WIP attempting to track output locations

lib/unparser.rb

@@ -57,14 +57,15 @@ def initialize(message, node)
   #   if the node passed is invalid
   #
   # @api public
-  def self.unparse(node, comment_array = [])
+  def self.unparse(node, comment_array = [], &callback)
     return '' if node.nil?
 
     Buffer.new.tap do |buffer|
       Emitter::Root.new(
         buffer,
         node,
-        Comments.new(comment_array)
+        Comments.new(comment_array),
+        callback
       ).write_to_buffer
     end.content
   end

lib/unparser/buffer.rb

@@ -31,7 +31,6 @@ def append(string)
         prefix
       end
       write(string)
-      self
     end
 
     # Append a string without an indentation prefix
@@ -44,7 +43,6 @@ def append(string)
     #
     def append_without_prefix(string)
       write(string)
-      self
     end
 
     # Increase indent
@@ -127,8 +125,13 @@ def capture_content
     #
     # @return [self]
     def write(fragment)
+      start_pos = @content.length
       @content << fragment
-      self
+      start_pos...@content.length
+    end
+
+    def length
+      @content.length
     end
 
   private

lib/unparser/concord.rb

@@ -8,7 +8,7 @@ class Concord < Module
     include Adamantium, Equalizer.new(:names)
 
     # The maximum number of objects the hosting class is composed of
-    MAX_NR_OF_OBJECTS = 3
+    MAX_NR_OF_OBJECTS = 4
 
     # Return names
     #

lib/unparser/emitter.rb

@@ -6,7 +6,7 @@ module Unparser
   # Emitter base class
   class Emitter
     include Adamantium, AbstractType, Constants, Generation, NodeHelpers
-    include Anima.new(:buffer, :comments, :node, :local_variable_scope)
+    include Anima.new(:buffer, :comments, :node, :local_variable_scope, :callback)
 
     public :node
 
@@ -67,7 +67,7 @@ def emit_mlhs
     # @api private
     #
     # rubocop:disable Metrics/ParameterLists
-    def self.emitter(buffer:, comments:, node:, local_variable_scope:)
+    def self.emitter(buffer:, comments:, node:, local_variable_scope:, callback:)
       type = node.type
 
       klass = REGISTRY.fetch(type) do
@@ -78,7 +78,8 @@ def self.emitter(buffer:, comments:, node:, local_variable_scope:)
         buffer:               buffer,
         comments:             comments,
         local_variable_scope: local_variable_scope,
-        node:                 node
+        node:                 node,
+        callback:             callback
       )
     end
     # rubocop:enable Metrics/ParameterLists

lib/unparser/emitter/argument.rb

@@ -87,7 +87,7 @@ class Argument < self
     private
 
       def dispatch
-        write(name.to_s)
+        write_loc(name.to_s, node.location.name.to_range)
       end
 
     end # Argument

lib/unparser/emitter/class.rb

@@ -13,7 +13,8 @@ class Class < self
     private
 
       def dispatch
-        write('class ')
+        write_loc('class', node.location.keyword.to_range)
+        write(' ')
         visit(name)
         emit_superclass
         emit_optional_body(body)

lib/unparser/emitter/def.rb

@@ -15,7 +15,8 @@ class Def < self
       private :body
 
       def dispatch
-        write('def ')
+        write_loc('def', node.location.keyword.to_range)
+        write(' ')
         emit_name
         emit_arguments
         emit_optional_body_ensure_rescue(body)
@@ -39,7 +40,7 @@ class Instance < self
       private
 
         def emit_name
-          write(name.to_s)
+          write_loc(name.to_s, node.location.name.to_range)
         end
 
       end # Instance
@@ -57,7 +58,8 @@ def emit_name
           conditional_parentheses(!subject_without_parens?) do
             visit(subject)
           end
-          write('.', name.to_s)
+          write_loc('.', node.location.operator.to_range)
+          write_loc(name.to_s, node.location.name.to_range)
         end
 
         def subject_without_parens?

