25.for.each.cpp

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#include <algorithm>     // for for_each
#include <cstddef>       // for ptrdiff_t
 
#include <rw_alg_test.h>
#include <rw_value.h>       // for UserClass
#include <rw_driver.h>      // for rw_test(), ...
 
 
struct FunctionBase
{
    static std::size_t  funcalls_;
    static int          sum_;
    bool                is_const_;
 
    FunctionBase (bool is_const)
        : is_const_ (is_const) {
        funcalls_ = 0;
        sum_      = 0;
    }
 
private:
    void operator= (FunctionBase&);   // not assignable
};
 
std::size_t FunctionBase::funcalls_;
int         FunctionBase::sum_;
 
 
struct ConstFunction: FunctionBase
{
    // dummy arguments provided to prevent the class
    // from being default constructible
    ConstFunction (int, int): FunctionBase (true) { }
 
    void operator() (UserClass val)  /* not const */ {
        ++funcalls_;
        sum_ += val.data_.val_;
    }
 
    static const char* name () { return "ConstFunction"; }
};
 
 
struct MutableFunction: FunctionBase
{
    // dummy arguments provided to prevent the class
    // from being default constructible
    MutableFunction (int, int): FunctionBase (false) { }
 
    void operator() (UserClass &val) /* not const */ {
        ++funcalls_;
        val.data_.val_ = -val.data_.val_;
    }
 
    static const char* name () { return "MutableFunction"; }
};
 
 
// exercises std::for_each()
template <class InputIterator, class T, class Function>
void test_for_each (std::size_t N, InputIterator dummy, T*, Function*)
{
    static const char* const itname = type_name (dummy, (T*)0);
    static const char* const fnname = Function::name ();
 
    rw_info (0, 0, 0, "std::for_each (%s, %1$s, %s)", itname, fnname);
 
    // generate sequential values for each default constructed UserClass
    UserClass::gen_ = gen_seq;
 
    UserClass *buf = new UserClass [N];
 
    const int first_val = buf [0].data_.val_;
 
    for (std::size_t i = 0; i != N; ++i) {
 
        UserClass* const buf_end = buf + i;
 
        const InputIterator first (buf, buf, buf_end);
        const InputIterator last  (buf_end, buf_end, buf_end);
 
        // create a const function object and zero out all its counters
        const Function fun (0, 0);
 
        std::for_each (first, last, fun);
 
        // compute the sum of elements in the sequence and check each
        // element's value against the expected one
        int sum = 0;
 
        for (std::size_t j = 0; j != i; ++j) {
 
            int expect;
 
            if (fun.is_const_) {
                // const function object doesn't modify the subject
                // sequence; the expected value of the element is
                // the same as the original value
                expect = first_val + int (j);
            }
            else {
                // non-const function object negates each argument
                expect = -(first_val + int (j));
            }
 
            // compute the sum (computed by the const function object)
            sum += buf [j].data_.val_;
 
            // assert the element value as the same as the expected value
            rw_assert (expect == buf [j].data_.val_, 0, __LINE__,
                       "for_each (%s, %1$s, %s); element [%zu] == %d, got %d",
                       itname, fnname, j, expect, buf [j].data_.val_);
 
            if (expect != buf [j].data_.val_) {
                // break out of both loops on failure
                i = N;
                break;
            }
 
            // restore the original value of the element
            buf [j].data_.val_ = first_val + int (j);
        }
 
        // assert that for_each invoked the function object's operator()
        // exactly as many times as necessary and required
        rw_assert (i == fun.funcalls_, 0, __LINE__,
                   "for_each (%s, %1$s, %s); expected %zu invocations of "
                   "Function::operator(), got %zu", itname, fnname,
                   i, fun.funcalls_);
 
        if (fun.is_const_) {
            rw_assert (sum == fun.sum_, 0, __LINE__,
                       "for_each (%s, %1$s, %s); sum of %zu elements == %d, "
                       "got %d", itname, fnname, sum, fun.sum_);
        }
    }
 
    delete[] (buf);
}
 
 
static int rw_opt_nloops = 32;     // --nloops=#
static int rw_opt_no_input_iter;   // --no-InputIterator
static int rw_opt_no_fwd_iter;     // --no-ForwardIterator
static int rw_opt_no_bidir_iter;   // --no-BidirectionalIterator
static int rw_opt_no_rnd_iter;     // --no-RandomAccessIterator
 
 
static int
run_test (int, char*[])
{
    const std::size_t N = std::size_t (rw_opt_nloops);
 
    rw_info (0, 0, 0,
             "template <class %s, class %s> "
             "%2$s std::for_each (%1$s, %1$s, %2$s)",
             "InputIterator", "Function");
 
    if (rw_opt_no_input_iter) {
        rw_note (0, __FILE__, __LINE__, "InputIterator test disabled");
    }
    else {
        test_for_each (N, InputIter<UserClass>(0, 0, 0), (UserClass*)0,
                       (ConstFunction*)0);
    }
 
    if (rw_opt_no_fwd_iter) {
        rw_note (0, __FILE__, __LINE__, "ForwardIterator test disabled");
    }
    else {
        test_for_each (N, ConstFwdIter<UserClass>(), (UserClass*)0,
                       (ConstFunction*)0);
        test_for_each (N, FwdIter<UserClass>(), (UserClass*)0,
                       (ConstFunction*)0);
        test_for_each (N, FwdIter<UserClass>(), (UserClass*)0,
                       (MutableFunction*)0);
    }
 
    if (rw_opt_no_bidir_iter) {
        rw_note (0, __FILE__, __LINE__, "BidirectionalIterator test disabled");
    }
    else {
        test_for_each (N, ConstBidirIter<UserClass>(), (UserClass*)0,
                       (ConstFunction*)0);
        test_for_each (N, BidirIter<UserClass>(), (UserClass*)0,
                       (ConstFunction*)0);
        test_for_each (N, BidirIter<UserClass>(), (UserClass*)0,
                       (MutableFunction*)0);
    }
 
    if (rw_opt_no_rnd_iter) {
        rw_note (0, __FILE__, __LINE__, "RandomAccessIterator test disabled");
    }
    else {
        test_for_each (N, ConstRandomAccessIter<UserClass>(), (UserClass*)0,
                       (ConstFunction*)0);
        test_for_each (N, RandomAccessIter<UserClass>(), (UserClass*)0,
                       (ConstFunction*)0);
        test_for_each (N, RandomAccessIter<UserClass>(), (UserClass*)0,
                       (MutableFunction*)0);
    }
 
    return 0;
}
 
 
int main (int argc, char *argv[])
{
    return rw_test (argc, argv, __FILE__,
                    "lib.alg.foreach",
                    0 /* no comment */, run_test,
                    "|-nloops#0 "   // must be non-negative
                    "|-no-InputIterator# "
                    "|-no-ForwardIterator# "
                    "|-no-BidirectionalIterator# "
                    "|-no-RandomAccessIterator#",
                    &rw_opt_nloops,
                    &rw_opt_no_input_iter,
                    &rw_opt_no_fwd_iter,
                    &rw_opt_no_bidir_iter,
                    &rw_opt_no_rnd_iter);
}