1 files changed, 71 insertions, 0 deletions
diff --git a/lib/syntax_suggest/capture/falling_indent_lines.rb b/lib/syntax_suggest/capture/falling_indent_lines.rb
new file mode 100644
index 0000000000..1e046b2ba5
--- /dev/null
+++ b/lib/syntax_suggest/capture/falling_indent_lines.rb
@@ -0,0 +1,71 @@
+# frozen_string_literal: true
+
+module SyntaxSuggest
+  module Capture
+    # Shows the context around code provided by "falling" indentation
+    #
+    # If this is the original code lines:
+    #
+    #   class OH
+    #     def hello
+    #       it "foo" do
+    #     end
+    #   end
+    #
+    # And this is the line that is captured
+    #
+    #       it "foo" do
+    #
+    # It will yield its surrounding context:
+    #
+    #   class OH
+    #     def hello
+    #     end
+    #   end
+    #
+    # Example:
+    #
+    #   FallingIndentLines.new(
+    #       block: block,
+    #       code_lines: @code_lines
+    #   ).call do |line|
+    #     @lines_to_output << line
+    #   end
+    #
+    class FallingIndentLines
+      def initialize(code_lines:, block:)
+        @lines = nil
+        @scanner = ScanHistory.new(code_lines: code_lines, block: block)
+        @original_indent = block.current_indent
+      end
+
+      def call(&yieldable)
+        last_indent_up = @original_indent
+        last_indent_down = @original_indent
+
+        @scanner.commit_if_changed
+        @scanner.scan(
+          up: ->(line, _, _) {
+            next true if line.empty?
+
+            if line.indent < last_indent_up
+              yieldable.call(line)
+              last_indent_up = line.indent
+            end
+            true
+          },
+          down: ->(line, _, _) {
+            next true if line.empty?
+
+            if line.indent < last_indent_down
+              yieldable.call(line)
+              last_indent_down = line.indent
+            end
+            true
+          }
+        )
+        @scanner.stash_changes
+      end
+    end
+  end
+end