Extracted String#truncate from TextHelper#truncate [DHH]

Author: David Heinemeier Hansson

actionpack/lib/action_view/helpers/text_helper.rb

@@ -1,4 +1,5 @@
 require 'active_support/core_ext/object/blank'
+require 'active_support/core_ext/string/filters'
 require 'action_view/helpers/tag_helper'
 
 module ActionView
@@ -42,17 +43,14 @@ def safe_concat(string)
       # ==== Examples
       #
       #   truncate("Once upon a time in a world far far away")
-      #   # => Once upon a time in a world...
+      #   # => Once upon a time in a worl...
       #
       #   truncate("Once upon a time in a world far far away", :separator => ' ')
       #   # => Once upon a time in a world...
       #
       #   truncate("Once upon a time in a world far far away", :length => 14)
       #   # => Once upon a...
       #
-      #   truncate("And they found that many people were sleeping better.", :length => 25, "(clipped)")
-      #   # => And they found t(clipped)
-      #
       #   truncate("And they found that many people were sleeping better.", :omission => "... (continued)", :length => 25)
       #   # => And they f... (continued)
       #
@@ -73,14 +71,10 @@ def truncate(text, *args)
           options[:length] = args[0] || 30
           options[:omission] = args[1] || "..."
         end
-        options.reverse_merge!(:length => 30, :omission => "...")
 
-        if text
-          l = options[:length] - options[:omission].mb_chars.length
-          chars = text.mb_chars
-          stop = options[:separator] ? (chars.rindex(options[:separator].mb_chars, l) || l) : l
-          (chars.length > options[:length] ? chars[0...stop] + options[:omission] : text).to_s
-        end
+        options.reverse_merge!(:length => 30)
+
+        text.truncate(options.delete(:length), options) if text
       end
 
       # Highlights one or more +phrases+ everywhere in +text+ by inserting it into

activesupport/CHANGELOG

@@ -1,5 +1,7 @@
 *Rails 3.0.0 [beta 4/release candidate] (unreleased)*
 
+* Extracted String#truncate from TextHelper#truncate [DHH]
+
 * Ruby 1.9: support UTF-8 case folding.  #4595 [Norman Clarke]
 
 * Renames Array#rand -> Array#random_element. [Santiago Pastorino, Rizwan Reza]

activesupport/lib/active_support/core_ext/string/filters.rb

@@ -1,3 +1,5 @@
+require 'active_support/core_ext/string/multibyte'
+
 class String
   # Returns the string, first removing all whitespace on both ends of
   # the string, and then changing remaining consecutive whitespace
@@ -17,4 +19,35 @@ def squish!
     gsub!(/\s+/, ' ')
     self
   end
+
+  # Truncates a given +text+ after a given <tt>length</tt> if +text+ is longer than <tt>length</tt>.
+  # The last characters will be replaced with the <tt>:omission</tt> (defaults to "...")
+  # for a total length not exceeding <tt>:length</tt>.
+  #
+  # Pass a <tt>:separator</tt> to truncate +text+ at a natural break.
+  #
+  # ==== Examples
+  #
+  #   "Once upon a time in a world far far away".truncate(30)
+  #   # => Once upon a time in a worl...
+  #
+  #   "Once upon a time in a world far far away".truncate(30, :separator => ' ')
+  #   # => Once upon a time in a world...
+  #
+  #   "Once upon a time in a world far far away".truncate(14)
+  #   # => Once upon a...
+  #
+  #   "And they found that many people were sleeping better.".truncate(25, :omission => "... (continued)")
+  #   # => And they f... (continued)
+  def truncate(length, options = {})
+    text = self.dup
+    options[:omission] ||= "..."
+
+    length_with_room_for_omission = length - options[:omission].mb_chars.length
+    chars = text.mb_chars
+    stop = options[:separator] ?
+      (chars.rindex(options[:separator].mb_chars, length_with_room_for_omission) || length_with_room_for_omission) : length_with_room_for_omission
+
+    (chars.length > length ? chars[0...stop] + options[:omission] : text).to_s
+  end
 end

activesupport/test/core_ext/string_ext_test.rb

@@ -210,6 +210,35 @@ def test_string_squish
     # And changes the original string:
     assert_equal original, expected
   end
+  
+  def test_truncate
+    assert_equal "Hello World!", "Hello World!".truncate(12)
+    assert_equal "Hello Wor...", "Hello World!!".truncate(12)
+  end
+
+  def test_truncate_with_omission_and_seperator
+    assert_equal "Hello[...]", "Hello World!".truncate(10, :omission => "[...]")
+    assert_equal "Hello[...]", "Hello Big World!".truncate(13, :omission => "[...]", :separator => ' ')
+    assert_equal "Hello Big[...]", "Hello Big World!".truncate(14, :omission => "[...]", :separator => ' ')
+    assert_equal "Hello Big[...]", "Hello Big World!".truncate(15, :omission => "[...]", :separator => ' ')
+  end
+
+  if RUBY_VERSION < '1.9.0'
+    def test_truncate_multibyte
+      with_kcode 'none' do
+        assert_equal "\354\225\210\353\205\225\355...", "\354\225\210\353\205\225\355\225\230\354\204\270\354\232\224".truncate(10)
+      end
+      with_kcode 'u' do
+        assert_equal "\354\225\204\353\246\254\353\236\221 \354\225\204\353\246\254 ...",
+          "\354\225\204\353\246\254\353\236\221 \354\225\204\353\246\254 \354\225\204\353\235\274\353\246\254\354\230\244".truncate(10)
+      end
+    end
+  else
+    def test_truncate_multibyte
+      assert_equal "\354\225\204\353\246\254\353\236\221 \354\225\204\353\246\254 ...".force_encoding('UTF-8'),
+        "\354\225\204\353\246\254\353\236\221 \354\225\204\353\246\254 \354\225\204\353\235\274\353\246\254\354\230\244".force_encoding('UTF-8').truncate(10)
+    end
+  end
 end
 
 class StringBehaviourTest < Test::Unit::TestCase