builder: Add convenience API for building JSON trees.

https://bugzilla.gnome.org/show_bug.cgi?id=621141

Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>

1 files changed, 682 insertions, 0 deletions

diff --git a/json-glib/json-builder.c b/json-glib/json-builder.c
new file mode 100644
index 0000000..ea9bc05
--- /dev/null
+++ b/json-glib/json-builder.c
@@ -0,0 +1,682 @@
+/* json-generator.c - JSON tree builder
+ *
+ * This file is part of JSON-GLib
+ * Copyright (C) 2010  Luca Bruno <lethalman88@gmail.com>
+ *
+ * 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:
+ *   Luca Bruno  <lethalman88@gmail.com>
+ */
+
+/**
+ * SECTION:json-builder
+ * @short_description: Generates JSON trees
+ *
+ * #JsonBuilder provides an object for generating a JSON tree.
+ * You can generate only one tree with one #JsonBuilder instance.
+ *
+ * The root of the JSON tree can be either a #JsonObject or a #JsonArray.
+ * Thus the first call must necessarily be either
+ * json_builder_begin_object() or json_builder_begin_array().
+ *
+ * For convenience to language bindings, #JsonBuilder returns itself from
+ * most of functions, making it easy to chain function calls.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "json-types-private.h"
+
+#include "json-builder.h"
+
+#define JSON_BUILDER_GET_PRIVATE(obj) \
+        (G_TYPE_INSTANCE_GET_PRIVATE ((obj), JSON_TYPE_BUILDER, JsonBuilderPrivate))
+
+struct _JsonBuilderPrivate
+{
+  GQueue *stack;
+  JsonNode *root;
+};
+
+typedef enum
+{
+  JSON_BUILDER_MODE_OBJECT,
+  JSON_BUILDER_MODE_ARRAY,
+  JSON_BUILDER_MODE_MEMBER
+} JsonBuilderMode;
+
+typedef struct
+{
+  JsonBuilderMode mode;
+
+  union
+  {
+    JsonObject *object;
+    JsonArray *array;
+  } data;
+  gchar *member_name;
+} JsonBuilderState;
+
+static void
+json_builder_state_free (JsonBuilderState *state)
+{
+  if (G_LIKELY (state))
+    {
+      switch (state->mode)
+        {
+        case JSON_BUILDER_MODE_OBJECT:
+        case JSON_BUILDER_MODE_MEMBER:
+          json_object_unref (state->data.object);
+          g_free (state->member_name);
+          state->data.object = NULL;
+          state->member_name = NULL;
+          break;
+        case JSON_BUILDER_MODE_ARRAY:
+          json_array_unref (state->data.array);
+          state->data.array = NULL;
+          break;
+        default:
+          g_assert_not_reached ();
+        }
+
+      g_slice_free (JsonBuilderState, state);
+    }
+}
+
+G_DEFINE_TYPE (JsonBuilder, json_builder, G_TYPE_OBJECT);
+
+static void
+json_builder_free_all_state (JsonBuilder *builder)
+{
+  JsonBuilderState *state;
+
+  while (!g_queue_is_empty (builder->priv->stack))
+    {
+      state = g_queue_pop_head (builder->priv->stack);
+      json_builder_state_free (state);
+    }
+
+  if (builder->priv->root)
+    {
+      json_node_free (builder->priv->root);
+      builder->priv->root = NULL;
+    }
+}
+
+static void
+json_builder_finalize (GObject *gobject)
+{
+  JsonBuilderPrivate *priv = JSON_BUILDER_GET_PRIVATE (gobject);
+
+  json_builder_free_all_state (JSON_BUILDER (gobject));
+
+  g_queue_free (priv->stack);
+  priv->stack = NULL;
+
+  G_OBJECT_CLASS (json_builder_parent_class)->finalize (gobject);
+}
+
+static void
+json_builder_class_init (JsonBuilderClass *klass)
+{
+  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
+
+  g_type_class_add_private (klass, sizeof (JsonBuilderPrivate));
+
+  gobject_class->finalize = json_builder_finalize;
+}
+
+static void
+json_builder_init (JsonBuilder *builder)
+{
+  JsonBuilderPrivate *priv;
+
+  builder->priv = priv = JSON_BUILDER_GET_PRIVATE (builder);
