sort.qh File Reference

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Macros
#define	heapify(_count)
#define	siftdown(_start, _end)

Typedefs
using	comparefunc_t = int (int i1, int i2, entity pass)
	<0 for <, ==0 for ==, >0 for > (like strcmp)
using	swapfunc_t = void (int i1, int i2, entity pass)
	is only ever called for i1 < i2

Functions
ERASEABLE void	heapsort (int n, swapfunc_t swap, comparefunc_t cmp, entity pass)
ERASEABLE void	shuffle (float n, swapfunc_t swap, entity pass)

Macro Definition Documentation

heapify

#define heapify

(

_count

)

Value:

    MACRO_BEGIN \
    for (int start = floor(((_count) - 2) / 2); start >= 0; --start) \
        siftdown(start, (_count) - 1); \
MACRO_END

Referenced by heapsort().

siftdown

#define siftdown	(		_start,
			_end )

Value:

    MACRO_BEGIN \
    for (int root = (_start); root * 2 + 1 <= (_end); ) \
    { \
        int child = root * 2 + 1; \
        if (child < (_end) && cmp(child, child + 1, pass) < 0) \
            ++child; \
        if (cmp(root, child, pass) >= 0) \
            break; \
        swap(root, child, pass); \
        root = child; \
    } \
MACRO_END

Referenced by heapsort().

Typedef Documentation

comparefunc_t

using comparefunc_t = int (int i1, int i2, entity pass)

<0 for <, ==0 for ==, >0 for > (like strcmp)

Definition at line 6 of file sort.qh.

swapfunc_t

using swapfunc_t = void (int i1, int i2, entity pass)

is only ever called for i1 < i2

Definition at line 4 of file sort.qh.

Function Documentation

heapsort()

ERASEABLE void heapsort	(	int	n,
		swapfunc_t	swap,
		comparefunc_t	cmp,
		entity	pass )

Definition at line 9 of file sort.qh.

{
    #define heapify(_count) MACRO_BEGIN \
        for (int start = floor(((_count) - 2) / 2); start >= 0; --start) \
            siftdown(start, (_count) - 1); \
    MACRO_END
 
    #define siftdown(_start, _end) MACRO_BEGIN \
        for (int root = (_start); root * 2 + 1 <= (_end); ) \
        { \
            int child = root * 2 + 1; \
            if (child < (_end) && cmp(child, child + 1, pass) < 0) \
                ++child; \
            if (cmp(root, child, pass) >= 0) \
                break; \
            swap(root, child, pass); \
            root = child; \
        } \
    MACRO_END
 
    heapify(n);
    int end = n - 1;
    while (end > 0)
    {
        swap(0, end, pass);
        --end;
        siftdown(0, end);
    }
}

References entity(), heapify, pass, and siftdown.

Referenced by _MapInfo_FilterGametype(), Dump_Turret_Settings(), Dump_Weapon_Settings(), HUD_Weapons(), MapInfo_FilterString(), MapVote_CheckRules_count(), and W_FixWeaponOrder_BuildImpulseList().

shuffle()

ERASEABLE void shuffle	(	float	n,
		swapfunc_t	swap,
		entity	pass )

Definition at line 40 of file sort.qh.

{
    for (int i = 1; i < n; ++i)
    {
        // swap i-th item at a random position from 0 to i
        // proof for even distribution:
        //   n = 1: obvious
        //   n -> n+1:
        //     item n+1 gets at any position with chance 1/(n+1)
        //     all others will get their 1/n chance reduced by factor n/(n+1)
        //     to be on place n+1, their chance will be 1/(n+1)
        //     1/n * n/(n+1) = 1/(n+1)
        //     q.e.d.
        int j = floor(random() * (i + 1));
        if (j != i)
            swap(j, i, pass);
    }
}

References entity(), floor(), pass, and random().

Referenced by shufflewords().