1 files changed, 43 insertions, 0 deletions
diff --git a/sample/prism/relocate_constants.rb b/sample/prism/relocate_constants.rb
new file mode 100644
index 0000000000..faa48f6388
--- /dev/null
+++ b/sample/prism/relocate_constants.rb
@@ -0,0 +1,43 @@
+# This script finds the declaration of all classes and modules and stores them
+# in a hash for an in-memory database of constants.
+
+require "prism"
+
+class RelocationVisitor < Prism::Visitor
+  attr_reader :index, :repository, :scope
+
+  def initialize(index, repository, scope = [])
+    @index = index
+    @repository = repository
+    @scope = scope
+  end
+
+  def visit_class_node(node)
+    next_scope = scope + node.constant_path.full_name_parts
+    index[next_scope.join("::")] << node.constant_path.save(repository)
+    node.body&.accept(RelocationVisitor.new(index, repository, next_scope))
+  end
+
+  def visit_module_node(node)
+    next_scope = scope + node.constant_path.full_name_parts
+    index[next_scope.join("::")] << node.constant_path.save(repository)
+    node.body&.accept(RelocationVisitor.new(index, repository, next_scope))
+  end
+end
+
+# Create an index that will store a mapping between the names of constants to a
+# list of the locations where they are declared or re-opened.
+index = Hash.new { |hash, key| hash[key] = [] }
+
+# Loop through every file in the lib directory of this repository and parse them
+# with Prism. Then visit them using the RelocateVisitor to store their
+# repository entries in the index.
+Dir[File.expand_path("../../lib/**/*.rb", __dir__)].each do |filepath|
+  repository = Prism::Relocation.filepath(filepath).filepath.lines.code_unit_columns(Encoding::UTF_16LE)
+  Prism.parse_file(filepath).value.accept(RelocationVisitor.new(index, repository))
+end
+
+puts index["Prism::ParametersNode"].map { |entry| "#{entry.filepath}:#{entry.start_line}:#{entry.start_code_units_column}" }
+# =>
+# prism/lib/prism/node.rb:13889:8
+# prism/lib/prism/node_ext.rb:267:8