/* json-path.h - JSONPath implementation
*
* This file is part of JSON-GLib
* Copyright © 2011 Intel Corp.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*
* Author:
* Emmanuele Bassi <ebassi@linux.intel.com>
*/
/**
* SECTION:json-path
* @Title: JsonPath
* @short_description: JSONPath implementation
*
* #JsonPath is a simple class implementing the JSONPath syntax for extracting
* data out of a JSON tree. While the semantics of the JSONPath expressions are
* heavily borrowed by the XPath specification for XML, the syntax follows the
* ECMAScript origins of JSON.
*
* Once a #JsonPath instance has been created, it has to compile a JSONPath
* expression using json_path_compile() before being able to match it to a
* JSON tree; the same #JsonPath instance can be used to match multiple JSON
* trees. It it also possible to compile a new JSONPath expression using the
* same #JsonPath instance; the previous expression will be discarded only if
* the compilation of the new expression is successful.
*
* The simple convenience function json_path_query() can be used for one-off
* matching.
*
* ## Syntax of the JSONPath expressions ##
*
* A JSONPath expression is composed by path indices and operators.
* Each path index can either be a member name or an element index inside
* a JSON tree. A JSONPath expression must start with the '$' operator; each
* path index is separated using either the dot notation or the bracket
* notation, e.g.:
*
* |[<!-- language="plain" -->
* // dot notation
* $.store.book[0].title
*
* // bracket notation
* $['store']['book'][0]['title']
* ]|
*
* The available operators are:
*
* * Root node
* The `$` character represents the root node of the JSON tree, and
* matches the entire document.
*
* * Child nodes can either be matched using `.` or `[]`. For instance,
* both `$.store.book` and `$['store']['book']` match the contents of
* the book member of the store object.
*
* * Child nodes can be reached without specifying the whole tree structure
* through the recursive descent operator, or `..`. For instance,
* `$..author` matches all author member in every object.
*
* * Child nodes can grouped through the wildcard operator, or `*`. For
* instance, `$.store.book[*].author` matches all author members of any
* object element contained in the book array of the store object.
*
* * Element nodes can be accessed using their index (starting from zero)
* in the subscript operator `[]`. For instance, `$.store.book[0]` matches
* the first element of the book array of the store object.
*
* * Subsets of element nodes can be accessed using the set notation
* operator `[i,j,...]`. For instance, `$.store.book[0,2]` matches the
* elements 0 and 2 (the first and third) of the book array of the store
* object.
*
* * Slices of element nodes can be accessed using the slice notation
* operation `[start:end:step]`. If start is omitted, the starting index
* of the slice is implied to be zero; if end is omitted, the ending index
* of the slice is implied to be the length of the array; if step is
* omitted, the step of the slice is implied to be 1. For instance,
* `$.store.book[:2]` matches the first two elements of the book array
* of the store object.
*
* More information about JSONPath is available on Stefan Gössner's
* [JSONPath website](http://goessner.net/articles/JsonPath/).
*
* ## Example of JSONPath matches
* The following example shows some of the results of using #JsonPath
* on a JSON tree. We use the following JSON description of a bookstore:
