[Library] improve handling of dangling refs

masque/file/utils.py

@@ -75,7 +75,8 @@ def preflight(
             raise PatternError('Non-numeric layers found:' + pformat(named_layers))
 
     if prune_empty_patterns:
-        pruned = lib.prune_empty()
+        prune_dangling = 'error' if allow_dangling_refs is False else 'ignore'
+        pruned = lib.prune_empty(dangling=prune_dangling)
         if pruned:
             logger.info(f'Preflight pruned {len(pruned)} empty patterns')
             logger.debug('Pruned: ' + pformat(pruned))

masque/library.py

@@ -59,6 +59,9 @@ TreeView: TypeAlias = Mapping[str, 'Pattern']
 Tree: TypeAlias = MutableMapping[str, 'Pattern']
 """ A mutable name-to-`Pattern` mapping which is expected to have only one top-level cell """
 
+dangling_mode_t: TypeAlias = Literal['error', 'ignore', 'include']
+""" How helpers should handle refs whose targets are not present in the library. """
+
 
 SINGLE_USE_PREFIX = '_'
 """
@@ -418,6 +421,21 @@ class ILibraryView(Mapping[str, 'Pattern'], metaclass=ABCMeta):
         """
         return self[self.top()]
 
+    @staticmethod
+    def _dangling_refs_error(dangling: set[str], context: str) -> LibraryError:
+        dangling_list = sorted(dangling)
+        return LibraryError(f'Dangling refs found while {context}: ' + pformat(dangling_list))
+
+    def _raw_child_graph(self) -> tuple[dict[str, set[str]], set[str]]:
+        existing = set(self.keys())
+        graph: dict[str, set[str]] = {}
+        dangling: set[str] = set()
+        for name, pat in self.items():
+            children = {child for child, refs in pat.refs.items() if child is not None and refs}
+            graph[name] = children
+            dangling |= children - existing
+        return graph, dangling
+
     def dfs(
             self,
             pattern: 'Pattern',
@@ -523,46 +541,88 @@ class ILibraryView(Mapping[str, 'Pattern'], metaclass=ABCMeta):
 
         return self
 
-    def child_graph(self) -> dict[str, set[str | None]]:
+    def child_graph(
+            self,
+            dangling: dangling_mode_t = 'error',
+            ) -> dict[str, set[str]]:
         """
           Return a mapping from pattern name to a set of all child patterns
         (patterns it references).
 
+        Only non-empty ref lists with non-`None` targets are treated as graph edges.
+
+        Args:
+            dangling: How refs to missing targets are handled. `'error'` raises,
+                `'ignore'` drops those edges, and `'include'` exposes them as
+                synthetic leaf nodes.
+
         Returns:
             Mapping from pattern name to a set of all pattern names it references.
         """
-        graph = {name: set(pat.refs.keys()) for name, pat in self.items()}
+        graph, dangling_refs = self._raw_child_graph()
+        if dangling == 'error':
+            if dangling_refs:
+                raise self._dangling_refs_error(dangling_refs, 'building child graph')
+            return graph
+        if dangling == 'ignore':
+            existing = set(graph)
+            return {name: {child for child in children if child in existing} for name, children in graph.items()}
+
+        for target in dangling_refs:
+            graph.setdefault(target, set())
         return graph
 
-    def parent_graph(self) -> dict[str, set[str]]:
+    def parent_graph(
+            self,
+            dangling: dangling_mode_t = 'error',
+            ) -> dict[str, set[str]]:
         """
           Return a mapping from pattern name to a set of all parent patterns
         (patterns which reference it).
 
+        Args:
+            dangling: How refs to missing targets are handled. `'error'` raises,
+                `'ignore'` drops those targets, and `'include'` adds them as
+                synthetic keys whose values are their existing parents.
+
         Returns:
             Mapping from pattern name to a set of all patterns which reference it.
         """
-        igraph: dict[str, set[str]] = {name: set() for name in self}
-        for name, pat in self.items():
-            for child, reflist in pat.refs.items():
-                if reflist and child is not None:
-                    igraph[child].add(name)
+        child_graph, dangling_refs = self._raw_child_graph()
+        if dangling == 'error' and dangling_refs:
+            raise self._dangling_refs_error(dangling_refs, 'building parent graph')
+
+        existing = set(child_graph)
+        igraph: dict[str, set[str]] = {name: set() for name in existing}
+        for parent, children in child_graph.items():
+            for child in children:
+                if child in existing:
+                    igraph[child].add(parent)
+                elif dangling == 'include':
+                    igraph.setdefault(child, set()).add(parent)
         return igraph
 
-    def child_order(self) -> list[str]:
+    def child_order(
+            self,
+            dangling: dangling_mode_t = 'error',
+            ) -> list[str]:
         """
-          Return a topologically sorted list of all contained pattern names.
+          Return a topologically sorted list of graph node names.
         Child (referenced) patterns will appear before their parents.
 
