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Defines rb_intern. More...

#include "ruby/internal/config.h"
#include "ruby/internal/attr/noalias.h"
#include "ruby/internal/attr/nonnull.h"
#include "ruby/internal/attr/pure.h"
#include "ruby/internal/cast.h"
#include "ruby/internal/constant_p.h"
#include "ruby/internal/dllexport.h"
#include "ruby/internal/has/builtin.h"
#include "ruby/internal/value.h"

Include dependency graph for symbol.h:

This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Macros
#define	RB_ID2SYM rb_id2sym
	Just another name of rb_id2sym.

#define	RB_SYM2ID rb_sym2id
	Just another name of rb_sym2id.

#define	ID2SYM RB_ID2SYM
	Old name of RB_ID2SYM.

#define	SYM2ID RB_SYM2ID
	Old name of RB_SYM2ID.

#define	CONST_ID_CACHE RUBY_CONST_ID_CACHE
	Old name of RUBY_CONST_ID_CACHE.

#define	CONST_ID RUBY_CONST_ID
	Old name of RUBY_CONST_ID.

#define	RUBY_CONST_ID_CACHE(result, str)
	Old implementation detail of rb_intern().

#define	RUBY_CONST_ID(var, str)
	Returns the cached ID for the given str in var, in compiler independent manner.

Functions
ID	rb_sym2id (VALUE obj)
	Converts an instance of rb_cSymbol into an ID.

VALUE	rb_id2sym (ID id)
	Allocates an instance of rb_cSymbol that has the given id.

ID	rb_intern (const char *name)
	Finds or creates a symbol of the given name.

ID	rb_intern2 (const char *name, long len)
	Identical to rb_intern(), except it additionally takes the length of the string.

ID	rb_intern_str (VALUE str)
	Identical to rb_intern(), except it takes an instance of rb_cString.

const char *	rb_id2name (ID id)
	Retrieves the name mapped to the given id.

ID	rb_check_id (volatile VALUE *namep)
	Detects if the given name is already interned or not.

ID	rb_to_id (VALUE str)

VALUE	rb_id2str (ID id)
	Identical to rb_id2name(), except it returns a frozen Ruby String instead of a C String.

VALUE	rb_sym2str (VALUE symbol)
	Obtain a frozen string representation of a symbol (not including the leading colon).

VALUE	rb_to_symbol (VALUE name)
	Identical to rb_intern_str(), except it generates a dynamic symbol if necessary.

VALUE	rb_check_symbol (volatile VALUE *namep)
	Identical to rb_check_id(), except it returns an instance of rb_cSymbol instead.

static ID	rb_intern_const (const char *str)
	This is a "tiny optimisation" over rb_intern().

Detailed Description

Defines rb_intern.

Author: Ruby developers ruby-.nosp@m.core.nosp@m.@ruby.nosp@m.-lan.nosp@m.g.org

Copyright: This file is a part of the programming language Ruby. Permission is hereby granted, to either redistribute and/or modify this file, provided that the conditions mentioned in the file COPYING are met. Consult the file for details.

Warning: Symbols prefixed with either RBIMPL or rbimpl are implementation details. Don't take them as canon. They could rapidly appear then vanish. The name (path) of this header file is also an implementation detail. Do not expect it to persist at the place it is now. Developers are free to move it anywhere anytime at will.

Note: To ruby-core: remember that this header can be possibly recursively included from extension libraries written in C++. Do not expect for instance __VA_ARGS__ is always available. We assume C99 for ruby itself but we don't assume languages of extension libraries. They could be written in C++98.

Definition in file symbol.h.

Macro Definition Documentation

◆ RB_ID2SYM

#define RB_ID2SYM rb_id2sym

Just another name of rb_id2sym.

Definition at line 42 of file symbol.h.

◆ RB_SYM2ID

#define RB_SYM2ID rb_sym2id

Just another name of rb_sym2id.

Definition at line 43 of file symbol.h.

◆ RUBY_CONST_ID

#define RUBY_CONST_ID	(	var,
		str
	)

Value:

    do { \
        static ID rbimpl_id; \
        (var) = rbimpl_intern_const(&rbimpl_id, (str)); \
    } while (0)

Returns the cached ID for the given str in var, in compiler independent manner.

Use this instead of GCC specific rb_intern() when you want to cache the ID on all platforms certainly.

Definition at line 323 of file symbol.h.

◆ RUBY_CONST_ID_CACHE

#define RUBY_CONST_ID_CACHE	(	result,
		str
	)

Value:

    {                                                   \
        static ID rb_intern_id_cache;                   \
        rbimpl_intern_const(&rb_intern_id_cache, (str)); \
        result rb_intern_id_cache;                      \
    }

Old implementation detail of rb_intern().