*
* |[<!-- language="plain" -->
* { "store": {
* "book": [
* { "category": "reference", "author": "Nigel Rees",
* "title": "Sayings of the Century", "price": "8.95" },
* { "category": "fiction", "author": "Evelyn Waugh",
* "title": "Sword of Honour", "price": "12.99" },
* { "category": "fiction", "author": "Herman Melville",
* "title": "Moby Dick", "isbn": "0-553-21311-3",
* "price": "8.99" },
* { "category": "fiction", "author": "J. R. R. Tolkien",
* "title": "The Lord of the Rings", "isbn": "0-395-19395-8",
* "price": "22.99" }
* ],
* "bicycle": { "color": "red", "price": "19.95" }
* }
* }
* ]|
*
* We can parse the JSON using #JsonParser:
*
* |[<!-- language="C" -->
* JsonParser *parser = json_parser_new ();
* json_parser_load_from_data (parser, json_data, -1, NULL);
* ]|
*
* If we run the following code:
*
* |[<!-- language="C" -->
* JsonNode *result;
* JsonPath *path = json_path_new ();
* json_path_compile (path, "$.store..author", NULL);
* result = json_path_match (path, json_parser_get_root (parser));
* ]|
*
* The result #JsonNode will contain an array with all values of the
* author member of the objects in the JSON tree. If we use a
* #JsonGenerator to convert the #JsonNode to a string and print it:
*
* |[<!-- language="C" -->
* JsonGenerator *generator = json_generator_new ();
* json_generator_set_root (generator, result);
* char *str = json_generator_to_data (generator, NULL);
* g_print ("Results: %s\n", str);
* ]|
*
* The output will be:
*
* |[<!-- language="plain" -->
* ["Nigel Rees","Evelyn Waugh","Herman Melville","J. R. R. Tolkien"]
* ]|
*
* #JsonPath is available since JSON-GLib 0.14
*/
#include "config.h"
#include <string.h>
#include <glib/gi18n-lib.h>
#include "json-path.h"
#include "json-debug.h"
#include "json-types-private.h"
typedef enum {
JSON_PATH_NODE_ROOT,
JSON_PATH_NODE_CHILD_MEMBER,
JSON_PATH_NODE_CHILD_ELEMENT,
JSON_PATH_NODE_RECURSIVE_DESCENT,
JSON_PATH_NODE_WILDCARD_MEMBER,
JSON_PATH_NODE_WILDCARD_ELEMENT,
JSON_PATH_NODE_ELEMENT_SET,
JSON_PATH_NODE_ELEMENT_SLICE
} PathNodeType;
typedef struct _PathNode PathNode;
struct _JsonPath
{
GObject parent_instance;
/* the compiled path */
GList *nodes;
guint is_compiled : 1;
};
struct _JsonPathClass
{
GObjectClass parent_class;
};
struct _PathNode
{
PathNodeType node_type;
union {
/* JSON_PATH_NODE_CHILD_ELEMENT */
int element_index;
/* JSON_PATH_NODE_CHILD_MEMBER */
char *member_name;
/* JSON_PATH_NODE_ELEMENT_SET */
struct { int n_indices; int *indices; } set;
/* JSON_PATH_NODE_ELEMENT_SLICE */
struct { int start, end, step; } slice;
} data;
};
G_DEFINE_QUARK (json-path-error-quark, json_path_error)
G_DEFINE_TYPE (JsonPath, json_path, G_TYPE_OBJECT)
static void
path_node_free (gpointer data)
{
if (data != NULL)
{
PathNode *node = data;
switch (node->node_type)
{
case JSON_PATH_NODE_CHILD_MEMBER:
g_free (node->data.member_name);
break;
case JSON_PATH_NODE_ELEMENT_SET:
g_free (node->data.set.indices);
break;
default:
break;
}
g_free (node);
}
}
static void
json_path_finalize (GObject *gobject)
{
JsonPath *self = JSON_PATH (gobject);
g_list_free_full (self->nodes, path_node_free);
G_OBJECT_CLASS (json_path_parent_class)->finalize (gobject);
}
static void
json_path_class_init (JsonPathClass *klass)
{
G_OBJECT_CLASS (klass)->finalize = json_path_finalize;
}
static void
json_path_init (JsonPath *self)
{
}
/**
* json_path_new:
*
* Creates a new #JsonPath instance.
*
* Once created, the #JsonPath object should be used with json_path_compile()
* and json_path_match().
