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* struct.c (scm_make_struct_layout, scm_make_struct,
scm_make_vtable_vtable): Updated documentation.
This commit is contained in:
Mikael Djurfeldt
parent
e478dffa01
commit
04323af4ad
1 changed files with 59 additions and 58 deletions
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@ -74,7 +74,7 @@ SCM_DEFINE (scm_make_struct_layout, "make-struct-layout", 1, 0, 0,
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"strung together. The first character of each pair describes a field\n"
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"type, the second a field protection. Allowed types are 'p' for\n"
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"GC-protected Scheme data, 'u' for unprotected binary data, and 's' for\n"
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"fields that should point to the structure itself. Allowed protections\n"
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"a field that points to the structure itself. Allowed protections\n"
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"are 'w' for mutable fields, 'r' for read-only fields, and 'o' for opaque \n"
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"fields. The last field protection specification may be capitalized to\n"
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"indicate that the field is a tail-array.")
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@ -362,11 +362,21 @@ SCM_DEFINE (scm_make_struct, "make-struct", 2, 0, 1,
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"@var{tail-elts} must be a non-negative integer. If the layout\n"
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"specification indicated by @var{type} includes a tail-array,\n"
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"this is the number of elements allocated to that array.\n\n"
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"The @var{inits} are optional arguments describing how successive fields\n"
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"of the structure should be initialized. Only fields with protection 'r'\n"
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"or 'w' can be initialized -- fields of protection 's' are automatically\n"
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"initialized to point to the new structure itself; fields of protection 'o'\n"
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"can not be initialized by Scheme programs.")
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"The @var{init1}, @dots are optional arguments describing how\n"
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"successive fields of the structure should be initialized. Only fields\n"
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"with protection 'r' or 'w' can be initialized, except for fields of\n"
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"type 's', which are automatically initialized to point to the new\n"
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"structure itself; fields with protection 'o' can not be initialized by\n"
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"Scheme programs.\n\n"
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"If fewer optional arguments than initializable fields are supplied,\n"
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"fields of type 'p' get default value #f while fields of type 'u' are\n"
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"initialized to 0.\n\n"
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"Structs are currently the basic representation for record-like data\n"
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"structures in Guile. The plan is to eventually replace them with a\n"
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"new representation which will at the same time be easier to use and\n"
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"more powerful.\n\n"
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"For more information, see the documentation for @code{make-vtable-vtable}.\n"
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"")
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#define FUNC_NAME s_scm_make_struct
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{
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SCM layout;
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@ -407,59 +417,50 @@ SCM_DEFINE (scm_make_struct, "make-struct", 2, 0, 1,
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SCM_DEFINE (scm_make_vtable_vtable, "make-vtable-vtable", 2, 0, 1,
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(SCM extra_fields, SCM tail_array_size, SCM init),
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(SCM user_fields, SCM tail_array_size, SCM init),
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"Return a new, self-describing vtable structure.\n\n"
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"@var{new-fields} is a layout specification describing fields\n"
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"of the resulting structure beginning at the position bound to\n"
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"@code{vtable-offset-user}.\n\n"
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"@var{user-fields} is a string describing user defined fields of the\n"
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"vtable beginning at index @code{vtable-offset-user}\n"
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"(see @code{make-struct-layout}).\n\n"
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"@var{tail-size} specifies the size of the tail-array (if any) of\n"
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"this vtable.\n\n"
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"@var{inits} initializes the fields of the vtable. Minimally, one\n"
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"initializer must be provided: the layout specification for instances\n"
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"of the type this vtable will describe. If a second initializer is\n"
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"provided, it will be interpreted as a print call-back function.\n\n"
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"@var{init1}, @dots are the optional initializers for the fields of\n"
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"the vtable.\n\n"
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"Vtables have one initializable system field---the struct printer.\n"
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"This field comes before the user fields in the initializers passed\n"
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"to @code{make-vtable-vtable} and @code{make-struct}, and thus works as\n"
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"a third optional argument to @code{make-vtable-vtable} and a fourth to\n"
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"@code{make-struct} when creating vtables:\n\n"
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"If the value is a procedure, it will be called instead of the standard\n"
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"printer whenever a struct described by this vtable is printed.\n"
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"The procedure will be called with arguments STRUCT and PORT.\n\n"
