From c34316243e35223d446e0fb06ffee014ec604e08 Mon Sep 17 00:00:00 2001
From: Simon Brunel <simonbrunel@users.noreply.github.com>
Date: Fri, 9 Feb 2018 23:18:05 +0100
Subject: [PATCH] Make QPromise::all accept more container types

Currently, QPromise can't be added dynamically to QVector (::push_* | ::append) because it doesn't expose a default constructor. Until deciding if a default constructor should be added (private/public?), let's make the `QPromise::all` method work with any container types that are STL compatible.
---
 README.md                                     |   6 +-
 src/qtpromise/qpromise.h                      |   8 +-
 src/qtpromise/qpromise.inl                    |  19 ++--
 src/qtpromise/qpromisehelpers.h               |   7 +-
 tests/auto/qtpromise/qpromise/all/all.pro     |   4 +
 tests/auto/qtpromise/qpromise/all/tst_all.cpp | 103 ++++++++++++++++++
 tests/auto/qtpromise/qpromise/qpromise.pro    |   1 +
 7 files changed, 134 insertions(+), 14 deletions(-)
 create mode 100644 tests/auto/qtpromise/qpromise/all/all.pro
 create mode 100644 tests/auto/qtpromise/qpromise/all/tst_all.cpp

diff --git a/README.md b/README.md
index b3cbda7..ce7efea 100644
--- a/README.md
+++ b/README.md
@@ -385,9 +385,11 @@ QPromise<int> compute(const QString& type)
 }
 ```
 
-### <a name="qpromise-all"></a> `[static] QPromise<T>::all(QVector<QPromise<T>>) -> QPromise<QVector<T>>`
+### <a name="qpromise-all"></a> `[static] QPromise<T>::all(Sequence<QPromise<T>>) -> QPromise<QVector<T>>`
 Returns a `QPromise<QVector<T>>` that fulfills when **all** `promises` of (the same) type `T` have been fulfilled. The `output` value is a vector containing **all** the values of `promises`, in the same order. If any of the given `promises` fail, `output` immediately rejects with the error of the promise that rejected, whether or not the other promises are resolved.
 
+`Sequence` is any STL compatible container (eg. `QVector`, `QList`, `std::vector`, etc.)
+
 ```cpp
 QVector<QPromise<QByteArray> > promises{
     download(QUrl("http://a...")),
@@ -417,7 +419,7 @@ auto promise = qPromise(QString("foo"));  // QPromise<QString>
 
 This method also allows to convert `QFuture<T>` to `QPromise<T>` delayed until the `QFuture` is finished ([read more](#qtconcurrent-convert)).
 
-### <a name="helpers-qpromiseall"></a> `qPromiseAll(QVector<QPromise<T> promises) -> QPromise<QVector<T>>`
+### <a name="helpers-qpromiseall"></a> `qPromiseAll(Sequence<QPromise<T> promises) -> QPromise<QVector<T>>`
 This method simply calls the appropriated [`QPromise<T>::all`](#qpromise-all) static method based on the given `QVector` type. In some cases, this method is more convenient than the static one since it avoid some extra typing:
 
 ```cpp
diff --git a/src/qtpromise/qpromise.h b/src/qtpromise/qpromise.h
index d1c110f..ed7d7c5 100644
--- a/src/qtpromise/qpromise.h
+++ b/src/qtpromise/qpromise.h
@@ -85,7 +85,9 @@ public:
     QPromise(F&& resolver): QPromiseBase<T>(std::forward<F>(resolver)) { }
 
 public: // STATIC
-    inline static QPromise<QVector<T> > all(const QVector<QPromise<T> >& promises);
+    template <template <typename, typename...> class Sequence = QVector, typename ...Args>
+    inline static QPromise<QVector<T> > all(const Sequence<QPromise<T>, Args...>& promises);
+
     inline static QPromise<T> resolve(T&& value);
 
 private:
@@ -100,7 +102,9 @@ public:
     QPromise(F&& resolver): QPromiseBase<void>(std::forward<F>(resolver)) { }
 
 public: // STATIC
-    inline static QPromise<void> all(const QVector<QPromise<void> >& promises);
