// Macros for sorting lists using C's qsort()

struct _List{len:Int, items:Pointer}
extern qsort(items:Pointer, count:Int, size:Int, compare:(Pointer,Pointer)=>Int32)

macro _sort_by_expr(_xs,T,x,expr)
    def compare(a:Pointer, b:Pointer):Int32
        x := (a:struct{val:T}).val
        ka := expr
        x = (b:struct{val:T}).val
        kb := expr
        if ka == kb
            return 0:Int32
        elseif ka < kb
            return -1:Int32
        else
            return 1:Int32

    xs := _xs
    info := xs:_List
    qsort(info.items, info.len, sizeof xs[1], compare)

macro sort(_xs,x,expr)
    xs := _xs
    _sort_by_expr(xs, typeof(xs[1] or fail), x, expr)

macro _sort(_xs,T)
    def compare(a:Pointer, b:Pointer):Int32
        ka := (a:struct{val:T}).val
        kb := (b:struct{val:T}).val
        if ka == kb
            return 0:Int32
        elseif ka < kb
            return -1:Int32
        else
            return 1:Int32

    xs := _xs
    info := xs:_List
    qsort(info.items, info.len, sizeof xs[1], compare)

macro sort(_xs)
    xs := _xs
    _sort(xs, typeof(xs[1] or fail))

macro contains(list, item)
    has_item := no
    for x in list
        if x == item
            has_item = yes
            stop
    has_item

nums := [5,3,6,1,2]
$puts "2: $(nums|contains 2)  999: $(nums|contains 999)"

// nums := [5,2,7,3,5,1,-2,-3,-1]
// sort(nums)
// $puts "$nums"
// sort(nums, x, x*x)
// $puts "$nums"

// struct Foo {
//     junk:Int
//     str:String
// }
// foos := [Foo{1,"hi"}, Foo{5,"bye"}, Foo{3,"xxx"}]
// sort(foos, f, f.str)
// $puts "$foos"
// sort(foos, f, f.junk)
// $puts "$foos"