From c4ef4c79aa48c4dd0fb98a5311f666ea54fc1cac Mon Sep 17 00:00:00 2001
From: Marc-Andre Lafortune <github@marc-andre.ca>
Date: Sun, 7 Mar 2021 16:28:00 -0500
Subject: [PATCH] + `Source::TreeRewriter#inspect` [#728]

---
 lib/parser/source/tree_rewriter.rb | 27 +++++++++++++++++++++++++++
 test/test_source_tree_rewriter.rb  | 11 +++++++++++
 2 files changed, 38 insertions(+)

diff --git a/lib/parser/source/tree_rewriter.rb b/lib/parser/source/tree_rewriter.rb
index 9e0ec8fef..cef8c2a8a 100644
--- a/lib/parser/source/tree_rewriter.rb
+++ b/lib/parser/source/tree_rewriter.rb
@@ -330,6 +330,11 @@ def in_transaction?
         @in_transaction
       end
 
+      # :nodoc:
+      def inspect
+        "#<#{self.class} #{source_buffer.name}: #{action_summary}>"
+      end
+
       ##
       # @api private
       # @deprecated Use insert_after or wrap
@@ -361,6 +366,28 @@ def insert_after_multi(range, text)
 
       private
 
+      def action_summary
+        replacements = as_replacements
+        case replacements.size
+        when 0 then return 'empty'
+        when 1..3 then #ok
+        else
+          replacements = replacements.first(3)
+          suffix = '…'
+        end
+        parts = replacements.map do |(range, str)|
+          if str.empty?
+            "-#{range.to_range}"
+          elsif range.size == 0
+            "+#{str.inspect}@#{range.begin_pos}"
+          else
+            "^#{str.inspect}@#{range.to_range}"
+          end
+        end
+        parts << suffix if suffix
+        parts.join(', ')
+      end
+
       ACTIONS = %i[accept warn raise].freeze
       def check_policy_validity
         invalid = @policy.values - ACTIONS
diff --git a/test/test_source_tree_rewriter.rb b/test/test_source_tree_rewriter.rb
index 4fca87be1..c1b470b17 100644
--- a/test/test_source_tree_rewriter.rb
+++ b/test/test_source_tree_rewriter.rb
@@ -358,4 +358,15 @@ def test_empty_import
     assert_equal @rewriter, @rewriter.import!(@rewriter2)
     assert_equal @rewriter, @rewriter.import!(@rewriter, offset: 42)
   end
+
+  def test_inspect
+    assert_equal '#<Parser::Source::TreeRewriter (rewriter): empty>', @rewriter.inspect
+    @rewriter.insert_before(@hello, '[')
+    @rewriter.replace(@ll, 'xxx')
+    @rewriter.remove(@comma_space)
+    assert_equal '#<Parser::Source::TreeRewriter (rewriter): +"["@5, ^"xxx"@8...10, -11...13>', @rewriter.inspect
+    @rewriter.insert_before(@hello, '{')
+    @rewriter.remove(@world)
+    assert_equal '#<Parser::Source::TreeRewriter (rewriter): +"{["@5, ^"xxx"@8...10, -11...13, …>', @rewriter.inspect
+  end
 end