Migrate pretty print to Prism #262

Gemfile

@@ -7,7 +7,7 @@ gemspec
 gem "debug", platform: :mri unless ENV["CI"] == "true"
 
 gem "method_source"
-gem "unparser"
+gem "prism"
 
 gem 'sqlite3', "~> 1.4.0", platform: :mri
 gem 'activerecord-jdbcsqlite3-adapter', '~> 50.0', platform: :jruby

docs/debugging.md

@@ -2,7 +2,7 @@
 
 **NOTE:** this functionality requires two additional gems to be available in the app:
 
-- [unparser](https://github.com/mbj/unparser)
+- [prism](https://github.com/ruby/prism)
 - [method_source](https://github.com/banister/method_source).
 
 We usually describe policy rules using _boolean expressions_ (e.g. `A or (B and C)` where each of `A`, `B` and `C` is a simple boolean expression or predicate method).

forspell.dict

@@ -12,7 +12,7 @@ matchers
 non-inferrable
 Railsy
 testability
-unparser
+prism
 utils
 transpiled
 supersets

gemfiles/rails6.gemfile

@@ -3,6 +3,6 @@ source "https://rubygems.org"
 gem "sqlite3", "~> 1.4"
 gem "rails", "~> 6.0"
 gem "method_source"
-gem "unparser"
+gem "prism"
 
 gemspec path: ".."

gemfiles/rails7.gemfile

@@ -3,7 +3,7 @@ source "https://rubygems.org"
 gem "sqlite3", "~> 1.4"
 gem "rails", "~> 7.0.0"
 gem "method_source"
-gem "unparser"
+gem "prism"
 
 if ENV["COVERAGE"] == "true"
   gem "simplecov"

gemfiles/rails71.gemfile

@@ -3,7 +3,7 @@ source "https://rubygems.org"
 gem "sqlite3", "~> 1.4"
 gem "rails", "~> 7.1.0"
 gem "method_source"
-gem "unparser"
+gem "prism"
 
 if ENV["COVERAGE"] == "true"
   gem "simplecov"

lib/action_policy/policy/core.rb

@@ -147,7 +147,7 @@ def resolve_rule(activity)
       end
 
       # Return annotated source code for the rule
-      # NOTE: require "method_source" and "unparser" gems to be installed.
+      # NOTE: require "method_source" and "prism" gems to be installed.
       # Otherwise returns empty string.
       def inspect_rule(rule) = PrettyPrint.print_method(self, rule)
 

lib/action_policy/utils/pretty_print.rb

@@ -7,8 +7,7 @@
   # Ignore parse warnings when patch
   # Ruby version mismatches
   $VERBOSE = nil
-  require "parser/current"
-  require "unparser"
+  require "prism"
 rescue LoadError
   # do nothing
 ensure
@@ -42,7 +41,7 @@ module PrettyPrint
     FALSE = "\e[31mfalse\e[0m"
 
     class Visitor
-      attr_reader :lines, :object
+      attr_reader :lines, :object, :source
       attr_accessor :indent
 
       def initialize(object)
@@ -52,6 +51,8 @@ def initialize(object)
       def collect(ast)
         @lines = []
         @indent = 0
+        @source = ast.source.source
+        ast = ast.value.child_nodes[0].child_nodes[0].body
 
         visit_node(ast)
 
@@ -67,7 +68,7 @@ def visit_node(ast)
       end
 
       def expression_with_result(sexp)
-        expression = Unparser.unparse(sexp)
+        expression = source[sexp.location.start_offset...sexp.location.end_offset]
         "#{expression} #=> #{PrettyPrint.colorize(eval_exp(expression))}"
       end
 
@@ -78,36 +79,33 @@ def eval_exp(exp)
         "Failed: #{e.message}"
       end
 
-      def visit_and(ast)
-        visit_node(ast.children[0])
+      def visit_and_node(ast)
+        visit_node(ast.left)
         lines << indented("AND")
-        visit_node(ast.children[1])
+        visit_node(ast.right)
       end
 
-      def visit_or(ast)
-        visit_node(ast.children[0])
+      def visit_or_node(ast)
+        visit_node(ast.left)
         lines << indented("OR")
-        visit_node(ast.children[1])
+        visit_node(ast.right)
       end
 
-      def visit_begin(ast)
-        #  Parens
-        if ast.children.size == 1
-          lines << indented("(")
-          self.indent += 2
-          visit_node(ast.children[0])
+      def visit_statements_node(ast)
+        ast.child_nodes.each do |node|
+          visit_node(node)
+          # restore indent after each expression
           self.indent -= 2
-          lines << indented(")")
-        else
-          # Multiple expressions
-          ast.children.each do |node|
-            visit_node(node)
-            # restore indent after each expression
-            self.indent -= 2
-          end
         end
       end
 
+      def visit_parentheses_node(ast)
+        lines << indented("(")
+        self.indent += 2
+        visit_node(ast.child_nodes[0])
+        lines << indented(")")
+      end
+
       def visit_missing(ast)
         lines << indented(expression_with_result(ast))
       end
@@ -128,15 +126,13 @@ def ignore_exp?(exp)
     class << self
       attr_accessor :ignore_expressions
 
-      if defined?(::Unparser) && defined?(::MethodSource)
+      if defined?(::Prism) && defined?(::MethodSource)
         def available?() = true
 
         def print_method(object, method_name)
-          ast = object.method(method_name).source.then(&Unparser.:parse)
-          # outer node is a method definition itself
-          body = ast.children[2]
+          ast = Prism.parse(object.method(method_name).source)
 
-          Visitor.new(object).collect(body)
+          Visitor.new(object).collect(ast)
         end
       else
         def available?() = false