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|
# frozen_string_literal: true
module Unparser
# Namespace for AST processing tools
module AST
FIRST_CHILD = ->(node) { node.children.first }.freeze
TAUTOLOGY = ->(_node) { true }.freeze
RESET_NODES = %i[module class sclass def defs].freeze
INHERIT_NODES = [:block].freeze
CLOSE_NODES = (RESET_NODES + INHERIT_NODES).freeze
# Nodes that assign a local variable
ASSIGN_NODES =
%i[
arg
kwarg
kwoptarg
lvasgn
optarg
procarg0
restarg
].to_set.freeze
# Test for local variable inherited scope reset
#
# @param [Parser::AST::Node] node
#
# @return [Boolean]
#
# @api private
#
def self.not_close_scope?(node)
!CLOSE_NODES.include?(node.type)
end
# Test for local variable scope reset
#
# @param [Parser::AST::Node] node
#
# @return [Boolean]
#
# @api private
#
def self.not_reset_scope?(node)
!RESET_NODES.include?(node.type)
end
# Return local variables that get assigned in scope
#
# @param [Parser::AST::Node] node
#
# @return [Set<Symbol>]
#
# @api private
#
def self.local_variable_assignments(node)
Enumerator.new(
node,
method(:not_reset_scope?)
).types(ASSIGN_NODES)
end
# Return local variables read
#
# @param [Parser::AST::Node] node
#
# @return [Set<Symbol>]
#
# @api private
#
def self.local_variable_reads(node)
Enumerator.new(
node,
method(:not_close_scope?)
).type(:lvar).map(&FIRST_CHILD).to_set
end
# AST enumerator
class Enumerator
include Adamantium, Concord.new(:node, :controller), Enumerable
# Return new instance
#
# @param [Parser::AST::Node] node
# @param [#call(node)] controller
#
# @return [Enumerator]
#
# @api private
#
def self.new(node, controller = TAUTOLOGY)
super
end
# Return each node
#
# @return [Enumerator<Parser::AST::Node>]
# if no block given
#
# @return [self]
# otherwise
#
# @api private
#
def each(&block)
Walker.call(node, controller, &block)
end
# Return nodes selected by types
#
# @param [Enumerable<Symbol>] types
#
# @return [Enumerable<Parser::AST::Node>]
#
# @api private
#
def types(types)
select { |node| types.include?(node.type) }
end
# Return nodes selected by type
#
# @param [Symbol] type
#
# @return [Enumerable<Parser::AST::Node>]
#
# @api private
#
def type(type)
select { |node| node.type.equal?(type) }
end
# Return frozne set of objects
#
# @param [Enumerable] enumerable
#
# @return [Set]
#
# @api private
#
def self.set(enumerable)
enumerable.to_set.freeze
end
private_class_method :set
# Return nodes of type
#
# @param [Parser::AST::Node] node
# @param [Symbol] type
#
# @return [Enumerable<Parser::AST::Node]
#
# @api private
#
def self.type(node, type)
new(node).type(type)
end
private_class_method :type
end # Enumerator
# Controlled AST walker walking the AST in deeth first search with pre order
class Walker
include Concord.new(:block, :controller)
# Call ast walker
#
# @param [Parser::AST::Node] node
#
# @return [self]
#
# @api private
#
def self.call(node, controller = TAUTOLOGY, &block)
new(block, controller).call(node)
self
end
# Call walker with node
#
# @param [Parser::AST::Node] node
#
# @return [undefined]
#
# @api private
#
def call(node)
return unless controller.call(node)
block.call(node)
node.children.each do |child|
break unless child.instance_of?(Parser::AST::Node)
call(child)
end
end
end # Walker
end # AST
end # Unparser
|
