Merge pull request #168 from DillonZChen/main

Implement ordering on Variable objects

Author: haz

pddl/logic/terms.py

@@ -65,13 +65,11 @@ def __eq__(self, other):
 
     def __lt__(self, other):
         """Compare with another term."""
-        if isinstance(other, Constant):
-            return (self.name, sorted(self.type_tags)) < (
-                other.name,
-                sorted(other.type_tags),
-            )
-        else:
+        if not isinstance(other, Term):
             return super().__lt__(other)
+        lhs = (type(self).__name__, self.name, sorted(self.type_tags))
+        rhs = (type(other).__name__, other.name, sorted(other.type_tags))
+        return lhs < rhs
 
 
 # TODO check correctness

tests/test_logic/test_terms.py

@@ -13,7 +13,7 @@
 """Test pddl.logic.terms module."""
 import pytest
 
-from pddl.logic.terms import Variable
+from pddl.logic.terms import Constant, Variable
 
 
 def test_no_duplicated_type_tags() -> None:
@@ -22,3 +22,47 @@ def test_no_duplicated_type_tags() -> None:
         ValueError, match=r"duplicate element in collection \['b', 'b'\]: 'b'"
     ):
         Variable("a", ["b", "b"])
+
+
+def test_variable_ordering() -> None:
+    """Test variable ordering."""
+    v1 = Variable("x", ["type1"])
+    v2 = Variable("y", ["type3"])
+    v3 = Variable("z", ["type2"])
+    assert v1 < v2
+    assert v1 < v3
+    assert v2 < v3
+    assert not (v1 > v2)
+    assert not (v1 > v3)
+    assert not (v2 > v3)
+
+
+def test_constant_ordering() -> None:
+    """Test constant ordering."""
+    c1 = Constant("a", "type1")
+    c2 = Constant("b", "type2")
+    c3 = Constant("c", "type1")
+    assert c1 < c2
+    assert c1 < c3
+    assert c2 < c3
+    assert not (c1 > c2)
+    assert not (c1 > c3)
+    assert not (c2 > c3)
+
+
+def test_term_ordering() -> None:
+    """Test term ordering between variables and constants."""
+    v1 = Variable("x", ["type1"])
+    v2 = Variable("y", ["type3"])
+    v3 = Variable("z", ["type2"])
+    c1 = Constant("a", "type1")
+    c2 = Constant("b", "type2")
+    c3 = Constant("c", "type1")
+    assert c1 < v1
+    assert c2 < v2
+    assert c3 < v3
+    assert not (v1 < c1)
+    assert not (v2 < c2)
+    assert not (v3 < c3)
+    array = [c1, c2, c3, v1, v2, v3]
+    assert array == sorted(array)