Class: String

Inherits:
Object show all
Defined in:
activesupport/lib/active_support/core_ext/string/inflections.rb,
activesupport/lib/active_support/json/encoding.rb,
activesupport/lib/active_support/core_ext/object/blank.rb,
activesupport/lib/active_support/core_ext/string/strip.rb,
activesupport/lib/active_support/core_ext/string/access.rb,
activesupport/lib/active_support/core_ext/string/filters.rb,
activesupport/lib/active_support/core_ext/string/exclude.rb,
activesupport/lib/active_support/core_ext/string/inquiry.rb,
activesupport/lib/active_support/core_ext/string/encoding.rb,
activesupport/lib/active_support/core_ext/string/behavior.rb,
activesupport/lib/active_support/core_ext/string/multibyte.rb,
activesupport/lib/active_support/core_ext/string/conversions.rb,
activesupport/lib/active_support/core_ext/string/output_safety.rb,
activesupport/lib/active_support/core_ext/string/starts_ends_with.rb

Overview

String inflections define new methods on the String class to transform names for different purposes. For instance, you can figure out the name of a table from the name of a class.

"ScaleScore".tableize # => "scale_scores"

Constant Summary collapse

NON_WHITESPACE_REGEXP =

0x3000: fullwidth whitespace

%r![^\s#{[0x3000].pack("U")}]!

Instance Method Summary collapse

Instance Method Details

#acts_like_string? ⇒ Boolean

Enable more predictable duck-typing on String-like classes. See Object#acts_like?.

Returns:

  • (Boolean) 


3
4
5
 
# File 'activesupport/lib/active_support/core_ext/string/behavior.rb', line 3

def acts_like_string?
  true
end

#as_json(options = nil) ⇒ Object

:nodoc:



176
 
# File 'activesupport/lib/active_support/json/encoding.rb', line 176

def as_json(options = nil) self end

#at(position) ⇒ Object

Returns the character at the position treating the string as an array (where 0 is the first character).

Examples:

"hello".at(0)  # => "h"
"hello".at(4)  # => "o"
"hello".at(10) # => ERROR if < 1.9, nil in 1.9



11
12
13
 
# File 'activesupport/lib/active_support/core_ext/string/access.rb', line 11

def at(position)
  mb_chars[position, 1].to_s
end

#blank? ⇒ Boolean

A string is blank if it’s empty or contains whitespaces only:

"".blank?                 # => true
"   ".blank?              # => true
"　".blank?               # => true
" something here ".blank? # => false

Returns:

  • (Boolean) 


102
103
104
105
106
107
108
109
 
# File 'activesupport/lib/active_support/core_ext/object/blank.rb', line 102

def blank?
  # 1.8 does not takes [:space:] properly
  if encoding_aware?
    self !~ /[^[:space:]]/
  else
    self !~ NON_WHITESPACE_REGEXP
  end
end

#camelize(first_letter = :upper) ⇒ Object Also known as: camelcase

By default, camelize converts strings to UpperCamelCase. If the argument to camelize is set to :lower then camelize produces lowerCamelCase.

camelize will also convert ‘/’ to ‘::’ which is useful for converting paths to namespaces.

"active_record".camelize                # => "ActiveRecord"
"active_record".camelize(:lower)        # => "activeRecord"
"active_record/errors".camelize         # => "ActiveRecord::Errors"
"active_record/errors".camelize(:lower) # => "activeRecord::Errors"



78
79
80
81
82
83
 
# File 'activesupport/lib/active_support/core_ext/string/inflections.rb', line 78

def camelize(first_letter = :upper)
  case first_letter
    when :upper then ActiveSupport::Inflector.camelize(self, true)
    when :lower then ActiveSupport::Inflector.camelize(self, false)
  end
end

#classify ⇒ Object

Create a class name from a plural table name like Rails does for table names to models. Note that this returns a string and not a class. (To convert to an actual class follow classify with constantize.)

"egg_and_hams".classify # => "EggAndHam"
"posts".classify        # => "Post"

Singular names are not handled correctly.

