Class: Symbol

Inherits:
Object show all
Includes:
Comparable
Defined in:
string.c

Overview

Symbol objects represent names and some strings inside the Ruby interpreter. They are generated using the :name and :"string" literals syntax, and by the various to_sym methods. The same Symbol object will be created for a given name or string for the duration of a program???s execution, regardless of the context or meaning of that name. Thus if Fred is a constant in one context, a method in another, and a class in a third, the Symbol :Fred will be the same object in all three contexts.

module One
  class Fred
  end
  $f1 = :Fred
end
module Two
  Fred = 1
  $f2 = :Fred
end
def Fred()
end
$f3 = :Fred
$f1.object_id   #=> 2514190
$f2.object_id   #=> 2514190
$f3.object_id   #=> 2514190

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Comparable

#<, #<=, #>, #>=, #between?

Class Method Details

.all_symbols ⇒ Array

Returns an array of all the symbols currently in Ruby's symbol table.

Symbol.all_symbols.size    #=> 903
Symbol.all_symbols[1,20]   #=> [:floor, :ARGV, :Binding, :symlink,
                                :chown, :EOFError, :$;, :String,
                                :LOCK_SH, :"setuid?", :$<,
                                :default_proc, :compact, :extend,
                                :Tms, :getwd, :$=, :ThreadGroup,
                                :wait2, :$>]

Returns:




# File 'string.c'

/*
 *  call-seq:
 *     Symbol.all_symbols    => array
 *
 *  Returns an array of all the symbols currently in Ruby's symbol
 *  table.
 *
 *     Symbol.all_symbols.size    #=> 903
 *     Symbol.all_symbols[1,20]   #=> [:floor, :ARGV, :Binding, :symlink,
 *                                     :chown, :EOFError, :$;, :String,
 *                                     :LOCK_SH, :"setuid?", :$<,
 *                                     :default_proc, :compact, :extend,
 *                                     :Tms, :getwd, :$=, :ThreadGroup,
 *                                     :wait2, :$>]
 */

VALUE
rb_sym_all_symbols(void)
{
    VALUE ary = rb_ary_new2(global_symbols.sym_id->num_entries);

    st_foreach(global_symbols.sym_id, symbols_i, ary);
    return ary;
}

Instance Method Details

#<=>(other) ⇒ -1, ...

Compares sym with other in string form.

Returns:

  • (-1, 0, +1, nil) 



# File 'string.c'

/*
 * call-seq:
 *
 *   str <=> other       -> -1, 0, +1 or nil
 *
 * Compares _sym_ with _other_ in string form.
 */

static VALUE
sym_cmp(VALUE sym, VALUE other)
{
    if (!SYMBOL_P(other)) {
    return Qnil;
    }
    return rb_str_cmp_m(rb_sym_to_s(sym), rb_sym_to_s(other));
}

#==(obj) ⇒ Boolean

Equality---If sym and obj are exactly the same symbol, returns true.

Returns:

  • (Boolean) 



# File 'string.c'

/*
 *  call-seq:
 *     sym == obj   -> true or false
 *
 *  Equality---If <i>sym</i> and <i>obj</i> are exactly the same
 *  symbol, returns <code>true</code>.
 */

static VALUE
sym_equal(VALUE sym1, VALUE sym2)
{
    if (sym1 == sym2) return Qtrue;
    return Qfalse;
}

#==(obj) ⇒ Boolean

Equality---If sym and obj are exactly the same symbol, returns true.

Returns:

  • (Boolean) 



# File 'string.c'

/*
 *  call-seq:
 *     sym == obj   -> true or false
 *
 *  Equality---If <i>sym</i> and <i>obj</i> are exactly the same
 *  symbol, returns <code>true</code>.
 */

static VALUE
sym_equal(VALUE sym1, VALUE sym2)
{
    if (sym1 == sym2) return Qtrue;
    return Qfalse;
}

#=~(obj) ⇒ Fixnum?

Returns sym.to_s =~ obj.

Returns:




# File 'string.c'

/*
 * call-seq:
 *   sym =~ obj   -> fixnum or nil
 *
 * Returns <code>sym.to_s =~ obj</code>.
 */

static VALUE
sym_match(VALUE sym, VALUE other)
{
    return rb_str_match(rb_sym_to_s(sym), other);
}

#[](idx) ⇒ Object #[](b, n) ⇒ Object

Returns sym.to_s[].




# File 'string.c'

/*
 * call-seq:
 *   sym[idx]      -> char
 *   sym[b, n]     -> char
 *
 * Returns <code>sym.to_s[]</code>.
 */

static VALUE
sym_aref(int argc, VALUE *argv, VALUE sym)
{
    return rb_str_aref_m(argc, argv, rb_sym_to_s(sym));
}

#capitalize ⇒ Object

Same as sym.to_s.capitalize.intern.




# File 'string.c'

/*
 * call-seq:
 *   sym.capitalize  -> symbol
 *
 * Same as <code>sym.to_s.capitalize.intern</code>.
 */

static VALUE
sym_capitalize(VALUE sym)
{
    return rb_str_intern(rb_str_capitalize(rb_id2str(SYM2ID(sym))));
}

#casecmp(other) ⇒ -1, ...

