core: Add support for reader/query plugins.

[sysdb.git] / src / include / core / store.h

diff --git a/src/include/core/store.h b/src/include/core/store.h
index 289bc2f88684ef6a82be2d63935d1b5bcb85d22a..e851dd9f955ee38cb3bec993fe753aa3e4f5a537 100644 (file)
--- a/src/include/core/store.h
+++ b/src/include/core/store.h
@@ -229,6 +229,32 @@ typedef struct {
                        sdb_object_t *user_data);
 } sdb_store_writer_t;
 
+/*
+ * A store reader describes the interface to query a store implementation.
+ */
+typedef struct {
+       /*
+        * prepare_query:
+        * Prepare the query described by 'ast' for execution.
+        */
+       sdb_object_t *(*prepare_query)(sdb_ast_node_t *ast,
+                       sdb_strbuf_t *errbuf, sdb_object_t *user_data);
+
+       /*
+        * execute_query:
+        * Execute a previously prepared query. The callback may expect that only
+        * queries prepared by its respective prepare callback will be passed to
+        * this function.
+        *
+        * TODO: Instead of letting the executor write directly to a string buffer
+        *       (which cannot easily be merged with other results), let it hand
+        *       all objects to a store-writer.
+        */
+       int (*execute_query)(sdb_object_t *q,
+                       sdb_strbuf_t *buf, sdb_strbuf_t *errbuf,
+                       sdb_object_t *user_data);
+} sdb_store_reader_t;
+
 /*
  * sdb_store_init:
  * Initialize the store sub-system. This function has to be called before