forall( __CFA_tysys_id_only_X & ) struct tag {};
#define ttag(T) ((tag(T)){})
#define ztag(n) ttag(n)


//
// Single-dim array sruct (with explicit packing and atom)
//

forall( [N], S & | sized(S), Timmed &, Tbase & ) {
    struct arpk {
        S strides[N];
    };

    // About the choice of integral types offered as subscript overloads:
    // Intent is to cover these use cases:
    //    float foo( ptrdiff_t i ) { return a[i]; }           // i : ptrdiff_t
    //    forall( [N] ) ... for( i; N ) { total += a[i]; }    // i : typeof( sizeof(42) )
    //    for( i; 5 ) { total += a[i]; }                      // i : int
    // It gets complicated by:
    // -  CFA does overloading on concrete types, like int and unsigned int, not on typedefed
    //    types like size_t.  So trying to overload on ptrdiff_t vs int works in 64-bit mode
    //    but not in 32-bit mode.
    // -  Given bug of Trac #247, CFA gives sizeof expressions type unsigned long int, when it
    //    should give them type size_t.
    //    
    //                          gcc -m32         cfa -m32 given bug         gcc -m64
    // ptrdiff_t                int              int                        long int
    // size_t                   unsigned int     unsigned int               unsigned long int
    // typeof( sizeof(42) )     unsigned int     unsigned long int          unsigned long int
    // int                      int              int                        int

    static inline Timmed & ?[?]( arpk(N, S, Timmed, Tbase) & a, int i ) {
        return (Timmed &) a.strides[i];
    }

    static inline Timmed & ?[?]( arpk(N, S, Timmed, Tbase) & a, unsigned int i ) {
        return (Timmed &) a.strides[i];
    }

    static inline Timmed & ?[?]( arpk(N, S, Timmed, Tbase) & a, long int i ) {
        return (Timmed &) a.strides[i];
    }

    static inline Timmed & ?[?]( arpk(N, S, Timmed, Tbase) & a, unsigned long int i ) {
        return (Timmed &) a.strides[i];
    }

    static inline size_t ?`len( arpk(N, S, Timmed, Tbase) & a ) {
        return N;
    }

    // workaround #226 (and array relevance thereof demonstrated in mike102/otype-slow-ndims.cfa)
    static inline void ?{}( arpk(N, S, Timmed, Tbase) & this ) {
        void ?{}( S (&inner)[N] ) {}
        ?{}(this.strides);
    }
    static inline void ^?{}( arpk(N, S, Timmed, Tbase) & this ) {
        void ^?{}( S (&inner)[N] ) {}
        ^?{}(this.strides);
    }
}

//
// Sugar for declaring array structure instances
//

forall( Te )
static inline Te mkar_( tag(Te) ) {}

forall( [N], ZTags ... , Trslt &, Tatom & | { Trslt mkar_( tag(Tatom), ZTags ); } )
static inline arpk(N, Trslt, Trslt, Tatom) mkar_( tag(Tatom), tag(N), ZTags ) {}

// based on https://stackoverflow.com/questions/1872220/is-it-possible-to-iterate-over-arguments-in-variadic-macros

    // Make a FOREACH macro
    #define FE_0(WHAT)
    #define FE_1(WHAT, X) WHAT(X) 
    #define FE_2(WHAT, X, ...) WHAT(X)FE_1(WHAT, __VA_ARGS__)
    #define FE_3(WHAT, X, ...) WHAT(X)FE_2(WHAT, __VA_ARGS__)
    #define FE_4(WHAT, X, ...) WHAT(X)FE_3(WHAT, __VA_ARGS__)
    #define FE_5(WHAT, X, ...) WHAT(X)FE_4(WHAT, __VA_ARGS__)
    //... repeat as needed

    #define GET_MACRO(_0,_1,_2,_3,_4,_5,NAME,...) NAME 
    #define FOR_EACH(action,...) \
    GET_MACRO(_0,__VA_ARGS__,FE_5,FE_4,FE_3,FE_2,FE_1,FE_0)(action,__VA_ARGS__)

#define COMMA_ttag(X) , ttag(X)
#define array( TE, ...) typeof( mkar_( ttag(TE)  FOR_EACH( COMMA_ttag, __VA_ARGS__ ) ) )

#define COMMA_ztag(X) , ztag(X)
#define zarray( TE, ...) typeof( mkar_( ttag(TE)  FOR_EACH( COMMA_ztag, __VA_ARGS__ ) ) )

//
// Sugar for multidimensional indexing
//

// Core -[[-,-,-]] operator

#ifdef TRY_BROKEN_DESIRED_MD_SUBSCRIPT

// Desired form.  One definition with recursion on IxBC (worked until Jan 2021, see trac #__TODO__)

forall( TA &, TB &, TC &, IxAB, IxBC ... | { TB & ?[?]( TA &, IxAB ); TC & ?[?]( TB &, IxBC ); } )
static inline TC & ?[?]( TA & this, IxAB ab, IxBC bc ) {
    return this[ab][bc];
}

#else 

// Workaround form.  Listing all possibilities up to 4 dims.

forall( TA &, TB &, TC &, IxAB_0, IxBC | { TB & ?[?]( TA &, IxAB_0 ); TC & ?[?]( TB &, IxBC ); } )
static inline TC & ?[?]( TA & this, IxAB_0 ab, IxBC bc ) {
    return this[ab][bc];
}

forall( TA &, TB &, TC &, IxAB_0, IxAB_1, IxBC | { TB & ?[?]( TA &, IxAB_0, IxAB_1 ); TC & ?[?]( TB &, IxBC ); } )
static inline TC & ?[?]( TA & this, IxAB_0 ab0, IxAB_1 ab1, IxBC bc ) {
    return this[[ab0,ab1]][bc];
}

forall( TA &, TB &, TC &, IxAB_0, IxAB_1, IxAB_2, IxBC | { TB & ?[?]( TA &, IxAB_0, IxAB_1, IxAB_2 ); TC & ?[?]( TB &, IxBC ); } )
static inline TC & ?[?]( TA & this, IxAB_0 ab0, IxAB_1 ab1, IxAB_2 ab2, IxBC bc ) {
    return this[[ab0,ab1,ab2]][bc];
}

#endif

//
// Rotation
//

// Base
forall( [Nq], Sq & | sized(Sq), Tbase & )
static inline tag(arpk(Nq, Sq, Tbase, Tbase)) enq_( tag(Tbase), tag(Nq), tag(Sq), tag(Tbase) ) {
    tag(arpk(Nq, Sq, Tbase, Tbase)) ret;
    return ret;
}

// Rec
forall( [Nq], Sq & | sized(Sq), [N], S & | sized(S), recq &, recr &, Tbase & | { tag(recr) enq_( tag(Tbase), tag(Nq), tag(Sq), tag(recq) ); } )
static inline tag(arpk(N, S, recr, Tbase)) enq_( tag(Tbase), tag(Nq), tag(Sq), tag(arpk(N, S, recq, Tbase)) ) {
    tag(arpk(N, S, recr, Tbase)) ret;
    return ret;
}

// Wrapper
struct all_t {} all;
forall( [N], S & | sized(S), Te &, result &, Tbase & | { tag(result) enq_( tag(Tbase), tag(N), tag(S), tag(Te) ); } )
static inline result & ?[?]( arpk(N, S, Te, Tbase) & this, all_t ) {
    return (result&) this;
}

//
// Trait of array or slice
//

trait ar(A &, Tv &) {
    Tv& ?[?]( A&, ptrdiff_t );
    size_t ?`len( A& );
};