Promote did_you_mean to default gem

At the moment, there are some problems with regard to bundler + did_you_mean because of did_you_mean being a bundled gem. Since the vendored version of thor inside bundler and ruby itself explicitly requires did_you_mean, it can become difficult to load it when using Bundler.setup. See this issue: https://github.com/yuki24/did_you_mean/issues/117#issuecomment-482733159 for more details.

6 files changed, 234 insertions, 0 deletions

diff --git a/lib/did_you_mean/spell_checkers/key_error_checker.rb b/lib/did_you_mean/spell_checkers/key_error_checker.rb
new file mode 100644
index 0000000000..be4bea7789
--- /dev/null
+++ b/lib/did_you_mean/spell_checkers/key_error_checker.rb
@@ -0,0 +1,20 @@
+require_relative "../spell_checker"
+
+module DidYouMean
+  class KeyErrorChecker
+    def initialize(key_error)
+      @key = key_error.key
+      @keys = key_error.receiver.keys
+    end
+
+    def corrections
+      @corrections ||= exact_matches.empty? ? SpellChecker.new(dictionary: @keys).correct(@key).map(&:inspect) : exact_matches
+    end
+
+    private
+
+    def exact_matches
+      @exact_matches ||= @keys.select { |word| @key == word.to_s }.map(&:inspect)
+    end
+  end
+end
diff --git a/lib/did_you_mean/spell_checkers/method_name_checker.rb b/lib/did_you_mean/spell_checkers/method_name_checker.rb
new file mode 100644
index 0000000000..3ca8a37e08
--- /dev/null
+++ b/lib/did_you_mean/spell_checkers/method_name_checker.rb
@@ -0,0 +1,56 @@
+require_relative "../spell_checker"
+
+module DidYouMean
+  class MethodNameChecker
+    attr_reader :method_name, :receiver
+
+    NAMES_TO_EXCLUDE = { NilClass => nil.methods }
+    NAMES_TO_EXCLUDE.default = []
+
+    # +MethodNameChecker::RB_RESERVED_WORDS+ is the list of reserved words in
+    # Ruby that take an argument. Unlike
+    # +VariableNameChecker::RB_RESERVED_WORDS+, these reserved words require
+    # an argument, and a +NoMethodError+ is raised due to the presence of the
+    # argument.
+    #
+    # The +MethodNameChecker+ will use this list to suggest a reversed word if
+    # a +NoMethodError+ is raised and found closest matches.
+    #
+    # Also see +VariableNameChecker::RB_RESERVED_WORDS+.
+    RB_RESERVED_WORDS = %i(
+      alias
+      case
+      def
+      defined?
+      elsif
+      end
+      ensure
+      for
+      rescue
+      super
+      undef
+      unless
+      until
+      when
+      while
+      yield
+    )
+
+    def initialize(exception)
+      @method_name  = exception.name
+      @receiver     = exception.receiver
+      @private_call = exception.respond_to?(:private_call?) ? exception.private_call? : false
+    end
+
+    def corrections
+      @corrections ||= SpellChecker.new(dictionary: RB_RESERVED_WORDS + method_names).correct(method_name) - NAMES_TO_EXCLUDE[@receiver.class]
+    end
+
+    def method_names
+      method_names = receiver.methods + receiver.singleton_methods
+      method_names += receiver.private_methods if @private_call
+      method_names.uniq!
+      method_names
+    end
+  end
+end
diff --git a/lib/did_you_mean/spell_checkers/name_error_checkers.rb b/lib/did_you_mean/spell_checkers/name_error_checkers.rb
new file mode 100644
index 0000000000..6e2aaa4cb1
--- /dev/null
+++ b/lib/did_you_mean/spell_checkers/name_error_checkers.rb
@@ -0,0 +1,20 @@
+require_relative 'name_error_checkers/class_name_checker'
+require_relative 'name_error_checkers/variable_name_checker'
+
+module DidYouMean
+  class << (NameErrorCheckers = Object.new)
+    def new(exception)
+      case exception.original_message
+      when /uninitialized constant/
+        ClassNameChecker
+      when /undefined local variable or method/,
+           /undefined method/,
+           /uninitialized class variable/,
+           /no member '.*' in struct/
+        VariableNameChecker
+      else
+        NullChecker
+      end.new(exception)
+    end
+  end
+end
diff --git a/lib/did_you_mean/spell_checkers/name_error_checkers/class_name_checker.rb b/lib/did_you_mean/spell_checkers/name_error_checkers/class_name_checker.rb
new file mode 100644
index 0000000000..3bd048b27c
--- /dev/null
