Enhance rake debug tasks

* Allow passing a local file containing the pattern
* Fix tokenize task

tasks/debug.rake

@@ -1,50 +1,72 @@
 # frozen_string_literal: true
 
+def pattern_or_file(input)
+  if input && File.exist?(input)
+    File.read(input)
+  else
+    input
+  end
+end
+
 desc 'Compile pattern to Ruby code for debugging purposes'
 task compile: :generate do
-  if (pattern = ARGV[1])
+  if (pattern = pattern_or_file(ARGV[1]))
     require_relative '../lib/rubocop/ast'
     puts RuboCop::AST::NodePattern.new(pattern).compile_as_lambda
   else
-    puts 'Usage:'
-    puts "  rake compile '(send nil? :example...)'"
+    puts <<~USAGE
+      Usage:
+        rake compile '(send nil? :example...)'
+        rake compile pattern.txt
+    USAGE
   end
   exit(0)
 end
 
 desc 'Parse pattern to AST for debugging purposes'
 task parse: :generate do
-  if (pattern = ARGV[1])
+  if (pattern = pattern_or_file(ARGV[1]))
     require_relative '../lib/rubocop/ast'
     puts RuboCop::AST::NodePattern::Parser.new.parse(pattern)
   else
-    puts 'Usage:'
-    puts "  rake parse '(send nil? :example...)'"
+    puts <<~USAGE
+      Usage:
+        rake parse '(send nil? :example...)'
+        rake parse pattern.txt
+    USAGE
   end
   exit(0)
 end
 
 desc 'Tokens of pattern for debugging purposes'
 task tokenize: :generate do
-  if (pattern = ARGV[1])
+  if (pattern = pattern_or_file(ARGV[1]))
     require_relative '../lib/rubocop/ast'
-    puts RuboCop::AST::NodePattern::Parser::WithMeta.new.tokenize(pattern).last
+    parser = RuboCop::AST::NodePattern::Parser::WithMeta.new
+    parser.parse(pattern)
+    puts parser.tokens
   else
-    puts 'Usage:'
-    puts "  rake parse '(send nil? :example...)'"
+    puts <<~USAGE
+      Usage:
+        rake tokenize '(send nil? :example...)'
+        rake tokenize pattern.txt
+    USAGE
   end
   exit(0)
 end
 
 desc 'Test pattern against ruby code'
 task test_pattern: :generate do
-  if (pattern = ARGV[1]) && (ruby = ARGV[2])
+  if (pattern = pattern_or_file(ARGV[1])) && (ruby = pattern_or_file(ARGV[2]))
     require_relative '../lib/rubocop/ast'
     colorizer = RuboCop::AST::NodePattern::Compiler::Debug::Colorizer.new(pattern)
     puts colorizer.test(ruby).colorize
   else
-    puts 'Usage:'
-    puts "  rake test-pattern '(send nil? :example...)' 'example(42)'"
+    puts <<~USAGE
+      Usage:
+        rake test_pattern '(send nil? :example...)' 'example(42)'
+        rake test_pattern pattern.txt code.rb
+    USAGE
   end
   exit(0)
 end