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include/ruby/internal/core/rstring.h: add doxygen

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Must not be a bad idea to improve documents. [ci skip]
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卜部昌平 2021-02-01 12:10:21 +09:00
parent 746996e6c9
commit 1bd1339492
Notes: git 2021-09-10 20:01:43 +09:00
1 changed files with 347 additions and 8 deletions
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355
include/ruby/internal/core/rstring.h
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@ -32,14 +32,20 @@
#include "ruby/internal/warning_push.h"
#include "ruby/assert.h"
/**
* Convenient casting macro.
*
* @param obj An object, which is in fact an ::RString.
* @return The passed object casted to ::RString.
*/
#define RSTRING(obj) RBIMPL_CAST((struct RString *)(obj))
/** @cond INTERNAL_MACRO */
#define RSTRING_NOEMBED RSTRING_NOEMBED
#define RSTRING_EMBED_LEN_MASK RSTRING_EMBED_LEN_MASK
#define RSTRING_EMBED_LEN_SHIFT RSTRING_EMBED_LEN_SHIFT
#define RSTRING_EMBED_LEN_MAX RSTRING_EMBED_LEN_MAX
#define RSTRING_FSTR RSTRING_FSTR
/** @cond INTERNAL_MACRO */
#define RSTRING_EMBED_LEN RSTRING_EMBED_LEN
#define RSTRING_LEN RSTRING_LEN
#define RSTRING_LENINT RSTRING_LENINT
@ -47,59 +53,343 @@
#define RSTRING_END RSTRING_END
/** @endcond */
/**
* @name Conversion of Ruby strings into C's
*
* @{
*/
/**
* Ensures that the parameter object is a String. This is done by calling its
* `to_str` method.
*
* @param[in,out] v Arbitrary Ruby object.
* @exception rb_eTypeError No implicit conversion defined.
* @post `v` is a String.
*/
#define StringValue(v) rb_string_value(&(v))
/**
* Identical to #StringValue, except it returns a `char*`.
*
* @param[in,out] v Arbitrary Ruby object.
* @exception rb_eTypeError No implicit conversion defined.
* @return Converted Ruby string's backend C string.
* @post `v` is a String.
*/
#define StringValuePtr(v) rb_string_value_ptr(&(v))
/**
* Identical to #StringValuePtr, except it additionally checks for the contents
* for viability as a C string. Ruby can accept wider range of contents as
* strings, compared to C. This function is to check that.
*
* @param[in,out] v Arbitrary Ruby object.
* @exception rb_eTypeError No implicit conversion defined.
* @exception rb_eArgError String is not C-compatible.
* @return Converted Ruby string's backend C string.
* @post `v` is a String.
*/
#define StringValueCStr(v) rb_string_value_cstr(&(v))
/**
* @private
*
* @deprecated This macro once was a thing in the old days, but makes no sense
* any longer today. Exists here for backwards compatibility
* only. You can safely forget about it.
*/
#define SafeStringValue(v) StringValue(v)
/**
* Identical to #StringValue, except it additionally converts the string's
* encoding to default external encoding. Ruby has a concept called encodings.
* A string can have different encoding than the environment expects. Someone
* has to make sure its contents be converted to something suitable. This is
* that routine. Call it when necessary.
*
* @param[in,out] v Arbitrary Ruby object.
* @exception rb_eTypeError No implicit conversion defined.
* @return Converted Ruby string's backend C string.
* @post `v` is a String.
*
* @internal
*
* Not sure but it seems this macro does not raise on encoding
* incompatibilities? Doesn't sound right to @shyouhei.
*/
#define ExportStringValue(v) do { \
StringValue(v); \
(v) = rb_str_export(v); \
} while (0)
/** @} */
/**
* @private
*
* Bits that you can set to ::RBasic::flags.
*
* @warning These enums are not the only bits we use for strings.
*
* @internal
*
* Actually all bits through FL_USER1 to FL_USER19 are used for strings. Why
* only this tiny part of them are made public here? @shyouhei can find no
* reason.
*/
enum ruby_rstring_flags {
/**
* This flag has something to do with memory footprint. If the string is
* short enough, ruby tries to be creative to abuse padding bits of struct
* ::RString for storing contents. If this flag is set that string does
* _not_ do that, to resort to good old fashioned external allocation
* strategy instead.
*
* @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 a string 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 a string. Might better be hidden.
*/
RSTRING_NOEMBED = RUBY_FL_USER1,
/**
* When a string employs embedded strategy (see ::RSTRING_NOEMBED), these
* bits are used to store the number of bytes actually filled into
* ::RString::ary.
*
* @internal
*
* 3rd parties must not be aware that there even is more than one way to
* store a string. Might better be hidden.
