operator - method

dynamic operator -(Object o)

Implementation

operator -(Object o){
  switch(o){
    case NamedLine n:
      return this - n.expression;
    case (double, PxUnit) l:
      return this - Expression.literal(l);
    case LiteralGetter lg:
      return this - Expression.literalGetter(lg);
    case double p:
      return this - Expression.percent(p);
    case PercentGetter pg:
      return this - Expression.percentGetter(pg);
    case Expression e:
      if(literal != null || e.literal != null){
        return Expression((Size size)=>percentGetter(size) - e.percentGetter(size), (Size size){
          final a = literal?.call(size);
          final b = e.literal?.call(size);
          if(a?.$2 == b?.$2 || a == null || b == null){
            return (((a?.$1 ?? 0) - (b?.$1 ?? 0)), (a?.$2 ?? b?.$2)!);
          /// 单位里有 wpc 和 hpc 的统一到[w,h]pc
          }if(a.$2 == PxUnit.wpc){
            return (a.$1 - pxUnitDoubleWidthPercentGetter(b)(size), PxUnit.wpc);
          }else
          if(a.$2 == PxUnit.hpc){
            return (a.$1 - pxUnitDoubleHeightPercentGetter(b)(size), PxUnit.hpc);
          }else
          if(b.$2 == PxUnit.wpc){
            return (pxUnitDoubleWidthPercentGetter(a)(size) - b.$1, PxUnit.wpc);
          }else
          if(b.$2 == PxUnit.hpc){
            return (pxUnitDoubleWidthPercentGetter(a)(size) - b.$1, PxUnit.hpc);
          /// 单位里没有 wpc 和 hpc 的统一到 px
          }else{
            return (pxUnitDoubleGetter(a)(size) - pxUnitDoubleGetter(b)(size), PxUnit.px);
          }
        });
      }else{
        return Expression((Size size)=>percentGetter(size) - e.percentGetter(size), null);
      }
  }
}