lib/opal/nodes/masgn.rb
# frozen_string_literal: true
require 'opal/nodes/base'
module Opal
module Nodes
class MassAssignNode < Base
SIMPLE_ASSIGNMENT = %i[lvasgn ivasgn lvar gvasgn cdecl casgn].freeze
handle :masgn
children :lhs, :rhs
def compile
with_temp do |array|
if rhs.type == :array
push "#{array} = ", expr(rhs)
rhs_len = rhs.children.any? { |c| c.type == :splat } ? nil : rhs.children.size
compile_masgn(lhs.children, array, rhs_len)
push ", #{array}" # a mass assignment evaluates to the RHS
else
helper :to_ary
with_temp do |retval|
push "#{retval} = ", expr(rhs)
push ", #{array} = $to_ary(#{retval})"
compile_masgn(lhs.children, array)
push ", #{retval}"
end
end
end
end
# 'len' is how many rhs items are we sure we have
def compile_masgn(lhs_items, array, len = nil)
pre_splat = lhs_items.take_while { |child| child.type != :splat }
post_splat = lhs_items.drop(pre_splat.size)
pre_splat.each_with_index do |child, idx|
compile_assignment(child, array, idx, len)
end
unless post_splat.empty?
splat = post_splat.shift
if post_splat.empty? # trailing splat
if part = splat.children[0]
helper :slice
part = part.dup << s(:js_tmp, "$slice(#{array}, #{pre_splat.size})")
push ', '
push expr(part)
end
else
tmp = scope.new_temp # end index for items consumed by splat
push ", #{tmp} = #{array}.length - #{post_splat.size}"
push ", #{tmp} = (#{tmp} < #{pre_splat.size}) ? #{pre_splat.size} : #{tmp}"
if part = splat.children[0]
helper :slice
part = part.dup << s(:js_tmp, "$slice(#{array}, #{pre_splat.size}, #{tmp})")
push ', '
push expr(part)
end
post_splat.each_with_index do |child, idx|
if idx == 0
compile_assignment(child, array, tmp)
else
compile_assignment(child, array, "#{tmp} + #{idx}")
end
end
scope.queue_temp(tmp)
end
end
end
def compile_assignment(child, array, idx, len = nil)
assign =
if !len || idx >= len
s(:js_tmp, "(#{array}[#{idx}] == null ? nil : #{array}[#{idx}])")
else
s(:js_tmp, "#{array}[#{idx}]")
end
part = child.updated
if SIMPLE_ASSIGNMENT.include?(child.type)
part = part.updated(nil, part.children + [assign])
elsif child.type == :send
part = part.updated(nil, part.children + [assign])
elsif child.type == :attrasgn
part.last << assign
elsif child.type == :mlhs
helper :to_ary
# nested destructuring
tmp = scope.new_temp
push ", (#{tmp} = $to_ary(#{assign.children[0]})"
compile_masgn(child.children, tmp)
push ')'
scope.queue_temp(tmp)
return
else
raise "Bad child node in masgn LHS: #{child}. LHS: #{lhs}"
end
push ', '
push expr(part)
end
end
end
end