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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
78 lines
1.6 KiB
CMake
78 lines
1.6 KiB
CMake
set(LLVM_LINK_COMPONENTS
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Support
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)
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add_llvm_unittest(ADTTests
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AnyTest.cpp
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APFloatTest.cpp
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APIntTest.cpp
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APSIntTest.cpp
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ArrayRefTest.cpp
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BitmaskEnumTest.cpp
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BitVectorTest.cpp
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BreadthFirstIteratorTest.cpp
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BumpPtrListTest.cpp
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DAGDeltaAlgorithmTest.cpp
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DeltaAlgorithmTest.cpp
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DenseMapTest.cpp
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DenseSetTest.cpp
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DepthFirstIteratorTest.cpp
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EquivalenceClassesTest.cpp
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FallibleIteratorTest.cpp
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FoldingSet.cpp
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FunctionExtrasTest.cpp
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FunctionRefTest.cpp
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HashingTest.cpp
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IListBaseTest.cpp
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IListIteratorTest.cpp
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IListNodeBaseTest.cpp
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IListNodeTest.cpp
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IListSentinelTest.cpp
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IListTest.cpp
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ImmutableListTest.cpp
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ImmutableMapTest.cpp
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ImmutableSetTest.cpp
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IntEqClassesTest.cpp
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IntervalMapTest.cpp
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IntrusiveRefCntPtrTest.cpp
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IteratorTest.cpp
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MakeUniqueTest.cpp
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MappedIteratorTest.cpp
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MapVectorTest.cpp
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OptionalTest.cpp
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PackedVectorTest.cpp
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PointerEmbeddedIntTest.cpp
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PointerIntPairTest.cpp
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PointerSumTypeTest.cpp
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PointerUnionTest.cpp
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PostOrderIteratorTest.cpp
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PriorityWorklistTest.cpp
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RangeAdapterTest.cpp
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SCCIteratorTest.cpp
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STLExtrasTest.cpp
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ScopeExitTest.cpp
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SequenceTest.cpp
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SetVectorTest.cpp
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SimpleIListTest.cpp
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SmallPtrSetTest.cpp
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SmallSetTest.cpp
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SmallStringTest.cpp
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SmallVectorTest.cpp
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SparseBitVectorTest.cpp
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SparseMultiSetTest.cpp
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SparseSetTest.cpp
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StatisticTest.cpp
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StringExtrasTest.cpp
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StringMapTest.cpp
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StringRefTest.cpp
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StringSwitchTest.cpp
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TinyPtrVectorTest.cpp
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TripleTest.cpp
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TwineTest.cpp
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VariadicFunctionTest.cpp
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)
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target_link_libraries(ADTTests PRIVATE LLVMTestingSupport)
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add_dependencies(ADTTests intrinsics_gen)
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