*
* Return value: (transfer full): the newly created #JsonPath instance. Use
* g_object_unref() to free the allocated resources when done
*
* Since: 0.14
*/
JsonPath *
json_path_new (void)
{
return g_object_new (JSON_TYPE_PATH, NULL);
}
#ifdef JSON_ENABLE_DEBUG
/* used as the function for a g_list_foreach() on a list of PathNode; needs
* a GString as the payload to build the output string
*/
static void
json_path_foreach_print (gpointer data,
gpointer user_data)
{
PathNode *cur_node = data;
GString *buf = user_data;
switch (cur_node->node_type)
{
case JSON_PATH_NODE_ROOT:
g_string_append (buf, "<root");
break;
case JSON_PATH_NODE_CHILD_MEMBER:
g_string_append_printf (buf, "<member '%s'", cur_node->data.member_name);
break;
case JSON_PATH_NODE_CHILD_ELEMENT:
g_string_append_printf (buf, "<element '%d'", cur_node->data.element_index);
break;
case JSON_PATH_NODE_RECURSIVE_DESCENT:
g_string_append (buf, "<recursive descent");
break;
case JSON_PATH_NODE_WILDCARD_MEMBER:
g_string_append (buf, "<wildcard member");
break;
case JSON_PATH_NODE_WILDCARD_ELEMENT:
g_string_append (buf, "<wildcard element");
break;
case JSON_PATH_NODE_ELEMENT_SET:
{
int i;
g_string_append (buf, "<element set ");
for (i = 0; i < cur_node->data.set.n_indices - 1; i++)
g_string_append_printf (buf, "'%d', ", cur_node->data.set.indices[i]);
g_string_append_printf (buf, "'%d'", cur_node->data.set.indices[i]);
}
break;
case JSON_PATH_NODE_ELEMENT_SLICE:
g_string_append_printf (buf, "<slice start '%d', end '%d', step '%d'",
cur_node->data.slice.start,
cur_node->data.slice.end,
cur_node->data.slice.step);
break;
default:
g_string_append (buf, "<unknown node");
break;
}
g_string_append (buf, ">");
}
#endif /* JSON_ENABLE_DEBUG */
/**
* json_path_compile:
* @path: a #JsonPath
* @expression: a JSONPath expression
* @error: return location for a #GError, or %NULL
*
* Validates and decomposes @expression.
*
* A JSONPath expression must be compiled before calling json_path_match().
*
* Return value: %TRUE on success; on error, @error will be set with
* the %JSON_PATH_ERROR domain and a code from the #JsonPathError
* enumeration, and %FALSE will be returned
*
* Since: 0.14
*/
gboolean
json_path_compile (JsonPath *path,
const char *expression,
GError **error)
{
const char *p, *end_p;
PathNode *root = NULL;
GList *nodes = NULL;
g_return_val_if_fail (expression != NULL, FALSE);
p = expression;
while (*p != '\0')
{
switch (*p)
{
case '$':
{
PathNode *node;
if (root != NULL)
{
g_set_error_literal (error, JSON_PATH_ERROR,
JSON_PATH_ERROR_INVALID_QUERY,
_("Only one root node is allowed in a JSONPath expression"));
return FALSE;
}
if (!(*(p + 1) == '.' || *(p + 1) == '[' || *(p + 1) == '\0'))
{
g_set_error (error, JSON_PATH_ERROR,
JSON_PATH_ERROR_INVALID_QUERY,
/* translators: the %c is the invalid character */
_("Root node followed by invalid character “%c”"),
*(p + 1));
return FALSE;
}
node = g_new0 (PathNode, 1);
node->node_type = JSON_PATH_NODE_ROOT;
root = node;
nodes = g_list_prepend (NULL, root);
}
break;
case '.':
case '[':
{
PathNode *node = NULL;
if (*p == '.' && *(p + 1) == '.')
{
node = g_new0 (PathNode, 1);
node->node_type = JSON_PATH_NODE_RECURSIVE_DESCENT;
}
else if (*p == '.' && *(p + 1) == '*')
{
node = g_new0 (PathNode, 1);
node->node_type = JSON_PATH_NODE_WILDCARD_MEMBER;
p += 1;
}
else if (*p == '.')
