1 files changed, 79 insertions, 0 deletions
diff --git a/railties/lib/rails/code_statistics_calculator.rb b/railties/lib/rails/code_statistics_calculator.rb
new file mode 100644
index 0000000000..60e4aef9b7
--- /dev/null
+++ b/railties/lib/rails/code_statistics_calculator.rb
@@ -0,0 +1,79 @@
+class CodeStatisticsCalculator #:nodoc:
+  attr_reader :lines, :code_lines, :classes, :methods
+
+  PATTERNS = {
+    rb: {
+      line_comment: /^\s*#/,
+      begin_block_comment: /^=begin/,
+      end_block_comment: /^=end/,
+      class: /^\s*class\s+[_A-Z]/,
+      method: /^\s*def\s+[_a-z]/,
+    },
+    js: {
+      line_comment: %r{^\s*//},
+      begin_block_comment: %r{^\s*/\*},
+      end_block_comment: %r{\*/},
+      method: /function(\s+[_a-zA-Z][\da-zA-Z]*)?\s*\(/,
+    },
+    coffee: {
+      line_comment: /^\s*#/,
+      begin_block_comment: /^\s*###/,
+      end_block_comment: /^\s*###/,
+      class: /^\s*class\s+[_A-Z]/,
+      method: /[-=]>/,
+    }
+  }
+
+  def initialize(lines = 0, code_lines = 0, classes = 0, methods = 0)
+    @lines = lines
+    @code_lines = code_lines
+    @classes = classes
+    @methods = methods
+  end
+
+  def add(code_statistics_calculator)
+    @lines += code_statistics_calculator.lines
+    @code_lines += code_statistics_calculator.code_lines
+    @classes += code_statistics_calculator.classes
+    @methods += code_statistics_calculator.methods
+  end
+
+  def add_by_file_path(file_path)
+    File.open(file_path) do |f|
+      self.add_by_io(f, file_type(file_path))
+    end
+  end
+
+  def add_by_io(io, file_type)
+    patterns = PATTERNS[file_type] || {}
+
+    comment_started = false
+
+    while line = io.gets
+      @lines += 1
+
+      if comment_started
+        if patterns[:end_block_comment] && line =~ patterns[:end_block_comment]
+          comment_started = false
+        end
+        next
+      else
+        if patterns[:begin_block_comment] && line =~ patterns[:begin_block_comment]
+          comment_started = true
+          next
+        end
+      end
+
+      @classes   += 1 if patterns[:class] && line =~ patterns[:class]
+      @methods   += 1 if patterns[:method] && line =~ patterns[:method]
+      if line !~ /^\s*$/ && (patterns[:line_comment].nil? || line !~ patterns[:line_comment])
+        @code_lines += 1
+      end
+    end
+  end
+
+  private
+    def file_type(file_path)
+      File.extname(file_path).sub(/\A\./, '').downcase.to_sym
+    end
+end