[close #16] Replace Parser with Ripper

Ripper is the built in parsing library from Ruby. It is much faster than Parser and it has everything we need.

This PR replaces the parser gem with ripper.

Author: schneems

CHANGELOG.md

@@ -1,5 +1,9 @@
 ## HEAD (unreleased)
 
+## 0.1.4
+
+- Parser gem replaced with Ripper (https://github.com/zombocom/syntax_search/pull/17)
+
 ## 0.1.3
 
 - Internal refactor (https://github.com/zombocom/syntax_search/pull/13)

Gemfile.lock

@@ -1,16 +1,12 @@
 PATH
   remote: .
   specs:
-    syntax_search (0.1.3)
-      parser
+    syntax_search (0.1.4)
 
 GEM
   remote: https://rubygems.org/
   specs:
-    ast (2.4.1)
     diff-lcs (1.4.4)
-    parser (2.7.2.0)
-      ast (~> 2.4.1)
     rake (12.3.3)
     rspec (3.10.0)
       rspec-core (~> 3.10.0)

lib/syntax_search.rb

@@ -2,10 +2,10 @@
 
 require_relative "syntax_search/version"
 
-require 'parser/current'
 require 'tmpdir'
 require 'stringio'
 require 'pathname'
+require 'ripper'
 
 module SyntaxErrorSearch
   class Error < StandardError; end
@@ -80,6 +80,13 @@ def self.valid_without?(without_lines: , code_lines:)
     end
   end
 
+  def self.invalid?(source)
+    source = source.join if source.is_a?(Array)
+    source = source.to_s
+
+    Ripper.new(source).tap(&:parse).error?
+  end
+
   # Returns truthy if a given input source is valid syntax
   #
   #   SyntaxErrorSearch.valid?(<<~EOM) # => true
@@ -115,38 +122,12 @@ def self.valid_without?(without_lines: , code_lines:)
   # so passing a CodeLine in as an object or as an array
   # will convert it to it's code representation.
   def self.valid?(source)
-    source = source.join if source.is_a?(Array)
-    source = source.to_s
-
-    # Parser writes to stderr even if you catch the error
-    stderr = $stderr
-    $stderr = StringIO.new
-
-    Parser::CurrentRuby.parse(source)
-    true
-  rescue Parser::SyntaxError => e
-    yield e if block_given?
-    false
-  ensure
-    $stderr = stderr if stderr
+    !invalid?(source)
   end
 
-  def self.invalid_type(source)
-    message = nil
-    self.valid?(source) do |error|
-      message = error.message
-    end
 
-    case message
-    when nil
-      :none
-    when /token kEND/
-      :unmatched_end
-    when /token \$end/ #
-      :missing_end
-    else
-      raise "Unexpected message #{message}"
-    end
+  def self.invalid_type(source)
+    WhoDisSyntaxError.new(source).call.error_symbol
   end
 end
 
@@ -159,3 +140,4 @@ def self.invalid_type(source)
 require_relative "syntax_search/parse_blocks_from_indent_line"
 
 require_relative "syntax_search/code_search"
+require_relative "syntax_search/who_dis_syntax_error"

lib/syntax_search/version.rb

@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module SyntaxErrorSearch
-  VERSION = "0.1.3"
+  VERSION = "0.1.4"
 end

lib/syntax_search/who_dis_syntax_error.rb

@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+
+module SyntaxErrorSearch
+  # Determines what type of syntax error is in the source
+  #
+  # Example:
+  #
+  #   puts WhoDisSyntaxError.new("def foo;").call.error_symbol
+  #   # => :missing_end
+  class WhoDisSyntaxError < Ripper
+    attr_reader :error, :run_once, :error_symbol
+
+    def call
+      @run_once ||= begin
+        parse
+        true
+      end
+      self
+    end
+
+    def on_parse_error(msg)
+      @error = msg
+      if @error.match?(/unexpected end-of-input/)
+        @error_symbol = :missing_end
+      elsif @error.match?(/unexpected `end'/) || @error.match?(/expecting end-of-input/)
+        @error_symbol = :unmatched_end
+      else
+        @error_symbol = :nope
+      end
+    end
+  end
+end

spec/unit/who_dis_syntax_error_spec.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+require_relative "../spec_helper.rb"
+
+module SyntaxErrorSearch
+  RSpec.describe WhoDisSyntaxError do
+    it  "determines the type of syntax error" do
+      expect(
+        WhoDisSyntaxError.new("def foo;").call.error_symbol
+      ).to eq(:missing_end)
+
+      expect(
+        WhoDisSyntaxError.new("def foo; end; end").call.error_symbol
+      ).to eq(:unmatched_end)
+    end
+  end
+end

syntax_search.gemspec

@@ -25,6 +25,4 @@ Gem::Specification.new do |spec|
   spec.bindir        = "exe"
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
-
-  spec.add_dependency "parser"
 end