{
end_p = p + 1;
while (!(*end_p == '.' || *end_p == '[' || *end_p == '\0'))
end_p += 1;
if (end_p == p + 1)
{
g_set_error_literal (error, JSON_PATH_ERROR,
JSON_PATH_ERROR_INVALID_QUERY,
_("Missing member name or wildcard after . character"));
goto fail;
}
node = g_new0 (PathNode, 1);
node->node_type = JSON_PATH_NODE_CHILD_MEMBER;
node->data.member_name = g_strndup (p + 1, end_p - p - 1);
p = end_p - 1;
}
else if (*p == '[' && *(p + 1) == '\'')
{
if (*(p + 2) == '*' && *(p + 3) == '\'' && *(p + 4) == ']')
{
node = g_new0 (PathNode, 1);
node->node_type = JSON_PATH_NODE_WILDCARD_MEMBER;
p += 4;
}
else
{
node = g_new0 (PathNode, 1);
node->node_type = JSON_PATH_NODE_CHILD_MEMBER;
end_p = strchr (p + 2, '\'');
node->data.member_name = g_strndup (p + 2, end_p - p - 2);
p = end_p + 1;
}
}
else if (*p == '[' && *(p + 1) == '*' && *(p + 2) == ']')
{
node = g_new0 (PathNode, 1);
node->node_type = JSON_PATH_NODE_WILDCARD_ELEMENT;
p += 1;
}
else if (*p == '[')
{
int sign = 1;
int idx;
end_p = p + 1;
if (*end_p == '-')
{
sign = -1;
end_p += 1;
}
/* slice with missing start */
if (*end_p == ':')
{
int slice_end = g_ascii_strtoll (end_p + 1, (char **) &end_p, 10) * sign;
int slice_step = 1;
if (*end_p == ':')
{
end_p += 1;
if (*end_p == '-')
{
sign = -1;
end_p += 1;
}
else
sign = 1;
slice_step = g_ascii_strtoll (end_p, (char **) &end_p, 10) * sign;
if (*end_p != ']')
{
g_set_error (error, JSON_PATH_ERROR,
JSON_PATH_ERROR_INVALID_QUERY,
_("Malformed slice expression “%*s”"),
(int)(end_p - p),
p + 1);
goto fail;
}
}
node = g_new0 (PathNode, 1);
node->node_type = JSON_PATH_NODE_ELEMENT_SLICE;
node->data.slice.start = 0;
node->data.slice.end = slice_end;
node->data.slice.step = slice_step;
nodes = g_list_prepend (nodes, node);
p = end_p;
break;
}
idx = g_ascii_strtoll (end_p, (char **) &end_p, 10) * sign;
if (*end_p == ',')
{
GArray *indices = g_array_new (FALSE, TRUE, sizeof (int));
g_array_append_val (indices, idx);
while (*end_p != ']')
{
end_p += 1;
if (*end_p == '-')
{
sign = -1;
end_p += 1;
}
else
sign = 1;
idx = g_ascii_strtoll (end_p, (char **) &end_p, 10) * sign;
if (!(*end_p == ',' || *end_p == ']'))
{
g_array_unref (indices);
g_set_error (error, JSON_PATH_ERROR,
JSON_PATH_ERROR_INVALID_QUERY,
_("Invalid set definition “%*s”"),
(int)(end_p - p),
p + 1);
goto fail;
}
g_array_append_val (indices, idx);
}
node = g_new0 (PathNode, 1);
node->node_type = JSON_PATH_NODE_ELEMENT_SET;
node->data.set.n_indices = indices->len;
node->data.set.indices = (int *) g_array_free (indices, FALSE);
nodes = g_list_prepend (nodes, node);
p = end_p;
break;
}
else if (*end_p == ':')
{
int slice_start = idx;
int slice_end = 0;
int slice_step = 1;
end_p += 1;
if (*end_p == '-')
{
sign = -1;
end_p += 1;
}
else
sign = 1;
slice_end = g_ascii_strtoll (end_p, (char **) &end_p, 10) * sign;
if (*end_p == ':')
{
end_p += 1;
if (*end_p == '-')
{
sign = -1;
end_p += 1;
}
else
sign = 1;
slice_step = g_ascii_strtoll (end_p + 1, (char **) &end_p, 10) * sign;
}
if (*end_p != ']')
{
g_set_error (error, JSON_PATH_ERROR,
JSON_PATH_ERROR_INVALID_QUERY,
_("Invalid slice definition “%*s”"),
(int)(end_p - p),
p + 1);
goto fail;
}
node = g_new0 (PathNode, 1);
node->node_type = JSON_PATH_NODE_ELEMENT_SLICE;
node->data.slice.start = slice_start;
node->data.slice.end = slice_end;
node->data.slice.step = slice_step;
nodes = g_list_prepend (nodes, node);
p = end_p;
break;
}
else if (*end_p == ']')
{
node = g_new0 (PathNode, 1);
node->node_type = JSON_PATH_NODE_CHILD_ELEMENT;
node->data.element_index = idx;
nodes = g_list_prepend (nodes, node);
p = end_p;
break;
}
else
{
g_set_error (error, JSON_PATH_ERROR,
JSON_PATH_ERROR_INVALID_QUERY,
_("Invalid array index definition “%*s”"),
(int)(end_p - p),
