Runtime: proper semantic for weak

CHANGES.md

@@ -7,6 +7,7 @@
 * Misc: use 4.14 in the CI
 * Lib: add missing options for Intl.DateTimeFormat
 * Lib: add missing options for Intl.NumberFormat
+* Runtime: Implement weak semantic for weak and ephemeron
 
 ## Bug fixes
 * Compiler: fix rewriter bug in share_constant (fix #1247)

README.md

@@ -72,8 +72,6 @@ js_of_ocaml cubes.byte
 
 Most of the OCaml standard library is supported. However,
 
-- Weak semantic cannot be implemented using JavaScript. A dummy implementation
-  is provided.
 - Most of the Sys module is not supported.
 
 Extra libraries distributed with OCaml (such as Thread) are not supported in

manual/overview.wiki

@@ -60,8 +60,6 @@ You can find an OCaml toplevel running in the browser <<a_file src="toplevel/ind
 == Supported features ==
 
 Most of the OCaml standard library is supported. However,
-  * Weak semantic cannot be implemented using JavaScript.
-    A dummy implementation is provided.
   * Most of Sys module is not supported.
 
 Extra libraries distributed with Ocaml (such as Thread) are not

runtime/weak.js

@@ -17,16 +17,60 @@
 // along with this program; if not, write to the Free Software
 // Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 
-// Weak API, but without the weak semantics
+// Weak API
 
 //Provides: caml_ephe_key_offset
 var caml_ephe_key_offset = 3
 
 //Provides: caml_ephe_data_offset
 var caml_ephe_data_offset = 2
 
+//Provides: caml_ephe_set_key
+//Requires: caml_invalid_argument, caml_ephe_key_offset
+function caml_ephe_set_key(x, i, v) {
+  if(i < 0 || caml_ephe_key_offset + i >= x.length)
+    caml_invalid_argument ("Weak.set");
+  if (v instanceof Object && globalThis.WeakRef) {
+    if(x[1].register) x[1].register(v, undefined, v);
+    x[caml_ephe_key_offset + i] = new globalThis.WeakRef(v);
+  }
+  else x[caml_ephe_key_offset + i] = v;
+  return 0
+}
+
+//Provides: caml_ephe_unset_key
+//Requires: caml_invalid_argument, caml_ephe_key_offset
+function caml_ephe_unset_key(x, i) {
+  if(i < 0 || caml_ephe_key_offset + i >= x.length)
+    caml_invalid_argument ("Weak.set");
+  if(globalThis.WeakRef && x[caml_ephe_key_offset + i] instanceof globalThis.WeakRef && x[1].unregister) {
+    var old = x[caml_ephe_key_offset + i].deref();
+    if(old !== undefined) {
+      var count = 0
+      for(var j = caml_ephe_key_offset; j < x.length; j++){
+        var key = x[j];
+        if(key instanceof globalThis.WeakRef){
+          key = key.deref()
+          if(key === old) count++;
+        }
+      }
+      if(count == 1) x[1].unregister(old);
+    }
+  }
+  x[caml_ephe_key_offset + i] = undefined;
+  return 0
+}
+
+
+//Provides: caml_ephe_create
+//Requires: caml_weak_create, caml_ephe_data_offset
+function caml_ephe_create (n) {
+  var x = caml_weak_create(n);
+  return x;
+}
+
 //Provides: caml_weak_create
-//Requires: caml_ephe_key_offset, caml_invalid_argument
+//Requires: caml_ephe_key_offset, caml_invalid_argument,caml_ephe_data_offset
 function caml_weak_create (n) {
   if (n < 0) caml_invalid_argument ("Weak.create");
   var x = [251,"caml_ephe_list_head"];
@@ -35,89 +79,80 @@ function caml_weak_create (n) {
 }
 
 //Provides: caml_weak_set
-//Requires: caml_ephe_key_offset, caml_invalid_argument
+//Requires: caml_invalid_argument
+//Requires: caml_ephe_set_key, caml_ephe_unset_key
 function caml_weak_set(x, i, v) {
-  if(i < 0 || caml_ephe_key_offset + i >= x.length)
-    caml_invalid_argument ("Weak.set");
-  x[caml_ephe_key_offset + i] = v;
+  if(v == 0) caml_ephe_unset_key(x,i)
+  else caml_ephe_set_key(x,i,v[1])
   return 0;
 }
-//Provides: caml_weak_get
+//Provides: caml_ephe_get_key
 //Requires: caml_ephe_key_offset, caml_invalid_argument
-function caml_weak_get(x, i) {
+function caml_ephe_get_key(x, i) {
   if(i < 0 || caml_ephe_key_offset + i >= x.length)
     caml_invalid_argument ("Weak.get_key");
-  return (x[caml_ephe_key_offset + i ]===undefined)?0:x[caml_ephe_key_offset + i];
+  var weak = x[caml_ephe_key_offset + i ];
+  if(globalThis.WeakRef && weak instanceof globalThis.WeakRef) weak = weak.deref();
+  return (weak===undefined)?0:[0, weak];
 }
-//Provides: caml_weak_get_copy
-//Requires: caml_weak_get,caml_ephe_key_offset
+//Provides: caml_ephe_get_key_copy
+//Requires: caml_ephe_get_key,caml_ephe_key_offset
 //Requires: caml_obj_dup, caml_invalid_argument
-function caml_weak_get_copy(x, i) {
+function caml_ephe_get_key_copy(x, i) {
   if(i < 0 || caml_ephe_key_offset + i >= x.length)
     caml_invalid_argument ("Weak.get_copy");
-  var y = caml_weak_get(x, i);
+  var y = caml_ephe_get_key(x, i);
   if (y === 0) return y;
   var z = y[1];
   if (z instanceof Array) return [0, caml_obj_dup(z)];
   return y;
 }
 