+
+  priv->stack = g_queue_new ();
+  priv->root = NULL;
+}
+
+static inline JsonBuilderMode
+json_builder_current_mode (JsonBuilder *builder)
+{
+  JsonBuilderState *state = g_queue_peek_head (builder->priv->stack);
+  return state->mode;
+}
+
+static inline gboolean
+json_builder_is_valid_add_mode (JsonBuilder *builder)
+{
+  JsonBuilderMode mode = json_builder_current_mode (builder);
+  return mode == JSON_BUILDER_MODE_MEMBER || mode == JSON_BUILDER_MODE_ARRAY;
+}
+
+/**
+ * json_builder_new:
+ *
+ * Creates a new #JsonBuilder. You can use this object to generate a
+ * JSON tree and obtain the root #JsonNode<!-- -->s.
+ *
+ * Return value: the newly created #JsonBuilder instance
+ */
+JsonBuilder *
+json_builder_new (void)
+{
+  return g_object_new (JSON_TYPE_BUILDER, NULL);
+}
+
+/**
+ * json_builder_get_root:
+ * @builder: a #JsonBuilder
+ *
+ * Returns the root of the current constructed tree, if the build is complete
+ * (ie: all opened objects, object members and arrays are being closed).
+ *
+ * Return value: (transfer full): the #JsonNode, or %NULL if the build is not complete.
+ *   Free the returned value with json_node_free().
+ */
+JsonNode *
+json_builder_get_root (JsonBuilder *builder)
+{
+  JsonNode *root = NULL;
+
+  g_return_val_if_fail (JSON_IS_BUILDER (builder), NULL);
+
+  if (builder->priv->root)
+    root = json_node_copy (builder->priv->root);
+
+  return root;
+}
+
+/**
+ * json_builder_reset:
+ * @builder: a #JsonBuilder
+ *
+ * Resets the state of the @builder back to its initial state.
+ */
+void
+json_builder_reset (JsonBuilder *builder)
+{
+  g_return_if_fail (JSON_IS_BUILDER (builder));
+
+  json_builder_free_all_state (builder);
+}
+
+/**
+ * json_builder_begin_object:
+ * @builder: a #JsonBuilder
+ *
+ * Opens a subobject inside the given @builder. When done adding members to
+ * the subobject, json_builder_end_object() must be called.
+ *
+ * Can be called for first or only if the call is associated to an object member
+ * or an array element.
+ *
+ * Return value: the #JsonBuilder, or %NULL if the call was inconsistent
+ */
+JsonBuilder *
+json_builder_begin_object (JsonBuilder *builder)
+{
+  JsonObject *object;
+  JsonBuilderState *state;
+  JsonBuilderState *cur_state;
+
+  g_return_val_if_fail (JSON_IS_BUILDER (builder), NULL);
+  g_return_val_if_fail (builder->priv->root == NULL, NULL);
+  g_return_val_if_fail (g_queue_is_empty (builder->priv->stack) || json_builder_is_valid_add_mode (builder), NULL);
+
+  object = json_object_new ();
+  cur_state = g_queue_peek_head (builder->priv->stack);
+  if (cur_state)
+    {
+      switch (cur_state->mode)
+        {
+        case JSON_BUILDER_MODE_ARRAY:
+          json_array_add_object_element (cur_state->data.array, json_object_ref (object));
+          break;
+
+        case JSON_BUILDER_MODE_MEMBER:
+          json_object_set_object_member (cur_state->data.object, cur_state->member_name, json_object_ref (object));
+          g_free (cur_state->member_name);
+          cur_state->member_name = NULL;
+          cur_state->mode = JSON_BUILDER_MODE_OBJECT;
+          break;
+
+        default:
+          g_assert_not_reached ();
+        }
+    }
+
+  state = g_slice_new (JsonBuilderState);
+  state->data.object = object;
+  state->mode = JSON_BUILDER_MODE_OBJECT;
+  g_queue_push_head (builder->priv->stack, state);
+
+  return builder;
+}
+
+/**
+ * json_builder_end_object:
+ * @builder: a #JsonBuilder
+ *
+ * Closes the subobject inside the given @builder that was opened by the most
+ * recent call to json_builder_begin_object().