p + 1);
goto fail;
}
}
else
break;
if (node != NULL)
nodes = g_list_prepend (nodes, node);
}
break;
default:
if (nodes == NULL)
{
g_set_error(error, JSON_PATH_ERROR,
JSON_PATH_ERROR_INVALID_QUERY,
_("Invalid first character “%c”"),
*p);
return FALSE;
}
break;
}
p += 1;
}
nodes = g_list_reverse (nodes);
#ifdef JSON_ENABLE_DEBUG
if (JSON_HAS_DEBUG (PATH))
{
GString *buf = g_string_new (NULL);
g_list_foreach (nodes, json_path_foreach_print, buf);
g_message ("[PATH] " G_STRLOC ": expression '%s' => '%s'", expression, buf->str);
g_string_free (buf, TRUE);
}
#endif /* JSON_ENABLE_DEBUG */
g_list_free_full (path->nodes, path_node_free);
path->nodes = nodes;
path->is_compiled = (path->nodes != NULL);
return path->nodes != NULL;
fail:
g_list_free_full (nodes, path_node_free);
return FALSE;
}
static void
walk_path_node (GList *path,
JsonNode *root,
JsonArray *results)
{
PathNode *node = path->data;
switch (node->node_type)
{
case JSON_PATH_NODE_ROOT:
if (path->next != NULL)
walk_path_node (path->next, root, results);
else
json_array_add_element (results, json_node_copy (root));
break;
case JSON_PATH_NODE_CHILD_MEMBER:
if (JSON_NODE_HOLDS_OBJECT (root))
{
JsonObject *object = json_node_get_object (root);
if (json_object_has_member (object, node->data.member_name))
{
JsonNode *member = json_object_get_member (object, node->data.member_name);
if (path->next == NULL)
{
JSON_NOTE (PATH, "end of path at member '%s'", node->data.member_name);
json_array_add_element (results, json_node_copy (member));
}
else
walk_path_node (path->next, member, results);
}
}
break;
case JSON_PATH_NODE_CHILD_ELEMENT:
if (JSON_NODE_HOLDS_ARRAY (root))
{
JsonArray *array = json_node_get_array (root);
if (json_array_get_length (array) >= node->data.element_index)
{
JsonNode *element = json_array_get_element (array, node->data.element_index);
if (path->next == NULL)
{
JSON_NOTE (PATH, "end of path at element '%d'", node->data.element_index);
json_array_add_element (results, json_node_copy (element));
}
else
walk_path_node (path->next, element, results);
}
}
break;
case JSON_PATH_NODE_RECURSIVE_DESCENT:
{
PathNode *tmp = path->next->data;
switch (json_node_get_node_type (root))
{
case JSON_NODE_OBJECT:
{
JsonObject *object = json_node_get_object (root);
GQueue *members = json_object_get_members_internal (object);
GList *l;
for (l = members->head; l != NULL; l = l->next)
{
JsonNode *m = json_object_get_member (object, l->data);
if (tmp->node_type == JSON_PATH_NODE_CHILD_MEMBER &&
strcmp (tmp->data.member_name, l->data) == 0)
{
JSON_NOTE (PATH, "entering '%s'", tmp->data.member_name);
walk_path_node (path->next, root, results);
}
else
{
JSON_NOTE (PATH, "recursing into '%s'", (char *) l->data);
walk_path_node (path, m, results);
}
}
}
break;
case JSON_NODE_ARRAY:
{
JsonArray *array = json_node_get_array (root);
GList *members, *l;
int i;
members = json_array_get_elements (array);
for (l = members, i = 0; l != NULL; l = l->next, i += 1)
{
JsonNode *m = l->data;
if (tmp->node_type == JSON_PATH_NODE_CHILD_ELEMENT &&
tmp->data.element_index == i)
{
JSON_NOTE (PATH, "entering '%d'", tmp->data.element_index);
walk_path_node (path->next, root, results);
}
else
{
JSON_NOTE (PATH, "recursing into '%d'", i);
walk_path_node (path, m, results);
}
}
g_list_free (members);
}
break;
default:
break;
}
}
break;
case JSON_PATH_NODE_WILDCARD_MEMBER:
if (JSON_NODE_HOLDS_OBJECT (root))
{
JsonObject *object = json_node_get_object (root);
GQueue *members = json_object_get_members_internal (object);
GList *l;
for (l = members->head; l != NULL; l = l->next)
{
JsonNode *member = json_object_get_member (object, l->data);
if (path->next != NULL)
walk_path_node (path->next, member, results);
else
{