+    template <template <typename, typename...> class Sequence = QVector, typename ...Args>
+    inline static QPromise<void> all(const Sequence<QPromise<void>, Args...>& promises);
+
     inline static QPromise<void> resolve();
 
 private:
diff --git a/src/qtpromise/qpromise.inl b/src/qtpromise/qpromise.inl
index def9017..7df7bb0 100644
--- a/src/qtpromise/qpromise.inl
+++ b/src/qtpromise/qpromise.inl
@@ -210,9 +210,10 @@ inline QPromise<T> QPromiseBase<T>::reject(E&& error)
 }
 
 template <typename T>
-inline QPromise<QVector<T> > QPromise<T>::all(const QVector<QPromise<T> >& promises)
+template <template <typename, typename...> class Sequence, typename ...Args>
+inline QPromise<QVector<T> > QPromise<T>::all(const Sequence<QPromise<T>, Args...>& promises)
 {
-    const int count = promises.size();
+    const int count = (int)promises.size();
     if (count == 0) {
         return QPromise<QVector<T> >::resolve({});
     }
@@ -224,8 +225,9 @@ inline QPromise<QVector<T> > QPromise<T>::all(const QVector<QPromise<T> >& promi
         QSharedPointer<int> remaining(new int(count));
         QSharedPointer<QVector<T> > results(new QVector<T>(count));
 
-        for (int i=0; i<count; ++i) {
-            promises[i].then([=](const T& res) mutable {
+        int i = 0;
+        for (const auto& promise: promises) {
+            promise.then([=](const T& res) mutable {
                 (*results)[i] = res;
                 if (--(*remaining) == 0) {
                     resolve(*results);
@@ -236,6 +238,8 @@ inline QPromise<QVector<T> > QPromise<T>::all(const QVector<QPromise<T> >& promi
                     reject(std::current_exception());
                 }
             });
+
+            i++;
         }
     });
 }
@@ -248,9 +252,10 @@ inline QPromise<T> QPromise<T>::resolve(T&& value)
     });
 }
 
-inline QPromise<void> QPromise<void>::all(const QVector<QPromise<void> >& promises)
+template <template <typename, typename...> class Sequence, typename ...Args>
+inline QPromise<void> QPromise<void>::all(const Sequence<QPromise<void>, Args...>& promises)
 {
-    const int count = promises.size();
+    const int count = (int)promises.size();
     if (count == 0) {
         return QPromise<void>::resolve();
     }
@@ -259,7 +264,7 @@ inline QPromise<void> QPromise<void>::all(const QVector<QPromise<void> >& promis
         const QPromiseResolve<void>& resolve,
         const QPromiseReject<void>& reject) {
 
-        QSharedPointer<int> remaining(new int(promises.size()));
+        QSharedPointer<int> remaining(new int(count));
 
         for (const auto& promise: promises) {
             promise.then([=]() {
diff --git a/src/qtpromise/qpromisehelpers.h b/src/qtpromise/qpromisehelpers.h
index 206a4a6..91dffb5 100644
--- a/src/qtpromise/qpromisehelpers.h
+++ b/src/qtpromise/qpromisehelpers.h
@@ -26,13 +26,14 @@ static inline QPromise<void> qPromise()
     });
 }
 
-template <typename T>
-static inline QPromise<QVector<T> > qPromiseAll(const QVector<QPromise<T> >& promises)
+template <typename T, template <typename, typename...> class Sequence = QVector, typename ...Args>
+static inline QPromise<QVector<T> > qPromiseAll(const Sequence<QPromise<T>, Args...>& promises)
 {
     return QPromise<T>::all(promises);
 }
 
-static inline QPromise<void> qPromiseAll(const QVector<QPromise<void> >& promises)
+template <template <typename, typename...> class Sequence = QVector, typename ...Args>
+static inline QPromise<void> qPromiseAll(const Sequence<QPromise<void>, Args...>& promises)
 {
     return QPromise<void>::all(promises);
 }
