Make var_c shifts easier to get from the assembly mapper

Author: b0d0nne11

src/hgvs/assemblymapper.py

@@ -285,6 +285,14 @@ def _maybe_normalize(self, var):
                 # fall through to return unnormalized variant
         return var
 
+    def _var_c_shifts(self, var_c):
+        """Try to shift c. variants to find alternative representations."""
+        alt_ac = self._alt_ac_for_tx_ac(var_c.ac)
+        yield from super(AssemblyMapper, self)._var_c_shifts(
+            var_c, alt_ac, alt_aln_method=self.alt_aln_method
+        )
+
+
 
 # <LICENSE>
 # Copyright 2018 HGVS Contributors (https://github.com/biocommons/hgvs)

src/hgvs/variantmapper.py

@@ -454,7 +454,7 @@ def c_to_p(self, var_c, pro_ac=None, alt_ac=None, alt_aln_method=hgvs.global_con
             ):
                 if alt_ac is None:
                     raise HGVSUnsupportedOperationError(f'mapping specific variant {var_c} requires alt_ac')
-                for shifted_var_c in self._var_c_shifts(var_c, alt_ac, alt_aln_method):
+                for shifted_var_c in VariantMapper._var_c_shifts(self, var_c, alt_ac, alt_aln_method):
                     shifted_reference_data = RefTranscriptData(self.hdp, shifted_var_c.ac, pro_ac)
                     shifted_builder = altseqbuilder.AltSeqBuilder(shifted_var_c, shifted_reference_data)
                     shifted_region = shifted_builder.get_variant_region()
@@ -665,6 +665,8 @@ def _update_gene_symbol(self, var, symbol):
 
     def _var_c_shifts(self, var_c, alt_ac, alt_aln_method):
         """Try to shift c. variants to find alternative representations."""
+        if not var_c.posedit or var_c.posedit.edit.type not in ("ins", "dup"):
+            return
         strand = self._fetch_AlignmentMapper(tx_ac=var_c.ac, alt_ac=alt_ac, alt_aln_method=alt_aln_method).strand
         var_g = VariantMapper.c_to_g(self, var_c, alt_ac=alt_ac, alt_aln_method=alt_aln_method)
         for shifted_var_g in self._var_g_shifts(var_g, strand=strand, alt_aln_method=alt_aln_method):