From 770750d3f959953ed4da34e0f9e44912ce387faf Mon Sep 17 00:00:00 2001
From: Philippe Proulx <eeppeliteloop@gmail.com>
Date: Fri, 26 Feb 2016 01:27:47 -0500
Subject: [PATCH] values: add bt_value_map_extend()
MIME-Version: 1.0
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Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 include/babeltrace/values.h | 63 +++++++++++++++++++++++++++++++
 lib/values.c                | 75 +++++++++++++++++++++++++++++++++++++
 2 files changed, 138 insertions(+)

diff --git a/include/babeltrace/values.h b/include/babeltrace/values.h
index 78fa4e5d..d5ffef0b 100644
--- a/include/babeltrace/values.h
+++ b/include/babeltrace/values.h
@@ -1422,6 +1422,69 @@ On success, \p key is copied.
 extern enum bt_value_status bt_value_map_insert_empty_map(
 		struct bt_value *map_obj, const char *key);
 
+/**
+@brief  Creates a copy of the base map value object \p base_map_obj
+	superficially extended with the entries of the extension map
+	value object \p extension_map_obj.
+
+This function creates a superficial extension of \p base_map_obj with
+\p extension_map_obj by adding new entries to it and replacing the
+ones that share the keys in the extension object. The extension is
+\em superficial because it does not merge internal array and map
+value objects.
+
+For example, consider the following \p base_map_obj (JSON representation):
+
+@code{.unparsed}
+{
+  "hello": 23,
+  "code": -17,
+  "em": false,
+  "return": [5, 6, null]
+}
+@endcode
+
+and the following \p extension_map_obj (JSON representation):
+
+@code{.unparsed}
+{
+  "comma": ",",
+  "code": 22,
+  "return": 17.88
+}
+@endcode
+
+The extended object is (JSON representation):
+
+@code{.unparsed}
+{
+  "hello": 23,
+  "code": 22,
+  "em": false,
+  "return": 17.88,
+  "comma": ","
+}
+@endcode
+
+@param[in] base_map_obj		Base map value object with initial
+				entries.
+@param[in] extension_map_obj	Extension map value object containing
+				the entries to add to or replace in
+				\p base_map_obj.
+@returns			Created extended map value object, or
+				\c NULL on error.
+
+@prenotnull{base_map_obj}
+@prenotnull{extension_map_obj}
+@pre \p base_map_obj is a map value object.
+@pre \p extension_map_obj is a map value object.
+@postrefcountsame{base_map_obj}
+@postrefcountsame{extension_map_obj}
+@postsuccessrefcountret1
+*/
+extern struct bt_value *bt_value_map_extend(struct bt_value *base_map_obj,
+		struct bt_value *extension_map_obj);
+
 /** @} */
 
 /** @} */
diff --git a/lib/values.c b/lib/values.c
index bd217bf6..cea4b10b 100644
--- a/lib/values.c
+++ b/lib/values.c
@@ -1168,6 +1168,81 @@ end:
 	return ret;
 }
 
+struct extend_map_element_data {
+	struct bt_value *extended_obj;
+	bool got_error;
+};
+
+static
+bool extend_map_element(const char *key,
+		struct bt_value *extension_obj_elem, void *data)
+{
+	bool ret = true;
+
+	struct extend_map_element_data *extend_data = data;
+
+	/* Copy object which is to replace the current one */
+	struct bt_value *extension_obj_elem_copy =
+		bt_value_copy(extension_obj_elem);
+
+	/* Replace in extended object */
+	if (bt_value_map_insert(extend_data->extended_obj, key,
+			extension_obj_elem_copy)) {
+		goto error;
+	}
+
+	goto end;
+
+error:
+	ret = false;
+	extend_data->got_error = true;
+
+end:
+	BT_PUT(extension_obj_elem_copy);
+
+	return ret;
+}
+
+struct bt_value *bt_value_map_extend(struct bt_value *base_map_obj,
+		struct bt_value *extension_obj)
+{
+	struct bt_value *extended_obj = NULL;
+	struct extend_map_element_data extend_data = { 0 };
+
+	if (!bt_value_is_map(base_map_obj) || !bt_value_is_map(extension_obj)) {
+		goto error;
+	}
+
+	/* Create copy of base map object to start with */
+	extended_obj = bt_value_copy(base_map_obj);
+	if (!extended_obj) {
+		goto error;
+	}
+
+	/*
+	 * For each key in the extension map object, replace this key
+	 * in the copied map object.
+	 */
+	extend_data.extended_obj = extended_obj;
+
+	if (bt_value_map_foreach(extension_obj, extend_map_element,
+			&extend_data)) {
+		goto error;
+	}
+
+	if (extend_data.got_error) {
+		goto error;
+	}
+
+	goto end;
+
+error:
+	BT_PUT(extended_obj);
+
+end:
+	return extended_obj;
+}
+
 struct bt_value *bt_value_copy(const struct bt_value *object)
 {
 	struct bt_value *copy_obj = NULL;
-- 
2.34.1