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#ifndef RBIMPL_RARRAY_H /*-*-C++-*-vi:se ft=cpp:*/
#define RBIMPL_RARRAY_H
/**
* @file
* @author Ruby developers <ruby-core@ruby-lang.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.
* @brief Defines struct ::RArray.
*/
#include "ruby/internal/arithmetic/long.h"
#include "ruby/internal/attr/artificial.h"
#include "ruby/internal/attr/constexpr.h"
#include "ruby/internal/attr/maybe_unused.h"
#include "ruby/internal/attr/pure.h"
#include "ruby/internal/cast.h"
#include "ruby/internal/core/rbasic.h"
#include "ruby/internal/dllexport.h"
#include "ruby/internal/fl_type.h"
#include "ruby/internal/gc.h"
#include "ruby/internal/stdbool.h"
#include "ruby/internal/value.h"
#include "ruby/internal/value_type.h"
#include "ruby/assert.h"
/**
* Convenient casting macro.
*
* @param obj An object, which is in fact an ::RArray.
* @return The passed object casted to ::RArray.
*/
#define RARRAY(obj) RBIMPL_CAST((struct RArray *)(obj))
/** @cond INTERNAL_MACRO */
#define RARRAY_EMBED_FLAG RARRAY_EMBED_FLAG
#define RARRAY_EMBED_LEN_MASK RARRAY_EMBED_LEN_MASK
#define RARRAY_EMBED_LEN_MAX RARRAY_EMBED_LEN_MAX
#define RARRAY_EMBED_LEN_SHIFT RARRAY_EMBED_LEN_SHIFT
/** @endcond */
#define RARRAY_LEN rb_array_len /**< @alias{rb_array_len} */
#define RARRAY_CONST_PTR rb_array_const_ptr /**< @alias{rb_array_const_ptr} */
/** @cond INTERNAL_MACRO */
#if defined(__fcc__) || defined(__fcc_version) || \
defined(__FCC__) || defined(__FCC_VERSION)
/* workaround for old version of Fujitsu C Compiler (fcc) */
# define FIX_CONST_VALUE_PTR(x) ((const VALUE *)(x))
#else
# define FIX_CONST_VALUE_PTR(x) (x)
#endif
#define RARRAY_EMBED_LEN RARRAY_EMBED_LEN
#define RARRAY_LENINT RARRAY_LENINT
#define RARRAY_ASET RARRAY_ASET
#define RARRAY_PTR RARRAY_PTR
/** @endcond */
/**
* @private
*
* Bits that you can set to ::RBasic::flags.
*
* @warning These enums are not the only bits we use for arrays.
*
* @internal
*
* Unlike strings, flag usages for arrays are scattered across the entire
* source codes. @shyouhei doesn't know the complete list. But what is listed
* here is at least incomplete.
*/
enum ruby_rarray_flags {
/**
* This flag has something to do with memory footprint. If the array is
* "small" enough, ruby tries to be creative to abuse padding bits of
* struct ::RArray for storing its contents. This flag denotes that
* situation.
*
* @warning This bit has to be considered read-only. Setting/clearing
* this bit without corresponding fix up must cause immediate
* SEGV. Also, internal structures of an array change
* dynamically and transparently throughout of its lifetime.
* Don't assume it being persistent.
*
* @internal
*
* 3rd parties must not be aware that there even is more than one way to
* store array elements. It was a bad idea to expose this to them.
*/
RARRAY_EMBED_FLAG = RUBY_FL_USER1,
/* RUBY_FL_USER2 is for ELTS_SHARED */
/**
* When an array employs embedded strategy (see ::RARRAY_EMBED_FLAG), these
* bits are used to store the number of elements actually filled into
* ::RArray::ary.
*
* @internal
*
* 3rd parties must not be aware that there even is more than one way to
* store array elements. It was a bad idea to expose this to them.
*/
RARRAY_EMBED_LEN_MASK = RUBY_FL_USER9 | RUBY_FL_USER8 | RUBY_FL_USER7 | RUBY_FL_USER6 |
RUBY_FL_USER5 | RUBY_FL_USER4 | RUBY_FL_USER3
};
/**
* This is an enum because GDB wants it (rather than a macro). People need not
* bother.
