lib/rubocop/ast/node_pattern/compiler.rb
# frozen_string_literal: true module RuboCop module AST class NodePattern # The top-level compiler holding the global state # Defers work to its subcompilers # # Doc on how this fits in the compiling process: # /docs/modules/ROOT/pages/node_pattern.adoc class Compiler extend Forwardable attr_reader :captures, :named_parameters, :positional_parameters, :binding def initialize @temp_depth = 0 # avoid name clashes between temp variables @captures = 0 # number of captures seen @positional_parameters = 0 # highest % (param) number seen @named_parameters = Set[] # keyword parameters @binding = Binding.new # bound variables @atom_subcompiler = self.class::AtomSubcompiler.new(self) end def_delegators :binding, :bind def positional_parameter(number) @positional_parameters = number if number > @positional_parameters "param#{number}" end def named_parameter(name) @named_parameters << name name end # Enumerates `enum` while keeping track of state across # union branches (captures and unification). def each_union(enum, &block) enforce_same_captures(binding.union_bind(enum), &block) end def compile_as_atom(node) @atom_subcompiler.compile(node) end def compile_as_node_pattern(node, **options) self.class::NodePatternSubcompiler.new(self, **options).compile(node) end def compile_sequence(sequence, var:) self.class::SequenceSubcompiler.new(self, sequence: sequence, var: var).compile_sequence end def parser @parser ||= Parser.new end # Utilities def with_temp_variables(*names, &block) @temp_depth += 1 suffix = @temp_depth if @temp_depth > 1 names = block.parameters.map(&:last) if names.empty? names.map! { |name| "#{name}#{suffix}" } yield(*names) ensure @temp_depth -= 1 end def next_capture "captures[#{new_capture}]" end def freeze @named_parameters.freeze super end private def enforce_same_captures(enum) return to_enum __method__, enum unless block_given? captures_before = captures_after = nil enum.each do |node| captures_before ||= @captures @captures = captures_before yield node captures_after ||= @captures if captures_after != @captures raise Invalid, 'each branch must have same number of captures' end end end def new_capture @captures ensure @captures += 1 end end end end end