Native based optimisations

[dwarring]

I'm pretty sure this can be made to run much faster with the appropriate use of native representations and some C binding code to do some of the heavy lifting in areas such as initialization inheritance and optimisation.

[dwarring]

Some initial thought on what the data-structures might look like.

use NativeCall;
enum Types ( :f, :d, :l, :s, :rgb, :rgba, :hsl, :hsla );
enum Flags ( :important(1), :inherit(2), :initial(4) );

class CSSColor is repr('CStruct') {
    # three color channels
    has uint32 $.c1;
    has uint32 $.c2;
    has uint32 $.c3;
    has uint32 $.alpha; 
}

class CSSValue is repr('CUnion') {
    has num64    $.f;
    has uint32   $.d;
    has long     $.l;
    has Str      $.s;
    has CSSColor $.rgb;
    has CSSColor $.rgba;
    has CSSColor $.hsl;
    has CSSColor $.hsla;
}

class CSSProp is repr('CStruct') {
   has uint8 $.prop;
   has uint8 $.flags;
   has CSSProp $.next;
   has CSSValue $.value;
   has uint8 $.type; # Types enum
   has uint8 $.units;
}

class CSSBox is repr('CStruct') {
   has uint8 $.prop;
   has uint8 $.flags;
   has CSSProp $.next;
   has CSSProp $.bottom;
   has CSSProp $.left;
   has CSSProp $.top;
   has CSSProp $.right;
}

The beauty is that there is only a finite number of properties, so we only needs arrays, and to map property names to numbers.