now using 'retry' (in read loop) to switch input objects in input_stack

This is so we can make the switch to the new input object seemless on encountering EOFError in previous input object.
We also detect whether we are going to go into an infinite EOFError state (i.e if Pry.config.input generates EOFError) and so we break out of the REPL with an error message
and a throw(:breakout)

CHANGELOG

@@ -13,6 +13,7 @@
 * local ./.pryrc now loaded after ~/.pryrc if it exists
 * cat --ex N and edit --ex N now can navigate through backtrace, where cat --ex (with no args) moves throuh successive levels of the backtrace automatically with state stored on the exceptino object itself
 * new option Pry.config.exception_window_size determines window size for cat --ex
+* input_stack now implemented - pushing objects onto a pry instance's input_stack causes the instance to read from those objects in turn as it encounters EOF on the previous object. On finishing the input_stack the input object for the pry instance is set back to Pry.config.input, if this fails, pry breaks out of the REPL (throw(:breakout)) with an error message
 
 8/9/2011 version 0.9.5
 

lib/pry/pry_instance.rb

@@ -395,6 +395,7 @@ class Pry
       Pry.history << line.dup if line
       line
     else
+      should_retry = true
       begin
         if input.method(:readline).arity == 1
           input.readline(current_prompt)
@@ -403,8 +404,18 @@ class Pry
         end
 
       rescue EOFError
-        self.input = input_stack.empty? ? Pry.config.input : input_stack.pop
-        ""
+        if input_stack.empty?
+          self.input = Pry.config.input
+          if !should_retry
+            output.puts "Error: Pry ran out of things to read from! Attempting to break out of REPL."
+            throw(:breakout)
+          end
+
+          should_retry = false
+        else
+          self.input = input_stack.pop
+        end
+        retry
       end
     end
   end

test/test_input_stack.rb

@@ -12,7 +12,7 @@ describe "Pry#input_stack" do
     Pry.config.input_stack = []
   end
 
-  it 'should read from all input objects on stack and exit session' do
+  it 'should read from all input objects on stack and exit session (usingn repl)' do
     stack = [b = StringIO.new(":cloister\nexit\n"), c = StringIO.new(":baron\n")]
     instance = Pry.new(:input => StringIO.new(":alex\n"),
                        :output => str_output = StringIO.new,
@@ -24,4 +24,47 @@ describe "Pry#input_stack" do
     str_output.string.should =~ /:cloister/
   end
 
+  it 'input objects should be popped off stack as they are used up' do
+    stack = [StringIO.new(":cloister\n"), StringIO.new(":baron\n")]
+    instance = Pry.new(:input => StringIO.new(":alex\n"),
+                       :output => str_output = StringIO.new,
+                       :input_stack => stack)
+
+    stack.size.should == 2
+
+    instance.rep
+    str_output.string.should =~ /:alex/
+    instance.rep
+    str_output.string.should =~ /:baron/
+    stack.size.should == 1
+    instance.rep
+    str_output.string.should =~ /:cloister/
+    stack.size.should == 0
+  end
+
+  it 'should revert to Pry.config.input when it runs out of input objects in input_stack' do
+    redirect_pry_io(StringIO.new(":rimbaud\nexit\n"), StringIO.new) do
+      stack = [StringIO.new(":cloister\n"), StringIO.new(":baron\n")]
+      instance = Pry.new(:input => StringIO.new(":alex\n"),
+                         :output => str_output = StringIO.new,
+                         :input_stack => stack)
+
+      instance.repl
+      str_output.string.should =~ /:alex/
+      str_output.string.should =~ /:baron/
+      str_output.string.should =~ /:cloister/
+      str_output.string.should =~ /:rimbaud/
+    end
+  end
+
+  it 'should display error and throw(:breakout) if at end of input after using up input_stack objects' do
+    str_output = StringIO.new
+    catch(:breakout) do
+      redirect_pry_io(StringIO.new(":rimbaud\n"), str_output) do
+        Pry.new(:input_stack => [StringIO.new(":a\n"), StringIO.new(":b\n")]).repl
+      end
+    end
+    str_output.string.should =~ /Error: Pry ran out of things to read/
+  end
+
 end

test/test_pry.rb

@@ -86,16 +86,14 @@ describe Pry do
         o.instance_variable_get(:@x).should == 10
       end
 
-      it 'should not output anything for no input' do
-        outp = StringIO.new
-
-        # note i could not use mock_pry() for this test for some
-        # reason, as i'd always get "\n" as output instead of ""
-        redirect_pry_io(StringIO.new(""), outp) do
-          Pry.new.rep(self)
+      it 'should display error and throw(:breakout) if Pry instance runs out of input' do
+        str_output = StringIO.new
+        catch(:breakout) do
+          redirect_pry_io(StringIO.new(":nothing\n"), str_output) do
+            Pry.new.repl
+          end
         end
-
-        outp.string.empty?.should == true
+        str_output.string.should =~ /Error: Pry ran out of things to read/
       end
 
       it 'should make self evaluate to the receiver of the rep session' do