Class: Encoding

Inherits:
Object show all
Defined in:
encoding.c

Overview

An Encoding instance represents a character encoding usable in Ruby. It is defined as a constant under the Encoding namespace. It has a name and, optionally, aliases:

Encoding::US_ASCII.name  # => "US-ASCII"
Encoding::US_ASCII.names # => ["US-ASCII", "ASCII", "ANSI_X3.4-1968", "646"]

A Ruby method that accepts an encoding as an argument will accept:

  • An Encoding object.

  • The name of an encoding.

  • An alias for an encoding name.

These are equivalent:

'foo'.encode(Encoding::US_ASCII) # Encoding object.
'foo'.encode('US-ASCII')         # Encoding name.
'foo'.encode('ASCII')            # Encoding alias.

For a full discussion of encodings and their uses, see the Encodings document.

Encoding::ASCII_8BIT is a special-purpose encoding that is usually used for a string of bytes, not a string of characters. But as the name indicates, its characters in the ASCII range are considered as ASCII characters. This is useful when you use other ASCII-compatible encodings.

Defined Under Namespace

Classes: CompatibilityError, Converter, ConverterNotFoundError, InvalidByteSequenceError, UndefinedConversionError

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

._load(str) ⇒ Object

:nodoc:



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# File 'encoding.c', line 1432

static VALUE
enc_load(VALUE klass, VALUE str)
{
    return str;
}

.aliases ⇒ Object

Returns the hash of available encoding alias and original encoding name.

Encoding.aliases
#=> {"BINARY"=>"ASCII-8BIT", "ASCII"=>"US-ASCII", "ANSI_X3.4-1968"=>"US-ASCII",
      "SJIS"=>"Windows-31J", "eucJP"=>"EUC-JP", "CP932"=>"Windows-31J"}



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# File 'encoding.c', line 1853

static VALUE
rb_enc_aliases(VALUE klass)
{
    VALUE aliases[2];
    aliases[0] = rb_hash_new();
    aliases[1] = rb_ary_new();

    st_foreach(global_enc_table.names, rb_enc_aliases_enc_i, (st_data_t)aliases);

    return aliases[0];
}

.compatible?(obj1, obj2) ⇒ nil

Checks the compatibility of two objects.

If the objects are both strings they are compatible when they are concatenatable. The encoding of the concatenated string will be returned if they are compatible, nil if they are not.

Encoding.compatible?("\xa1".force_encoding("iso-8859-1"), "b")
#=> #<Encoding:ISO-8859-1>

Encoding.compatible?(
  "\xa1".force_encoding("iso-8859-1"),
  "\xa1\xa1".force_encoding("euc-jp"))
#=> nil

If the objects are non-strings their encodings are compatible when they have an encoding and:

  • Either encoding is US-ASCII compatible

  • One of the encodings is a 7-bit encoding

Returns:

  • (nil) 


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# File 'encoding.c', line 1402

static VALUE
enc_compatible_p(VALUE klass, VALUE str1, VALUE str2)
{
    rb_encoding *enc;

    if (!enc_capable(str1)) return Qnil;
    if (!enc_capable(str2)) return Qnil;
    enc = rb_enc_compatible(str1, str2);
    if (!enc) return Qnil;
    return rb_enc_from_encoding(enc);
}

.default_external ⇒ Object

Returns default external encoding.

The default external encoding is used by default for strings created from the following locations:

  • CSV

  • File data read from disk

  • SDBM

  • StringIO

  • Zlib::GzipReader

  • Zlib::GzipWriter

  • String#inspect

  • Regexp#inspect

While strings created from these locations will have this encoding, the encoding may not be valid. Be sure to check String#valid_encoding?.

File data written to disk will be transcoded to the default external encoding when written, if default_internal is not nil.

The default external encoding is initialized by the -E option. If -E isn’t set, it is initialized to UTF-8 on Windows and the locale on other operating systems.



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# File 'encoding.c', line 1619

static VALUE
get_default_external(VALUE klass)
{
    return rb_enc_default_external();
}

.default_external=(enc) ⇒ Object

Sets default external encoding. You should not set Encoding::default_external in ruby code as strings created before changing the value may have a different encoding from strings created after the value was changed., instead you should use ruby -E to invoke ruby with the correct default_external.

