lib/rubocop/ast/node_pattern/builder.rb
# frozen_string_literal: true module RuboCop module AST class NodePattern # Responsible to build the AST nodes for `NodePattern` # # Doc on how this fits in the compiling process: # /docs/modules/ROOT/pages/node_pattern.adoc class Builder def emit_capture(capture_token, node) return node if capture_token.nil? emit_unary_op(:capture, capture_token, node) end def emit_atom(type, value) n(type, [value]) end def emit_unary_op(type, _operator = nil, *children) n(type, children) end def emit_list(type, _begin, children, _end) n(type, children) end def emit_call(type, selector, args = nil) _begin_t, arg_nodes, _end_t = args n(type, [selector, *arg_nodes]) end def emit_union(begin_t, pattern_lists, end_t) children = union_children(pattern_lists) type = optimizable_as_set?(children) ? :set : :union emit_list(type, begin_t, children, end_t) end def emit_subsequence(node_list) return node_list.first if node_list.size == 1 # Don't put a single child in a subsequence emit_list(:subsequence, nil, node_list, nil) end private def optimizable_as_set?(children) children.all?(&:matches_within_set?) end def n(type, *args) Node::MAP[type].new(type, *args) end def union_children(pattern_lists) if pattern_lists.size == 1 # {a b c} => [[a, b, c]] => [a, b, c] children = pattern_lists.first raise NodePattern::Invalid, 'A union can not be empty' if children.empty? children else # { a b | c } => [[a, b], [c]] => [s(:subsequence, a, b), c] pattern_lists.map do |list| emit_subsequence(list) end end end end end end end