Min max size functions added

lib/src/metta/runner/stdlib.metta

@@ -415,6 +415,24 @@
     (@param "Tail of an expression")))
   (@return "New expression consists of two input arguments"))
 
+(@doc min-atom
+  (@desc "Returns atom with min value in the expression (first argument). Only numbers allowed")
+  (@params (
+    (@param "Expression")))
+  (@return "Min value in the expression. Error if expression contains non-numeric value or is empty"))
+
+(@doc max-atom
+  (@desc "Returns atom with max value in the expression (first argument). Only numbers allowed")
+  (@params (
+    (@param "Expression")))
+  (@return "Max value in the expression. Error if expression contains non-numeric value or is empty"))
+
+(@doc size-atom
+  (@desc "Returns size of an expression (first argument)")
+  (@params (
+    (@param "Expression")))
+  (@return "Size of an expression"))
+
 (@doc index-atom
   (@desc "Returns atom from an expression (first argument) using index (second argument) or error if index is out of bounds")
   (@params (

lib/src/metta/runner/stdlib.rs

@@ -1161,6 +1161,94 @@ impl CustomExecute for IntersectionAtomOp {
     }
 }
 
+#[derive(Clone, Debug)]
+pub struct MaxAtomOp {}
+
+grounded_op!(MaxAtomOp, "max-atom");
+
+impl Grounded for MaxAtomOp {
+    fn type_(&self) -> Atom {
+        Atom::expr([ARROW_SYMBOL, ATOM_TYPE_EXPRESSION, ATOM_TYPE_ATOM])
+    }
+
+    fn as_execute(&self) -> Option<&dyn CustomExecute> {
+        Some(self)
+    }
+}
+
+impl CustomExecute for MaxAtomOp {
+    fn execute(&self, args: &[Atom]) -> Result<Vec<Atom>, ExecError> {
+        let arg_error = || ExecError::from("max-atom expects one argument: expression");
+        let children = TryInto::<&ExpressionAtom>::try_into(args.get(0).ok_or_else(arg_error)?)?.children();
+        for x in children.iter() {
+            match AsPrimitive::from_atom(x).as_number() {
+                None => Err(ExecError::from("Only numbers allowed in expression")),
+                _ => Ok({}),
+            }?
+        };
+        match children.into_iter().map(|x| Into::<f64>::into(AsPrimitive::from_atom(x).as_number().unwrap())).reduce(f64::max) {
+            Some(max) => Ok(vec![Atom::gnd(Number::Float(max))]),
+            None      => Err(ExecError::from("Empty expression")),
+        }
+    }
+}
+
+#[derive(Clone, Debug)]
+pub struct MinAtomOp {}
+
+grounded_op!(MinAtomOp, "min-atom");
+
+impl Grounded for MinAtomOp {
+    fn type_(&self) -> Atom {
+        Atom::expr([ARROW_SYMBOL, ATOM_TYPE_EXPRESSION, ATOM_TYPE_ATOM])
+    }
+
+    fn as_execute(&self) -> Option<&dyn CustomExecute> {
+        Some(self)
+    }
+}
+
+impl CustomExecute for MinAtomOp {
+    fn execute(&self, args: &[Atom]) -> Result<Vec<Atom>, ExecError> {
+        let arg_error = || ExecError::from("min-atom expects one argument: expression");
+        let children = TryInto::<&ExpressionAtom>::try_into(args.get(0).ok_or_else(arg_error)?)?.children();
+        for x in children.iter() {
+            match AsPrimitive::from_atom(x).as_number() {
+                None => Err(ExecError::from("Only numbers allowed in expression")),
+                _ => Ok({}),
+            }?
+        };
+        match children.into_iter().map(|x| Into::<f64>::into(AsPrimitive::from_atom(x).as_number().unwrap())).reduce(f64::min) {
+            Some(min) => Ok(vec![Atom::gnd(Number::Float(min))]),
+            None      => Err(ExecError::from("Empty expression")),
+        }
+    }
+}
+
+#[derive(Clone, Debug)]
+pub struct SizeAtomOp {}
+
+grounded_op!(SizeAtomOp, "size-atom");
+
+impl Grounded for SizeAtomOp {
+    fn type_(&self) -> Atom {
+        Atom::expr([ARROW_SYMBOL, ATOM_TYPE_EXPRESSION, ATOM_TYPE_NUMBER])
+    }
+
+    fn as_execute(&self) -> Option<&dyn CustomExecute> {
+        Some(self)
+    }
+}
+
+impl CustomExecute for SizeAtomOp {
+    fn execute(&self, args: &[Atom]) -> Result<Vec<Atom>, ExecError> {
+        let arg_error = || ExecError::from("size-atom expects one argument: expression");
+        let children = TryInto::<&ExpressionAtom>::try_into(args.get(0).ok_or_else(arg_error)?)?.children();
+        let size = children.len();
+        Ok(vec![Atom::gnd(Number::Integer(size as i64))])
+    }
+}
+
 #[derive(Clone, Debug)]
 pub struct IndexAtomOp {}
 