"business".classify # => "Busines"



178
179
180
 
# File 'activesupport/lib/active_support/core_ext/string/inflections.rb', line 178

def classify
  ActiveSupport::Inflector.classify(self)
end

#constantize ⇒ Object

constantize tries to find a declared constant with the name specified in the string. It raises a NameError when the name is not in CamelCase or is not initialized. See ActiveSupport::Inflector.constantize

Examples

"Module".constantize  # => Module
"Class".constantize   # => Class
"blargle".constantize # => NameError: wrong constant name blargle



53
54
55
 
# File 'activesupport/lib/active_support/core_ext/string/inflections.rb', line 53

def constantize
  ActiveSupport::Inflector.constantize(self)
end

#dasherize ⇒ Object

Replaces underscores with dashes in the string.

"puni_puni" # => "puni-puni"



112
113
114
 
# File 'activesupport/lib/active_support/core_ext/string/inflections.rb', line 112

def dasherize
  ActiveSupport::Inflector.dasherize(self)
end

#deconstantize ⇒ Object

Removes the rightmost segment from the constant expression in the string.

"Net::HTTP".deconstantize   # => "Net"
"::Net::HTTP".deconstantize # => "::Net"
"String".deconstantize      # => ""
"::String".deconstantize    # => ""
"".deconstantize            # => ""

See also demodulize.



135
136
137
 
# File 'activesupport/lib/active_support/core_ext/string/inflections.rb', line 135

def deconstantize
  ActiveSupport::Inflector.deconstantize(self)
end

#demodulize ⇒ Object

Removes the module part from the constant expression in the string.

"ActiveRecord::CoreExtensions::String::Inflections".demodulize # => "Inflections"
"Inflections".demodulize                                       # => "Inflections"

See also deconstantize.



122
123
124
 
# File 'activesupport/lib/active_support/core_ext/string/inflections.rb', line 122

def demodulize
  ActiveSupport::Inflector.demodulize(self)
end

#encode_json(encoder) ⇒ Object

:nodoc:



177
 
# File 'activesupport/lib/active_support/json/encoding.rb', line 177

def encode_json(encoder) encoder.escape(self) end

#encoding_aware? ⇒ Boolean

Returns:

  • (Boolean) 


3
4
5
 
# File 'activesupport/lib/active_support/core_ext/string/encoding.rb', line 3

def encoding_aware?
  true
end

#exclude?(string) ⇒ Boolean

The inverse of String#include?. Returns true if the string does not include the other string.

"hello".exclude? "lo" #=> false
"hello".exclude? "ol" #=> true
"hello".exclude? ?h   #=> false

Returns:

  • (Boolean) 


8
9
10
 
# File 'activesupport/lib/active_support/core_ext/string/exclude.rb', line 8

def exclude?(string)
  !include?(string)
end

#first(limit = 1) ⇒ Object

Returns the first character of the string or the first limit characters.

Examples:

"hello".first     # => "h"
"hello".first(2)  # => "he"
"hello".first(10) # => "hello"



41
42
43
44
45
46
47
48
49
 
# File 'activesupport/lib/active_support/core_ext/string/access.rb', line 41

def first(limit = 1)
  if limit == 0
    ''
  elsif limit >= size
    self
  else
    mb_chars[0...limit].to_s
  end
end

#foreign_key(separate_class_name_and_id_with_underscore = true) ⇒ Object

Creates a foreign key name from a class name. separate_class_name_and_id_with_underscore sets whether the method should put ‘_’ between the name and ‘id’.

Examples

"Message".foreign_key        # => "message_id"
"Message".foreign_key(false) # => "messageid"
"Admin::Post".foreign_key    # => "post_id"



199
200
201
 
# File 'activesupport/lib/active_support/core_ext/string/inflections.rb', line 199

def foreign_key(separate_class_name_and_id_with_underscore = true)
  ActiveSupport::Inflector.foreign_key(self, separate_class_name_and_id_with_underscore)
end

#from(position) ⇒ Object

Returns the remaining of the string from the position treating the string as an array (where 0 is the first character).

Examples:

"hello".from(0)  # => "hello"
"hello".from(2)  # => "llo"
"hello".from(10) # => "" if < 1.9, nil in 1.9



21
22
23
 
# File 'activesupport/lib/active_support/core_ext/string/access.rb', line 21

def from(position)
  mb_chars[position..-1].to_s
end

#html_safe ⇒ Object 



183
184
185
 
# File 'activesupport/lib/active_support/core_ext/string/output_safety.rb', line 183

def html_safe
  ActiveSupport::SafeBuffer.new(self)
end

#humanize ⇒ Object

Capitalizes the first word, turns underscores into spaces, and strips ‘_id’. Like titleize, this is meant for creating pretty output.

