always print a space between prefix operator and its operand

src/heap_print.rs

@@ -590,31 +590,21 @@ impl<'a, Outputter: HCValueOutputter> HCPrinter<'a, Outputter> {
                 right_directed_op,
             ));
         } else if is_prefix!(spec.get_spec()) {
-            match name {
-                atom!("-") | atom!("\\") => {
-                    self.format_prefix_op_with_space(max_depth, name, spec);
-                    return;
-                }
-                _ => {}
-            };
-
             if self.check_max_depth(&mut max_depth) {
                 self.iter.pop_stack();
 
                 self.state_stack.push(TokenOrRedirect::Atom(atom!("...")));
-                self.state_stack.push(TokenOrRedirect::Op(name, spec));
+                self.state_stack.push(TokenOrRedirect::Space);
+                self.state_stack.push(TokenOrRedirect::Atom(name));
 
                 return;
             }
 
-            let left_directed_op = DirectedOp::Left(name, spec);
+            let op = DirectedOp::Left(name, spec);
 
-            self.state_stack.push(TokenOrRedirect::CompositeRedirect(
+            self.state_stack.push(TokenOrRedirect::CompositeRedirect(max_depth, op));
-                max_depth,
+            self.state_stack.push(TokenOrRedirect::Space);
-                left_directed_op,
+            self.state_stack.push(TokenOrRedirect::Atom(name));
-            ));
-
-            self.state_stack.push(TokenOrRedirect::Op(name, spec));
         } else {
             match name.as_str() {
                 "|" => {
@@ -687,24 +677,6 @@ impl<'a, Outputter: HCValueOutputter> HCPrinter<'a, Outputter> {
         true
     }
 
-    fn format_prefix_op_with_space(&mut self, mut max_depth: usize, name: Atom, spec: OpDesc) {
-        if self.check_max_depth(&mut max_depth) {
-            self.iter.pop_stack();
-
-            self.state_stack.push(TokenOrRedirect::Atom(atom!("...")));
-            self.state_stack.push(TokenOrRedirect::Space);
-            self.state_stack.push(TokenOrRedirect::Atom(name));
-
-            return;
-        }
-
-        let op = DirectedOp::Left(name, spec);
-
-        self.state_stack.push(TokenOrRedirect::CompositeRedirect(max_depth, op));
-        self.state_stack.push(TokenOrRedirect::Space);
-        self.state_stack.push(TokenOrRedirect::Atom(name));
-    }
-
     fn format_bar_separator_op(&mut self, mut max_depth: usize, name: Atom, spec: OpDesc) {
         if self.check_max_depth(&mut max_depth) {
             self.iter.pop_stack();
@@ -1348,8 +1320,10 @@ impl<'a, Outputter: HCValueOutputter> HCPrinter<'a, Outputter> {
             self.state_stack.push(TokenOrRedirect::Open);
 
             if let Some(ref op) = &op {
-                if op.is_left() && requires_space(op.as_atom().as_str(), "(") {
+                if !self.outputter.ends_with(" ") {
-                    self.state_stack.push(TokenOrRedirect::Space);
+                    if op.is_left() && requires_space(op.as_atom().as_str(), "(") {
+                        self.state_stack.push(TokenOrRedirect::Space);
+                    }
                 }
             }
         }

tests-pl/iso-conformity-tests.pl

@@ -341,7 +341,7 @@ test_67 :- setup_call_cleanup((  current_op(P,fy,+),
                               op(P,fy,+)).
 
 test_257 :- writeq_term_to_chars([+{a},+[]], Chars),
-            Chars == "[+{a},+[]]".
+            Chars == "[+ {a},+ []]".
 
 test_68 :- [(:-)|(:-)]=[:-|:-].
 
@@ -568,7 +568,7 @@ test_131_132_133 :-
                           C0 == "' op' '1 '",
                           read_from_chars("' op'[].", T1),
                           writeq_term_to_chars(T1, C1),
-                          C1 == "' op'[]"
+                          C1 == "' op' []"
                        ),
                        op(0, fx, ' op')
                       ).
@@ -932,7 +932,7 @@ test_274_275 :-
     setup_call_cleanup(op(20,fx,--),
                        (  read_from_chars("--(a).", T0),
                           writeq_term_to_chars(T0, C0),
-                          C0 == "--a",
+                          C0 == "-- a",
                           op(0,fx,--),
                           read_from_chars("--(a).", T1),
                           writeq_term_to_chars(T1, C1),
@@ -981,7 +981,7 @@ test_305 :- writeq_term_to_chars(\ (a = b), C),
             C == "\\ (a=b)".
 
 test_306 :- writeq_term_to_chars(+ (a = b), C),
-            C == "+(a=b)".
+            C == "+ (a=b)".
 
 test_307 :- writeq_term_to_chars([/**/], C),
             C == "[]".