+        Args:
+            dangling: Passed to `child_graph()`.
+
         Return:
             Topologically sorted list of pattern names.
         """
-        return cast('list[str]', list(TopologicalSorter(self.child_graph()).static_order()))
+        return cast('list[str]', list(TopologicalSorter(self.child_graph(dangling=dangling)).static_order()))
 
     def find_refs_local(
             self,
             name: str,
             parent_graph: dict[str, set[str]] | None = None,
+            dangling: dangling_mode_t = 'error',
             ) -> dict[str, list[NDArray[numpy.float64]]]:
         """
           Find the location and orientation of all refs pointing to `name`.
@@ -575,6 +635,8 @@ class ILibraryView(Mapping[str, 'Pattern'], metaclass=ABCMeta):
                 The provided graph may be for a superset of `self` (i.e. it may
                 contain additional patterns which are not present in self; they
                 will be ignored).
+            dangling: How refs to missing targets are handled if `parent_graph`
+                is not provided. `'include'` also allows querying missing names.
 
         Returns:
             Mapping of {parent_name: transform_list}, where transform_list
@@ -583,8 +645,18 @@ class ILibraryView(Mapping[str, 'Pattern'], metaclass=ABCMeta):
         """
         instances = defaultdict(list)
         if parent_graph is None:
-            parent_graph = self.parent_graph()
-        for parent in parent_graph[name]:
+            graph_mode = 'ignore' if dangling == 'ignore' else 'include'
+            parent_graph = self.parent_graph(dangling=graph_mode)
+
+        if name not in self:
+            if name not in parent_graph:
+                return instances
+            if dangling == 'error':
+                raise self._dangling_refs_error({name}, f'finding local refs for {name!r}')
+            if dangling == 'ignore':
+                return instances
+
+        for parent in parent_graph.get(name, set()):
             if parent not in self:          # parent_graph may be a for a superset of self
                 continue
             for ref in self[parent].refs[name]:
@@ -597,6 +669,7 @@ class ILibraryView(Mapping[str, 'Pattern'], metaclass=ABCMeta):
             name: str,
             order: list[str] | None = None,
             parent_graph: dict[str, set[str]] | None = None,
+            dangling: dangling_mode_t = 'error',
             ) -> dict[tuple[str, ...], NDArray[numpy.float64]]:
         """
           Find the absolute (top-level) location and orientation of all refs (including
@@ -613,18 +686,28 @@ class ILibraryView(Mapping[str, 'Pattern'], metaclass=ABCMeta):
                 The provided graph may be for a superset of `self` (i.e. it may
                 contain additional patterns which are not present in self; they
                 will be ignored).
+            dangling: How refs to missing targets are handled if `order` or
+                `parent_graph` are not provided. `'include'` also allows
+                querying missing names.
 
         Returns:
             Mapping of `{hierarchy: transform_list}`, where `hierarchy` is a tuple of the form
                 `(toplevel_pattern, lvl1_pattern, ..., name)` and `transform_list` is an Nx4 ndarray
                 with rows `(x_offset, y_offset, rotation_ccw_rad, mirror_across_x)`.
         """
-        if name not in self:
-            return {}
+        graph_mode = 'ignore' if dangling == 'ignore' else 'include'
         if order is None:
-            order = self.child_order()
+            order = self.child_order(dangling=graph_mode)
         if parent_graph is None:
-            parent_graph = self.parent_graph()
+            parent_graph = self.parent_graph(dangling=graph_mode)
+
+        if name not in self:
+            if name not in parent_graph:
+                return {}
+            if dangling == 'error':
+                raise self._dangling_refs_error({name}, f'finding global refs for {name!r}')
+            if dangling == 'ignore':
+                return {}
 
         self_keys = set(self.keys())
 
@@ -633,16 +716,16 @@ class ILibraryView(Mapping[str, 'Pattern'], metaclass=ABCMeta):
                 NDArray[numpy.float64]
                 ]]]
         transforms = defaultdict(list)
-        for parent, vals in self.find_refs_local(name, parent_graph=parent_graph).items():
+        for parent, vals in self.find_refs_local(name, parent_graph=parent_graph, dangling=dangling).items():
             transforms[parent] = [((name,), numpy.concatenate(vals))]
 
         for next_name in order:
             if next_name not in transforms:
                 continue
-            if not parent_graph[next_name] & self_keys:
+            if not parent_graph.get(next_name, set()) & self_keys:
                 continue
 
-            outers = self.find_refs_local(next_name, parent_graph=parent_graph)
+            outers = self.find_refs_local(next_name, parent_graph=parent_graph, dangling=dangling)
             inners = transforms.pop(next_name)
             for parent, outer in outers.items():
                 for path, inner in inners:
@@ -1119,17 +1202,19 @@ class ILibrary(ILibraryView, MutableMapping[str, 'Pattern'], metaclass=ABCMeta):
     def prune_empty(
             self,
             repeat: bool = True,
+            dangling: dangling_mode_t = 'error',
             ) -> set[str]:
         """
         Delete any empty patterns (i.e. where `Pattern.is_empty` returns `True`).
 