See Encoding::default_external for information on how the default external encoding is used.



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# File 'encoding.c', line 1648

static VALUE
set_default_external(VALUE klass, VALUE encoding)
{
    rb_warning("setting Encoding.default_external");
    rb_enc_set_default_external(encoding);
    return encoding;
}

.default_internal ⇒ Object

Returns default internal encoding. Strings will be transcoded to the default internal encoding in the following places if the default internal encoding is not nil:

  • CSV

  • Etc.sysconfdir and Etc.systmpdir

  • File data read from disk

  • File names from Dir

  • Integer#chr

  • String#inspect and Regexp#inspect

  • Strings returned from Readline

  • Strings returned from SDBM

  • Time#zone

  • Values from ENV

  • Values in ARGV including $PROGRAM_NAME

Additionally String#encode and String#encode! use the default internal encoding if no encoding is given.

The script encoding (__ENCODING__), not default_internal, is used as the encoding of created strings.

Encoding::default_internal is initialized with -E option or nil otherwise.



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# File 'encoding.c', line 1702

static VALUE
get_default_internal(VALUE klass)
{
    return rb_enc_default_internal();
}

.default_internal=(enc) ⇒ Object

Sets default internal encoding or removes default internal encoding when passed nil. You should not set Encoding::default_internal in ruby code as strings created before changing the value may have a different encoding from strings created after the change. Instead you should use ruby -E to invoke ruby with the correct default_internal.

See Encoding::default_internal for information on how the default internal encoding is used.



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# File 'encoding.c', line 1728

static VALUE
set_default_internal(VALUE klass, VALUE encoding)
{
    rb_warning("setting Encoding.default_internal");
    rb_enc_set_default_internal(encoding);
    return encoding;
}

.find(string) ⇒ Object

Search the encoding with specified name. name should be a string.

Encoding.find("US-ASCII")  #=> #<Encoding:US-ASCII>

Names which this method accept are encoding names and aliases including following special aliases

“external”

default external encoding

“internal”

default internal encoding

“locale”

locale encoding

“filesystem”

filesystem encoding

An ArgumentError is raised when no encoding with name. Only Encoding.find("internal") however returns nil when no encoding named “internal”, in other words, when Ruby has no default internal encoding.



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# File 'encoding.c', line 1367

static VALUE
enc_find(VALUE klass, VALUE enc)
{
    int idx;
    if (is_obj_encoding(enc))
        return enc;
    idx = str_to_encindex(enc);
    if (idx == UNSPECIFIED_ENCODING) return Qnil;
    return rb_enc_from_encoding_index(idx);
}

.list ⇒ Array

Returns the list of loaded encodings.

Encoding.list
#=> [#<Encoding:ASCII-8BIT>, #<Encoding:UTF-8>,
      #<Encoding:ISO-2022-JP (dummy)>]

Encoding.find("US-ASCII")
#=> #<Encoding:US-ASCII>

Encoding.list
#=> [#<Encoding:ASCII-8BIT>, #<Encoding:UTF-8>,
      #<Encoding:US-ASCII>, #<Encoding:ISO-2022-JP (dummy)>]

Returns:



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# File 'encoding.c', line 1337

static VALUE
enc_list(VALUE klass)
{
    VALUE ary = rb_ary_new2(0);
    rb_ary_replace(ary, rb_encoding_list);
    return ary;
}

.locale_charmap ⇒ String

Returns the locale charmap name. It returns nil if no appropriate information.

Debian GNU/Linux
  LANG=C
    Encoding.locale_charmap  #=> "ANSI_X3.4-1968"
  LANG=ja_JP.EUC-JP
    Encoding.locale_charmap  #=> "EUC-JP"

SunOS 5
  LANG=C
    Encoding.locale_charmap  #=> "646"
  LANG=ja
    Encoding.locale_charmap  #=> "eucJP"

The result is highly platform dependent. So Encoding.find(Encoding.locale_charmap) may cause an error. If you need some encoding object even for unknown locale, Encoding.find(“locale”) can be used.

Returns:



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# File 'localeinit.c', line 90

VALUE
rb_locale_charmap(VALUE klass)
{
#if NO_LOCALE_CHARMAP
    return rb_usascii_str_new_cstr("US-ASCII");
#else
    return locale_charmap(rb_usascii_str_new_cstr);
#endif
}

.name_list ⇒ Array

Returns the list of available encoding names.