lib/unparser/emitter/module.rb

@@ -13,7 +13,8 @@ class Module < self
     private
 
       def dispatch
-        write('module ')
+        write_loc('module', node.location.keyword.to_range)
+        write(' ')
         visit(name)
         emit_optional_body(body)
         k_end

lib/unparser/emitter/primitive.rb

@@ -7,18 +7,33 @@ class Primitive < self
 
       children :value
 
-      # Emitter for primitives based on Object#inspect
-      class Inspect < self
+      class Str < self
 
-        handle :sym, :str
+        handle :str
 
       private
 
         def dispatch
-          write(value.inspect)
+          new_loc = buffer.append(value.inspect)
+          return unless callback
+
+          new_loc_adjusted = (new_loc.first + 1)...(new_loc.last - 1)
+          callback.call(buffer, node.location.expression.to_range, new_loc_adjusted)
+        end
+
+      end # Str
+
+      class Sym < self
+
+        handle :sym
+
+      private
+
+        def dispatch
+          write_loc(value.inspect, node.location.expression.to_range)
         end
 
-      end # Inspect
+      end # Sym
 
       # Emitter for complex literals
       class Complex < self

lib/unparser/emitter/root.rb

@@ -4,7 +4,7 @@ module Unparser
   class Emitter
     # Root emitter a special case
     class Root < self
-      include Concord::Public.new(:buffer, :node, :comments)
+      include Concord::Public.new(:buffer, :node, :comments, :callback)
       include LocalVariableRoot
 
       END_NL = %i[class sclass module begin].freeze

lib/unparser/emitter/variable.rb

@@ -12,7 +12,7 @@ class Variable < self
     private
 
       def dispatch
-        write(name.to_s)
+        write_loc(name.to_s, node.location.name.to_range)
       end
 
     end # Access
@@ -27,14 +27,14 @@ class Const < self
 
       def dispatch
         emit_scope
-        write(name.to_s)
+        write_loc(name.to_s, node.location.name.to_range)
       end
 
       def emit_scope
         return unless scope
 
         visit(scope)
-        write('::') unless n_cbase?(scope)
+        write_loc('::', node.location.double_colon.to_range) unless n_cbase?(scope)
       end
     end
 
@@ -48,8 +48,7 @@ class NthRef < self
     private
 
       def dispatch
-        write(PREFIX)
-        write(name.to_s)
+        write_loc([PREFIX, name.to_s], node.location.expression.to_range)
       end
 
     end # NthRef

lib/unparser/generation.rb

@@ -90,17 +90,27 @@ def write(*strings)
       strings.each(&buffer.method(:append))
     end
 
+    def write_loc(strings, old_location, new_location = nil)
+      locs = Array(strings).map(&buffer.method(:append))
+      return unless callback
+
+      if old_location
+        new_location ||= locs.first.first...locs.last.last
+        callback.call(buffer, old_location, new_location)
+      end
+    end
+
     def k_end
       buffer.indent
       emit_comments_before(:end)
       buffer.unindent
-      write('end')
+      write_loc('end', node.location.end.to_range)
     end
 
     def parentheses(open = '(', close = ')')
-      write(open)
+      write_loc(open, node.location.begin.to_range) if node.location.respond_to?(:begin)
       yield
-      write(close)
+      write_loc(close, node.location.end.to_range) if node.location.respond_to?(:begin)
     end
 
     def indented

lib/unparser/writer.rb

@@ -6,7 +6,7 @@ module Writer
 
     def self.included(descendant)
       descendant.class_eval do
-        include Anima.new(:buffer, :comments, :node, :local_variable_scope)
+        include Anima.new(:buffer, :comments, :node, :local_variable_scope, :callback)
 
         extend DSL
       end

lib/unparser/writer/send.rb

@@ -27,7 +27,7 @@ def emit_mlhs
       end
 
       def emit_selector
-        write(details.string_selector)
+        write_loc(details.string_selector, node.location.selector.to_range)
       end
 
       def emit_heredoc_reminders
@@ -59,7 +59,7 @@ def write_as_attribute_assignment?
       end
 
       def emit_operator
-        write(OPERATORS.fetch(node.type))
+        write_loc(OPERATORS.fetch(node.type), node.location.dot.to_range)
       end
 
       def emit_arguments