"employee_salary" # => "Employee salary"
"author_id"       # => "Author"



187
188
189
 
# File 'activesupport/lib/active_support/core_ext/string/inflections.rb', line 187

def humanize
  ActiveSupport::Inflector.humanize(self)
end

#inquiry ⇒ Object

Wraps the current string in the ActiveSupport::StringInquirer class, which gives you a prettier way to test for equality. Example:

env = "production".inquiry
env.production?  # => true
env.development? # => false



10
11
12
 
# File 'activesupport/lib/active_support/core_ext/string/inquiry.rb', line 10

def inquiry
  ActiveSupport::StringInquirer.new(self)
end

#is_utf8? ⇒ Boolean

Returns true if the string has UTF-8 semantics (a String used for purely byte resources is unlikely to have them), returns false otherwise.

Returns:

  • (Boolean) 


68
69
70
71
72
73
74
75
76
77
 
# File 'activesupport/lib/active_support/core_ext/string/multibyte.rb', line 68

def is_utf8?
  case encoding
  when Encoding::UTF_8
    valid_encoding?
  when Encoding::ASCII_8BIT, Encoding::US_ASCII
    dup.force_encoding(Encoding::UTF_8).valid_encoding?
  else
    false
  end
end

#last(limit = 1) ⇒ Object

Returns the last character of the string or the last limit characters.

Examples:

"hello".last     # => "o"
"hello".last(2)  # => "lo"
"hello".last(10) # => "hello"



57
58
59
60
61
62
63
64
65
 
# File 'activesupport/lib/active_support/core_ext/string/access.rb', line 57

def last(limit = 1)
  if limit == 0
    ''
  elsif limit >= size
    self
  else
    mb_chars[(-limit)..-1].to_s
  end
end

#mb_chars ⇒ Object

Multibyte proxy

mb_chars is a multibyte safe proxy for string methods.

In Ruby 1.8 and older it creates and returns an instance of the ActiveSupport::Multibyte::Chars class which encapsulates the original string. A Unicode safe version of all the String methods are defined on this proxy class. If the proxy class doesn’t respond to a certain method, it’s forwarded to the encapsulated string.

name = 'Claus Müller'
name.reverse # => "rell??M sualC"
name.length  # => 13

name.mb_chars.reverse.to_s # => "rellüM sualC"
name.mb_chars.length       # => 12

In Ruby 1.9 and newer mb_chars returns self because String is (mostly) encoding aware. This means that it becomes easy to run one version of your code on multiple Ruby versions.

Method chaining

All the methods on the Chars proxy which normally return a string will return a Chars object. This allows method chaining on the result of any of these methods.

name.mb_chars.reverse.length # => 12

Interoperability and configuration

The Chars object tries to be as interchangeable with String objects as possible: sorting and comparing between String and Char work like expected. The bang! methods change the internal string representation in the Chars object. Interoperability problems can be resolved easily with a to_s call.

For more information about the methods defined on the Chars proxy see ActiveSupport::Multibyte::Chars. For information about how to change the default Multibyte behavior see ActiveSupport::Multibyte.



39
40
41
42
43
44
45
 
# File 'activesupport/lib/active_support/core_ext/string/multibyte.rb', line 39

def mb_chars
  if ActiveSupport::Multibyte.proxy_class.consumes?(self)
    ActiveSupport::Multibyte.proxy_class.new(self)
  else
    self
  end
end

#ord ⇒ Object

Returns the codepoint of the first character of the string, assuming a single-byte character encoding:

"a".ord # => 97
"à".ord # => 224, in ISO-8859-1

This method is defined in Ruby 1.8 for Ruby 1.9 forward compatibility on these character encodings.

ActiveSupport::Multibyte::Chars#ord is forward compatible with Ruby 1.9 on UTF8 strings:

"a".mb_chars.ord # => 97
"à".mb_chars.ord # => 224, in UTF8

Note that the 224 is different in both examples. In ISO-8859-1 “à” is represented as a single byte, 224. In UTF8 it is represented with two bytes, namely 195 and 160, but its Unicode codepoint is 224. If we call ord on the UTF8 string “à” the return value will be 195. That is not an error, because UTF8 is unsupported, the call itself would be bogus.