diff --git a/tests/auto/qtpromise/qpromise/all/all.pro b/tests/auto/qtpromise/qpromise/all/all.pro
new file mode 100644
index 0000000..80abf7d
--- /dev/null
+++ b/tests/auto/qtpromise/qpromise/all/all.pro
@@ -0,0 +1,4 @@
+TARGET = tst_qpromise_all
+SOURCES += $$PWD/tst_all.cpp
+
+include(../../qtpromise.pri)
diff --git a/tests/auto/qtpromise/qpromise/all/tst_all.cpp b/tests/auto/qtpromise/qpromise/all/tst_all.cpp
new file mode 100644
index 0000000..9ccf690
--- /dev/null
+++ b/tests/auto/qtpromise/qpromise/all/tst_all.cpp
@@ -0,0 +1,103 @@
+// Tests
+#include "../../shared/utils.h"
+
+// QtPromise
+#include <QtPromise>
+
+// Qt
+#include <QtTest>
+
+using namespace QtPromise;
+
+class tst_qpromise_all : public QObject
+{
+    Q_OBJECT
+
+private Q_SLOTS:
+    void qList();
+    //void qVector();
+    void stdList();
+    void stdVector();
+};
+
+QTEST_MAIN(tst_qpromise_all)
+#include "tst_all.moc"
+
+namespace {
+
+template <class Sequence>
+struct SequenceTester
+{
+};
+
+template <template <typename, typename...> class Sequence, typename ...Args>
+struct SequenceTester<Sequence<QPromise<int>, Args...> >
+{
+    static void exec()
+    {
+        Sequence<QPromise<int>, Args...> promises{
+            QPromise<int>::resolve(42),
+            QPromise<int>::resolve(43),
+            QPromise<int>::resolve(44)
+        };
+
+        promises.push_back(QPromise<int>::resolve(45));
+        promises.insert(++promises.begin(), QPromise<int>::resolve(46));
+        promises.pop_back();
+
+        auto p = QPromise<int>::all(promises);
+
+        Q_STATIC_ASSERT((std::is_same<decltype(p), QPromise<QVector<int> > >::value));
+        QCOMPARE(waitForValue(p, QVector<int>()), QVector<int>({42, 46, 43, 44}));
+    }
+};
+
+template <template <typename, typename...> class Sequence, typename ...Args>
+struct SequenceTester<Sequence<QPromise<void>, Args...> >
+{
+    static void exec()
+    {
+        Sequence<QPromise<void>, Args...> promises{
+            QPromise<void>::resolve(),
+            QPromise<void>::resolve(),
+            QPromise<void>::resolve()
+        };
+
+        promises.push_back(QPromise<void>::resolve());
+        promises.insert(++promises.begin(), QPromise<void>::resolve());
+        promises.pop_back();
+
+        auto p = QPromise<void>::all(promises);
+
+        Q_STATIC_ASSERT((std::is_same<decltype(p), QPromise<void> >::value));
+        QCOMPARE(waitForValue(p, -1, 42), 42);
+    }
+};
+
+} // anonymous namespace
+
+void tst_qpromise_all::qList()
+{
+    SequenceTester<QList<QPromise<int> > >::exec();
+    SequenceTester<QList<QPromise<void> > >::exec();
+}
+
+// QVector::push_back/append isn't supported since it requires a default
+// constructor (see https://github.com/simonbrunel/qtpromise/issues/3)
+//void tst_qpromise_all::qVector()
+//{
+//    SequenceTester<QVector<QPromise<int> > >::exec();
+//    SequenceTester<QVector<QPromise<void> > >::exec();
+//}
+
+void tst_qpromise_all::stdList()
+{
+    SequenceTester<std::list<QPromise<int> > >::exec();
+    SequenceTester<std::list<QPromise<void> > >::exec();
+}
+
+void tst_qpromise_all::stdVector()
+{
+    SequenceTester<std::vector<QPromise<int> > >::exec();
+    SequenceTester<std::vector<QPromise<void> > >::exec();
+}
diff --git a/tests/auto/qtpromise/qpromise/qpromise.pro b/tests/auto/qtpromise/qpromise/qpromise.pro
index e166df4..9d5d6be 100644
--- a/tests/auto/qtpromise/qpromise/qpromise.pro
+++ b/tests/auto/qtpromise/qpromise/qpromise.pro
@@ -1,5 +1,6 @@
 TEMPLATE = subdirs
 SUBDIRS += \
+    all \
     construct \
     delay \
     fail \