+ *
+ * Cannot be called after json_builder_set_member_name().
+ *
+ * Return value: the #JsonBuilder, or %NULL if the call was inconsistent
+ */
+JsonBuilder *
+json_builder_end_object (JsonBuilder *builder)
+{
+  JsonBuilderState *state;
+
+  g_return_val_if_fail (JSON_IS_BUILDER (builder), NULL);
+  g_return_val_if_fail (!g_queue_is_empty (builder->priv->stack), NULL);
+  g_return_val_if_fail (json_builder_current_mode (builder) == JSON_BUILDER_MODE_OBJECT, NULL);
+
+  state = g_queue_pop_head (builder->priv->stack);
+
+  if (g_queue_is_empty (builder->priv->stack))
+    {
+      builder->priv->root = json_node_new (JSON_NODE_OBJECT);
+      json_node_take_object (builder->priv->root, json_object_ref (state->data.object));
+    }
+
+  json_builder_state_free (state);
+
+  return builder;
+}
+
+/**
+ * json_builder_begin_array:
+ * @builder: a #JsonBuilder
+ *
+ * Opens a subarray inside the given @builder. When done adding members to
+ * the subarray, json_builder_end_array() must be called.
+ *
+ * Can be called for first or only if the call is associated to an object member
+ * or an array element.
+ *
+ * Return value: the #JsonBuilder, or %NULL if the call was inconsistent
+ */
+JsonBuilder *
+json_builder_begin_array (JsonBuilder *builder)
+{
+  JsonArray *array;
+  JsonBuilderState *state;
+  JsonBuilderState *cur_state;
+
+  g_return_val_if_fail (JSON_IS_BUILDER (builder), NULL);
+  g_return_val_if_fail (builder->priv->root == NULL, NULL);
+  g_return_val_if_fail (g_queue_is_empty (builder->priv->stack) || json_builder_is_valid_add_mode (builder), NULL);
+
+  array = json_array_new ();
+  cur_state = g_queue_peek_head (builder->priv->stack);
+  if (cur_state)
+    {
+      switch (cur_state->mode)
+        {
+        case JSON_BUILDER_MODE_ARRAY:
+          json_array_add_array_element (cur_state->data.array, json_array_ref (array));
+          break;
+
+        case JSON_BUILDER_MODE_MEMBER:
+          json_object_set_array_member (cur_state->data.object, cur_state->member_name, json_array_ref (array));
+          g_free (cur_state->member_name);
+          cur_state->member_name = NULL;
+          cur_state->mode = JSON_BUILDER_MODE_OBJECT;
+          break;
+
+        default:
+          g_assert_not_reached ();
+        }
+    }
+
+  state = g_slice_new (JsonBuilderState);
+  state->data.array = array;
+  state->mode = JSON_BUILDER_MODE_ARRAY;
+  g_queue_push_head (builder->priv->stack, state);
+
+  return builder;
+}
+
+/**
+ * json_builder_end_array:
+ * @builder: a #JsonBuilder
+ *
+ * Closes the subarray inside the given @builder that was opened by the most
+ * recent call to json_builder_begin_array().
+ *
+ * Cannot be called after json_builder_set_member_name().