+++ b/lib/did_you_mean/spell_checkers/name_error_checkers/class_name_checker.rb
@@ -0,0 +1,50 @@
+# frozen-string-literal: true
+
+require 'delegate'
+require_relative "../../spell_checker"
+
+module DidYouMean
+  class ClassNameChecker
+    attr_reader :class_name
+
+    def initialize(exception)
+      @class_name, @receiver, @original_message = exception.name, exception.receiver, exception.original_message
+    end
+
+    def corrections
+      @corrections ||= SpellChecker.new(dictionary: class_names)
+                         .correct(class_name)
+                         .map(&:full_name)
+                         .reject {|qualified_name| @original_message.include?(qualified_name) }
+    end
+
+    def class_names
+      scopes.flat_map do |scope|
+        scope.constants.map do |c|
+          ClassName.new(c, scope == Object ? "" : "#{scope}::")
+        end
+      end
+    end
+
+    def scopes
+      @scopes ||= @receiver.to_s.split("::").inject([Object]) do |_scopes, scope|
+        _scopes << _scopes.last.const_get(scope)
+      end.uniq
+    end
+
+    class ClassName < SimpleDelegator
+      attr :namespace
+
+      def initialize(name, namespace = '')
+        super(name)
+        @namespace = namespace
+      end
+
+      def full_name
+        self.class.new("#{namespace}#{__getobj__}")
+      end
+    end
+
+    private_constant :ClassName
+  end
+end
diff --git a/lib/did_you_mean/spell_checkers/name_error_checkers/variable_name_checker.rb b/lib/did_you_mean/spell_checkers/name_error_checkers/variable_name_checker.rb
new file mode 100644
index 0000000000..3e51b4fa3a
--- /dev/null
+++ b/lib/did_you_mean/spell_checkers/name_error_checkers/variable_name_checker.rb
@@ -0,0 +1,82 @@
+# frozen-string-literal: true
+
+require_relative "../../spell_checker"
+
+module DidYouMean
+  class VariableNameChecker
+    attr_reader :name, :method_names, :lvar_names, :ivar_names, :cvar_names
+
+    NAMES_TO_EXCLUDE = { 'foo' => [:fork, :for] }
+    NAMES_TO_EXCLUDE.default = []
+
+    # +VariableNameChecker::RB_RESERVED_WORDS+ is the list of all reserved
+    # words in Ruby. They could be declared like methods are, and a typo would
+    # cause Ruby to raise a +NameError+ because of the way they are declared.
+    #
+    # The +:VariableNameChecker+ will use this list to suggest a reversed word
+    # if a +NameError+ is raised and found closest matches, excluding:
+    #
+    #   * +do+
+    #   * +if+
+    #   * +in+
+    #   * +or+
+    #
+    # Also see +MethodNameChecker::RB_RESERVED_WORDS+.
+    RB_RESERVED_WORDS = %i(
+      BEGIN
+      END
+      alias
+      and
+      begin
+      break
+      case
+      class
+      def
+      defined?
+      else
+      elsif
+      end
+      ensure
+      false
+      for
+      module
+      next
+      nil
+      not
+      redo
+      rescue
+      retry
+      return
+      self
+      super
+      then
+      true
+      undef
+      unless
+      until
+      when
+      while
+      yield
+      __LINE__
+      __FILE__
+      __ENCODING__
+    )
+
+    def initialize(exception)
+      @name       = exception.name.to_s.tr("@", "")
+      @lvar_names = exception.respond_to?(:local_variables) ? exception.local_variables : []
+      receiver    = exception.receiver
+
+      @method_names = receiver.methods + receiver.private_methods
+      @ivar_names   = receiver.instance_variables
+      @cvar_names   = receiver.class.class_variables
+      @cvar_names  += receiver.class_variables if receiver.kind_of?(Module)
+    end
+
+    def corrections
+      @corrections ||= SpellChecker
+                     .new(dictionary: (RB_RESERVED_WORDS + lvar_names + method_names + ivar_names + cvar_names))
+                     .correct(name) - NAMES_TO_EXCLUDE[@name]
+    end
+  end
+end
diff --git a/lib/did_you_mean/spell_checkers/null_checker.rb b/lib/did_you_mean/spell_checkers/null_checker.rb
new file mode 100644
index 0000000000..1306f69d4a
--- /dev/null
+++ b/lib/did_you_mean/spell_checkers/null_checker.rb
@@ -0,0 +1,6 @@
+module DidYouMean
+  class NullChecker
+    def initialize(*);  end
+    def corrections; [] end
+  end
+end