Add Parser::Source::Range#line_span

CHANGELOG.md

@@ -9,6 +9,7 @@
 * [#82](https://github.com/rubocop-hq/rubocop-ast/pull/82): `NodePattern`: Allow comments ([@marcandre][])
 * [#83](https://github.com/rubocop-hq/rubocop-ast/pull/83): Add `ProcessedSource#comment_at_line` ([@marcandre][])
 * [#83](https://github.com/rubocop-hq/rubocop-ast/pull/83): Add `ProcessedSource#each_comment_in_lines` ([@marcandre][])
+* [#84](https://github.com/rubocop-hq/rubocop-ast/pull/84): Add `Source::Range#line_span` ([@marcandre][])
 
 ### Bug fixes
 

lib/rubocop/ast.rb

@@ -4,6 +4,7 @@
 require 'forwardable'
 require 'set'
 
+require_relative 'ast/ext/range'
 require_relative 'ast/node_pattern'
 require_relative 'ast/sexp'
 require_relative 'ast/node'

lib/rubocop/ast/ext/range.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module AST
+    module Ext
+      # Extensions to Parser::AST::Range
+      module Range
+        # @return [Range] the range of line numbers for the node
+        # If `exclude_end` is `true`, then the range will be exclusive.
+        #
+        # Assume that `node` corresponds to the following array literal:
+        #
+        #   [
+        #     :foo,
+        #     :bar
+        #   ]
+        #
+        #   node.loc.begin.line_span                         # => 1..1
+        #   node.loc.expression.line_span(exclude_end: true) # => 1...4
+        def line_span(exclude_end: false)
+          ::Range.new(first_line, last_line, exclude_end)
+        end
+      end
+    end
+  end
+end
+
+::Parser::Source::Range.include ::RuboCop::AST::Ext::Range

spec/rubocop/ast/ext/range_spec.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::AST::Ext::Range do
+  let(:source) { <<~RUBY }
+    [
+      1,
+      2
+    ]
+  RUBY
+
+  let(:node) { parse_source(source).ast }
+
+  describe '#line_span' do
+    it 'returns the range of lines a range occupies' do
+      expect(node.loc.begin.line_span).to eq 1..1
+    end
+
+    it 'accepts an `exclude_end` keyword argument' do
+      expect(node.loc.expression.line_span(exclude_end: true)).to eq 1...4
+    end
+  end
+end