+ *
+ * Return value: the #JsonBuilder, or %NULL if the call was inconsistent
+ */
+JsonBuilder *
+json_builder_end_array (JsonBuilder *builder)
+{
+  JsonBuilderState *state;
+
+  g_return_val_if_fail (JSON_IS_BUILDER (builder), NULL);
+  g_return_val_if_fail (!g_queue_is_empty (builder->priv->stack), NULL);
+  g_return_val_if_fail (json_builder_current_mode (builder) == JSON_BUILDER_MODE_ARRAY, NULL);
+
+  state = g_queue_pop_head (builder->priv->stack);
+
+  if (g_queue_is_empty (builder->priv->stack))
+    {
+      builder->priv->root = json_node_new (JSON_NODE_ARRAY);
+      json_node_take_array (builder->priv->root, json_array_ref (state->data.array));
+    }
+
+  json_builder_state_free (state);
+
+  return builder;
+}
+
+/**
+ * json_builder_set_member_name:
+ * @builder: a #JsonBuilder
+ * @member_name: the name of the member
+ *
+ * Set the name of the next member in an object. The next call must add a value,
+ * open an object or an array.
+ *
+ * Can be called only if the call is associated to an object.
+ *
+ * Return value: the #JsonBuilder, or %NULL if the call was inconsistent
+ */
+JsonBuilder *
+json_builder_set_member_name (JsonBuilder *builder, const gchar *member_name)
+{
+  JsonBuilderState *state;
+
+  g_return_val_if_fail (JSON_IS_BUILDER (builder), NULL);
+  g_return_val_if_fail (member_name != NULL, NULL);
+  g_return_val_if_fail (!g_queue_is_empty (builder->priv->stack), NULL);
+  g_return_val_if_fail (json_builder_current_mode (builder) == JSON_BUILDER_MODE_OBJECT, NULL);
+
+  state = g_queue_peek_head (builder->priv->stack);
+  state->member_name = g_strdup (member_name);
+  state->mode = JSON_BUILDER_MODE_MEMBER;
+
+  return builder;
+}
+
+/**
+ * json_builder_add_value:
+ * @builder: a #JsonBuilder
+ * @node: the value of the member or element
+ *
+ * If called after json_builder_set_member_name(), sets @node as member of the
+ * most recent opened object, otherwise @node is added as element of the most
+ * recent opened array.
+ *
+ * Return value: the #JsonBuilder, or %NULL if the call was inconsistent
+ */
+JsonBuilder *
+json_builder_add_value (JsonBuilder *builder, JsonNode *node)
+{
+  JsonBuilderState *state;
+
+  g_return_val_if_fail (JSON_IS_BUILDER (builder), NULL);
+  g_return_val_if_fail (node != NULL, NULL);
+  g_return_val_if_fail (!g_queue_is_empty (builder->priv->stack), NULL);
+  g_return_val_if_fail (json_builder_is_valid_add_mode (builder), NULL);
+
+  state = g_queue_peek_head (builder->priv->stack);
+  switch (state->mode)
+    {
+    case JSON_BUILDER_MODE_MEMBER:
+      json_object_set_member (state->data.object, state->member_name, node);
+      g_free (state->member_name);
+      state->member_name = NULL;
+      state->mode = JSON_BUILDER_MODE_OBJECT;
+      break;
+
+    case JSON_BUILDER_MODE_ARRAY:
+      json_array_add_element (state->data.array, node);
+      break;
+
+    default:
+      g_assert_not_reached ();
+    }
+
+  return builder;
+}
+
+/**
+ * json_builder_add_int_value:
+ * @builder: a #JsonBuilder
+ * @value: the value of the member or element
+ *
+ * If called after json_builder_set_member_name(), sets @value as member of the
+ * most recent opened object, otherwise @value is added as element of the most
+ * recent opened array.
