Introduce type_fingerprint

Author: soutaro

docs/type_fingerprint.md

@@ -0,0 +1,21 @@
+# Type Fingerprint of RBS Inline AST
+
+Type fingerprint of RBS Inline AST is an object that can be used to detect if the RBS Inline AST is updated and the type checker should type check the whole codebase again.
+
+1. If the AST update is related to the type information, the fingerprint is changed -- adding new type, including new module, changing method type, etc. The type checker should type check the codebase with updated type information.
+2. If the AST updated is not related to the type information, the fingerprint keeps the last value -- changing the method implementation, adding a method call in the top level, adding white spaces and new lines, etc. The type checker can skip updating the type information, and type checking only the implementation of the file is sufficient.
+3. Documentation comments are considered type related information for now.
+
+## Type Fingerprint Calculation
+
+The type fingerprint is calculated by converting AST nodes to standardized data structures that represent only the type-relevant information. Each AST class implements a `type_fingerprint` method that returns mainly arrays and strings.
+
+We expect not using the values for something other than change detection. Compare old and new fingerprints, and we can detect the change between the RBS inline AST if the fingerprints are different.
+
+The fingerprint methods are implemented across:
+
+- `AST::Ruby::Annotations::*#type_fingerprint` - Returns `untyped` (arrays, strings, or nil)
+- `AST::Ruby::Members::*#type_fingerprint` - Returns `untyped` (typically arrays)
+- `AST::Ruby::Declarations::*#type_fingerprint` - Returns `untyped` (typically arrays)
+- `InlineParser::Result#type_fingerprint` - Returns `untyped` (array of declaration fingerprints)
+

lib/rbs/ast/ruby/annotations.rb

@@ -31,6 +31,13 @@ def map_type_name
               type: type.map_type_name { yield _1 }
             ) #: self
           end
+
+          def type_fingerprint
+            [
+              "annots/node_type_assertion",
+              type.to_s
+            ]
+          end
         end
 
         class AliasAnnotation < Base
@@ -55,9 +62,21 @@ def map_type_name
         end
 
         class ClassAliasAnnotation < AliasAnnotation
+          def type_fingerprint
+            [
+              "annots/class-alias",
+              type_name&.to_s
+            ]
+          end
         end
 
         class ModuleAliasAnnotation < AliasAnnotation
+          def type_fingerprint
+            [
+              "annots/module-alias",
+              type_name&.to_s
+            ]
+          end
         end
 
         class ColonMethodTypeAnnotation < Base
@@ -77,6 +96,14 @@ def map_type_name
               method_type: method_type.map_type {|type| type.map_type_name { yield _1 }}
             ) #: self
           end
+
+          def type_fingerprint
+            [
+              "annots/colon_method_type",
+              annotations.map(&:to_s),
+              method_type.to_s
+            ]
+          end
         end
 
         class MethodTypesAnnotation < Base
@@ -100,6 +127,13 @@ def map_type_name(&block)
 
             self.class.new(location:, prefix_location:, overloads: ovs, vertical_bar_locations:) #: self
           end
+
+          def type_fingerprint
+            [
+              "annots/method_types",
+              overloads.map { |o| [o.annotations.map(&:to_s), o.method_type.to_s] }
+            ]
+          end
         end
 
         class SkipAnnotation < Base
@@ -110,6 +144,10 @@ def initialize(location:, prefix_location:, skip_location:, comment_location:)
             @skip_location = skip_location
             @comment_location = comment_location
           end
+
+          def type_fingerprint
+            "annots/skip"
+          end
         end
 
         class ReturnTypeAnnotation < Base
@@ -139,6 +177,14 @@ def map_type_name(&block)
               comment_location: comment_location
             ) #: self
           end
+
+          def type_fingerprint
+            [
+              "annots/return_type",
+              return_type.to_s,
+              comment_location&.source
+            ]
+          end
         end
 
         class TypeApplicationAnnotation < Base
@@ -162,6 +208,13 @@ def map_type_name(&block)
               comma_locations:
             ) #: self
           end
+
+          def type_fingerprint
+            [
+              "annots/type_application",
+              type_args.map(&:to_s)
+            ]
+          end
         end
 
