIter;
+ }
+ }
+
+ OuterIterator mOuterIter;
+ const OuterIterator mOuterEnd;
+
+ InnerIterator mInnerIter;
+ InnerIterator mInnerEnd;
+};
+
+template <typename T, typename NestedRange>
+struct FlatRange {
+ explicit FlatRange(NestedRange aRange) : mRange{std::move(aRange)} {}
+
+ auto begin() const {
+ using std::begin;
+ return FlatIter<T, NestedRange>{mRange, begin(mRange)};
+ }
+ auto end() const {
+ using std::end;
+ return FlatIter<T, NestedRange>{mRange, end(mRange)};
+ }
+
+ private:
+ NestedRange mRange;
+};
+
+template <typename T, typename NestedRange>
+auto Flatten(NestedRange&& aRange) -> std::enable_if_t<
+ !std::is_same_v<
+ T, std::decay_t<typename decltype(begin(
+ std::declval<const std::decay_t<NestedRange>&>()))::value_type>>,
+ FlatRange<T, NestedRange>> {
+ return FlatRange<T, NestedRange>{std::forward<NestedRange>(aRange)};
+}
+
+} // namespace detail
+
+template <typename T, typename NestedRange>
+auto Flatten(NestedRange&& aRange) -> decltype(auto) {
+ return detail::Flatten<T>(std::forward<NestedRange>(aRange));
+}
+
+} // namespace mozilla::dom::quota
+
+#endif