Help with macros

[Franco Salinas]

Hello everyone, I'm new around here and I need some help about macros. I want to do the following:

Given an Array<Array<Int>> where each Int is a static inline variable which takes values between 0-31, for example:

class Class1 {
    public static inline var A = 0;
    public static inline var B = 1;
    public static inline var C = 2;
    ...
}

...

var arr:Array<Array<Int>> = [ [ Class1.A, Class1.B,  Class1.E ], [  Class1.A,  Class1.C,  Class1.D ], ... ];

I want to generate an Array<Int> encoding the prior array like following:

new_array[ i ] = ( 1 << arr[ i ][ 0 ] ) | ( 1 << arr[ i ][ 1 ] ) | ...;

This means:

new_array[ 0 ] = 1|2|16; // = (1<<Class1.A)|(1|Class1.B)|(1<<Class1.E) = (1<<0)|(1<<1)|(1<<5)
new_array[ 1 ] = 1|4|8; // = (1<<Class1.A)|(1|Class1.C)|(1<<Class1.D) = (1<<0)|(1<<2)|(1<<4)
...

The point is using it like this:

private static inline var _list:Array<Int> = Macros.encodeList( [
    [ Class1.A, Class1.B, Class1.E ],
    [ Class1.A, Class1.C, Class1.D ]
 ] );

So far I have this:

@:macro public static function encodeList( list:Array<Array<Expr>> ) : Expr {
 
 var codes:Array<Int> = [];
 var index:Int = 0;
 
 for ( element in list ) {
 
     for( type in element ) {
         switch( type.expr ) {
             case EField( e, field ):
                 switch( field ) { // I'd like to do this without switch but this works anyway
                     case "A":
                         codes[ index ] |= 1 << 0;
                     case "B":
                         codes[ index ] |= 1 << 1;
                     case "C":
                         codes[ index ] |= 1 << 2;
                     ...
                     case "LAST":
                         codes[ index ] |= 1 << 31;
                     default:
 
                 }
             default:
         }
    }
    ++index;
 
 }

 // Here I should build an expression using the array "codes"


 }

Well, the point is I don't know how to build the expression. To be honest I don't fully understand the macro system. I don't know if I should return an expression or an Array<Field>. I saw the examples but I don't understand. I hope someone can help me. Thanks

[Juraj Kirchheim]

Context.makeExpr will do that. However I believe there was a bug
before 3.0.1. where it didn't always work correctly.

You could also try { expr: EArrayDecl(codes.map(Context.makeExpr)),
pos: Context.currentPos() }.

Regards,
Juraj

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[Franco Salinas]

Thanks for your answer. I am working with haxe 2.10 and I tried this (because codes.map() didn't worked):

 @:macro public static function encodeList( list:Array<Array<Expr>> ) : Expr {
    var codes:Array<Int> = [];

    ...

    var exprs:Array<Expr> = [];
    for ( c in codes )
        exprs.push( Context.makeExpr( c, Context.currentPos() ) );

 
    return { expr: EArrayDecl( exprs ), pos:Context.currentPos() };
}

But I get "haxe.macro.Expr should be Array<Array<haxe.macro.Expr>>" at line 18 which contains:

private static inline var _list:Array<Int> = Macros.encodeList( [ [ Class1.A, Class1.B, Class1.C ] ] );

Any ideas?