@@ -1829,6 +1917,12 @@ mod non_minimal_only_stdlib {
         tref.register_token(regex(r"cdr-atom"), move |_| { cdr_atom_op.clone() });
         let cons_atom_op = Atom::gnd(ConsAtomOp{});
         tref.register_token(regex(r"cons-atom"), move |_| { cons_atom_op.clone() });
+        let max_atom_op = Atom::gnd(MaxAtomOp{});
+        tref.register_token(regex(r"max-atom"), move |_| { max_atom_op.clone() });
+        let min_atom_op = Atom::gnd(MinAtomOp{});
+        tref.register_token(regex(r"min-atom"), move |_| { min_atom_op.clone() });
+        let size_atom_op = Atom::gnd(SizeAtomOp{});
+        tref.register_token(regex(r"size-atom"), move |_| { size_atom_op.clone() });
         let index_atom_op = Atom::gnd(IndexAtomOp{});
         tref.register_token(regex(r"index-atom"), move |_| { index_atom_op.clone() });
         let random_int_op = Atom::gnd(RandomIntOp{});
@@ -2122,6 +2216,34 @@ mod tests {
         assert_eq!(res, vec![expr!(("A" "F") ("B" "C") "D")]);
     }
 
+    #[test]
+    fn size_atom_op() {
+        let res = SizeAtomOp{}.execute(&mut vec![expr!({Number::Integer(5)} {Number::Integer(4)} {Number::Integer(3)} {Number::Integer(2)} {Number::Integer(1)})]).expect("No result returned");
+        assert_eq!(res, vec![expr!({Number::Integer(5)})]);
+        let res = SizeAtomOp{}.execute(&mut vec![expr!()]).expect("No result returned");
+        assert_eq!(res, vec![expr!({Number::Integer(0)})]);
+    }
+
+    #[test]
+    fn min_atom_op() {
+        let res = MinAtomOp{}.execute(&mut vec![expr!({Number::Integer(5)} {Number::Integer(4)} {Number::Float(5.5)})]).expect("No result returned");
+        assert_eq!(res, vec![expr!({Number::Integer(4)})]);
+        let res = MinAtomOp{}.execute(&mut vec![expr!({Number::Integer(5)} {Number::Integer(4)} "A")]);
+        assert_eq!(res, Err(ExecError::from("Only numbers allowed in expression")));
+        let res = MinAtomOp{}.execute(&mut vec![expr!()]);
+        assert_eq!(res, Err(ExecError::from("Empty expression")));
+    }
+
+    #[test]
+    fn max_atom_op() {
+        let res = MaxAtomOp{}.execute(&mut vec![expr!({Number::Integer(5)} {Number::Integer(4)} {Number::Float(5.5)})]).expect("No result returned");
+        assert_eq!(res, vec![expr!({Number::Float(5.5)})]);
+        let res = MaxAtomOp{}.execute(&mut vec![expr!({Number::Integer(5)} {Number::Integer(4)} "A")]);
+        assert_eq!(res, Err(ExecError::from("Only numbers allowed in expression")));
+        let res = MaxAtomOp{}.execute(&mut vec![expr!()]);
+        assert_eq!(res, Err(ExecError::from("Empty expression")));
+    }
+
     #[test]
     fn index_atom_op() {
         let res = IndexAtomOp{}.execute(&mut vec![expr!({Number::Integer(5)} {Number::Integer(4)} {Number::Integer(3)} {Number::Integer(2)} {Number::Integer(1)}), expr!({Number::Integer(2)})]).expect("No result returned");

lib/src/metta/runner/stdlib_minimal.metta

@@ -72,6 +72,24 @@
   (@return "Deconsed expression"))
 (: decons-atom (-> Expression Expression))
 
