Fix method completion on string literals

* Remove quote characters from the "word break characters" list. This
  was done in IRB some 5 years ago, in ruby/ruby@f1ce1f1.

* Change completer_word_break_characters instead of
  basic_word_break_characters. The latter is only used during
  Readline's initialization, to maybe set the value of the former.

* Except for JRuby, where completer_word_break_characters= is broken.

* Perform this assignment as soon as we can. By the time the completer
  is created, Readline has already used this value at least once.

* Implement String-specific completion.

Fixes #1528.

5 files changed, 46 insertions, 9 deletions

diff --git a/lib/pry/config.rb b/lib/pry/config.rb
index 4f702863..ba2076c9 100644
--- a/lib/pry/config.rb
+++ b/lib/pry/config.rb
@@ -8,4 +8,19 @@ class Pry::Config < Pry::BasicObject
   def self.shortcuts
     Convenience::SHORTCUTS
   end
+
+  READLINE_WORD_ESCAPE_STR = " \t\n`><=;|&{("
+
+  def input=(input)
+    @lookup['input'] = input
+
+    if input.respond_to?(:completer_word_break_characters=)
+      begin
+        input.completer_word_break_characters = READLINE_WORD_ESCAPE_STR
+      rescue ArgumentError
+        # Hi JRuby
+        input.basic_word_break_characters = READLINE_WORD_ESCAPE_STR
+      end
+    end
+  end
 end
diff --git a/lib/pry/config/behavior.rb b/lib/pry/config/behavior.rb
index f487637d..ee67ac3f 100644
--- a/lib/pry/config/behavior.rb
+++ b/lib/pry/config/behavior.rb
@@ -219,9 +219,11 @@ private
   def __push(key,value)
     unless singleton_class.method_defined? key
       define_singleton_method(key) { self[key] }
+    end
+    unless singleton_class.method_defined? "#{key}="
       define_singleton_method("#{key}=") { |val| @lookup[key] = val }
     end
-    @lookup[key] = value
+    send("#{key}=", value)
   end
 
   def __remove(key)
diff --git a/lib/pry/input_completer.rb b/lib/pry/input_completer.rb
index 859cb667..b33668c1 100644
--- a/lib/pry/input_completer.rb
+++ b/lib/pry/input_completer.rb
@@ -12,7 +12,8 @@ class Pry::InputCompleter
   CONSTANT_OR_METHOD_REGEXP = /^([A-Z].*)::([^:.]*)$/
   HEX_REGEXP                = /^(-?0x[0-9a-fA-F_]+)\.([^.]*)$/
   GLOBALVARIABLE_REGEXP     = /^(\$[^.]*)$/
-  VARIABLE_REGEXP           = /^([^."].*)\.([^.]*)$/
+  VARIABLE_REGEXP           = /^(.*[^.'"])\.([^.]*)$/
+  STRING_REGEXP             = /^(.*["'])\.([^.]*)$/
 
   ReservedWords = [
                    "BEGIN", "END",
@@ -39,12 +40,9 @@ class Pry::InputCompleter
                "[]", "[]=", "^", "!", "!=", "!~"
               ]
 
-  WORD_ESCAPE_STR = " \t\n\"\\'`><=;|&{("
-
   def initialize(input, pry = nil)
     @pry = pry
     @input = input
-    @input.basic_word_break_characters = WORD_ESCAPE_STR if @input.respond_to?(:basic_word_break_characters=)
     @input.completion_append_character = nil if @input.respond_to?(:completion_append_character=)
   end
 
@@ -179,12 +177,13 @@ class Pry::InputCompleter
           }
         end
         select_message(path, receiver, message, candidates.sort)
-      when /^\.([^.]*)$/
-        # Unknown(maybe String)
-        receiver = ""
-        message = Regexp.quote($1)
+      when STRING_REGEXP
+        receiver = $1
+        message = Regexp.quote($2)
         candidates = String.instance_methods(true).collect(&:to_s)
         select_message(path, receiver, message, candidates)
+      # TODO: Handle the target-less calls (e.g. with a space before the dot).
+      # when /^\.([^.]*)$/
       else
         candidates = eval(
                           "methods | private_methods | local_variables | " \
diff --git a/spec/completion_spec.rb b/spec/completion_spec.rb
index 81996c07..40c73e5e 100644
--- a/spec/completion_spec.rb
+++ b/spec/completion_spec.rb
@@ -85,6 +85,13 @@ describe Pry::InputCompleter do
 
     # Absolute Constant
     completer_test(o).call('::IndexError')
+
+    # String
+    completer_test(Object.new).call('"".size')
+    completer_test(Object.new).call('abcd".size')
+
+    # Chain of calls starting with a string
+    completer_test(Object.new).call('abcd".size.times')
   end
 
   it 'should complete for target symbols' do
diff --git a/spec/config_spec.rb b/spec/config_spec.rb
index d6961c80..9d5c3956 100644
--- a/spec/config_spec.rb
+++ b/spec/config_spec.rb
@@ -239,4 +239,18 @@ describe Pry::Config do
       expect(local['output']).to eq(nil)
     end
   end
+
+  describe "#input=" do
+    it 'assigns a value on the key' do
+      local = Pry::Config.from_hash({})
+      local.input = :foo
+      expect(local.input).to eq(:foo)
+    end
+
+    it 'modifies input itself' do
+      input = OpenStruct.new(completer_word_break_characters: 'asdf')
+      local = Pry::Config.from_hash(input: input)
+      expect(input.completer_word_break_characters).to eq(Pry::Config::READLINE_WORD_ESCAPE_STR)
+    end
+  end
 end