         Args:
             repeat: Also recursively delete any patterns which only contain(ed) empty patterns.
+            dangling: Passed to `parent_graph()`.
 
         Returns:
             A set containing the names of all deleted patterns
         """
-        parent_graph = self.parent_graph()
+        parent_graph = self.parent_graph(dangling=dangling)
         empty = {name for name, pat in self.items() if pat.is_empty()}
         trimmed = set()
         while empty:

masque/test/test_library.py

@@ -1,10 +1,12 @@
 import pytest
 from typing import cast, TYPE_CHECKING
+from numpy.testing import assert_allclose
 from ..library import Library, LazyLibrary
 from ..pattern import Pattern
 from ..error import LibraryError, PatternError
 from ..ports import Port
 from ..repetition import Grid
+from ..file.utils import preflight
 
 if TYPE_CHECKING:
     from ..shapes import Polygon
@@ -41,6 +43,79 @@ def test_library_dangling() -> None:
     assert lib.dangling_refs() == {"missing"}
 
 
+def test_library_dangling_graph_modes() -> None:
+    lib = Library()
+    lib["parent"] = Pattern()
+    lib["parent"].ref("missing")
+
+    with pytest.raises(LibraryError, match="Dangling refs found"):
+        lib.child_graph()
+    with pytest.raises(LibraryError, match="Dangling refs found"):
+        lib.parent_graph()
+    with pytest.raises(LibraryError, match="Dangling refs found"):
+        lib.child_order()
+
+    assert lib.child_graph(dangling="ignore") == {"parent": set()}
+    assert lib.parent_graph(dangling="ignore") == {"parent": set()}
+    assert lib.child_order(dangling="ignore") == ["parent"]
+
+    assert lib.child_graph(dangling="include") == {"parent": {"missing"}, "missing": set()}
+    assert lib.parent_graph(dangling="include") == {"parent": set(), "missing": {"parent"}}
+    assert lib.child_order(dangling="include") == ["missing", "parent"]
+
+
+def test_find_refs_with_dangling_modes() -> None:
+    lib = Library()
+    lib["target"] = Pattern()
+
+    mid = Pattern()
+    mid.ref("target", offset=(2, 0))
+    lib["mid"] = mid
+
+    top = Pattern()
+    top.ref("mid", offset=(5, 0))
+    top.ref("missing", offset=(9, 0))
+    lib["top"] = top
+
+    assert lib.find_refs_local("missing", dangling="ignore") == {}
+    assert lib.find_refs_global("missing", dangling="ignore") == {}
+
+    local_missing = lib.find_refs_local("missing", dangling="include")
+    assert set(local_missing) == {"top"}
+    assert_allclose(local_missing["top"][0], [[9, 0, 0, 0, 1]])
+
+    global_missing = lib.find_refs_global("missing", dangling="include")
+    assert_allclose(global_missing[("top", "missing")], [[9, 0, 0, 0, 1]])
+
+    with pytest.raises(LibraryError, match="missing"):
+        lib.find_refs_local("missing")
+    with pytest.raises(LibraryError, match="missing"):
+        lib.find_refs_global("missing")
+
+    global_target = lib.find_refs_global("target")
+    assert_allclose(global_target[("top", "mid", "target")], [[7, 0, 0, 0, 1]])
+
+
+def test_preflight_prune_empty_preserves_dangling_policy(caplog: pytest.LogCaptureFixture) -> None:
+    def make_lib() -> Library:
+        lib = Library()
+        lib["empty"] = Pattern()
+        lib["top"] = Pattern()
+        lib["top"].ref("missing")
+        return lib
+
+    caplog.set_level("WARNING")
+    warned = preflight(make_lib(), allow_dangling_refs=None, prune_empty_patterns=True)
+    assert "empty" not in warned
+    assert any("Dangling refs found" in record.message for record in caplog.records)
+
+    allowed = preflight(make_lib(), allow_dangling_refs=True, prune_empty_patterns=True)
+    assert "empty" not in allowed
+
+    with pytest.raises(LibraryError, match="Dangling refs found"):
+        preflight(make_lib(), allow_dangling_refs=False, prune_empty_patterns=True)
+
+
 def test_library_flatten() -> None:
     lib = Library()
     child = Pattern()