From 5951bd365453f629b79418b8453a4ec1184a3041 Mon Sep 17 00:00:00 2001
From: Vitaly Bogdanov <vsbogd@gmail.com>
Date: Tue, 16 Apr 2024 16:43:31 +0300
Subject: [PATCH 1/2] Fix variable_operation feature to support nested
 expressions

---
 lib/src/metta/interpreter_minimal.rs | 26 ++++++++++++++++++++------
 lib/src/metta/old_interpreter.rs     | 10 ++++++++++
 2 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/lib/src/metta/interpreter_minimal.rs b/lib/src/metta/interpreter_minimal.rs
index 0aeec87df..8097fde52 100644
--- a/lib/src/metta/interpreter_minimal.rs
+++ b/lib/src/metta/interpreter_minimal.rs
@@ -517,12 +517,16 @@ fn call_to_stack(call: Atom, vars: Variables, prev: Option<Rc<RefCell<Stack>>>)
 #[cfg(not(feature = "variable_operation"))]
 fn is_variable_op(atom: &Atom) -> bool {
     match atom {
-        Atom::Expression(expr) => {
-            match expr.children().get(0) {
-                Some(Atom::Variable(_)) => true,
-                _ => false,
-            }
-        },
+        Atom::Expression(expr) => is_variable_op_expr(expr),
+        _ => false,
+    }
+}
+
+#[cfg(not(feature = "variable_operation"))]
+fn is_variable_op_expr(expr: &ExpressionAtom) -> bool {
+    match expr.children().get(0) {
+        Some(Atom::Variable(_)) => true,
+        Some(Atom::Expression(expr)) => is_variable_op_expr(expr),
         _ => false,
     }
 }
@@ -1486,6 +1490,16 @@ mod tests {
         assert_eq!(result[0], sym!("value"));
     }
 
+    #[test]
+    fn interpret_atom_evaluate_variable_operation_nested() {
+        let space = space("(= ((baz $a) $b) ($a $b))");
+        let result = call_interpret(&space, &metta_atom("(eval (($a A) B))"));
+        #[cfg(feature = "variable_operation")]
+        assert_eq!(result, vec![metta_atom("(A B)")]);
+        #[cfg(not(feature = "variable_operation"))]
+        assert_eq!(result, vec![NOT_REDUCIBLE_SYMBOL]);
+    }
+
 
     #[test]
     fn interpret_atom_chain_incorrect_args() {
diff --git a/lib/src/metta/old_interpreter.rs b/lib/src/metta/old_interpreter.rs
index 7f00b1e7c..c451d2700 100644
--- a/lib/src/metta/old_interpreter.rs
+++ b/lib/src/metta/old_interpreter.rs
@@ -317,6 +317,7 @@ fn is_grounded_op(expr: &ExpressionAtom) -> bool {
 fn is_variable_op(expr: &ExpressionAtom) -> bool {
     match expr.children().get(0) {
         Some(Atom::Variable(_)) => true,
+        Some(Atom::Expression(expr)) => is_variable_op(expr),
         _ => false,
     }
 }
@@ -1126,5 +1127,14 @@ mod tests {
         #[cfg(not(feature = "variable_operation"))]
         assert_eq!(actual, vec![expr!(op "arg")]);
     }
+
+    #[cfg(not(feature = "variable_operation"))]
+    #[test]
+    fn interpret_match_variable_operation_nested() {
+        let mut space = GroundingSpace::new();
+        space.add(expr!("=" (("baz" x) y) ("baz result" x y)));
+        let actual = interpret(&space, &expr!((op "arg1") "arg2")).unwrap();
+        assert_eq!(actual, vec![expr!((op "arg1") "arg2")]);
+    }
 }
 

From 0e261f47fdc4022236fae5714c2892a7949d54af Mon Sep 17 00:00:00 2001
From: Vitaly Bogdanov <vsbogd@gmail.com>
Date: Tue, 16 Apr 2024 17:01:39 +0300
Subject: [PATCH 2/2] Fix unit tests to pass when variable_operation feature is
 enabled