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"The structure of a struct is described by a vtable, so the vtable is\n"
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"in essence the type of the struct. The vtable is itself a struct with\n"
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"a vtable. This could go on forever if it weren't for the\n"
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"vtable-vtables which are self-describing vtables, and thus terminates\n"
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"the chain.\n\n"
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"There are several potential ways of using structs, but the standard\n"
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"one is to use three kinds of structs, together building up a type\n"
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"sub-system: one vtable-vtable working as the root and one or several\n"
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"\"types\", each with a set of \"instances\". (The vtable-vtable should be\n"
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"compared to the class <class> which is a class of itself.)\n\n"
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"@example\n"
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";;; loading ,a...\n"
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"(define x\n"
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" (make-vtable-vtable (make-struct-layout (quote pw))\n"
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" 0\n"
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" 'foo))\n\n"
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"(struct? x)\n"
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"@result{} #t\n"
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"(struct-vtable? x)\n"
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"@result{} #t\n"
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"(eq? x (struct-vtable x))\n"
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"@result{} #t\n"
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"(struct-ref x vtable-offset-user)\n"
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"@result{} foo\n"
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"(struct-ref x 0)\n"
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"@result{} pruosrpwpw\n\n\n"
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"(define y\n"
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" (make-struct x\n"
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" 0\n"
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" (make-struct-layout (quote pwpwpw))\n"
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" 'bar))\n\n"
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"(struct? y)\n"
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"@result{} #t\n"
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"(struct-vtable? y)\n"
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"@result{} #t\n"
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"(eq? x y)\n"
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"@result{} ()\n"
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"(eq? x (struct-vtable y))\n"
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"@result{} #t\n"
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"(struct-ref y 0)\n"
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"@result{} pwpwpw\n"
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"(struct-ref y vtable-offset-user)\n"
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"@result{} bar\n\n\n"
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"(define z (make-struct y 0 'a 'b 'c))\n\n"
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"(struct? z)\n"
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"@result{} #t\n"
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"(struct-vtable? z)\n"
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"@result{} ()\n"
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"(eq? y (struct-vtable z))\n"
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"@result{} #t\n"
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"(map (lambda (n) (struct-ref z n)) '(0 1 2))\n"
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"@result{} (a b c)\n"
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"(define ball-root (make-vtable-vtable \"pr\" 0))\n\n"
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"(define (make-ball-type ball-color)\n"
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" (make-struct ball-root 0\n"
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" (make-struct-layout \"pw\")\n"
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" (lambda (ball port)\n"
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" (format port \"#<a ~A ball owned by ~A>\"\n"
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" (color ball)\n"
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" (owner ball)))\n"
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" ball-color))\n"
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"(define (color ball) (struct-ref (struct-vtable ball) vtable-offset-user))\n"
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"(define (owner ball) (struct-ref ball 0))\n\n"
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"(define red (make-ball-type 'red))\n"
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"(define green (make-ball-type 'green))\n\n"
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"(define (make-ball type owner) (make-struct type 0 owner))\n\n"
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"(define ball (make-ball green 'Nisse))\n"
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"ball @result{} #<a green ball owned by Nisse>\n"
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"@end example\n"
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"")
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#define FUNC_NAME s_scm_make_vtable_vtable
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@ -471,12 +472,12 @@ SCM_DEFINE (scm_make_vtable_vtable, "make-vtable-vtable", 2, 0, 1,
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scm_bits_t * data;
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SCM handle;
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SCM_VALIDATE_ROSTRING (1,extra_fields);
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SCM_VALIDATE_INUM (2,tail_array_size);
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SCM_VALIDATE_ROSTRING (1, user_fields);
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SCM_VALIDATE_INUM (2, tail_array_size);
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SCM_VALIDATE_REST_ARGUMENT (init);
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fields = scm_string_append (scm_listify (required_vtable_fields,
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extra_fields,
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user_fields,
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SCM_UNDEFINED));
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layout = scm_make_struct_layout (fields);
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basic_size = SCM_LENGTH (layout) / 2;
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