sig
val build_prune_code :
Code_selection_context.code_selection_context ->
Algebra_type.algop_expr ->
Xquery_common_ast.crname * Xquery_common_ast.axis ->
Algebra_type.alg_eval_code_dep *
Code_selection_context.code_selection_context
val build_default_prune_code :
Code_selection_context.code_selection_context ->
Xquery_common_ast.axis ->
Xquery_common_ast.crname ->
'a ->
Physical_value.tuple_unit Cursor.cursor ->
Physical_value.tuple_unit Cursor.cursor
end