*/
RSTRING_EMBED_LEN_MASK = RUBY_FL_USER2 | RUBY_FL_USER3 | RUBY_FL_USER4 |
RUBY_FL_USER5 | RUBY_FL_USER6,
/* Actually, string encodings are also encoded into the flags, using
* remaining bits.*/
/**
* This flag has something to do with infamous "f"string. What is a
* fstring? Well it is a special subkind of strings that is immutable,
* deduped globally, and managed by our GC. It is much like a Symbol (in
* fact Symbols are dynamic these days and are backended using fstrings).
* This concept has been silently introduced at some point in 2.x era.
* Since then it gained wider acceptance in the core. But extension
* libraries could not know that until very recently. Strings of this flag
* live in a special Limbo deep inside of the interpreter. Never try to
* manipulate it by hand.
*
* @internal
*
* Fstrings are not the only variant strings that we implement today.
* Other things are behind-the-scene. This is the only one that is visible
* from extension library. There is no clear reason why it has to be.
* Given there are more "polite" ways to create fstrings, it seems this bit
* need not be exposed to extension libraries. Might better be hidden.
*/
RSTRING_FSTR = RUBY_FL_USER17
};
/**
* This is an enum because GDB wants it (rather than a macro). People need not
* bother.
*/
enum ruby_rstring_consts {
/** Where ::RSTRING_EMBED_LEN_MASK resides. */
RSTRING_EMBED_LEN_SHIFT = RUBY_FL_USHIFT + 2,
/** Max possible number of characters that can be embedded. */
RSTRING_EMBED_LEN_MAX = RBIMPL_EMBED_LEN_MAX_OF(char) - 1
};
/**
* Ruby's String. A string in ruby conceptually has these information:
*
* - Encoding of the string.
* - Length of the string.
* - Contents of the string.
*
* It is worth noting that a string is _not_ an array of characters in ruby.
* It has never been. In 1.x a string was an array of integers. Since 2.x a
* string is no longer an array of anything. A string is a string -- just like
* a Time is not an integer.
*/
struct RString {
/** Basic part, including flags and class. */
struct RBasic basic;
/** String's specific fields. */
union {
/**
* Strings that use separated memory region for contents use this
* pattern.
*/
struct {
/**
* Length of the string, not including terminating NUL character.
*
* @note This is in bytes.
*/
long len;
/**
* Pointer to the contents of the string. In the old days each
* string had dedicated memory regions. That is no longer true
* today, but there still are strings of such properties. This
* field could be used to point such things.
*/
char *ptr;
/** Auxiliary info. */
union {
/**
* Capacity of `*ptr`. A continuous memory region of at least
* `capa` bytes is expected to exist at `*ptr`. This can be
* bigger than `len`.
*/
long capa;
/**
* Parent of the string. Nowadays strings can share their
* contents each other, constructing gigantic nest of objects.
* This situation is called "shared", and this is the field to
* control such properties.
*/
VALUE shared;
} aux;
} heap;
/**
* Embedded contents. When a string is short enough, it uses this area
* to store the contents themselves. This was impractical in the 20th
* century, but these days 64 bit machines can typically hold 48 bytes
* here. Could be sufficiently large. In this case the length is
* encoded into the flags.
*/
char ary[RSTRING_EMBED_LEN_MAX + 1];
} as;
};
RBIMPL_SYMBOL_EXPORT_BEGIN()
VALUE rb_str_to_str(VALUE);
VALUE rb_string_value(volatile VALUE*);
char *rb_string_value_ptr(volatile VALUE*);
char *rb_string_value_cstr(volatile VALUE*);
VALUE rb_str_export(VALUE);
VALUE rb_str_export_locale(VALUE);
/**
* Identical to rb_check_string_type(), except it raises exceptions in case of
* conversion failures.
*
* @param[in] obj Target object.
* @exception rb_eTypeError No implicit conversion to String.
* @return Return value of `obj.to_str`.
* @see rb_io_get_io
* @see rb_ary_to_ary
*/
VALUE rb_str_to_str(VALUE obj);
/**
* Identical to rb_str_to_str(), except it fills the passed pointer with the
* converted object.
*
* @param[in,out] ptr Pointer to a variable of target object.
* @exception rb_eTypeError No implicit conversion to String.
* @return Return value of `obj.to_str`.
* @post `*ptr` is the return value.
*/
VALUE rb_string_value(volatile VALUE *ptr);
/**
* Identical to rb_str_to_str(), except it returns the converted string's
* backend memory region.
*
* @param[in,out] ptr Pointer to a variable of target object.
* @exception rb_eTypeError No implicit conversion to String.
* @post `*ptr` is the return value of `obj.to_str`.
* @return Pointer to the contents of the return value.
*/
char *rb_string_value_ptr(volatile VALUE *ptr);
/**
* Identical to rb_string_value_ptr(), except it additionally checks for the
* contents for viability as a C string. Ruby can accept wider range of
* contents as strings, compared to C. This function is to check that.
