+ Add String#ascii_only & #ascii_only!

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## master (unreleased)
 
+* Added `String#ascii_only`
+* Added `String#ascii_only!`
+
 ## 0.0.8 (13/09/2013)
 
 ### New features

lib/powerpack/string.rb

@@ -1,3 +1,4 @@
+require_relative 'string/ascii_only'
 require_relative 'string/blank'
 require_relative 'string/format'
 require_relative 'string/strip_indent'

lib/powerpack/string/ascii_only.rb

@@ -0,0 +1,42 @@
+# encoding: utf-8
+
+class String
+  # Return a copy of string with ASCII characters only
+  # Source: http://stackoverflow.com/questions/1268289/how-to-get-rid-of-non-ascii-characters-in-ruby
+  #
+  # @return [String] a copy of string with ASCII characters only
+  #
+  # @example
+  #   'abc'.ascii_only #=> 'abc'
+  #
+  # @example
+  #   '中文123'.ascii_only #=> '123'
+  unless String.method_defined? :ascii_only
+    def ascii_only
+      dup.ascii_only!
+    end
+  end
+
+  # Modify self and keep ASCII characters only
+  # Returns the string even if no changes were made.
+  # Source: http://stackoverflow.com/questions/1268289/how-to-get-rid-of-non-ascii-characters-in-ruby
+  #
+  # @return [String] The result string
+  #
+  # @example
+  #   'abc'.ascii_only! #=> 'abc'
+  #
+  # @example
+  #   '中文123'.ascii_only! #=> '123'
+  unless String.method_defined? :ascii_only!
+    def ascii_only!
+      encoding_options = {
+        :invalid                     => :replace,  # Replace invalid byte sequences
+        :undef                       => :replace,  # Replace anything not defined in ASCII
+        :replace                     => '',        # Use a blank for those replacements
+        :UNIVERSAL_NEWLINE_DECORATOR => true       # Always break lines with \n
+      }
+      self.encode! Encoding.find('ASCII'), encoding_options
+    end
+  end
+end

spec/powerpack/string/ascii_only_spec.rb

@@ -0,0 +1,43 @@
+# encoding: utf-8
+
+require 'spec_helper'
+
+describe 'String#ascii_only' do
+  it 'returns same value for string with ASCII chars only' do
+    expect('abc'.ascii_only).to eq 'abc'
+  end
+
+  it 'returns string without non-ASCII chars' do
+    expect("abc\u{6666}".force_encoding("UTF-8").ascii_only).to eq 'abc'
+  end
+
+  it 'returns string without non-ASCII chars and with ASCII chars' do
+    expect("\u{6666}".force_encoding("UTF-8").ascii_only).to eq ''
+  end
+
+  it 'does not change the original string' do
+    string = "abc\u{6666}".force_encoding("UTF-8")
+    string.ascii_only
+    expect(string).to eq "abc\u{6666}".force_encoding("UTF-8")
+  end
+end
+
+describe 'String#ascii_only!' do
+  it 'returns same value for string with ASCII chars only' do
+    expect('abc'.ascii_only!).to eq 'abc'
+  end
+
+  it 'returns string without non-ASCII chars' do
+    expect("abc\u{6666}".force_encoding("UTF-8").ascii_only!).to eq 'abc'
+  end
+
+  it 'returns string without non-ASCII chars and with ASCII chars' do
+    expect("\u{6666}".force_encoding("UTF-8").ascii_only!).to eq ''
+  end
+
+  it 'changes the original string' do
+    string = "abc\u{6666}".force_encoding("UTF-8")
+    string.ascii_only!
+    expect(string).to eq 'abc'
+  end
+end