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/// Author: Diffblue Ltd.
/// \file Tests for depth_iteratort and friends
#include <testing-utils/use_catch.h>
#include <util/expr_iterator.h>
#include <util/std_expr.h>
TEST_CASE("Depth iterator over empty exprt")
{
exprt expr;
std::vector<std::reference_wrapper<const exprt>> results;
std::copy(expr.depth_begin(),
expr.depth_end(),
std::back_inserter(results));
REQUIRE(results.size()==1);
REQUIRE(results.front().get()==expr);
}
TEST_CASE("Unique depth iterator over empty exprt")
{
exprt expr;
std::vector<std::reference_wrapper<const exprt>> results;
std::copy(expr.unique_depth_begin(),
expr.unique_depth_end(),
std::back_inserter(results));
REQUIRE(results.size()==1);
REQUIRE(results.front().get()==expr);
}
TEST_CASE("Iterate over a node with 3 children")
{
std::vector<exprt> input(4);
input[0].operands()={ input[1], input[2], input[3] };
std::vector<std::reference_wrapper<const exprt>> results;
std::copy(input[0].depth_begin(),
input[0].depth_end(),
std::back_inserter(results));
REQUIRE(results.size()==input.size());
auto it=results.begin();
for(const auto &expr : input)
{
REQUIRE(it->get()==expr);
it++;
}
}
TEST_CASE("Iterate over a node with 5 children, ignoring duplicates")
{
std::vector<exprt> input(4);
input[1].id(ID_int);
input[2].id(ID_symbol);
input[3].id(ID_array);
input[0].operands()={ input[1], input[2], input[1], input[3], input[2] };
std::vector<std::reference_wrapper<const exprt>> results;
std::copy(input[0].unique_depth_begin(),
input[0].unique_depth_end(),
std::back_inserter(results));
REQUIRE(results.size()==input.size());
auto it=results.begin();
for(const auto &expr : input)
{
REQUIRE(it->get()==expr);
it++;
}
}
TEST_CASE("Iterate over a 3-level node")
{
std::vector<exprt> input(4);
input[1].id(ID_int);
input[2].operands()={ input[3] };
input[0].operands()={ input[1], input[2] };
std::vector<std::reference_wrapper<const exprt>> results;
std::copy(input[0].depth_begin(),
input[0].depth_end(),
std::back_inserter(results));
REQUIRE(results.size()==input.size());
auto it=results.begin();
for(const auto &expr : input)
{
REQUIRE(it->get()==expr);
it++;
}
}
TEST_CASE("Iterate over a 3-level tree, ignoring duplicates")
{
std::vector<exprt> input(4);
input[1].id(ID_int);
input[2].operands()={ input[3], input[1] };
input[0].operands()={ input[1], input[2], input[3] };
std::vector<std::reference_wrapper<const exprt>> results;
std::copy(input[0].unique_depth_begin(),
input[0].unique_depth_end(),
std::back_inserter(results));
REQUIRE(results.size()==input.size());
auto it=results.begin();
for(const auto &expr : input)
{
REQUIRE(it->get()==expr);
it++;
}
}
TEST_CASE("Iterate over a 3-level tree, mutate - set all types to ID_symbol")
{
std::vector<exprt> input(4);
input[1].id(ID_int);
input[2].operands()={ input[3] };
input[0].operands()={ input[1], input[2] };
std::vector<std::reference_wrapper<exprt>> results;
for(auto it=input[0].depth_begin(),
end=input[0].depth_end();
it != end; ++it)
{
exprt &expr=it.mutate();
results.push_back(std::ref(expr));
REQUIRE(*it==expr);
expr.id(ID_symbol);
}
REQUIRE(results.size()==input.size());
for(const auto& expr : results)
{
REQUIRE(expr.get().id()==ID_symbol);
}
}
TEST_CASE("next_sibling_or_parent, next sibling")
{
std::vector<exprt> input(4);
input[1].operands()={ input[3] };
input[2].id(ID_int);
input[0].operands()={ input[1], input[2] };
auto it=input[0].depth_begin();
it++;
it.next_sibling_or_parent();
REQUIRE(*it==input[2]);
}
TEST_CASE("next_sibling_or_parent, next parent ")
{
std::vector<exprt> input(3);
input[1].operands()={ input[2] };
input[0].operands()={ input[1] };
auto it=input[0].depth_begin();
it++;
it.next_sibling_or_parent();
REQUIRE(it==input[0].depth_end());
}
/// The mutate_root feature of depth_iteratort can be useful when you have an
/// `exprt` and want to depth iterate its first operand. As part of that
/// iteration you may or may not decide to mutate one of the children,
/// depending on the state of those children. If you do not decide to mutate
/// a child then you probably don't want to call the non-const version of
/// `op0()` because that will break sharing, so you create the depth iterator
/// with the const `exprt` returned from the const invocation of `op0()`, but
/// if you decide during iteration that you do want to mutate a child then
/// you can call the non-const version of `op0()` on the original `exprt` in
/// order to get a non-const `exprt` that the iterator can copy-on-write
/// update to change the child. At this point the iterator needs to be
/// informed that it is now safe to write to the `exprt` it contains. This is
/// achieved by providing a call-back function to the iterator.
SCENARIO("depth_iterator_mutate_root", "[core][utils][depth_iterator]")
{
GIVEN("A sample expression with a child with id() == ID_1")
{
// Set up test expression
exprt test_expr;
// This is the expression we will iterate over
exprt test_root;
// This is the expression we might mutate when we find it
exprt test_operand(ID_1);
test_root.add_to_operands(std::move(test_operand));
test_expr.add_to_operands(std::move(test_root));
WHEN("Iteration occurs without mutation")
{
// Create shared copies
exprt original_expr = test_expr;
exprt expr = original_expr;
THEN("Shared copy should return object with same address from read()")
{
REQUIRE(&expr.read() == &original_expr.read());
}
// Create iterator on first operand of expr
// We don't want to copy-on-write expr, so we get its first operand
// using a const reference to it
const exprt &root = to_unary_expr(static_cast<const exprt &>(expr)).op();
// This function gets a mutable version of root but in so doing it
// copy-on-writes expr
auto get_non_const_root = [&expr]() -> exprt & {
return to_unary_expr(expr).op();
};
// Create the iterator over root
depth_iteratort it = root.depth_begin(get_non_const_root);
for(; it != root.depth_cend(); ++it)
{
if(it->id() == ID_0) // This will never happen
it.mutate().id(ID_1);
}
THEN("No breaking of sharing should have occurred")
{
REQUIRE(&expr.read() == &original_expr.read());
}
}
WHEN("Iteration occurs with mutation")
{
// Create shared copies
exprt original_expr = test_expr;
exprt expr = original_expr;
THEN("Shared copy should return object with same address from read()")
{
REQUIRE(&expr.read() == &original_expr.read());
}
// Create iterator on first operand of expr
// We don't want to copy-on-write expr, so we get its first operand
// using a const reference to it
const exprt &root = to_unary_expr(static_cast<const exprt &>(expr)).op();
// This function gets a mutable version of root but in so doing it
// copy-on-writes expr
auto get_non_const_root = [&expr]() -> exprt & {
return to_unary_expr(expr).op();
};
// Create the iterator over root
depth_iteratort it = root.depth_begin(get_non_const_root);
for(; it != root.depth_cend(); ++it)
{
if(it->id() == ID_1)
it.mutate().id(ID_0);
}
THEN("Breaking of sharing should have occurred")
{
REQUIRE(&expr.read() != &original_expr.read());
}
}
}
}
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