+(@doc min-atom
+  (@desc "Returns atom with min value in the expression (first argument). Only numbers allowed")
+  (@params (
+    (@param "Expression")))
+  (@return "Min value in the expression. Error if expression contains non-numeric value or is empty"))
+
+(@doc max-atom
+  (@desc "Returns atom with max value in the expression (first argument). Only numbers allowed")
+  (@params (
+    (@param "Expression")))
+  (@return "Max value in the expression. Error if expression contains non-numeric value or is empty"))
+
+(@doc size-atom
+  (@desc "Returns size of an expression (first argument)")
+  (@params (
+    (@param "Expression")))
+  (@return "Size of an expression"))
+
 (@doc index-atom
   (@desc "Returns atom from an expression (first argument) using index (second argument) or error if index is out of bounds")
   (@params (

lib/src/metta/runner/stdlib_minimal.rs

@@ -432,6 +432,12 @@ pub fn register_common_tokens(tref: &mut Tokenizer, _tokenizer: Shared<Tokenizer
     tref.register_token(regex(r"nop"), move |_| { nop_op.clone() });
     let match_op = Atom::gnd(stdlib::MatchOp{});
     tref.register_token(regex(r"match"), move |_| { match_op.clone() });
+    let min_atom_op = Atom::gnd(stdlib::MinAtomOp{});
+    tref.register_token(regex(r"min-atom"), move |_| { min_atom_op.clone() });
+    let max_atom_op = Atom::gnd(stdlib::MaxAtomOp{});
+    tref.register_token(regex(r"max-atom"), move |_| { max_atom_op.clone() });
+    let size_atom_op = Atom::gnd(stdlib::SizeAtomOp{});
+    tref.register_token(regex(r"size-atom"), move |_| { size_atom_op.clone() });
     let index_atom_op = Atom::gnd(stdlib::IndexAtomOp{});
     tref.register_token(regex(r"index-atom"), move |_| { index_atom_op.clone() });
     let random_int_op = Atom::gnd(stdlib::RandomIntOp{});
@@ -621,6 +627,26 @@ mod tests {
         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")})]]));
     }
 
+    #[test]
+    fn metta_size_atom() {
+        assert_eq!(run_program(&format!("!(size-atom (5 4 3 2 1))")), Ok(vec![vec![expr!({Number::Integer(5)})]]));
+        assert_eq!(run_program(&format!("!(size-atom ())")), Ok(vec![vec![expr!({Number::Integer(0)})]]));
+    }
+
+    #[test]
+    fn metta_min_atom() {
+        assert_eq!(run_program(&format!("!(min-atom (5 4 5.5))")), Ok(vec![vec![expr!({Number::Integer(4)})]]));
+        assert_eq!(run_program(&format!("!(min-atom ())")), Ok(vec![vec![expr!("Error" ({ stdlib::MinAtomOp{} } ()) "Empty expression")]]));
+        assert_eq!(run_program(&format!("!(min-atom (3 A B 5))")), Ok(vec![vec![expr!("Error" ({ stdlib::MinAtomOp{} } ({Number::Integer(3)} "A" "B" {Number::Integer(5)})) "Only numbers allowed in expression")]]));
+    }
+
+    #[test]
+    fn metta_max_atom() {
+        assert_eq!(run_program(&format!("!(max-atom (5 4 5.5))")), Ok(vec![vec![expr!({Number::Float(5.5)})]]));
+        assert_eq!(run_program(&format!("!(max-atom ())")), Ok(vec![vec![expr!("Error" ({ stdlib::MaxAtomOp{} } ()) "Empty expression")]]));
+        assert_eq!(run_program(&format!("!(max-atom (3 A B 5))")), Ok(vec![vec![expr!("Error" ({ stdlib::MaxAtomOp{} } ({Number::Integer(3)} "A" "B" {Number::Integer(5)})) "Only numbers allowed in expression")]]));
+    }
+
     #[test]
     fn metta_index_atom() {
         assert_eq!(run_program(&format!("!(index-atom (5 4 3 2 1) 2)")), Ok(vec![vec![expr!({Number::Integer(3)})]]));