Implement convenience functions for looking up the implemented entries.

include/table.h

@@ -68,6 +68,22 @@ void libab_table_init(libab_table* table);
  * @return the table entry, or NULL if an entry was not found.
  */
 libab_table_entry* libab_table_search(libab_table* table, const char* string);
+/**
+ * Searches for the given string in the table, returning a value only
+ * if it is an operator.
+ * @param table the table to search.
+ * @param string the string to search for.
+ * @return the found operator, or NULL if it was not found.
+ */
+libab_operator* libab_table_search_operator(libab_table* table, const char* string);
+/**
+ * Searches for the given string in the table, returning a value only
+ * if it is a function.
+ * @param table the table to search.
+ * @param string the string to search for.
+ * @return the found function, or NULL if it was not found.
+ */
+libab_function* libab_table_search_function(libab_table* table, const char* string);
 /**
  * Stores the given entry in the table under the given key.
  * @param table the table to store the entry into.

src/table.c

@@ -14,6 +14,22 @@ libab_table_entry* table_search(libab_table* table, const char* string) {
     } while(table && to_return == NULL);
     return to_return;
 }
+libab_operator* libab_table_search_operator(libab_table* table, const char* string) {
+    libab_table_entry* entry = table_search(table, string);
+    libab_operator* to_return = NULL;
+    if(entry && entry->variant == ENTRY_OPERATOR) {
+        to_return = &entry->data_u.op;
+    }
+    return to_return;
+}
+libab_function* libab_table_search_function(libab_table* table, const char* string) {
+    libab_table_entry* entry = table_search(table, string);
+    libab_function* to_return = NULL;
+    if(entry && entry->variant == ENTRY_FUNCTION) {
+        to_return = &entry->data_u.function;
+    }
+    return to_return;
+}
 libab_result libab_table_put(libab_table* table, const char* string, libab_table_entry* entry) {
     return libab_convert_ds_result(ht_put(&table->table, string, entry));
 }