*
* @param[in,out] ptr Pointer to a variable of target object.
* @exception rb_eTypeError No implicit conversion to String.
* @exception rb_eArgError String is not C-compatible.
* @post `*ptr` is the return value of `obj.to_str`.
* @return Pointer to the contents of the return value.
*/
char *rb_string_value_cstr(volatile VALUE *ptr);
/**
* Identical to rb_str_to_str(), except it additionally converts the string
* into default external encoding. Ruby has a concept called encodings. A
* string can have different encoding than the environment expects. Someone
* has to make sure its contents be converted to something suitable. This is
* that routine. Call it when necessary.
*
* @param[in] obj Target object.
* @exception rb_eTypeError No implicit conversion to String.
* @return Converted ruby string of default external encoding.
*/
VALUE rb_str_export(VALUE obj);
/**
* Identical to rb_str_export(), except it converts into the locale encoding
* instead.
*
* @param[in] obj Target object.
* @exception rb_eTypeError No implicit conversion to String.
* @return Converted ruby string of locale encoding.
*/
VALUE rb_str_export_locale(VALUE obj);
RBIMPL_ATTR_ERROR(("rb_check_safe_str() and Check_SafeStr() are obsolete; use StringValue() instead"))
/**
* @private
*
* @deprecated This function once was a thing in the old days, but makes no
* sense any longer today. Exists here for backwards
* compatibility only. You can safely forget about it.
*/
void rb_check_safe_str(VALUE);
/**
* @private
*
* @deprecated This macro once was a thing in the old days, but makes no sense
* any longer today. Exists here for backwards compatibility
* only. You can safely forget about it.
*/
#define Check_SafeStr(v) rb_check_safe_str(RBIMPL_CAST((VALUE)(v)))
RBIMPL_SYMBOL_EXPORT_END()
RBIMPL_ATTR_PURE_UNLESS_DEBUG()
RBIMPL_ATTR_ARTIFICIAL()
/**
* Queries the length of the string.
*
* @param[in] str String in question.
* @return Its length, in bytes.
* @pre `str` must be an instance of ::RString, and must has its
* ::RSTRING_NOEMBED flag off.
*
* @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
RSTRING_EMBED_LEN(VALUE str)
{
@ -119,6 +409,15 @@ RBIMPL_WARNING_IGNORED(413)
RBIMPL_ATTR_PURE_UNLESS_DEBUG()
RBIMPL_ATTR_ARTIFICIAL()
/**
* @private
*
* "Expands" an embedded string into an ordinal one. This is a function that
* returns aggregated type. The returned struct always has its `as.heap.len`
* an `as.heap.ptr` fields set appropriately.
*
* This is an implementation detail that 3rd parties should never bother.
*/
static inline struct RString
rbimpl_rstring_getmem(VALUE str)
{
@ -140,6 +439,13 @@ RBIMPL_WARNING_POP()
RBIMPL_ATTR_PURE_UNLESS_DEBUG()
RBIMPL_ATTR_ARTIFICIAL()
/**
* Queries the length of the string.
*
* @param[in] str String in question.
* @return Its length, in bytes.
* @pre `str` must be an instance of ::RString.
*/
static inline long
RSTRING_LEN(VALUE str)
{
@ -147,6 +453,13 @@ RSTRING_LEN(VALUE str)
}
RBIMPL_ATTR_ARTIFICIAL()
/**
* Queries the contents pointer of the string.
*
* @param[in] str String in question.
* @return Pointer to its contents.
* @pre `str` must be an instance of ::RString.
*/
static inline char *
RSTRING_PTR(VALUE str)
{
@ -175,6 +488,13 @@ RSTRING_PTR(VALUE str)
}
RBIMPL_ATTR_ARTIFICIAL()
/**
* Queries the end of the contents pointer of the string.
*
* @param[in] str String in question.
* @return Pointer to its end of contents.
* @pre `str` must be an instance of ::RString.
*/
static inline char *
RSTRING_END(VALUE str)
{
@ -194,12 +514,31 @@ RSTRING_END(VALUE str)
}
RBIMPL_ATTR_ARTIFICIAL()
/**
* Identical to RSTRING_LEN(), except it differs for the return type.
*
* @param[in] str String in question.
* @exception rb_eRangeError Too long.
* @return Its length, in bytes.
* @pre `str` must be an instance of ::RString.
*
* @internal
*
* This API seems redundant but has actual usages.
*/
static inline int
RSTRING_LENINT(VALUE str)
{
return rb_long2int(RSTRING_LEN(str));
}
/**
* Convenient macro to obtain the contents and length at once.
*
* @param str String in question.
* @param ptrvar Variable where its contents is stored.
* @param lenvar Variable where its length is stored.
*/
#ifdef HAVE_STMT_AND_DECL_IN_EXPR
# define RSTRING_GETMEM(str, ptrvar, lenvar) \
__extension__ ({ \