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llvm-project/llvm/unittests/ADT
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Lang Hames 3e040e05f8 [ADT] Add a fallible_iterator wrapper. 
A fallible iterator is one whose increment or decrement operations may fail.
This would usually be supported by replacing the ++ and -- operators with
methods that return error:

    class MyFallibleIterator {
    public:
      // ...
      Error inc();
      Errro dec();
      // ...
    };

The downside of this style is that it no longer conforms to the C++ iterator
concept, and can not make use of standard algorithms and features such as
range-based for loops.

The fallible_iterator wrapper takes an iterator written in the style above
and adapts it to (mostly) conform with the C++ iterator concept. It does this
by providing standard ++ and -- operator implementations, returning any errors
generated via a side channel (an Error reference passed into the wrapper at
construction time), and immediately jumping the iterator to a known 'end'
value upon error. It also marks the Error as checked any time an iterator is
compared with a known end value and found to be inequal, allowing early exit
from loops without redundant error checking*.

Usage looks like:

    MyFallibleIterator I = ..., E = ...;

    Error Err = Error::success();
    for (auto &Elem : make_fallible_range(I, E, Err)) {
      // Loop body is only entered when safe.

      // Early exits from loop body permitted without checking Err.
      if (SomeCondition)
        return;

    }
    if (Err)
      // Handle error.

* Since failure causes a fallible iterator to jump to end, testing that a
  fallible iterator is not an end value implicitly verifies that the error is a
  success value, and so is equivalent to an error check.

Reviewers: dblaikie, rupprecht

Subscribers: mgorny, dexonsmith, kristina, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D57618

llvm-svn: 353237
 		2019-02-05 23:17:11 +00:00
..
APFloatTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
APIntTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
APSIntTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
AnyTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
ArrayRefTest.cpp Revert r351954 "Add a value_type to ArrayRef." 2019-01-25 15:25:52 +00:00
BitVectorTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
BitmaskEnumTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
BreadthFirstIteratorTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
BumpPtrListTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
CMakeLists.txt [ADT] Add a fallible_iterator wrapper. 2019-02-05 23:17:11 +00:00
DAGDeltaAlgorithmTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
DeltaAlgorithmTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
DenseMapTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
DenseSetTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
DepthFirstIteratorTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
EquivalenceClassesTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
FallibleIteratorTest.cpp [ADT] Add a fallible_iterator wrapper. 2019-02-05 23:17:11 +00:00
FoldingSet.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
FunctionExtrasTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
FunctionRefTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
HashingTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
IListBaseTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
IListIteratorTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
IListNodeBaseTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
IListNodeTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
IListSentinelTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
IListTest.cpp [ADT] Notify ilist traits about in-list transfers 2019-01-23 22:59:52 +00:00
ImmutableListTest.cpp Replace llvm::isPodLike<...> by llvm::is_trivially_copyable<...> 2019-01-20 21:19:56 +00:00
ImmutableMapTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
ImmutableSetTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
IntEqClassesTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
IntervalMapTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
IntrusiveRefCntPtrTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
IteratorTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
MakeUniqueTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
MapVectorTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
MappedIteratorTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
OptionalTest.cpp Fix compilation error with gcc 4.8 2019-01-21 18:21:03 +00:00
PackedVectorTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
PointerEmbeddedIntTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
PointerIntPairTest.cpp Replace llvm::isPodLike<...> by llvm::is_trivially_copyable<...> 2019-01-20 21:19:56 +00:00
PointerSumTypeTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
PointerUnionTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
PostOrderIteratorTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
PriorityWorklistTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
RangeAdapterTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
SCCIteratorTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
STLExtrasTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
ScopeExitTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
SequenceTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
SetVectorTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
SimpleIListTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
SmallPtrSetTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
SmallSetTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
SmallStringTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
SmallVectorTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
SparseBitVectorTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
SparseMultiSetTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
SparseSetTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
StatisticTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
StringExtrasTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
StringMapTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
StringRefTest.cpp Replace llvm::isPodLike<...> by llvm::is_trivially_copyable<...> 2019-01-20 21:19:56 +00:00
StringSwitchTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
TestGraph.h Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
TinyPtrVectorTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
TripleTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
TwineTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
VariadicFunctionTest.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00