Add range constructor to hidl_vec.

Bug: b/36864090
Test: Unit test
Test: a device boots
Test: marlin boots and completes unit test
Change-Id: I7d37f75ec6c8ba0252c3c60afd515eff87dfc4dd
diff --git a/base/include/hidl/HidlSupport.h b/base/include/hidl/HidlSupport.h
index d7c3b83..3f45afd 100644
--- a/base/include/hidl/HidlSupport.h
+++ b/base/include/hidl/HidlSupport.h
@@ -316,6 +316,27 @@
         *this = other;
     }
 
+    template <typename InputIterator,
+              typename = typename std::enable_if<std::is_convertible<
+                  typename std::iterator_traits<InputIterator>::iterator_category,
+                  std::input_iterator_tag>::value>::type>
+    hidl_vec(InputIterator first, InputIterator last) : mOwnsBuffer(true) {
+        auto size = std::distance(first, last);
+        if (size > static_cast<int64_t>(UINT32_MAX)) {
+            details::logAlwaysFatal("hidl_vec can't hold more than 2^32 elements.");
+        }
+        if (size < 0) {
+            details::logAlwaysFatal("size can't be negative.");
+        }
+        mSize = static_cast<uint32_t>(size);
+        mBuffer = new T[mSize];
+
+        size_t idx = 0;
+        for (; first != last; ++first) {
+            mBuffer[idx++] = static_cast<T>(*first);
+        }
+    }
+
     ~hidl_vec() {
         if (mOwnsBuffer) {
             delete[] mBuffer;
diff --git a/test_main.cpp b/test_main.cpp
index bce9294..1f2f845 100644
--- a/test_main.cpp
+++ b/test_main.cpp
@@ -262,6 +262,30 @@
     EXPECT_TRUE(hv1 != hv3);
 }
 
+TEST_F(LibHidlTest, VecRangeCtorTest) {
+    struct ConvertibleType {
+        int val;
+
+        explicit ConvertibleType(int val) : val(val) {}
+        explicit operator int() const { return val; }
+        bool operator==(const int& other) const { return val == other; }
+    };
+
+    std::vector<ConvertibleType> input{
+        ConvertibleType(1), ConvertibleType(2), ConvertibleType(3),
+    };
+
+    android::hardware::hidl_vec<int> hv(input.begin(), input.end());
+
+    EXPECT_EQ(input.size(), hv.size());
+    int sum = 0;
+    for (unsigned i = 0; i < input.size(); i++) {
+        EXPECT_EQ(input[i], hv[i]);
+        sum += hv[i];
+    }
+    EXPECT_EQ(sum, 1 + 2 + 3);
+}
+
 TEST_F(LibHidlTest, ArrayTest) {
     using android::hardware::hidl_array;
     int32_t array[] = {5, 6, 7};