Issue/639 allow iteration over dict keys

changelogs/unreleased/639-allow-iteration-over-dict-keys.yml

@@ -0,0 +1,6 @@
+description: Add support in the Inmanta DSL to iterate over dictionary keys in for loops.
+issue-nr: 639
+change-type: minor
+destination-branches: [master, iso8]
+sections:
+  minor-improvement: "{{description}}"

src/inmanta/ast/statements/assign.py

@@ -192,7 +192,7 @@ def execute_direct(self, requires: abc.Mapping[str, object]) -> object:
 
     def _resolve(self, requires: dict[object, object], resolver: Resolver, queue: QueueScheduler) -> object:
         """
-        Create this list
+        Create this dict
         """
         qlist = {}
 

src/inmanta/ast/statements/generator.py

@@ -243,8 +243,8 @@ def execute(self, requires: dict[object, object], resolver: Resolver, queue: Que
         super().execute(requires, resolver, queue)
         var = self.base.execute(requires, resolver, queue)
 
-        if not isinstance(var, (list, Unknown)):
-            msg = "A for loop can only be applied to lists and relations."
+        if not isinstance(var, (list, Unknown, dict)):
+            msg = "A for loop can only be applied to lists, dictionaries and relations."
             if isinstance(self.base, Reference):
                 msg += " Hint: '%s' resolves to '%s'." % (self.base, str(var))
             else:

src/inmanta/execute/runtime.py

@@ -17,7 +17,7 @@
 """
 
 from abc import abstractmethod
-from collections.abc import Hashable, Sequence, Set
+from collections.abc import Hashable, Mapping, Sequence, Set
 from typing import TYPE_CHECKING, Deque, Generic, List, Literal, NewType, Optional, TypeVar, Union, cast
 
 import inmanta.ast
@@ -81,15 +81,24 @@ def receive_result(self, value: T_contra, location: Location) -> bool:
         """
         raise NotImplementedError()
 
-    def receive_result_flatten(self, value: Union[T_contra, Sequence[T_contra]], location: Location) -> bool:
+    def receive_result_flatten(
+        self, value: Union[T_contra, Sequence[T_contra], Mapping[T_contra, T]], location: Location
+    ) -> bool:
         """
         Receive one or more values for gradual execution. When a list is passed, its values will be passed to receive_result
         one by one. Otherwise the value itself is passed unmodified.
 
         :return: Whether this collector is complete, i.e. it does not need to receive any further results and its associated
             waiter will no longer cause progress. Once this is signalled, this instance should get no further results.
         """
-        for subvalue in value if isinstance(value, list) else [value]:
+        if isinstance(value, list):
+            _iterator = value
+        elif isinstance(value, dict):
+            _iterator = value.keys()  # type: ignore
+        else:
+            _iterator = [value]
+
+        for subvalue in _iterator:
             done: bool = self.receive_result(subvalue, location)
             if done:
                 return True

tests/compiler/test_loops.py

@@ -52,7 +52,7 @@ def test_for_error(snippetcompiler):
         implementation none for std::Entity:
         end
     """,
-        "A for loop can only be applied to lists and relations. Hint: 'a' resolves to "
+        "A for loop can only be applied to lists, dictionaries and relations. Hint: 'a' resolves to "
         "'__config__::A (instantiated at {dir}/main.cf:6)'. (reported in "
         "For(i) ({dir}/main.cf:7))",
     )
@@ -64,7 +64,7 @@ def test_for_error_2(snippetcompiler):
         for i in "foo":
         end
     """,
-        "A for loop can only be applied to lists and relations. Hint: 'foo' is not a "
+        "A for loop can only be applied to lists, dictionaries and relations. Hint: 'foo' is not a "
         "list. (reported in For(i) ({dir}/main.cf:2))",
     )
 
@@ -82,7 +82,7 @@ def test_for_error_nullable_list(snippetcompiler):
             std::print(element)
         end
     """,
-        "A for loop can only be applied to lists and relations. "
+        "A for loop can only be applied to lists, dictionaries and relations. "
         "Hint: 'a.elements' resolves to 'null'. (reported in For(element) ({dir}/main.cf:8))",
         ministd=True,
     )
@@ -234,3 +234,26 @@ def test_for_loop_fully_gradual(snippetcompiler):
         ministd=True,
     )
     compiler.do_compile()
+
+
+def test_dict_keys_iteration(snippetcompiler, capsys):
+
+    snippetcompiler.setup_for_snippet(
+        """
+my_d = {
+    "B": "F",
+    "A": "O",
+    "R": "O"
+}
+for i in my_d:
+    std::print(i)
+end
+        """,
+        autostd=True,
+    )
+
+    capsys.readouterr()
+    compiler.do_compile()
+    out, _ = capsys.readouterr()
+    output = out.strip()
+    assert output == "\n".join([str(x) for x in "BAR"])