Formally allow instances to point to None (i.e. an 'empty' pattern)

masque/file/gdsii.py

@@ -100,7 +100,9 @@ def write(patterns: Pattern or List[Pattern],
     # Get a dict of id(pattern) -> pattern
     patterns_by_id = {id(pattern): pattern for pattern in patterns}
     for pattern in patterns:
-        patterns_by_id.update(pattern.referenced_patterns_by_id())
+        for i, p in pattern.referenced_patterns_by_id().items():
+            if p is not None:
+                patterns_by_id[i] = p
 
     disambiguate_func(patterns_by_id.values())
 
@@ -170,7 +172,9 @@ def dose2dtype(patterns: List[Pattern],
     # Get a dict of id(pattern) -> pattern
     patterns_by_id = {id(pattern): pattern for pattern in patterns}
     for pattern in patterns:
-        patterns_by_id.update(pattern.referenced_patterns_by_id())
+        for i, p in pattern.referenced_patterns_by_id().items():
+            if p is not None:
+                patterns_by_id[i] = p
 
     # Get a table of (id(pat), written_dose) for each pattern and subpattern
     sd_table = make_dose_table(patterns)
@@ -466,6 +470,8 @@ def _subpatterns_to_refs(subpatterns: List[SubPattern or GridRepetition]
                         ) -> List[gdsii.elements.ARef or gdsii.elements.SRef]:
     refs = []
     for subpat in subpatterns:
+        if subpat.pattern is None:
+            continue
         encoded_name = subpat.pattern.name
 
         # Note: GDS mirrors first and rotates second

masque/file/svg.py

@@ -61,6 +61,8 @@ def writefile(pattern: Pattern,
     # Now create a group for each row in sd_table (ie, each pattern + dose combination)
     #  and add in any Boundary and Use elements
     for pat in patterns_by_id.values():
+        if pat is None:
+            continue
         svg_group = svg.g(id=mangle_name(pat), fill='blue', stroke='red')
 
         for shape in pat.shapes:
@@ -75,6 +77,8 @@ def writefile(pattern: Pattern,
                 svg_group.add(path)
 
         for subpat in pat.subpatterns:
+            if subpat.pattern is None:
+                continue
             transform = 'scale({:g}) rotate({:g}) translate({:g},{:g})'.format(
                 subpat.scale, subpat.rotation, subpat.offset[0], subpat.offset[1])
             use = svg.use(href='#' + mangle_name(subpat.pattern), transform=transform)

masque/file/utils.py

@@ -38,6 +38,8 @@ def make_dose_table(patterns: List[Pattern], dose_multiplier: float=1.0) -> Set[
     dose_table = {(id(pattern), dose_multiplier) for pattern in patterns}
     for pattern in patterns:
         for subpat in pattern.subpatterns:
+            if subpat.pattern is None:
+                continue
             subpat_dose_entry = (id(subpat.pattern), subpat.dose * dose_multiplier)
             if subpat_dose_entry not in dose_table:
                 subpat_dose_table = make_dose_table([subpat.pattern], subpat.dose * dose_multiplier)