feat: get fns for table column types

Author: molpopgen

src/table_column.rs

@@ -14,6 +14,18 @@ macro_rules! make_table_column {
             pub fn as_slice(&self) -> &[T] {
                 self.0
             }
+
+            pub fn get_with_id(&self, index: crate::$index) -> Option<&T> {
+                self.get_with_usize(usize::try_from(index).ok()?)
+            }
+
+            pub fn get_with_size_type(&self, index: crate::SizeType) -> Option<&T> {
+                self.get_with_usize(usize::try_from(index).ok()?)
+            }
+
+            pub fn get_with_usize(&self, index: usize) -> Option<&T> {
+                self.0.get(index)
+            }
         }
 
         impl<T> std::ops::Index<usize> for $name<'_, T> {

tests/test_tables.rs

@@ -559,10 +559,23 @@ fn test_node_table_column_access() {
         .unwrap();
     let individual = t.individual_column();
     assert_eq!(individual[node], tskit::IndividualId::NULL);
+    assert_eq!(
+        individual.get_with_id(node).unwrap(),
+        &tskit::IndividualId::NULL
+    );
     let population = t.population_column();
     assert_eq!(population[node], tskit::PopulationId::NULL);
+    assert_eq!(
+        population.get_with_id(node).unwrap(),
+        &tskit::PopulationId::NULL
+    );
     let time = t.time_column();
     assert_eq!(time[node], 0.0);
+    assert_eq!(time.get_with_id(node).unwrap(), &0.0);
     let flags = t.flags_column();
     assert_eq!(flags[node], tskit::NodeFlags::IS_SAMPLE);
+    assert_eq!(
+        flags.get_with_id(node).unwrap(),
+        &tskit::NodeFlags::IS_SAMPLE
+    );
 }