+SCM
+Spanner::get_cached_pure_property (SCM sym, int start, int end)
+{
+ // The pure property cache is indexed by (name start . end), where name is
+ // a symbol, and start and end are numbers referring to the starting and
+ // ending column ranks of the current line.
+ if (scm_hash_table_p (pure_property_cache_) == SCM_BOOL_F)
+ return SCM_UNDEFINED;
+
+ SCM key = scm_cons (sym, scm_cons (scm_from_int (start), scm_from_int (end)));
+ return scm_hash_ref (pure_property_cache_, key, SCM_UNDEFINED);
+}
+
+void
+Spanner::cache_pure_property (SCM sym, int start, int end, SCM val)
+{
+ if (scm_hash_table_p (pure_property_cache_) == SCM_BOOL_F)
+ pure_property_cache_ = scm_c_make_hash_table (17);
+
+ SCM key = scm_cons (sym, scm_cons (scm_from_int (start), scm_from_int (end)));
+ scm_hash_set_x (pure_property_cache_, key, val);
+}
+