Deprecated:: Does anyone use it? Preserved for backward compat.

Definition at line 311 of file symbol.h.

Function Documentation

◆ rb_check_id()

ID rb_check_id ( volatile VALUE * namep )

Detects if the given name is already interned or not.

It first tries to convert the argument to an instance of rb_cString if it is neither an instance of rb_cString nor rb_cSymbol. The conversion result is written back to the variable. Then queries if that name was already interned before. If found it returns such id, otherwise zero.

We eventually introduced this API to avoid inadvertent symbol pin-down. Before, there was no way to know if an ID was already interned or not without actually creating one (== leaking memory). By using this API you can avoid such situations:

bool does_interning_this_leak_memory(VALUE obj)
{
    auto tmp = obj;
    if (auto id = rb_check_id(&tmp); id) {
        return false;
    }
    else {
        return true; // Let GC sweep tmp if necessary.
    }
}

Parameters

[in,out] namep A pointer to a name to query.

Precondition: The object referred by *namep must either be an instance of rb_cSymbol, or an instance of rb_cString, or responds to #to_str method.

Exceptions

rb_eTypeError	Can't convert `*namep` into rb_cString.
rb_eEncodingError	Given string is non-ASCII.

Return values

0	No such id ever existed in the history.
otherwise	The id that represents the given name.

Postcondition: The object that *namep points to is a converted result object, which is always an instance of either rb_cSymbol or rb_cString.

See also: https://bugs.ruby-lang.org/issues/5072

Definition at line 1163 of file symbol.c.

Referenced by rb_check_id(), and rb_f_untrace_var().

◆ rb_check_symbol()

VALUE rb_check_symbol ( volatile VALUE * namep )

Identical to rb_check_id(), except it returns an instance of rb_cSymbol instead.

Parameters

[in,out] namep A pointer to a name to query.

Precondition: The object referred by *namep must either be an instance of rb_cSymbol, or an instance of rb_cString, or responds to #to_str method.

Exceptions

rb_eTypeError	Can't convert `*namep` into rb_cString.
rb_eEncodingError	Given string is non-ASCII.

Return values

RUBY_Qnil	No such id ever existed in the history.
otherwise	The id that represents the given name.

Postcondition: The object that *namep points to is a converted result object, which is always an instance of either rb_cSymbol or rb_cString.

See also: https://bugs.ruby-lang.org/issues/5072

Definition at line 1220 of file symbol.c.

Referenced by rb_check_symbol().

◆ rb_id2name()

const char * rb_id2name ( ID id )

Retrieves the name mapped to the given id.

Parameters

[in] id An id to query.

Return values

NULL	Unknown id.
otherwise	A name that the id represents.

Note: The return value is managed by the interpreter. Don't pass it to free().; The underlying name can contain internal NUL bytes, so the return value might be a truncated representation due to the nature of C strings.; This C string is backed by an underlying Ruby string. The Ruby string may move during GC compaction which would make this C string point to invalid memory. Do not use the return value of this function after a potential GC entry point.

Definition at line 1045 of file symbol.c.

◆ rb_id2str()

VALUE rb_id2str ( ID id )

Identical to rb_id2name(), except it returns a frozen Ruby String instead of a C String.

Parameters

[in] id An id to query.

Return values

RUBY_Qfalse	No such id ever existed in the history.
otherwise	An instance of rb_cString with the name of id.

Definition at line 1039 of file symbol.c.

◆ rb_id2sym()

VALUE rb_id2sym ( ID id )

Allocates an instance of rb_cSymbol that has the given id.

Parameters

[in] id An id.

Return values

RUBY_Qfalse	No such id ever existed in the history.
Otherwise	An allocated rb_cSymbol instance.

Definition at line 1004 of file symbol.c.

Referenced by rb_id2sym().

◆ rb_intern()

ID rb_intern ( const char * name )

Finds or creates a symbol of the given name.

Parameters

[in] name The name of the id.

Exceptions

rb_eRuntimeError Too many symbols.

Returns: A (possibly new) id whose value is the given name.

Note: These days Ruby internally has two kinds of symbols (static / dynamic). Symbols created using this function would become a static one; i.e. would never be garbage collected. It is up to you to avoid memory leaks. Think twice before using it.

Definition at line 882 of file symbol.c.

◆ rb_intern2()

ID rb_intern2	(	const char *	name,
		long	len
	)

Identical to rb_intern(), except it additionally takes the length of the string.

