parsav  Diff

Differences From Artifact [a251bec86e]:

• File mem.t — part of check-in [a4b4af5ca4] at 2021-01-13 15:01:13 on branch trunk — begin work on circles (user: lexi, size: 7356) [annotate] [blame] [check-ins using]

To Artifact [8c252399a5]:

• File mem.t — part of check-in [03ea3dffe7] at 2021-01-14 01:11:51 on branch trunk — more work on UI and circles (user: lexi, size: 8007) [annotate] [blame] [check-ins using]

   108    108   	end
   109    109   	terra t.methods.null(): t return t { ptr = nil, ct = 0 } end -- maybe should be a macro?
   110    110   	terra t:ref() return self.ptr ~= nil end
   111    111   	t.metamethods.__not = macro(function(self) return `not self:ref() end)
   112    112   	t.metamethods.__apply = macro(function(self,idx) return `self.ptr[ [idx or 0] ] end)
   113    113   	t.metamethods.__update = macro(function(self,idx,rhs)
   114    114   		return quote self.ptr[idx] = rhs end end)
          115  +	t.metamethods.__cast = function(from,to,exp)
          116  +		if to == t then
          117  +			if from == niltype then return `t.null()
          118  +			elseif from == &ty then return `t {ptr = exp, ct = 1}
          119  +			elseif from == ty then return `t {ptr = &exp, ct = 1}
          120  +			elseif from.N and from.type == ty then
          121  +				return `t {ptr = &exp[0], ct = from.N }
          122  +			end
          123  +			error('invalid cast to ' .. t.name .. ' from ' .. tostring(from))
          124  +		elseif from == t then
          125  +			if     to == &ty  then return `exp.ptr
          126  +			elseif to == ty   then return `@exp.ptr
          127  +			elseif to == bool then return `exp:ref() end
          128  +			error('invalid cast from ' .. t.name .. ' to ' .. tostring(to))
          129  +		end
          130  +		error('invalid pointer cast')
          131  +	end
   115    132   
   116    133   	if not ty:isstruct() then
   117    134   		terra t:cmp_raw(other: &ty)
   118    135   			for i=0, self.ct do
   119    136   				if self.ptr[i] ~= other[i] then return false end
   120    137   			end
   121    138   			return true