Case-insensitive version of Symbol#<=>.

Returns:

  • (-1, 0, +1, nil) 



# File 'string.c'

/*
 * call-seq:
 *
 *   sym.casecmp(other)  -> -1, 0, +1 or nil
 *
 * Case-insensitive version of <code>Symbol#<=></code>.
 */

static VALUE
sym_casecmp(VALUE sym, VALUE other)
{
    if (!SYMBOL_P(other)) {
    return Qnil;
    }
    return rb_str_casecmp(rb_sym_to_s(sym), rb_sym_to_s(other));
}

#downcase ⇒ Object

Same as sym.to_s.downcase.intern.




# File 'string.c'

/*
 * call-seq:
 *   sym.downcase  -> symbol
 *
 * Same as <code>sym.to_s.downcase.intern</code>.
 */

static VALUE
sym_downcase(VALUE sym)
{
    return rb_str_intern(rb_str_downcase(rb_id2str(SYM2ID(sym))));
}

#empty? ⇒ Boolean

Returns that sym is :"" or not.

Returns:

  • (Boolean) 



# File 'string.c'

/*
 * call-seq:
 *   sym.empty?   -> true or false
 *
 * Returns that _sym_ is :"" or not.
 */

static VALUE
sym_empty(VALUE sym)
{
    return rb_str_empty(rb_id2str(SYM2ID(sym)));
}

#encoding ⇒ Encoding

Returns the Encoding object that represents the encoding of sym.

Returns:




# File 'string.c'

/*
 * call-seq:
 *   sym.encoding   -> encoding
 *
 * Returns the Encoding object that represents the encoding of _sym_.
 */

static VALUE
sym_encoding(VALUE sym)
{
    return rb_obj_encoding(rb_id2str(SYM2ID(sym)));
}

#id2name ⇒ String #to_s ⇒ String

Returns the name or string corresponding to sym.

:fred.id2name   #=> "fred"

Overloads:




# File 'string.c'

/*
 *  call-seq:
 *     sym.id2name   -> string
 *     sym.to_s      -> string
 *
 *  Returns the name or string corresponding to <i>sym</i>.
 *
 *     :fred.id2name   #=> "fred"
 */


VALUE
rb_sym_to_s(VALUE sym)
{
    ID id = SYM2ID(sym);

    return str_new3(rb_cString, rb_id2str(id));
}

#inspect ⇒ String

Returns the representation of sym as a symbol literal.

:fred.inspect   #=> ":fred"

Returns:




# File 'string.c'

/*
 *  call-seq:
 *     sym.inspect    -> string
 *
 *  Returns the representation of <i>sym</i> as a symbol literal.
 *
 *     :fred.inspect   #=> ":fred"
 */

static VALUE
sym_inspect(VALUE sym)
{
    VALUE str;
    ID id = SYM2ID(sym);
    rb_encoding *enc;
    const char *ptr;
    long len;
    char *dest;
    rb_encoding *resenc = rb_default_internal_encoding();

    if (resenc == NULL) resenc = rb_default_external_encoding();
    sym = rb_id2str(id);
    enc = STR_ENC_GET(sym);
    ptr = RSTRING_PTR(sym);
    len = RSTRING_LEN(sym);
    if ((resenc != enc && !rb_str_is_ascii_only_p(sym)) || len != (long)strlen(ptr) ||
    !rb_enc_symname_p(ptr, enc) || !sym_printable(ptr, ptr + len, enc)) {
    str = rb_str_inspect(sym);
    len = RSTRING_LEN(str);
    rb_str_resize(str, len + 1);
    dest = RSTRING_PTR(str);
    memmove(dest + 1, dest, len);
    dest[0] = ':';
    }
    else {
    char *dest;
    str = rb_enc_str_new(0, len + 1, enc);
    dest = RSTRING_PTR(str);
    dest[0] = ':';
    memcpy(dest + 1, ptr, len);
    }
    return str;
}

#to_sym ⇒ Object #intern ⇒ Object

In general, to_sym returns the Symbol corresponding to an object. As sym is already a symbol, self is returned in this case.




# File 'string.c'

/*
 * call-seq:
 *   sym.to_sym   -> sym
 *   sym.intern   -> sym
 *
 * In general, <code>to_sym</code> returns the <code>Symbol</code> corresponding
 * to an object. As <i>sym</i> is already a symbol, <code>self</code> is returned
 * in this case.
 */

static VALUE
sym_to_sym(VALUE sym)
{
    return sym;
}

#length ⇒ Integer

Same as sym.to_s.length.

Returns:




# File 'string.c'

/*
 * call-seq:
 *   sym.length    -> integer
 *
 * Same as <code>sym.to_s.length</code>.
 */

static VALUE
sym_length(VALUE sym)
{
    return rb_str_length(rb_id2str(SYM2ID(sym)));
}

#=~(obj) ⇒ Fixnum?

Returns sym.to_s =~ obj.

