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Better Sort static assert error messages

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Robert burner Schadek 2023-02-08 22:20:18 +01:00
parent 73ba45329e
commit ef2eb4fdb7
2 changed files with 45 additions and 18 deletions
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8
changelog/sort_assert_messaged.dd Normal file
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@ -0,0 +1,8 @@
Better static assert messages for `std.algorithm.sorting.sort`
Up until now `sort` used a template constraint to check if the passed Range
could be used. If it were not, it was very tedious to figure out why.
As the template constraint is not used to overload the symbol template
function, the constrains are move into static asserts with expressive error
messages.

55
std/algorithm/sorting.d
View file

@ -1922,14 +1922,8 @@ See_Also:
$(REF binaryFun, std,functional)
*/
SortedRange!(Range, less)
sort(alias less = "a < b", SwapStrategy ss = SwapStrategy.unstable,
Range)(Range r)
if (((ss == SwapStrategy.unstable && (hasSwappableElements!Range ||
hasAssignableElements!Range)) ||
(ss != SwapStrategy.unstable && hasAssignableElements!Range)) &&
isRandomAccessRange!Range &&
hasSlicing!Range &&
hasLength!Range)
sort(alias less = "a < b", SwapStrategy ss = SwapStrategy.unstable, Range)
(Range r)
/+ Unstable sorting uses the quicksort algorithm, which uses swapAt,
which either uses swap(...), requiring swappable elements, or just
swaps using assignment.
@ -1937,21 +1931,46 @@ if (((ss == SwapStrategy.unstable && (hasSwappableElements!Range ||
requiring assignable elements. +/
{
import std.range : assumeSorted;
alias lessFun = binaryFun!(less);
alias LessRet = typeof(lessFun(r.front, r.front)); // instantiate lessFun
static if (is(LessRet == bool))
static if (ss == SwapStrategy.unstable)
{
static if (ss == SwapStrategy.unstable)
quickSortImpl!(lessFun)(r, r.length);
else //use Tim Sort for semistable & stable
TimSortImpl!(lessFun, Range).sort(r, null);
assert(isSorted!lessFun(r), "Failed to sort range of type " ~ Range.stringof);
static assert(hasSwappableElements!Range || hasAssignableElements!Range,
"When using SwapStragety.unstable, the passed Range '"
~ Range.stringof ~ "' must"
~ " either fulfill hasSwappableElements, or"
~ " hasAssignableElements, both were not the case");
}
else
{
static assert(false, "Invalid predicate passed to sort: " ~ less.stringof);
static assert(hasAssignableElements!Range, "When using a SwapStragety"
~ " != unstable, the"
~ " passed Range '" ~ Range.stringof ~ "' must fulfill"
~ " hasAssignableElements, which it did not");
}
static assert(isRandomAccessRange!Range, "The passed Range '"
~ Range.stringof ~ "' must be a Random AccessRange "
~ "(isRandomAccessRange)");
static assert(hasSlicing!Range, "The passed Range '"
~ Range.stringof ~ "' must allow Slicing (hasSlicing)");
static assert(hasLength!Range, "The passed Range '"
~ Range.stringof ~ "' must have a length (hasLength)");
alias lessFun = binaryFun!(less);
alias LessRet = typeof(lessFun(r.front, r.front)); // instantiate lessFun
static assert(is(LessRet == bool), "The return type of the template"
~ " argument 'less' when used with the binaryFun!less template"
~ " must be a bool. This is not the case, the returned type is '"
~ LessRet.stringof ~ "'");
static if (ss == SwapStrategy.unstable)
quickSortImpl!(lessFun)(r, r.length);
else //use Tim Sort for semistable & stable
TimSortImpl!(lessFun, Range).sort(r, null);
assert(isSorted!lessFun(r), "Failed to sort range of type " ~ Range.stringof);
return assumeSorted!less(r);
}