         class InstanceVariableAnnotation < Base
@@ -187,6 +240,15 @@ def map_type_name(&block)
               comment_location:
             ) #: self
           end
+
+          def type_fingerprint
+            [
+              "annots/instance_variable",
+              ivar_name.to_s,
+              type.to_s,
+              comment_location&.source
+            ]
+          end
         end
       end
     end

lib/rbs/ast/ruby/declarations.rb

@@ -54,6 +54,13 @@ def location
 
             alias name type_name
             alias args type_args
+
+            def type_fingerprint
+              [
+                type_name.to_s,
+                type_annotation&.type_fingerprint
+              ]
+            end
           end
 
           attr_reader :class_name
@@ -91,6 +98,17 @@ def location
           def name_location
             rbs_location(node.constant_path.location)
           end
+
+          def type_fingerprint
+            result = [] #: Array[untyped]
+
+            result << "decls/class"
+            result << class_name.to_s
+            result << super_class&.type_fingerprint
+            result << members.map { _1.type_fingerprint }
+
+            result
+          end
         end
 
         class ModuleDecl < Base
@@ -128,6 +146,16 @@ def location
           def name_location
             rbs_location(node.constant_path.location)
           end
+
+          def type_fingerprint
+            result = [] #: Array[untyped]
+
+            result << "decls/module"
+            result << module_name.to_s
+            result << members.map { _1.type_fingerprint}
+
+            result
+          end
         end
 
         class ConstantDecl < Base
@@ -181,6 +209,15 @@ def type
           def comment
             leading_comment&.as_comment
           end
+
+          def type_fingerprint
+            [
+              "decls/constant",
+              constant_name.to_s,
+              type.to_s,
+              leading_comment&.as_comment&.string
+            ]
+          end
         end
 
         class ClassModuleAliasDecl < Base
@@ -227,6 +264,16 @@ def old_name
           def comment
             leading_comment&.as_comment
           end
+
+          def type_fingerprint
+            [
+              "decls/class_module_alias",
+              annotation.type_fingerprint,
+              new_name.to_s,
+              old_name.to_s,
+              leading_comment&.as_comment&.string
+            ]
+          end
         end
       end
     end

lib/rbs/ast/ruby/members.rb

@@ -28,6 +28,10 @@ def map_type_name(&block)
               end #: self
             end
 
+            def type_fingerprint
+              return_type_annotation&.type_fingerprint
+            end
+
             def method_type
               return_type =
                 case return_type_annotation
@@ -175,6 +179,17 @@ def overloads
               ]
             end
           end
+
+          def type_fingerprint
+            case type_annotations
+            when DocStyle
+              type_annotations.type_fingerprint
+            when Array
+              type_annotations.map(&:type_fingerprint)
+            when nil
+              nil
+            end
+          end
         end
 
         class DefMember < Base
@@ -212,6 +227,15 @@ def annotations
           def name_location
             rbs_location(node.name_loc)
           end
+
+          def type_fingerprint
+            [
+              "members/def",
+              name.to_s,
+              method_type.type_fingerprint,
+              leading_comment&.as_comment&.string
+            ]
+          end
         end
 
         class MixinMember < Base
@@ -240,6 +264,15 @@ def name_location
           def type_args
             annotation&.type_args || []
           end
+
+          def type_fingerprint
+            [
+              "members/mixin",
+              self.class.name,
+              module_name.to_s,
+              annotation&.type_fingerprint
+            ]
+          end
         end
 
         class IncludeMember < MixinMember
@@ -284,6 +317,16 @@ def name_locations
           def type
             type_annotation&.type
           end
+
+          def type_fingerprint
+            [
+              "members/attribute",
+              self.class.name,
+              names.map(&:to_s),
+              type_annotation&.type_fingerprint,
+              leading_comment&.as_comment&.string
+            ]
+          end
         end
 
         class AttrReaderMember < AttributeMember
@@ -314,6 +357,13 @@ def type
           def location
             annotation.location
           end
+
+          def type_fingerprint
+            [
+              "members/instance_variable",
+              annotation.type_fingerprint
+            ]
+          end
         end
       end
     end

lib/rbs/inline_parser.rb

@@ -11,6 +11,10 @@ def initialize(buffer, prism)
         @declarations = []
         @diagnostics = []
       end
+
+      def type_fingerprint
+        declarations.map(&:type_fingerprint)
+      end
     end
 
     module Diagnostic