*/
enum ruby_rarray_consts {
/** Where ::RARRAY_EMBED_LEN_MASK resides. */
RARRAY_EMBED_LEN_SHIFT = RUBY_FL_USHIFT + 3
};
/** Ruby's array. */
struct RArray {
/** Basic part, including flags and class. */
struct RBasic basic;
/** Array's specific fields. */
union {
/**
* Arrays that use separated memory region for elements use this
* pattern.
*/
struct {
/** Number of elements of the array. */
long len;
/** Auxiliary info. */
union {
/**
* Capacity of `*ptr`. A continuous memory region of at least
* `capa` elements is expected to exist at `*ptr`. This can be
* bigger than `len`.
*/
long capa;
/**
* Parent of the array. Nowadays arrays can share their
* backend memory regions each other, constructing gigantic
* nest of objects. This situation is called "shared", and
* this is the field to control such properties.
*/
#if defined(__clang__) /* <- clang++ is sane */ || \
!defined(__cplusplus) /* <- C99 is sane */ || \
(__cplusplus > 199711L) /* <- C++11 is sane */
const
#endif
VALUE shared_root;
} aux;
/**
* Pointer to the C array that holds the elements of the array. In
* the old days each array had dedicated memory regions. That is
* no longer true today, but there still are arrays of such
* properties. This field could be used to point such things.
*/
const VALUE *ptr;
} heap;
/**
* Embedded elements. When an array is short enough, it uses this area
* to store its elements. In this case the length is encoded into the
* flags.
*/
/* This is a length 1 array because:
* 1. GCC has a bug that does not optimize C flexible array members
* (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102452)
* 2. Zero length arrays are not supported by all compilers
*/
const VALUE ary[1];
} as;
};
RBIMPL_SYMBOL_EXPORT_BEGIN()
/**
* @private
*
* Declares a section of code where raw pointers are used. This is an
* implementation detail of #RARRAY_PTR_USE. People don't use it directly.
*
* @param[in] ary An object of ::RArray.
* @return `ary`'s backend C array.
*/
VALUE *rb_ary_ptr_use_start(VALUE ary);
/**
* @private
*
* Declares an end of a section formerly started by rb_ary_ptr_use_start().
* This is an implementation detail of #RARRAY_PTR_USE. People don't use it
* directly.
*
* @param[in] a An object of ::RArray.
*/
void rb_ary_ptr_use_end(VALUE a);
RBIMPL_SYMBOL_EXPORT_END()
RBIMPL_ATTR_PURE_UNLESS_DEBUG()
RBIMPL_ATTR_ARTIFICIAL()
/**
* Queries the length of the array.
*
* @param[in] ary Array in question.
* @return Its number of elements.
* @pre `ary` must be an instance of ::RArray, and must has its
* ::RARRAY_EMBED_FLAG flag set.
*
* @internal
*
* This was a macro before. It was inevitable to be public, since macros are
* global constructs. But should it be forever? Now that it is a function,
* @shyouhei thinks it could just be eliminated, hidden into implementation
* details.
*/
static inline long
RARRAY_EMBED_LEN(VALUE ary)
{
RBIMPL_ASSERT_TYPE(ary, RUBY_T_ARRAY);
RBIMPL_ASSERT_OR_ASSUME(RB_FL_ANY_RAW(ary, RARRAY_EMBED_FLAG));
VALUE f = RBASIC(ary)->flags;
f &= RARRAY_EMBED_LEN_MASK;
f >>= RARRAY_EMBED_LEN_SHIFT;
return RBIMPL_CAST((long)f);
}
RBIMPL_ATTR_PURE_UNLESS_DEBUG()
/**
* Queries the length of the array.
*
* @param[in] a Array in question.
* @return Its number of elements.
* @pre `a` must be an instance of ::RArray.
*/
static inline long
rb_array_len(VALUE a)
{
RBIMPL_ASSERT_TYPE(a, RUBY_T_ARRAY);
if (RB_FL_ANY_RAW(a, RARRAY_EMBED_FLAG)) {
return RARRAY_EMBED_LEN(a);
}
else {
return RARRAY(a)->as.heap.len;
}
}
RBIMPL_ATTR_ARTIFICIAL()
/**
* Identical to rb_array_len(), except it differs for the return type.
*
* @param[in] ary Array in question.
* @exception rb_eRangeError Too long.
* @return Its number of elements.
* @pre `ary` must be an instance of ::RArray.
*
* @internal
*
* This API seems redundant but has actual usages.