Encoding.name_list
#=> ["US-ASCII", "ASCII-8BIT", "UTF-8",
      "ISO-8859-1", "Shift_JIS", "EUC-JP",
      "Windows-31J",
      "BINARY", "CP932", "eucJP"]

Returns:



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# File 'encoding.c', line 1810

static VALUE
rb_enc_name_list(VALUE klass)
{
    VALUE ary = rb_ary_new2(global_enc_table.names->num_entries);
    st_foreach(global_enc_table.names, rb_enc_name_list_i, (st_data_t)ary);
    return ary;
}

Instance Method Details

#_dump(*args) ⇒ Object

:nodoc:



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# File 'encoding.c', line 1424

static VALUE
enc_dump(int argc, VALUE *argv, VALUE self)
{
    rb_check_arity(argc, 0, 1);
    return enc_name(self);
}

#ascii_compatible? ⇒ Boolean

Returns whether ASCII-compatible or not.

Encoding::UTF_8.ascii_compatible?     #=> true
Encoding::UTF_16BE.ascii_compatible?  #=> false

Returns:

  • (Boolean) 


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# File 'encoding.c', line 628

static VALUE
enc_ascii_compatible_p(VALUE enc)
{
    return RBOOL(rb_enc_asciicompat(must_encoding(enc)));
}

#dummy? ⇒ Boolean

Returns true for dummy encodings. A dummy encoding is an encoding for which character handling is not properly implemented. It is used for stateful encodings.

Encoding::ISO_2022_JP.dummy?       #=> true
Encoding::UTF_8.dummy?             #=> false

Returns:

  • (Boolean) 


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# File 'encoding.c', line 612

static VALUE
enc_dummy_p(VALUE enc)
{
    return RBOOL(ENC_DUMMY_P(must_encoding(enc)));
}

#inspect ⇒ String

Returns a string which represents the encoding for programmers.

Encoding::UTF_8.inspect       #=> "#<Encoding:UTF-8>"
Encoding::ISO_2022_JP.inspect #=> "#<Encoding:ISO-2022-JP (dummy)>"

Returns:



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# File 'encoding.c', line 1255

static VALUE
enc_inspect(VALUE self)
{
    rb_encoding *enc;

    if (!is_data_encoding(self)) {
        not_encoding(self);
    }
    if (!(enc = DATA_PTR(self)) || rb_enc_from_index(rb_enc_to_index(enc)) != enc) {
        rb_raise(rb_eTypeError, "broken Encoding");
    }
    return rb_enc_sprintf(rb_usascii_encoding(),
                          "#<%"PRIsVALUE":%s%s%s>", rb_obj_class(self),
                          rb_enc_name(enc),
                          (ENC_DUMMY_P(enc) ? " (dummy)" : ""),
                          rb_enc_autoload_p(enc) ? " (autoload)" : "");
}

#name ⇒ String #to_s ⇒ String

Returns the name of the encoding.

Encoding::UTF_8.name      #=> "UTF-8"

Overloads:



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# File 'encoding.c', line 1282

static VALUE
enc_name(VALUE self)
{
    return rb_fstring_cstr(rb_enc_name((rb_encoding*)DATA_PTR(self)));
}

#names ⇒ Array

Returns the list of name and aliases of the encoding.

Encoding::WINDOWS_31J.names  #=> ["Windows-31J", "CP932", "csWindows31J", "SJIS", "PCK"]

Returns:



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# File 'encoding.c', line 1308

static VALUE
enc_names(VALUE self)
{
    VALUE args[2];

    args[0] = (VALUE)rb_to_encoding_index(self);
    args[1] = rb_ary_new2(0);
    st_foreach(global_enc_table.names, enc_names_i, (st_data_t)args);
    return args[1];
}

#name ⇒ String #to_s ⇒ String

Returns the name of the encoding.

Encoding::UTF_8.name      #=> "UTF-8"

Overloads:



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# File 'encoding.c', line 1282

static VALUE
enc_name(VALUE self)
{
    return rb_fstring_cstr(rb_enc_name((rb_encoding*)DATA_PTR(self)));
}