[ADT] Add a generic concatenating iterator and range.

This allows both defining convenience iterator/range accessors on types
which walk across N different independent ranges within the object, and
more direct and simple usages with range based for loops such as shown
in the unittest. The same facilities are used for both. They end up
quite small and simple as it happens.

I've also switched an iterator on `Module` to use this. I would like to
add another convenience iterator that includes even more sequences as
part of it and seeing this one already present motivated me to actually
abstract it away and introduce a general utility.

Differential Revision: https://reviews.llvm.org/D28093

llvm-svn: 290512

1 files changed, 23 insertions, 0 deletions

diff --git a/llvm/unittests/ADT/STLExtrasTest.cpp b/llvm/unittests/ADT/STLExtrasTest.cpp
index 76881296db6..d3bef6a2e05 100644
--- a/llvm/unittests/ADT/STLExtrasTest.cpp
+++ b/llvm/unittests/ADT/STLExtrasTest.cpp
@@ -10,6 +10,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "gtest/gtest.h"
 
+#include <list>
 #include <vector>
 
 using namespace llvm;
@@ -253,4 +254,26 @@ TEST(STLExtrasTest, CountAdaptor) {
   EXPECT_EQ(1, count(v, 3));
   EXPECT_EQ(1, count(v, 4));
 }
+
+TEST(STLExtrasTest, ConcatRange) {
+  std::vector<int> Expected = {1, 2, 3, 4, 5, 6, 7, 8};
+  std::vector<int> Test;
+
+  std::vector<int> V1234 = {1, 2, 3, 4};
+  std::list<int> L56 = {5, 6};
+  SmallVector<int, 2> SV78 = {7, 8};
+
+  // Use concat across different sized ranges of different types with different
+  // iterators.
+  for (int &i : concat<int>(V1234, L56, SV78))
+    Test.push_back(i);
+  EXPECT_EQ(Expected, Test);
+
+  // Use concat between a temporary, an L-value, and an R-value to make sure
+  // complex lifetimes work well.
+  Test.clear();
+  for (int &i : concat<int>(std::vector<int>(V1234), L56, std::move(SV78)))
+    Test.push_back(i);
+  EXPECT_EQ(Expected, Test);
+}
 }