Returns:




# File 'string.c'

/*
 * call-seq:
 *   sym =~ obj   -> fixnum or nil
 *
 * Returns <code>sym.to_s =~ obj</code>.
 */

static VALUE
sym_match(VALUE sym, VALUE other)
{
    return rb_str_match(rb_sym_to_s(sym), other);
}

#succ ⇒ Object

Same as sym.to_s.succ.intern.




# File 'string.c'

/*
 * call-seq:
 *
 *   sym.succ
 *
 * Same as <code>sym.to_s.succ.intern</code>.
 */

static VALUE
sym_succ(VALUE sym)
{
    return rb_str_intern(rb_str_succ(rb_sym_to_s(sym)));
}

#length ⇒ Integer

Same as sym.to_s.length.

Returns:




# File 'string.c'

/*
 * call-seq:
 *   sym.length    -> integer
 *
 * Same as <code>sym.to_s.length</code>.
 */

static VALUE
sym_length(VALUE sym)
{
    return rb_str_length(rb_id2str(SYM2ID(sym)));
}

#[](idx) ⇒ Object #[](b, n) ⇒ Object

Returns sym.to_s[].




# File 'string.c'

/*
 * call-seq:
 *   sym[idx]      -> char
 *   sym[b, n]     -> char
 *
 * Returns <code>sym.to_s[]</code>.
 */

static VALUE
sym_aref(int argc, VALUE *argv, VALUE sym)
{
    return rb_str_aref_m(argc, argv, rb_sym_to_s(sym));
}

#succ ⇒ Object

Same as sym.to_s.succ.intern.




# File 'string.c'

/*
 * call-seq:
 *
 *   sym.succ
 *
 * Same as <code>sym.to_s.succ.intern</code>.
 */

static VALUE
sym_succ(VALUE sym)
{
    return rb_str_intern(rb_str_succ(rb_sym_to_s(sym)));
}

#swapcase ⇒ Object

Same as sym.to_s.swapcase.intern.




# File 'string.c'

/*
 * call-seq:
 *   sym.swapcase  -> symbol
 *
 * Same as <code>sym.to_s.swapcase.intern</code>.
 */

static VALUE
sym_swapcase(VALUE sym)
{
    return rb_str_intern(rb_str_swapcase(rb_id2str(SYM2ID(sym))));
}

#to_proc ⇒ Object

Returns a Proc object which respond to the given method by sym.

(1..3).collect(&:to_s)  #=> ["1", "2", "3"]




# File 'string.c'

/*
 * call-seq:
 *   sym.to_proc
 *
 * Returns a _Proc_ object which respond to the given method by _sym_.
 *
 *   (1..3).collect(&:to_s)  #=> ["1", "2", "3"]
 */

static VALUE
sym_to_proc(VALUE sym)
{
    static VALUE sym_proc_cache = Qfalse;
    enum {SYM_PROC_CACHE_SIZE = 67};
    VALUE proc;
    long id, index;
    VALUE *aryp;

    if (!sym_proc_cache) {
    sym_proc_cache = rb_ary_tmp_new(SYM_PROC_CACHE_SIZE * 2);
    rb_gc_register_mark_object(sym_proc_cache);
    rb_ary_store(sym_proc_cache, SYM_PROC_CACHE_SIZE*2 - 1, Qnil);
    }

    id = SYM2ID(sym);
    index = (id % SYM_PROC_CACHE_SIZE) << 1;

    aryp = RARRAY_PTR(sym_proc_cache);
    if (aryp[index] == sym) {
    return aryp[index + 1];
    }
    else {
    proc = rb_proc_new(sym_call, (VALUE)id);
    aryp[index] = sym;
    aryp[index + 1] = proc;
    return proc;
    }
}

#id2name ⇒ String #to_s ⇒ String

Returns the name or string corresponding to sym.

:fred.id2name   #=> "fred"

Overloads:




# File 'string.c'

/*
 *  call-seq:
 *     sym.id2name   -> string
 *     sym.to_s      -> string
 *
 *  Returns the name or string corresponding to <i>sym</i>.
 *
 *     :fred.id2name   #=> "fred"
 */


VALUE
rb_sym_to_s(VALUE sym)
{
    ID id = SYM2ID(sym);

    return str_new3(rb_cString, rb_id2str(id));
}

#to_sym ⇒ Object #intern ⇒ Object

In general, to_sym returns the Symbol corresponding to an object. As sym is already a symbol, self is returned in this case.




# File 'string.c'

/*
 * call-seq:
 *   sym.to_sym   -> sym
 *   sym.intern   -> sym
 *
 * In general, <code>to_sym</code> returns the <code>Symbol</code> corresponding
 * to an object. As <i>sym</i> is already a symbol, <code>self</code> is returned
 * in this case.
 */

static VALUE
sym_to_sym(VALUE sym)
{
    return sym;
}

#upcase ⇒ Object

Same as sym.to_s.upcase.intern.




# File 'string.c'

/*
 * call-seq:
 *   sym.upcase    -> symbol
 *
 * Same as <code>sym.to_s.upcase.intern</code>.
 */

static VALUE
sym_upcase(VALUE sym)
{
    return rb_str_intern(rb_str_upcase(rb_id2str(SYM2ID(sym))));
}