libs/iovm/source/IoWeakLink.c

   1 /*#io
   2 WeakLink ioDoc(
   3                docCopyright("Steve Dekorte", 2002)
   4                docLicense("BSD revised")
   5                         docCategory("Core")
   6                docDescription("""A WeakLink is a primitive that can hold a reference to an object without preventing the garbage collector from collecting it. The link reference is set with the setLink() method. After the garbage collector collects an object, it informs any (uncollected) WeakLink objects whose link value pointed to that object by calling their "collectedLink" method.
   7 """)
   8                */
   9
  10 #include "IoWeakLink.h"
  11 #include "IoSeq.h"
  12 #include "IoState.h"
  13 #include "IoObject.h"
  14 #include "IoNumber.h"
  15
  16 #define DATA(self) ((IoWeakLinkData *)IoObject_dataPointer(self))
  17
  18 IoTag *IoWeakLink_newTag(void *state)
  19 {
  20         IoTag *tag = IoTag_newWithName_("WeakLink");
  21         IoTag_state_(tag, state);
  22         IoTag_cloneFunc_(tag, (IoTagCloneFunc *)IoWeakLink_rawClone);
  23         IoTag_freeFunc_(tag, (IoTagFreeFunc *)IoWeakLink_free);
  24         IoTag_notificationFunc_(tag, (IoTagNotificationFunc *)IoWeakLink_notification);
  25         IoTag_writeToStreamFunc_(tag, (IoTagWriteToStreamFunc *)IoWeakLink_writeToStream_);
  26         IoTag_readFromStreamFunc_(tag, (IoTagReadFromStreamFunc *)IoWeakLink_readFromStream_);
  27         return tag;
  28 }
  29
  30 void IoWeakLink_writeToStream_(IoWeakLink *self, BStream *stream)
  31 {
  32         if (DATA(self)->link)
  33         {
  34                 BStream_writeTaggedInt32_(stream, IoObject_pid(DATA(self)->link));
  35         }
  36         else
  37         {
  38                 BStream_writeTaggedInt32_(stream, 0);
  39         }
  40 }
  41
  42 void IoWeakLink_readFromStream_(IoWeakLink *self, BStream *stream)
  43 {
  44         PID_TYPE linkid = BStream_readTaggedInt32(stream);
  45
  46         if (linkid != 0)
  47         {
  48                 IoObject *link = IoState_objectWithPid_(IOSTATE, linkid);
  49                 IoWeakLink_rawSetLink(self, link);
  50         }
  51 }
  52
  53 IoObject *IoWeakLink_proto(void *state)
  54 {
  55         IoMethodTable methodTable[] = {
  56         {"setLink", IoWeakLink_setLink},
  57         {"link", IoWeakLink_link},
  58         {NULL, NULL},
  59         };
  60
  61         IoObject *self = IoObject_new(state);
  62
  63         IoObject_setDataPointer_(self, io_calloc(1, sizeof(IoWeakLinkData)));
  64         IoObject_tag_(self, IoWeakLink_newTag(state));
  65         DATA(self)->link = NULL;
  66         IoState_registerProtoWithFunc_((IoState *)state, self, IoWeakLink_proto);
  67
  68         IoObject_addMethodTable_(self, methodTable);
  69         return self;
  70 }
  71
  72 IoObject *IoWeakLink_rawClone(IoWeakLink *proto)
  73 {
  74         IoObject *self = IoObject_rawClonePrimitive(proto);
  75         IoObject_setDataPointer_(self, io_calloc(1, sizeof(IoWeakLinkData)));
  76         DATA(self)->link = NULL;
  77         return self;
  78 }
  79
  80 IoObject *IoWeakLink_new(void *state)
  81 {
  82         IoObject *proto = IoState_protoWithInitFunction_((IoState *)state, IoWeakLink_proto);
  83         return IOCLONE(proto);
  84 }
  85
  86 void IoWeakLink_rawStopListening(IoWeakLink *self)
  87 {
  88         if (DATA(self)->link) IoObject_removeListener_(DATA(self)->link, self);
  89 }
  90
  91 void IoWeakLink_free(IoWeakLink *self)
  92 {
  93         IoWeakLink_rawStopListening(self);
  94         io_free(IoObject_dataPointer(self));
  95 }
  96
  97 IoObject *IoWeakLink_newWithValue_(void *state, IoObject *v)
  98 {
  99         IoObject *self = IoWeakLink_new(state);
 100         DATA(self)->link = v;
 101         return self;
 102 }
 103
 104 void IoWeakLink_notification(IoWeakLink *self, void *notification) // called when link is freed
 105 {
 106         DATA(self)->link = NULL;
 107         //IoMessage_locals_performOn_(IOSTATE->collectedLinkMessage, self, self);
 108 }
 109
 110 // -----------------------------------------------------------
 111
 112 IoObject *IoWeakLink_setLink(IoWeakLink *self, IoObject *locals, IoMessage *m)
 113 {
 114         /*#io
 115         docSlot("setLink(aValue)", "Sets the link pointer. Returns self.")
 116         */
 117
 118         IoWeakLink_rawSetLink(self, IoMessage_locals_valueArgAt_(m, locals, 0));
 119         return self;
 120 }
 121
 122 void IoWeakLink_rawSetLink(IoWeakLink *self, IoObject *v)
 123 {
 124         IoWeakLink_rawStopListening(self);
 125
 126         if (ISNIL(v))
 127         {
 128                 DATA(self)->link = NULL;
 129         }
 130         else
 131         {
 132                 DATA(self)->link = v; // no IOREF needed since this is a weak link
 133                 IoObject_addListener_(v, self);
 134         }
 135 }
 136
 137 IoObject *IoWeakLink_link(IoWeakLink *self, IoObject *locals, IoMessage *m)
 138 {
 139         /*#io
 140         docSlot("link", "Returns the link pointer or Nil if none is set.")
 141         */
 142
 143         IoObject *v = DATA(self)->link;
 144         return v ? v : IONIL(self);
 145 }
 146