From a7b85e59931443dd33adeb02c7201c1bd1d7cd1d Mon Sep 17 00:00:00 2001
From: Ulf Hermann <ulf.hermann@qt.io>
Date: Tue, 8 Sep 2020 15:34:42 +0200
Subject: [PATCH] QMetaContainer: Add function to erase ranges from sequences

Change-Id: Ic51103c36d288f236106e2d3aec1401d53b97a15
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
---
 src/corelib/global/qcontainerinfo.h   |  5 +++++
 src/corelib/kernel/qmetacontainer.cpp | 24 ++++++++++++++++++++++++
 src/corelib/kernel/qmetacontainer.h   | 19 +++++++++++++++++++
 3 files changed, 48 insertions(+)

diff --git a/src/corelib/global/qcontainerinfo.h b/src/corelib/global/qcontainerinfo.h
index ad3ef301e4..c6ee9328ec 100644
--- a/src/corelib/global/qcontainerinfo.h
+++ b/src/corelib/global/qcontainerinfo.h
@@ -141,6 +141,11 @@ constexpr bool can_erase_at_iterator_v = false;
 template<typename C>
 constexpr bool can_erase_at_iterator_v<C, std::void_t<decltype(C().erase(C().begin()))>> = true;
 
+template<typename, typename = void>
+constexpr bool can_erase_range_at_iterator_v = false;
+template<typename C>
+constexpr bool can_erase_range_at_iterator_v<C, std::void_t<decltype(C().erase(C().begin(), C().end()))>> = true;
+
 QT_WARNING_POP
 
 }
diff --git a/src/corelib/kernel/qmetacontainer.cpp b/src/corelib/kernel/qmetacontainer.cpp
index e11381c1bd..9382909092 100644
--- a/src/corelib/kernel/qmetacontainer.cpp
+++ b/src/corelib/kernel/qmetacontainer.cpp
@@ -640,6 +640,30 @@ void QMetaSequence::eraseValueAtIterator(void *container, const void *iterator)
         d_ptr->eraseValueAtIteratorFn(container, iterator);
 }
 
+/*!
+    Returns \c true if a range between two iterators can be erased from the
+    container, \c false otherwise.
+ */
+bool QMetaSequence::canEraseRangeAtIterator() const
+{
+    if (d_ptr)
+        return d_ptr->eraseRangeAtIteratorFn;
+    return false;
+}
+
+/*!
+    Erases the range of values between the iterators \a iterator1 and
+    \a iterator2 from the \a container, if possible.
+
+    \sa canEraseValueAtIterator(), begin(), end()
+ */
+void QMetaSequence::eraseRangeAtIterator(void *container, const void *iterator1,
+                                         const void *iterator2) const
+{
+    if (canEraseRangeAtIterator())
+        d_ptr->eraseRangeAtIteratorFn(container, iterator1, iterator2);
+}
+
 /*!
     Returns \c true if the underlying container offers a const iterator,
     \c false otherwise.
diff --git a/src/corelib/kernel/qmetacontainer.h b/src/corelib/kernel/qmetacontainer.h
index f3a6266eb4..1f7771a0bc 100644
--- a/src/corelib/kernel/qmetacontainer.h
+++ b/src/corelib/kernel/qmetacontainer.h
@@ -113,6 +113,8 @@ public:
     InsertValueAtIteratorFn insertValueAtIteratorFn;
     using EraseValueAtIteratorFn = void(*)(void *, const void *);
     EraseValueAtIteratorFn eraseValueAtIteratorFn;
+    using EraseRangeAtIteratorFn = void(*)(void *, const void *, const void *);
+    EraseRangeAtIteratorFn eraseRangeAtIteratorFn;
 
     using CreateConstIteratorFn = void *(*)(const void *, Position);
     CreateConstIteratorFn createConstIteratorFn;
@@ -446,6 +448,19 @@ class QMetaSequenceForContainer
         }
     }
 
+    static constexpr QMetaSequenceInterface::EraseRangeAtIteratorFn getEraseRangeAtIteratorFn()
+    {
+        if constexpr (QContainerTraits::has_iterator_v<C>
+                && QContainerTraits::can_erase_range_at_iterator_v<C> && !std::is_const_v<C>) {
+            return [](void *c, const void *i, const void *j) {
+                static_cast<C *>(c)->erase(*static_cast<const QContainerTraits::iterator<C> *>(i),
+                                           *static_cast<const QContainerTraits::iterator<C> *>(j));
+            };
+        } else {
+            return nullptr;
+        }
+    }
+
     static constexpr QMetaSequenceInterface::CreateConstIteratorFn getCreateConstIteratorFn()
     {
         if constexpr (QContainerTraits::has_const_iterator_v<C>) {
@@ -565,6 +580,7 @@ QMetaSequenceInterface QMetaSequenceForContainer<C>::metaSequence = {
     /*.setValueAtIteratorFn=*/      getSetValueAtIteratorFn(),
     /*.insertValueAtIteratorFn=*/   getInsertValueAtIteratorFn(),
     /*.eraseValueAtIteratorFn=*/    getEraseValueAtIteratorFn(),
+    /*.eraseRangeAtIteratorFn=*/    getEraseRangeAtIteratorFn(),
     /*.createConstIteratorFn=*/     getCreateConstIteratorFn(),
     /*.destroyConstIteratorFn=*/    getDestroyConstIteratorFn(),
     /*.equalConstIteratorFn=*/      getCompareConstIteratorFn(),
@@ -659,6 +675,9 @@ public:
     void advanceConstIterator(void *iterator, qsizetype step) const;
     qsizetype diffConstIterator(const void *i, const void *j) const;
 
+    bool canEraseRangeAtIterator() const;
+    void eraseRangeAtIterator(void *container, const void *iterator1, const void *iterator2) const;
+
     bool canGetValueAtConstIterator() const;
     void valueAtConstIterator(const void *iterator, void *result) const;