Class: Opal::Nodes::MassAssignNode

Inherits:
Base
  • Object
show all
Defined in:
opal/lib/opal/nodes/masgn.rb

Constant Summary collapse

SIMPLE_ASSIGNMENT = 
%i[lvasgn ivasgn lvar gvasgn cdecl casgn].freeze

Instance Attribute Summary

Attributes inherited from Base

#compiler, #sexp, #type

Instance Method Summary collapse

Methods inherited from Base

#add_gvar, #add_ivar, #add_local, #add_temp, #children, children, #class_variable_owner, #class_variable_owner_nesting_level, #comments, #compile_to_fragments, #error, #expr, #expr?, #expr_or_nil, #fragment, handle, handlers, #has_rescue_else?, #helper, #in_ensure, #in_ensure?, #in_resbody, #in_resbody?, #in_rescue, #in_while?, #initialize, #process, #push, #recv, #recv?, #s, #scope, #source_location, #stmt, #stmt?, #top_scope, truthy_optimize?, #unshift, #while_loop, #with_temp, #wrap

Methods included from Helpers

#conditional_send, #current_indent, #empty_line, #indent, #js_truthy, #js_truthy_optimize, #line, #mid_to_jsid, #property, #valid_name?

Constructor Details

This class inherits a constructor from Opal::Nodes::Base

Instance Method Details

#compile ⇒ Object 



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# File 'opal/lib/opal/nodes/masgn.rb', line 13

def compile
  array = scope.new_temp

  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
    retval = scope.new_temp
    push "#{retval} = ", expr(rhs)
    push ", #{array} = $to_ary(#{retval})"
    compile_masgn(lhs.children, array)
    push ", #{retval}"
    scope.queue_temp(retval)
  end

  scope.queue_temp(array)
end

#compile_assignment(child, array, idx, len = nil) ⇒ Object 



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# File 'opal/lib/opal/nodes/masgn.rb', line 78

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

#compile_masgn(lhs_items, array, len = nil) ⇒ Object

'len' is how many rhs items are we sure we have



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# File 'opal/lib/opal/nodes/masgn.rb', line 35

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.call(#{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.call(#{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