1 files changed, 198 insertions, 0 deletions
diff --git a/genskel/exprefs.c b/genskel/exprefs.c
new file mode 100644
index 0000000..4ea44b4
--- /dev/null
+++ b/genskel/exprefs.c
@@ -0,0 +1,198 @@
+/*
+ * Copyright (C) 2016, 2017 "IoT.bzh"
+ * Author José Bollo <jose.bollo@iot.bzh>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/*
+ * This simple program expands the object { "$ref": "#/path/to/a/target" }
+ *
+ * For example:
+ *
+ *  {
+ *    "type":{
+ *      "a": "int",
+ *      "b": { "$ref": "#/type/a" }
+ *    }
+ *  }
+ *
+ * will be exapanded to
+ *
+ *  {
+ *    "type":{
+ *      "a": "int",
+ *      "b": "int"
+ *    }
+ *  }
+ *
+ * Invocation:   program  [file|-]...
+ *
+ * without arguments, it reads the input.
+ */
+
+#define _GNU_SOURCE
+#include <string.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include <json-c/json.h>
+
+/**
+ * records path to the expanded node
+ */
+struct path
+{
+	struct json_object *object;	/**< node being expanded */
+	struct path *upper;		/**< link to upper expanded nodes */
+};
+
+/**
+ * root of the JSON being parsed
+ */
+struct json_object *root;
+
+/**
+ * Search for a reference of type "#/a/b/c" int the
+ * parsed JSON object
+ */
+struct json_object *search(const char *path)
+{
+	char *d;
+	struct json_object *i;
+
+	/* does it match #/ at the beginning? */
+	if (path[0] != '#' || (path[0] && path[1] != '/'))
+		return NULL;
+
+	/* search from root to target */
+	i = root;
+	d = strdupa(path+2);
+	d = strtok(d, "/");
+	while(i && d) {
+		if (!json_object_object_get_ex(i, d, &i))
+			return NULL;
+		d = strtok(NULL, "/");
+	}
+	return i;
+}
+
+/**
+ * Expands the node designated by path and returns its expanded form
+ */
+struct json_object *expand(struct path path)
+{
+	struct path *p;
+	struct json_object *o, *x;
+	int n, i;
+	struct json_object_iterator ji, jn;
+
+	/* expansion depends of the type of the node */
+	switch (json_object_get_type(path.object)) {
+	case json_type_object:
+		/* for object, look if it contains a property "$ref" */
+		if (json_object_object_get_ex(path.object, "$ref", &o)) {
+			/* yes, reference, try to substitute its target */
+			if (!json_object_is_type(o, json_type_string)) {
+				fprintf(stderr, "found a $ref not being string. Is: %s\n", json_object_get_string(o));
+				exit(1);
+			}
+			x = search(json_object_get_string(o));
+			if (!x) {
+				fprintf(stderr, "$ref not found. Was: %s\n", json_object_get_string(o));
+				exit(1);
+			}
+			p = &path;
+			while(p) {
+				if (x == p->object) {
+					fprintf(stderr, "$ref recursive. Was: %s\n", json_object_get_string(o));
+					exit(1);
+				}
+				p = p->upper;
+			}
+			/* cool found, return a new instance of the target */
+			return json_object_get(x);
+		}
+		/* no, expand the values */
+		ji = json_object_iter_begin(path.object);
+		jn = json_object_iter_end(path.object);
+		while (!json_object_iter_equal(&ji, &jn)) {
+			o = json_object_iter_peek_value(&ji);
+			x = expand((struct path){ .object = o, .upper = &path });
+			if (x != o)
+				json_object_object_add(path.object, json_object_iter_peek_name(&ji), x);
+			json_object_iter_next(&ji);
+		}
+		break;
+	case json_type_array:
+		/* expand the values of arrays */
+		i = 0;
+		n = json_object_array_length(path.object);
+		while (i != n) {
+			o = json_object_array_get_idx(path.object, i);
+			x = expand((struct path){ .object = o, .upper = &path });
+			if (x != o)
+				json_object_array_put_idx(path.object, i, x);
+			i++;
+		}
+		break;
+	default:
+		/* otherwise no expansion */
+		break;
+	}
+	/* return the given node */
+	return path.object;
+}
+
+/**
+ * process a file and prints its expansion on stdout
+ */
+void process(char *filename)
+{
+	/* translate - */
+	if (!strcmp(filename, "-"))
+		filename = "/dev/stdin";
+
+	/* check access */
+	if (access(filename, R_OK)) {
+		fprintf(stderr, "can't access file %s\n", filename);
+		exit(1);
+	}
+
+	/* read the file */
+	root = json_object_from_file(filename);
+	if (!root) {
+		fprintf(stderr, "reading file %s produced null\n", filename);
+		exit(1);
+	}
+
+	/* expand */
+	root = expand((struct path){ .object = root, .upper = NULL });
+
+	/* print the result */
+	json_object_to_file_ext ("/dev/stdout", root, JSON_C_TO_STRING_PRETTY);
+
+	/* clean up */
+	json_object_put(root);
+}
+
+/** process the list of files or stdin if none */
+int main(int ac, char **av)
+{
+	if (!*++av)
+		process("-");
+	else {
+		do { process(*av); } while(*++av);
+	}
+	return 0;
+}
+