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local M = require 'macro'
List = require 'pl.List'
local list_check
-- list <var-list> [ = <init-list> ]
-- acts as a 'macro factory', making locally-scoped macros for the variables,
-- and emitting code to initialize plain variables.
M.define ('list',function(get)
get() -- skip space
-- 'list' acts as a 'type' followed by a variable list, which may be
-- followed by initial values
local values
local vars,endt = get:idens (function(t,v)
return t == '=' or (t == 'space' and v:find '\n')
end)
-- there is an initialization list
if endt[1] == '=' then
values,endt = get:list '\n'
else
values = {}
end
-- build up the initialization list
for i,name in ipairs(vars) do
M.define_scoped(name,list_check)
values[i] = 'List('..tostring(values[i] or '')..')'
end
local lcal = M._interactive and '' or 'local '
local res = lcal..table.concat(vars,',')..' = '..table.concat(values,',')..tostring(endt)
return res
end)
function list_check (get,put)
local t,v = get:peek(1)
if t ~= '[' then return nil, true end -- pass-through; plain var reference
get:expecting '['
local args = get:list(']',':')
-- it's just plain table access
if #args == 1 then return '['..tostring(args[1])..']',true end
-- two items separated by a colon; use sensible defaults
M.assert(#args == 2, "slice has two arguments!")
local start,finish = tostring(args[1]),tostring(args[2])
if start == '' then start = '1' end
if finish == '' then finish = '-1' end
-- look ahead to see if we're on the left hand side of an assignment
if get:peek(1) == '=' then
get:next() -- skip '='
local rest,eoln = get:upto '\n'
rest,eoln = tostring(rest),tostring(eoln)
return (':slice_assign(%s,%s,%s)%s'):format(start,finish,rest,eoln),true
else
return (':slice(%s,%s)'):format(start,finish),true
end
end
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