This way you can have a symbol that contains NUL characters.

Parameters

[in]	name	The name of the id.
[in]	len	Length of `name`.

Exceptions

rb_eRuntimeError Too many symbols.

Returns: A (possibly new) id whose value is the given name.

Note: These days Ruby internally has two kinds of symbols (static/dynamic). Symbols created using this function would become static ones; i.e. would never be garbage collected. It is up to you to avoid memory leaks. Think twice before using it.

Definition at line 875 of file symbol.c.

◆ rb_intern_const()

static ID rb_intern_const ( const char * str )

inlinestatic

This is a "tiny optimisation" over rb_intern().

If you pass a string literal, and if your C compiler can special-case strlen of such literal to strength-reduce into an integer constant expression, then this inline function can precalc a part of conversion.

Note: This function also works happily for non-constant strings. Why bother then? Just apply liberally to everything.; But rb_intern() could be faster on compilers with statement expressions, because they can cache the created ID.

Parameters

[in] str The name of the id.

Exceptions

rb_eRuntimeError Too many symbols.

Returns: A (possibly new) id whose value is the given str.

Note: These days Ruby internally has two kinds of symbols (static / dynamic). Symbols created using this function would become a static one; i.e. would never be garbage collected. It is up to you to avoid memory leaks. Think twice before using it.

Definition at line 284 of file symbol.h.

Referenced by Init_class_hierarchy().

◆ rb_intern_str()

ID rb_intern_str ( VALUE str )

Identical to rb_intern(), except it takes an instance of rb_cString.

Parameters

[in] str The name of the id.

Precondition: str must either be an instance of rb_cSymbol, or an instance of rb_cString, or responds to #to_str method.

Exceptions

rb_eTypeError	Can't convert `str` into rb_cString.
rb_eRuntimeError	Too many symbols.

Returns: A (possibly new) id whose value is the given str.

Note: These days Ruby internally has two kinds of symbols (static/dynamic). Symbols created using this function would become static ones; i.e. would never be garbage collected. It is up to you to avoid memory leaks. Think twice before using it.

Definition at line 888 of file symbol.c.

◆ rb_sym2id()

ID rb_sym2id ( VALUE obj )

Converts an instance of rb_cSymbol into an ID.

Parameters

[in] obj An instance of rb_cSymbol.

Exceptions

rb_eTypeError `obj` is not an instance of rb_cSymbol.

Returns: An ID of the identical symbol.

Definition at line 973 of file symbol.c.

Referenced by rb_id_attrset(), rb_intern3(), and rb_sym2id().

◆ rb_sym2str()

VALUE rb_sym2str ( VALUE symbol )

Obtain a frozen string representation of a symbol (not including the leading colon).

Done without any object allocations.

Parameters

[in] symbol A rb_cSymbol instance to query.

Returns: A frozen instance of rb_cString with the name of symbol.

Note: This does not create a permanent ID using the symbol.

Definition at line 1023 of file symbol.c.

Referenced by rb_enc_get_index(), rb_gc_latest_gc_info(), rb_gc_stat(), rb_str_format(), rb_sym2str(), and rb_sym_to_s().

◆ rb_to_id()

ID rb_to_id ( VALUE str )

Definition at line 12558 of file string.c.

Referenced by rb_f_trace_var().

◆ rb_to_symbol()

VALUE rb_to_symbol ( VALUE name )

Identical to rb_intern_str(), except it generates a dynamic symbol if necessary.

Parameters

[in] name The name of the id.

Precondition: name must either be an instance of rb_cSymbol, or an instance of rb_cString, or responds to #to_str method.

Exceptions

rb_eTypeError	Can't convert `name` into rb_cString.
rb_eRuntimeError	Too many symbols.

Returns: A (possibly new) id whose value is the given name.

Note: These days Ruby internally has two kinds of symbols (static/dynamic). Symbols created using this function would become dynamic ones; i.e. would be garbage collected. It could be safer for you to use it than alternatives, when applicable.

Definition at line 12568 of file string.c.

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Macros

Functions

Detailed Description

Macro Definition Documentation

◆ RB_ID2SYM

◆ RB_SYM2ID

◆ RUBY_CONST_ID

◆ RUBY_CONST_ID_CACHE

Function Documentation

◆ rb_check_id()

◆ rb_check_symbol()

◆ rb_id2name()

◆ rb_id2str()

◆ rb_id2sym()

◆ rb_intern()

◆ rb_intern2()

◆ rb_intern_const()

◆ rb_intern_str()

◆ rb_sym2id()

◆ rb_sym2str()

◆ rb_to_id()

◆ rb_to_symbol()