28
29
30
 
# File 'activesupport/lib/active_support/core_ext/string/conversions.rb', line 28

def ord
  self[0]
end

#parameterize(sep = '-') ⇒ Object

Replaces special characters in a string so that it may be used as part of a ‘pretty’ URL.

Examples

class Person
  def to_param
    "#{id}-#{name.parameterize}"
  end
end

@person = Person.find(1)
# => #<Person id: 1, name: "Donald E. Knuth">

<%= link_to(@person.name, person_path %>
# => <a href="/person/1-donald-e-knuth">Donald E. Knuth</a>



154
155
156
 
# File 'activesupport/lib/active_support/core_ext/string/inflections.rb', line 154

def parameterize(sep = '-')
  ActiveSupport::Inflector.parameterize(self, sep)
end

#pluralize(count = nil) ⇒ Object

Returns the plural form of the word in the string.

If the optional parameter count is specified, the singular form will be returned if count == 1. For any other value of count the plural will be returned.

Examples

"post".pluralize             # => "posts"
"octopus".pluralize          # => "octopi"
"sheep".pluralize            # => "sheep"
"words".pluralize            # => "words"
"the blue mailman".pluralize # => "the blue mailmen"
"CamelOctopus".pluralize     # => "CamelOctopi"
"apple".pluralize(1)         # => "apple"
"apple".pluralize(2)         # => "apples"



25
26
27
28
29
30
31
 
# File 'activesupport/lib/active_support/core_ext/string/inflections.rb', line 25

def pluralize(count = nil)
  if count == 1
    self
  else
    ActiveSupport::Inflector.pluralize(self)
  end
end

#safe_constantize ⇒ Object

safe_constantize tries to find a declared constant with the name specified in the string. It returns nil when the name is not in CamelCase or is not initialized. See ActiveSupport::Inflector.safe_constantize

Examples

"Module".safe_constantize  # => Module
"Class".safe_constantize   # => Class
"blargle".safe_constantize # => nil



65
66
67
 
# File 'activesupport/lib/active_support/core_ext/string/inflections.rb', line 65

def safe_constantize
  ActiveSupport::Inflector.safe_constantize(self)
end

#singularize ⇒ Object

The reverse of pluralize, returns the singular form of a word in a string.

"posts".singularize            # => "post"
"octopi".singularize           # => "octopus"
"sheep".singularize            # => "sheep"
"word".singularize             # => "word"
"the blue mailmen".singularize # => "the blue mailman"
"CamelOctopi".singularize      # => "CamelOctopus"



41
42
43
 
# File 'activesupport/lib/active_support/core_ext/string/inflections.rb', line 41

def singularize
  ActiveSupport::Inflector.singularize(self)
end

#squish ⇒ Object

Returns the string, first removing all whitespace on both ends of the string, and then changing remaining consecutive whitespace groups into one space each.

Examples:

%{ Multi-line
   string }.squish                   # => "Multi-line string"
" foo   bar    \n   \t   boo".squish # => "foo bar boo"



12
13
14
 
# File 'activesupport/lib/active_support/core_ext/string/filters.rb', line 12

def squish
  dup.squish!
end

#squish! ⇒ Object

Performs a destructive squish. See String#squish.



17
18
19
20
21
 
# File 'activesupport/lib/active_support/core_ext/string/filters.rb', line 17

def squish!
  strip!
  gsub!(/\s+/, ' ')
  self
end

#strip_heredoc ⇒ Object

Strips indentation in heredocs.

For example in

if options[:usage]
  puts <<-USAGE.strip_heredoc
    This command does such and such.

    Supported options are:
      -h         This message
      ...
  USAGE
end

the user would see the usage message aligned against the left margin.

Technically, it looks for the least indented line in the whole string, and removes that amount of leading whitespace.



22
23
24
25
 
# File 'activesupport/lib/active_support/core_ext/string/strip.rb', line 22

def strip_heredoc
  indent = scan(/^[ \t]*(?=\S)/).min.try(:size) || 0
  gsub(/^[ \t]{#{indent}}/, '')
end

#tableize ⇒ Object

Creates the name of a table like Rails does for models to table names. This method uses the pluralize method on the last word in the string.