JSON_NOTE (PATH, "glob match member '%s'", (char *) l->data);
json_array_add_element (results, json_node_copy (member));
}
}
}
else
json_array_add_element (results, json_node_copy (root));
break;
case JSON_PATH_NODE_WILDCARD_ELEMENT:
if (JSON_NODE_HOLDS_ARRAY (root))
{
JsonArray *array = json_node_get_array (root);
GList *elements, *l;
int i;
elements = json_array_get_elements (array);
for (l = elements, i = 0; l != NULL; l = l->next, i += 1)
{
JsonNode *element = l->data;
if (path->next != NULL)
walk_path_node (path->next, element, results);
else
{
JSON_NOTE (PATH, "glob match element '%d'", i);
json_array_add_element (results, json_node_copy (element));
}
}
g_list_free (elements);
}
else
json_array_add_element (results, json_node_copy (root));
break;
case JSON_PATH_NODE_ELEMENT_SET:
if (JSON_NODE_HOLDS_ARRAY (root))
{
JsonArray *array = json_node_get_array (root);
int i;
for (i = 0; i < node->data.set.n_indices; i += 1)
{
int idx = node->data.set.indices[i];
JsonNode *element = json_array_get_element (array, idx);
if (path->next != NULL)
walk_path_node (path->next, element, results);
else
{
JSON_NOTE (PATH, "set element '%d'", idx);
json_array_add_element (results, json_node_copy (element));
}
}
}
break;
case JSON_PATH_NODE_ELEMENT_SLICE:
if (JSON_NODE_HOLDS_ARRAY (root))
{
JsonArray *array = json_node_get_array (root);
int i, start, end;
if (node->data.slice.start < 0)
{
start = json_array_get_length (array)
+ node->data.slice.start;
end = json_array_get_length (array)
+ node->data.slice.end;
}
else
{
start = node->data.slice.start;
end = node->data.slice.end;
}
for (i = start; i < end; i += node->data.slice.step)
{
JsonNode *element = json_array_get_element (array, i);
if (path->next != NULL)
walk_path_node (path->next, element, results);
else
{
JSON_NOTE (PATH, "slice element '%d'", i);
json_array_add_element (results, json_node_copy (element));
}
}
}
break;
default:
break;
}
}
/**
* json_path_match:
* @path: a compiled #JsonPath
* @root: a #JsonNode
*
* Matches the JSON tree pointed by @root using the expression compiled
* into the #JsonPath.
*
* The matching #JsonNodes will be copied into a #JsonArray and
* returned wrapped in a #JsonNode.
*
* Return value: (transfer full): a newly-created #JsonNode of type
* %JSON_NODE_ARRAY containing an array of matching #JsonNodes.
* Use json_node_unref() when done
*
* Since: 0.14
*/
JsonNode *
json_path_match (JsonPath *path,
JsonNode *root)
{
JsonArray *results;
JsonNode *retval;
g_return_val_if_fail (JSON_IS_PATH (path), NULL);
g_return_val_if_fail (path->is_compiled, NULL);
g_return_val_if_fail (root != NULL, NULL);
results = json_array_new ();
walk_path_node (path->nodes, root, results);
retval = json_node_new (JSON_NODE_ARRAY);
json_node_take_array (retval, results);
return retval;
}
/**
* json_path_query:
* @expression: a JSONPath expression
* @root: the root of a JSON tree
* @error: return location for a #GError, or %NULL
*
* Queries a JSON tree using a JSONPath expression.
*
* This function is a simple wrapper around json_path_new(),
* json_path_compile() and json_path_match(). It implicitly
* creates a #JsonPath instance, compiles @expression and
* matches it against the JSON tree pointed by @root.
*
* Return value: (transfer full): a newly-created #JsonNode of type
* %JSON_NODE_ARRAY containing an array of matching #JsonNodes.
* Use json_node_unref() when done
*
* Since: 0.14
*/
JsonNode *
json_path_query (const char *expression,
JsonNode *root,
GError **error)
{
JsonPath *path = json_path_new ();
JsonNode *retval;
if (!json_path_compile (path, expression, error))
{
g_object_unref (path);
return NULL;
}
retval = json_path_match (path, root);
g_object_unref (path);
return retval;
}