unpack = unpack or table.unpack

ntype = (node) ->

if type(node) == "table"

return node[1]

"value"

chain_assignable = {index: true, dot: true, slice: true}

is_assignable = (node) ->

return false if node == "..."

switch ntype node

when "ref", "self", "value", "self_class", "table"

true

when "chain"

chain_assignable[ntype node[#node]]

else

false

flatten_or_mark = (name) ->

(tbl) ->

return tbl[1] if #tbl == 1

table.insert tbl, 1, name

tbl

flatten_explist = flatten_or_mark "explist"

format_assign = (lhs_exps, assign) ->

unless assign

return flatten_explist lhs_exps

for assign_exp in *lhs_exps

unless is_assignable assign_exp

error {assign_exp, "left hand expression is not assignable"}

t = ntype assign

switch t

when "assign"

{"assign", lhs_exps, unpack assign, 2}

when "update"

{"update", lhs_exps[1], unpack assign, 2}

else

error "unknown assign expression: #{t}"

format_single_assign = (lhs, assign) ->

if assign

return format_assign {lhs}, assign

lhs

join_chain = (callee, args) ->

return callee if #args == 0

args = {"call", args}

if ntype(callee) == "chain"

table.insert callee, args

return callee

{"chain", callee, args}

{ :ntype, :is_assignable, :format_assign, :format_single_assign, :join_chain }