Merge branch 'master' into doc/update-readme-wasm-example

src/heap_print.rs

@@ -874,12 +874,16 @@ impl<'a, Outputter: HCValueOutputter> HCPrinter<'a, Outputter> {
                                 None => {
                                     if self.max_depth == 0 || *max_depth == 0 {
                                         // otherwise, contract it to an ellipsis.
-                                        push_space_if_amb!(self, "...", {
-                                            append_str!(self, "...");
-                                        });
+                                        self.state_stack.push(TokenOrRedirect::Atom(atom!("...")));
                                     } else {
                                         debug_assert!(cell.is_ref());
 
+                                        let h = cell.get_value() as usize;
+                                        self.iter.push_stack(IterStackLoc::iterable_loc(
+                                            h,
+                                            HeapOrStackTag::Heap,
+                                        ));
+
                                         // as usual, the WAM's
                                         // optimization of the Lis tag
                                         // (conflating the location of
@@ -889,15 +893,17 @@ impl<'a, Outputter: HCValueOutputter> HCPrinter<'a, Outputter> {
                                         // lest we find ourselves in
                                         // an infinite loop.
                                         if cell.get_tag() == HeapCellValueTag::Lis {
-                                            *max_depth -= 1;
+                                            if self.iter.heap[cell.get_value() as usize]
+                                                .get_forwarding_bit()
+                                            {
+                                                self.state_stack
+                                                    .push(TokenOrRedirect::Atom(atom!("...")));
+                                                return None;
+                                            } else {
+                                                *max_depth -= 1;
+                                            }
                                         }
 
-                                        let h = cell.get_value() as usize;
-                                        self.iter.push_stack(IterStackLoc::iterable_loc(
-                                            h,
-                                            HeapOrStackTag::Heap,
-                                        ));
-
                                         if let Some(cell) = self.iter.next() {
                                             orig_cell = cell;
                                             continue;

src/lib/charsio.pl

@@ -195,7 +195,7 @@ get_single_char(C) :-
     ;  type_error(in_character, C, get_single_char/1)
     ).
 
-%% read_from_chars(+Chars, -Term).
+%% read_from_chars(+Chars, ?Term).
 %
 % Given a string made of chars which contains a representation of
 % a Prolog term, Term is the Prolog term represented. Example:
@@ -206,10 +206,10 @@ get_single_char(C) :-
 % ```
 read_from_chars(Chars, Term) :-
     must_be(chars, Chars),
-    must_be(var, Term),
-    '$read_from_chars'(Chars, Term).
+    '$read_from_chars'(Chars, Term0),
+    Term = Term0.
 
-%% read_term_from_chars(+Chars, -Term, +Options).
+%% read_term_from_chars(+Chars, ?Term, +Options).
 %
 % Like `read_from_chars`, except the reader is configured according to
 % `Options` which are those of `read_term`.
@@ -220,9 +220,9 @@ read_from_chars(Chars, Term) :-
 % ```
 read_term_from_chars(Chars, Term, Options) :-
     must_be(chars, Chars),
-    must_be(var, Term),
     builtins:parse_read_term_options(Options, [Singletons, VariableNames, Variables], read_term_from_chars/3),
-    '$read_term_from_chars'(Chars, Term, Singletons, Variables, VariableNames).
+    '$read_term_from_chars'(Chars, Term0, Singletons, Variables, VariableNames),
+    Term = Term0.
 
 %% write_term_to_chars(+Term, +Options, -Chars).
 %

src/wasm.rs

@@ -78,6 +78,7 @@ impl WasmMachine {
             ),
         }
         .into();
+        self_iterable(&query_state);
 
         Ok(query_state)
     }
@@ -174,6 +175,21 @@ impl WasmQueryState {
     }
 }
 
+/// Sets a [JsValue] as the `Symbol.iterator` property of the [JsValue].
+///
+/// If the [JsValue] conforms to the [JavaScript iterator interface](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Iterators_and_generators),
+/// this function will make the [JsValue] iterable.
+#[wasm_bindgen(inline_js = "
+    export function self_iterable(obj) {
+        obj[Symbol.iterator] = function () {
+            return this;
+        };
+    }
+")]
+extern "C" {
+    fn self_iterable(obj: &JsValue);
+}
+
 impl From<LeafAnswer> for JsValue {
     fn from(leaf_answer: LeafAnswer) -> JsValue {
         match leaf_answer {