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std.algorithm.reduce() should throw on empty ranges and no explicit seed instead of silently returning bogus results.

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This commit is contained in:
David Simcha 2010-08-30 23:09:39 +00:00
parent f9e540579b
commit 1725ddc8ed
1 changed files with 21 additions and 0 deletions
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21
std/algorithm.d
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@ -420,6 +420,8 @@ template reduce(fun...)
}
else
{
enforce(!args[$ - 1].empty,
"Cannot reduce an empty range w/o an explicit seed value.");
alias args[0] r;
static if (fun.length == 1)
{
@ -504,6 +506,9 @@ template reduce(fun...)
}
}
enforce(initialized,
"Cannot reduce an empty iterable w/o an explicit seed value.");
static if(fun.length == 1)
{
return result.field[0];
@ -544,9 +549,13 @@ unittest
// Test the opApply case.
struct OpApply
{
bool actEmpty;
int opApply(int delegate(ref int) dg)
{
int res;
if(actEmpty) return res;
foreach(i; 0..100)
{
res = dg(i);
@ -562,6 +571,18 @@ unittest
assert(reduce!"a + b"(oa) == hundredSum);
assert(reduce!("a + b", max)(oa) == tuple(hundredSum, 99));
assert(reduce!("a + b", max)(tuple(5, 0), oa) == tuple(hundredSum + 5, 99));
// Test for throwing on empty range plus no seed.
try {
reduce!"a + b"([1, 2][0..0]);
assert(0);
} catch(Exception) {}
oa.actEmpty = true;
try {
reduce!"a + b"(oa);
assert(0);
} catch(Exception) {}
}
unittest