Perf: simplify calculation of location

- caller is only used to determine file and line number as metadata is
  initialized. There is no need to store it.
- Also, the previous commit reduces the need for analysis of the caller
  stack. We therefore don't need to sling it around within the rspec
  codebase.
- Running the following 5000 times took 2.77 seconds before these last
  two commits, 1:58 after:

    describe "something" do
      it "does something" do
        1.should eq(1)
      end
    end

Please enter the commit message for your changes. Lines starting

lib/rspec/core/example_group.rb

@@ -42,7 +42,6 @@ def self.define_example_method(name, extra_options={})
         module_eval(<<-END_RUBY, __FILE__, __LINE__)
           def self.#{name}(desc=nil, options={}, &block)
             options.update(:pending => true) unless block
-            options.update(:caller => caller)
             options.update(#{extra_options.inspect})
             examples << RSpec::Core::Example.new(self, desc, options, block)
             examples.last
@@ -111,7 +110,6 @@ def self.describe(*args, &example_group_block)
         @_subclass_count += 1
         args << {} unless args.last.is_a?(Hash)
         args.last.update(:example_group_block => example_group_block)
-        args.last.update(:caller => caller)
 
         # TODO 2010-05-05: Because we don't know if const_set is thread-safe
         child = const_set(

lib/rspec/core/extensions/object.rb

@@ -3,7 +3,6 @@ module Core
     module ObjectExtensions
       def describe(*args, &example_group_block)
         args << {} unless args.last.is_a?(Hash)
-        args.last.update :caller => caller(1)
         RSpec::Core::ExampleGroup.describe(*args, &example_group_block)
       end
     end

lib/rspec/core/metadata.rb

@@ -32,9 +32,7 @@ def process(*args)
         self[:example_group][:full_description] = full_description_from(*args)
 
         self[:example_group][:block] = user_metadata.delete(:example_group_block)
-        self[:example_group][:caller] = user_metadata.delete(:caller) || caller(1)
-        self[:example_group][:file_path] = file_path_from(self[:example_group], user_metadata.delete(:file_path))
-        self[:example_group][:line_number] = line_number_from(self[:example_group], user_metadata.delete(:line_number))
+        self[:example_group][:file_path], self[:example_group][:line_number] = file_and_line_number_from(caller)
         self[:example_group][:location] = location_from(self[:example_group])
 
         update(user_metadata)
@@ -70,11 +68,7 @@ def configure_for_example(description, options)
         store(:description, description.to_s)
         store(:full_description, "#{self[:example_group][:full_description]} #{self[:description]}")
         store(:execution_result, {})
-        store(:caller, options.delete(:caller))
-        if self[:caller]
-          store(:file_path, file_path_from(self))
-          store(:line_number, line_number_from(self))
-        end
+        self[:file_path], self[:line_number] = file_and_line_number_from(caller)
         self[:location] = location_from(self)
         update(options)
       end
@@ -153,31 +147,19 @@ def described_class_from(*args)
         end
       end
 
-      def file_path_from(metadata, given_file_path=nil)
-        return given_file_path if given_file_path
-        file = file_and_line_number(metadata)[0] if file_and_line_number(metadata)
-        file.strip if file
+      def file_and_line_number_from(list)
+        entry = first_caller_from_outside_rspec_from_caller(list)
+        entry =~ /(.+?):(\d+)(|:\d+)/
+        return [$1, $2.to_i]
       end
 
-      def line_number_from(metadata, given_line_number=nil)
-        return given_line_number if given_line_number
-        line_number = file_and_line_number(metadata)[1] if file_and_line_number(metadata)
-        line_number && line_number.to_i
+      def first_caller_from_outside_rspec_from_caller(list)
+        list.detect {|l| l !~ /\/lib\/rspec\/core/}
       end
 
       def location_from(metadata)
         "#{metadata[:file_path]}:#{metadata[:line_number]}"
       end
-
-      def file_and_line_number(metadata)
-        entry = first_caller_from_outside_rspec(metadata)
-        entry && entry.match(/(.+?):(\d+)(|:\d+)/)[1..2]
-      end
-
-      def first_caller_from_outside_rspec(metadata)
-        metadata[:caller].detect {|l| l !~ /\/lib\/rspec\/core/}
-      end
-
     end
   end
 end

spec/rspec/core/example_group_spec.rb

@@ -186,12 +186,6 @@ module RSpec::Core
         ExampleGroup.describe(Object, nil, 'foo' => 'bar') { }.metadata.should include({ "foo" => 'bar' })
       end
 
-      it "adds the caller to metadata" do
-        ExampleGroup.describe(Object) { }.metadata[:example_group][:caller].any? {|f|
-          f =~ /#{__FILE__}/
-        }.should be_true
-      end
-
       it "adds the the file_path to metadata" do
         ExampleGroup.describe(Object) { }.metadata[:example_group][:file_path].should == __FILE__
       end

spec/rspec/core/metadata_spec.rb

@@ -149,22 +149,13 @@ module Core
           ])
           m[:example_group][:file_path].should == __FILE__
         end
-
-        it "finds the first spec file in the caller array with drive letter" do
-          m = Metadata.new
-          m.process(:caller => [ "C:/path/file_spec.rb:#{__LINE__}" ])
-          m[:example_group][:file_path].should == "C:/path/file_spec.rb"
-        end
       end
 
       describe "line number" do
         it "finds the line number with the first non-rspec lib file in the backtrace" do
           m = Metadata.new
-          m.process(:caller => [
-            "./lib/rspec/core/foo.rb",
-            "#{__FILE__}:#{__LINE__}",
-          ])
-          m[:example_group][:line_number].should == __LINE__ - 2
+          m.process({})
+          m[:example_group][:line_number].should == __LINE__ - 1
         end
 
         it "finds the line number with the first spec file with drive letter" do
@@ -181,10 +172,9 @@ module Core
       end
 
       describe "metadata for example" do
-        let(:caller_for_example) { caller(0) }
-        let(:line_number)        { __LINE__ - 1 }
         let(:metadata)           { Metadata.new.process("group description") }
-        let(:mfe)                { metadata.for_example("example description", {:caller => caller_for_example, :arbitrary => :options}) }
+        let(:mfe)                { metadata.for_example("example description", {:arbitrary => :options}) }
+        let(:line_number)        { __LINE__ - 1 }
 
         it "stores the description" do
           mfe[:description].should == "example description"
@@ -198,10 +188,6 @@ module Core
           mfe[:execution_result].should == {}
         end
 
-        it "stores the caller" do
-          mfe[:caller].should == caller_for_example
-        end
-
         it "extracts file path from caller" do
           mfe[:file_path].should == __FILE__
         end