-- Metalua extension --
-{ block:
local function index_builder(expr, indices)
indices = indices[1]
if #indices==1 then return `Index{ expr, indices[1] } end
local var = mlp.gensym()
return `Stat{
+{block: local -{var} = -{expr} },
`Call{ +{getmetatable(-{var}).__index}, var, unpack(indices) } }
end
mlp.expr.suffix:del '[' -- remove old "[...]" suffix parser
mlp.expr.suffix:add{ "[", gg.list{mlp.expr, separators=","}, "]", builder=index_builder }
}
-- Test code: a metatable with __index accepting several indices --
MT = { __index = |t, ...|
"requesting from " .. tostring(t) ..
" index " .. table.concat({...}, ", ") }
x = setmetatable({ }, MT)
-- Use the metatable --
print (x[1])
print (x[1,2])
print (x[1,2,3])
It generates normal code for 1-dimension indices; if there are several indices, it directly calls the __index metamethod with all the indices.
