add json_script, a minimalistic JSON based script interpreter

[project/libubox.git] / json_script.h

diff --git a/json_script.h b/json_script.h
new file mode 100644 (file)
index 0000000..e28b511
--- /dev/null
+++ b/json_script.h
@@ -0,0 +1,111 @@
+/*
+ * Copyright (C) 2013 Felix Fietkau <nbd@openwrt.org>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+#ifndef __JSON_SCRIPT_H
+#define __JSON_SCRIPT_H
+
+#include <libubox/avl.h>
+#include <libubox/blob.h>
+#include <libubox/blobmsg.h>
+#include <libubox/utils.h>
+
+struct json_script_file;
+
+struct json_script_ctx {
+       struct avl_tree files;
+       struct blob_buf buf;
+
+       uint32_t run_seq;
+
+       /*
+        * handle_command: handle a command that was not recognized by the
+        * json_script core (required)
+        *
+        * @cmd: blobmsg container of the processed command
+        * @vars: blobmsg container of current run variables
+        */
+       void (*handle_command)(struct json_script_ctx *ctx, const char *name,
+                              struct blob_attr *cmd, struct blob_attr *vars);
+
+       /*
+        * handle_expr: handle an expression that was not recognized by the
+        * json_script core (optional)
+        *
+        * @expr: blobmsg container of the processed expression
+        * @vars: blobmsg container of current runtime variables
+        */
+       int (*handle_expr)(struct json_script_ctx *ctx, const char *name,
+                          struct blob_attr *expr, struct blob_attr *vars);
+
+       /*
+        * handle_var - look up a variable that's not part of the runtime
+        * variable set (optional)
+        */
+       const char *(*handle_var)(struct json_script_ctx *ctx, const char *name,
+                                 struct blob_attr *vars);
+
+       /*
+        * handle_file - load a file by filename (optional)
+        *
+        * in case of wildcards, it can return a chain of json_script files
+        * linked via the ::next pointer. Only the first json_script file is
+        * added to the tree.
+        */
+       struct json_script_file *(*handle_file)(struct json_script_ctx *ctx,
+                                               const char *name);
+
+       /*
+        * handle_error - handle a processing error in a command or expression
+        * (optional)
+        * 
+        * @msg: error message
+        * @context: source file context of the error (blobmsg container)
+        */
+       void (*handle_error)(struct json_script_ctx *ctx, const char *msg,
+                            struct blob_attr *context);
+};
+
+struct json_script_file {
+       struct avl_node avl;
+       struct json_script_file *next;
+
+       unsigned int seq;
+       struct blob_attr data[];
+};
+
+void json_script_init(struct json_script_ctx *ctx);
+void json_script_free(struct json_script_ctx *ctx);
+
+/*
+ * json_script_run - run a json script with a set of runtime variables
+ *
+ * @filename: initial filename to run
+ * @vars: blobmsg container of the current runtime variables
+ */
+void json_script_run(struct json_script_ctx *ctx, const char *filename,
+                    struct blob_attr *vars);
+
+struct json_script_file *
+json_script_file_from_blobmsg(const char *name, void *data, int len);
+
+/*
+ * json_script_find_var - helper function to find a runtime variable from
+ * the list passed by json_script user.
+ * It is intended to be used by the .handle_var callback
+ */
+const char *json_script_find_var(struct json_script_ctx *ctx, struct blob_attr *vars,
+                                const char *name);
+
+#endif