---
 lib/src/metta/runner/stdlib.rs         | 14 +++++++-------
 lib/src/metta/runner/stdlib_minimal.rs |  4 ++--
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/lib/src/metta/runner/stdlib.rs b/lib/src/metta/runner/stdlib.rs
index c4b90ff0d..4bc7714dd 100644
--- a/lib/src/metta/runner/stdlib.rs
+++ b/lib/src/metta/runner/stdlib.rs
@@ -2407,8 +2407,8 @@ mod tests {
     fn let_op_keep_variables_equalities_issue290() {
         assert_eq_metta_results!(run_program("!(let* (($f f) ($f $x)) $x)"), Ok(vec![vec![expr!("f")]]));
         assert_eq_metta_results!(run_program("!(let* (($f $x) ($f f)) $x)"), Ok(vec![vec![expr!("f")]]));
-        assert_eq_metta_results!(run_program("!(let ($x $x) ($z $y) (let $y A ($z $y)))"), Ok(vec![vec![expr!("A" "A")]]));
-        assert_eq_metta_results!(run_program("!(let ($x $x) ($z $y) (let $z A ($z $y)))"), Ok(vec![vec![expr!("A" "A")]]));
+        assert_eq_metta_results!(run_program("!(let (quote ($x $x)) (quote ($z $y)) (let $y A ($z $y)))"), Ok(vec![vec![expr!("A" "A")]]));
+        assert_eq_metta_results!(run_program("!(let (quote ($x $x)) (quote ($z $y)) (let $z A ($z $y)))"), Ok(vec![vec![expr!("A" "A")]]));
     }
 
     #[test]
@@ -2524,11 +2524,11 @@ mod tests {
 
     #[test]
     fn sealed_op_runner() {
-        let nested = run_program("!(sealed ($x) (sealed ($a $b) (= ($a $x $c) ($b))))");
-        let simple_replace = run_program("!(sealed ($x $y) (= ($y) ($z)))");
+        let nested = run_program("!(sealed ($x) (sealed ($a $b) (quote (= ($a $x $c) ($b)))))");
+        let simple_replace = run_program("!(sealed ($x $y) (quote (= ($y $z))))");
 
-        assert!(crate::atom::matcher::atoms_are_equivalent(&nested.unwrap()[0][0], &expr!("="(a b c) (z))));
-        assert!(crate::atom::matcher::atoms_are_equivalent(&simple_replace.unwrap()[0][0], &expr!("="(y) (z))));
+        assert!(crate::atom::matcher::atoms_are_equivalent(&nested.unwrap()[0][0], &expr!("quote" ("=" (a b c) (z)))));
+        assert!(crate::atom::matcher::atoms_are_equivalent(&simple_replace.unwrap()[0][0], &expr!("quote" ("=" (y z)))));
     }
 
     #[test]
@@ -2540,7 +2540,7 @@ mod tests {
     #[test]
     fn use_sealed_to_make_scoped_variable() {
         assert_eq!(run_program("!(let $x (input $x) (output $x))"), Ok(vec![vec![expr!("output" ("input" x))]]));
-        assert_eq!(run_program("!(let ($sv $st) (sealed ($x) ($x (output $x)))
+        assert_eq!(run_program("!(let (quote ($sv $st)) (sealed ($x) (quote ($x (output $x))))
                (let $sv (input $x) $st))"), Ok(vec![vec![expr!("output" ("input" x))]]));
     }
 
diff --git a/lib/src/metta/runner/stdlib_minimal.rs b/lib/src/metta/runner/stdlib_minimal.rs
index f11fffd08..cee8e71ef 100644
--- a/lib/src/metta/runner/stdlib_minimal.rs
+++ b/lib/src/metta/runner/stdlib_minimal.rs
@@ -597,7 +597,7 @@ mod tests {
     #[test]
     fn metta_cdr_atom() {
         assert_eq!(run_program(&format!("!(cdr-atom (a b c))")), Ok(vec![vec![expr!("b" "c")]]));
-        assert_eq!(run_program(&format!("!(cdr-atom ($a $b $c))")), Ok(vec![vec![expr!(b c)]]));
+        assert_eq!(run_program(&format!("!(cdr-atom ($a b $c))")), Ok(vec![vec![expr!("b" c)]]));
         assert_eq!(run_program(&format!("!(cdr-atom ())")), Ok(vec![vec![expr!("Error" ("cdr-atom" ()) {Str::from_str("cdr-atom expects a non-empty expression as an argument")})]]));
         assert_eq!(run_program(&format!("!(cdr-atom a)")), Ok(vec![vec![expr!("Error" ("cdr-atom" "a") {Str::from_str("cdr-atom expects a non-empty expression as an argument")})]]));
         assert_eq!(run_program(&format!("!(cdr-atom $a)")), Ok(vec![vec![expr!("Error" ("cdr-atom" a) {Str::from_str("cdr-atom expects a non-empty expression as an argument")})]]));
@@ -1052,7 +1052,7 @@ mod tests {
     #[test]
     fn use_sealed_to_make_scoped_variable() {
         assert_eq!(run_program("!(let $x (input $x) (output $x))"), Ok(vec![vec![]]));
-        assert_eq!(run_program("!(let ($sv $st) (sealed ($x) ($x (output $x)))
+        assert_eq!(run_program("!(let (quote ($sv $st)) (sealed ($x) (quote ($x (output $x))))
                (let $sv (input $x) $st))"), Ok(vec![vec![expr!("output" ("input" x))]]));
     }