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better error when assigning invalid left hand side, fixes #36

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leaf corcoran 2012-10-31 00:43:26 -07:00
parent 021d4878a0
commit 5b9e1a4389
1 changed files with 36 additions and 10 deletions
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46
moonscript/parse.lua
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@ -166,10 +166,15 @@ end
-- makes sure the last item in a chain is an index
local _assignable = { index = true, dot = true, slice = true }
local function is_assignable(node)
local t = ntype(node)
return t == "self" or t == "value" or
t == "chain" and _assignable[ntype(node[#node])]
end
local function check_assignable(str, pos, value)
if ntype(value) == "chain" and _assignable[ntype(value[#value])]
or type(value) == "string"
then
if is_assignable(value) then
return true, value
end
return false
@ -181,6 +186,13 @@ local function format_assign(lhs_exps, assign)
return flatten_explist(lhs_exps)
end
for _, assign_exp in ipairs(lhs_exps) do
if not is_assignable(assign_exp) then
print(util.dump(assign_exp))
error {assign_exp, "left hand expression is not assignable"}
end
end
local t = ntype(assign)
if t == "assign" then
return {"assign", lhs_exps, unpack(assign, 2)}
@ -276,7 +288,7 @@ local function self_assign(name)
return {{"key_literal", name}, name}
end
local err_msg = "Failed to parse:\n [%d] >> %s (%d)"
local err_msg = "Failed to parse:%s\n [%d] >> %s"
local build_grammar = wrap_env(function()
local _indent = Stack(0) -- current indent
@ -559,16 +571,30 @@ local build_grammar = wrap_env(function()
end
local tree
local args = {...}
local pass, err = assert(pcall(function()
tree = self._g:match(str, unpack(args))
end))
local pass, err = pcall(function(...)
tree = self._g:match(str, ...)
end, ...)
-- regular error, let it bubble up
if type(err) == "string" then
error(err)
end
if not tree then
local line_no = pos_to_line(last_pos)
local pos = last_pos
local msg
if err then
local node
node, msg = unpack(err)
msg = msg and " " .. msg
pos = node[-1]
end
local line_no = pos_to_line(pos)
local line_str = get_line(line_no) or ""
return nil, err_msg:format(line_no, trim(line_str), _indent:top())
return nil, err_msg:format(msg or "", line_no, trim(line_str))
end
return tree
end