"RawScaledScorer".tableize # => "raw_scaled_scorers"
"egg_and_ham".tableize     # => "egg_and_hams"
"fancyCategory".tableize   # => "fancy_categories"



164
165
166
 
# File 'activesupport/lib/active_support/core_ext/string/inflections.rb', line 164

def tableize
  ActiveSupport::Inflector.tableize(self)
end

#titleize ⇒ Object Also known as: titlecase

Capitalizes all the words and replaces some characters in the string to create a nicer looking title. titleize is meant for creating pretty output. It is not used in the Rails internals.

titleize is also aliased as titlecase.

"man from the boondocks".titleize # => "Man From The Boondocks"
"x-men: the last stand".titleize  # => "X Men: The Last Stand"



94
95
96
 
# File 'activesupport/lib/active_support/core_ext/string/inflections.rb', line 94

def titleize
  ActiveSupport::Inflector.titleize(self)
end

#to(position) ⇒ Object

Returns the beginning of the string up to the position treating the string as an array (where 0 is the first character).

Examples:

"hello".to(0)  # => "h"
"hello".to(2)  # => "hel"
"hello".to(10) # => "hello"



31
32
33
 
# File 'activesupport/lib/active_support/core_ext/string/access.rb', line 31

def to(position)
  mb_chars[0..position].to_s
end

#to_date ⇒ Object

Converts a string to a Date value.

"1-1-2012".to_date   #=> Sun, 01 Jan 2012
"01/01/2012".to_date #=> Sun, 01 Jan 2012
"2012-12-13".to_date #=> Thu, 13 Dec 2012
"12/13/2012".to_date #=> ArgumentError: invalid date



49
50
51
52
 
# File 'activesupport/lib/active_support/core_ext/string/conversions.rb', line 49

def to_date
  return nil if self.blank?
  ::Date.new(*::Date._parse(self, false).values_at(:year, :mon, :mday))
end

#to_datetime ⇒ Object

Converts a string to a DateTime value.

"1-1-2012".to_datetime            #=> Sun, 01 Jan 2012 00:00:00 +0000
"01/01/2012 23:59:59".to_datetime #=> Sun, 01 Jan 2012 23:59:59 +0000
"2012-12-13 12:50".to_datetime    #=> Thu, 13 Dec 2012 12:50:00 +0000
"12/13/2012".to_datetime          #=> ArgumentError: invalid date



60
61
62
63
64
65
 
# File 'activesupport/lib/active_support/core_ext/string/conversions.rb', line 60

def to_datetime
  return nil if self.blank?
  d = ::Date._parse(self, false).values_at(:year, :mon, :mday, :hour, :min, :sec, :zone, :sec_fraction).map { |arg| arg || 0 }
  d[5] += d.pop
  ::DateTime.civil(*d)
end

#to_time(form = :utc) ⇒ Object

Form can be either :utc (default) or :local.



36
37
38
39
40
41
 
# File 'activesupport/lib/active_support/core_ext/string/conversions.rb', line 36

def to_time(form = :utc)
  return nil if self.blank?
  d = ::Date._parse(self, false).values_at(:year, :mon, :mday, :hour, :min, :sec, :sec_fraction, :offset).map { |arg| arg || 0 }
  d[6] *= 1000000
  ::Time.send("#{form}_time", *d[0..6]) - d[7]
end

#truncate(length, options = {}) ⇒ Object

Truncates a given text after a given length if text is longer than length:

"Once upon a time in a world far far away".truncate(27)
# => "Once upon a time in a wo..."

Pass a :separator to truncate text at a natural break:

"Once upon a time in a world far far away".truncate(27, :separator => ' ')
# => "Once upon a time in a..."

The last characters will be replaced with the :omission string (defaults to “…”) for a total length not exceeding :length:

"And they found that many people were sleeping better.".truncate(25, :omission => "... (continued)")
# => "And they f... (continued)"



38
39
40
41
42
43
44
45
46
47
48
 
# File 'activesupport/lib/active_support/core_ext/string/filters.rb', line 38

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

#underscore ⇒ Object

The reverse of camelize. Makes an underscored, lowercase form from the expression in the string.

underscore will also change ‘::’ to ‘/’ to convert namespaces to paths.

"ActiveModel".underscore         # => "active_model"
"ActiveModel::Errors".underscore # => "active_model/errors"



105
106
107
 
# File 'activesupport/lib/active_support/core_ext/string/inflections.rb', line 105

def underscore
  ActiveSupport::Inflector.underscore(self)
end