-//Provides: caml_weak_check mutable
+//Provides: caml_ephe_check_key mutable
 //Requires: caml_ephe_key_offset
-function caml_weak_check(x, i) {
-  if(x[caml_ephe_key_offset + i]!==undefined && x[caml_ephe_key_offset + i] !==0)
-    return 1;
-  else
+function caml_ephe_check_key(x, i) {
+  var weak = x[caml_ephe_key_offset + i];
+  if(globalThis.WeakRef && weak instanceof globalThis.WeakRef) weak = weak.deref();
+  if(weak===undefined)
     return 0;
+  else
+    return 1;
 }
 
-//Provides: caml_weak_blit
+//Provides: caml_ephe_blit_key
 //Requires: caml_array_blit
 //Requires: caml_ephe_key_offset
-function caml_weak_blit(a1, i1, a2, i2, len) {
+function caml_ephe_blit_key(a1, i1, a2, i2, len) {
   // minus one because caml_array_blit works on ocaml array
   caml_array_blit(a1, caml_ephe_key_offset + i1 - 1,
                   a2, caml_ephe_key_offset + i2 - 1,
                   len);
   return 0;
 }
 
-//Provides: caml_ephe_create
-//Requires: caml_weak_create
-var caml_ephe_create = caml_weak_create
-
-//Provides: caml_ephe_blit_key
-//Requires: caml_weak_blit
-var caml_ephe_blit_key = caml_weak_blit
-
-//Provides: caml_ephe_get_key
-//Requires: caml_weak_get
-var caml_ephe_get_key = caml_weak_get
+//Provides: caml_weak_blit
+//Requires: caml_ephe_blit_key
+var caml_weak_blit = caml_ephe_blit_key
 
-//Provides: caml_ephe_get_key_copy
-//Requires: caml_weak_get_copy
-var caml_ephe_get_key_copy = caml_weak_get_copy
+//Provides: caml_weak_get
+//Requires: caml_ephe_get_key
+var caml_weak_get = caml_ephe_get_key
 
-//Provides: caml_ephe_check_key
-//Requires: caml_weak_check
-var caml_ephe_check_key = caml_weak_check
 
-//Provides: caml_ephe_set_key
-//Requires: caml_weak_set
-function caml_ephe_set_key(x, i, v) {
-  return caml_weak_set(x, i, [0, v])
-}
+//Provides: caml_weak_get_copy
+//Requires: caml_ephe_get_key_copy
+var caml_weak_get_copy = caml_ephe_get_key_copy
 
-//Provides: caml_ephe_unset_key
-//Requires: caml_weak_set
-function caml_ephe_unset_key(x, i) {
-  return caml_weak_set(x, i, 0)
-}
+//Provides: caml_weak_check
+//Requires: caml_ephe_check_key
+var caml_weak_check = caml_ephe_check_key
 
 //Provides: caml_ephe_blit_data
-//Requires: caml_ephe_data_offset
+//Requires: caml_ephe_data_offset, caml_ephe_set_data, caml_ephe_unset_data
 function caml_ephe_blit_data(src, dst){
-  dst[caml_ephe_data_offset] = src[caml_ephe_data_offset];
+  var n = src[caml_ephe_data_offset];
+  if(n === undefined) caml_ephe_unset_data(dst);
+  else caml_ephe_set_data(dst, n);
   return 0;
 }
 
@@ -141,15 +176,40 @@ function caml_ephe_get_data_copy(x){
 }
 
 //Provides: caml_ephe_set_data
-//Requires: caml_ephe_data_offset
+//Requires: caml_ephe_data_offset, caml_ephe_key_offset, caml_ephe_unset_data
 function caml_ephe_set_data(x, data){
+  if(globalThis.FinalizationRegistry && globalThis.WeakRef) {
+    if(! (x[1] instanceof globalThis.FinalizationRegistry)) {
+      x[1] = new globalThis.FinalizationRegistry(function () { caml_ephe_unset_data(x) });
+      //register all keys
+      for(var j = caml_ephe_key_offset; j < x.length; j++){
+        var key = x[j];
+        if(key instanceof globalThis.WeakRef) {
+          key = key.deref();
+          if(key) x[1].register(key, undefined, key);
+        }
+      }
+    }
+  }
   x[caml_ephe_data_offset] = data;
   return 0;
 }
 
 //Provides: caml_ephe_unset_data
-//Requires: caml_ephe_data_offset
-function caml_ephe_unset_data(x, data){
+//Requires: caml_ephe_data_offset, caml_ephe_key_offset
+function caml_ephe_unset_data(x){
+  if(globalThis.FinalizationRegistry && globalThis.WeakRef) {
+    if(x[1] instanceof globalThis.FinalizationRegistry){
+      //unregister all keys
+      for(var j = caml_ephe_key_offset; j < x.length; j++){
+        var key = x[j];
+        if(key instanceof globalThis.WeakRef) {
+          key = key.deref();
+          if(key) x[1].unregister(key);
+        }
+      }
+    }
+  }
   x[caml_ephe_data_offset] = undefined;
   return 0;
 }