*/
static inline int
RARRAY_LENINT(VALUE ary)
{
return rb_long2int(RARRAY_LEN(ary));
}
RBIMPL_ATTR_PURE_UNLESS_DEBUG()
/**
* @private
*
* This is an implementation detail of RARRAY_PTR(). People do not use it
* directly.
*
* @param[in] a An object of ::RArray.
* @return Its backend storage.
*/
static inline const VALUE *
rb_array_const_ptr(VALUE a)
{
RBIMPL_ASSERT_TYPE(a, RUBY_T_ARRAY);
if (RB_FL_ANY_RAW(a, RARRAY_EMBED_FLAG)) {
return FIX_CONST_VALUE_PTR(RARRAY(a)->as.ary);
}
else {
return FIX_CONST_VALUE_PTR(RARRAY(a)->as.heap.ptr);
}
}
/**
* @private
*
* This is an implementation detail of #RARRAY_PTR_USE. People do not use it
* directly.
*/
#define RBIMPL_RARRAY_STMT(ary, var, expr) do { \
RBIMPL_ASSERT_TYPE((ary), RUBY_T_ARRAY); \
const VALUE rbimpl_ary = (ary); \
VALUE *var = rb_ary_ptr_use_start(rbimpl_ary); \
expr; \
rb_ary_ptr_use_end(rbimpl_ary); \
} while (0)
/**
* Declares a section of code where raw pointers are used. In case you need to
* touch the raw C array instead of polite CAPIs, then that operation shall be
* wrapped using this macro.
*
* ```CXX
* const auto ary = rb_eval_string("[...]");
* const auto len = RARRAY_LENINT(ary);
* const auto symwrite = rb_intern("write");
*
* RARRAY_PTR_USE(ary, ptr, {
* rb_funcallv(rb_stdout, symwrite, len, ptr);
* });
* ```
*
* @param ary An object of ::RArray.
* @param ptr_name A variable name which points the C array in `expr`.
* @param expr The expression that touches `ptr_name`.
*
* @internal
*
* For historical reasons use of this macro is not enforced. There are
* extension libraries in the wild which call RARRAY_PTR() without it. We want
* them use it... Maybe some transition path can be implemented later.
*/
#define RARRAY_PTR_USE(ary, ptr_name, expr) \
RBIMPL_RARRAY_STMT(ary, ptr_name, expr)
/**
* Wild use of a C pointer. This function accesses the backend storage
* directly. This is slower than #RARRAY_PTR_USE. It exercises
* extra manoeuvres to protect our generational GC. Use of this function is
* considered archaic. Use a modern way instead.
*
* @param[in] ary An object of ::RArray.
* @return The backend C array.
*
* @internal
*
* That said... there are extension libraries in the wild who uses it. We
* cannot but continue supporting.
*/
static inline VALUE *
RARRAY_PTR(VALUE ary)
{
RBIMPL_ASSERT_TYPE(ary, RUBY_T_ARRAY);
VALUE tmp = RB_OBJ_WB_UNPROTECT_FOR(ARRAY, ary);
return RBIMPL_CAST((VALUE *)RARRAY_CONST_PTR(tmp));
}
/**
* Assigns an object in an array.
*
* @param[out] ary Destination array object.
* @param[in] i Index of `ary`.
* @param[in] v Arbitrary ruby object.
* @pre `ary` must be an instance of ::RArray.
* @pre `ary`'s length must be longer than or equal to `i`.
* @pre `i` must be greater than or equal to zero.
* @post `ary`'s `i`th element is set to `v`.
*/
static inline void
RARRAY_ASET(VALUE ary, long i, VALUE v)
{
RARRAY_PTR_USE(ary, ptr,
RB_OBJ_WRITE(ary, &ptr[i], v));
}
/**
* @deprecated
*
* :FIXME: we want to convert RARRAY_AREF into an inline function (to add rooms
* for more sanity checks). However there were situations where the address of
* this macro is taken i.e. &RARRAY_AREF(...). They cannot be possible if this
* is not a macro. Such usages are abuse, and we eliminated them internally.
* However we are afraid of similar things to remain in the wild. This macro
* remains as it is due to that. If we could warn such usages we can set a
* transition path, but currently no way is found to do so.
*/
#define RARRAY_AREF(a, i) RARRAY_CONST_PTR(a)[i]
#endif /* RBIMPL_RARRAY_H */