+ *
+ * See also: json_builder_add_value()
+ *
+ * Return value: the #JsonBuilder, or %NULL if the call was inconsistent
+ */
+JsonBuilder *
+json_builder_add_int_value (JsonBuilder *builder, gint64 value)
+{
+  JsonBuilderState *state;
+
+  g_return_val_if_fail (JSON_IS_BUILDER (builder), NULL);
+  g_return_val_if_fail (!g_queue_is_empty (builder->priv->stack), NULL);
+  g_return_val_if_fail (json_builder_is_valid_add_mode (builder), NULL);
+
+  state = g_queue_peek_head (builder->priv->stack);
+  switch (state->mode)
+    {
+    case JSON_BUILDER_MODE_MEMBER:
+      json_object_set_int_member (state->data.object, state->member_name, value);
+      g_free (state->member_name);
+      state->member_name = NULL;
+      state->mode = JSON_BUILDER_MODE_OBJECT;
+      break;
+
+    case JSON_BUILDER_MODE_ARRAY:
+      json_array_add_int_element (state->data.array, value);
+      break;
+
+    default:
+      g_assert_not_reached ();
+    }
+
+  return builder;
+}
+
+/**
+ * json_builder_add_double_value:
+ * @builder: a #JsonBuilder
+ * @value: the value of the member or element
+ *
+ * If called after json_builder_set_member_name(), sets @value as member of the
+ * most recent opened object, otherwise @value is added as element of the most
+ * recent opened array.
+ *
+ * See also: json_builder_add_value()
+ *
+ * Return value: the #JsonBuilder, or %NULL if the call was inconsistent
+ */
+JsonBuilder *
+json_builder_add_double_value (JsonBuilder *builder, gdouble value)
+{
+  JsonBuilderState *state;
+
+  g_return_val_if_fail (JSON_IS_BUILDER (builder), NULL);
+  g_return_val_if_fail (!g_queue_is_empty (builder->priv->stack), NULL);
+  g_return_val_if_fail (json_builder_is_valid_add_mode (builder), NULL);
+
+  state = g_queue_peek_head (builder->priv->stack);
+
+  switch (state->mode)
+    {
+    case JSON_BUILDER_MODE_MEMBER:
+      json_object_set_double_member (state->data.object, state->member_name, value);
+      g_free (state->member_name);
+      state->member_name = NULL;
+      state->mode = JSON_BUILDER_MODE_OBJECT;
+      break;
+
+    case JSON_BUILDER_MODE_ARRAY:
+      json_array_add_double_element (state->data.array, value);
+      break;
+
+    default:
+      g_assert_not_reached ();
+    }
+
+  return builder;
+}
+
+/**
+ * json_builder_add_boolean_value:
+ * @builder: a #JsonBuilder
+ * @value: the value of the member or element
+ *
+ * If called after json_builder_set_member_name(), sets @value as member of the
+ * most recent opened object, otherwise @value is added as element of the most
+ * recent opened array.
+ *
+ * See also: json_builder_add_value()
+ *
+ * Return value: the #JsonBuilder, or %NULL if the call was inconsistent
+ */
+JsonBuilder *
+json_builder_add_boolean_value (JsonBuilder *builder, gboolean value)
+{
+  JsonBuilderState *state;
+
+  g_return_val_if_fail (JSON_IS_BUILDER (builder), NULL);
+  g_return_val_if_fail (!g_queue_is_empty (builder->priv->stack), NULL);
+  g_return_val_if_fail (json_builder_is_valid_add_mode (builder), NULL);
+
+  state = g_queue_peek_head (builder->priv->stack);
+
+  switch (state->mode)
+    {
+    case JSON_BUILDER_MODE_MEMBER:
+      json_object_set_boolean_member (state->data.object, state->member_name, value);
+      g_free (state->member_name);
+      state->member_name = NULL;
+      state->mode = JSON_BUILDER_MODE_OBJECT;
+      break;
+
+    case JSON_BUILDER_MODE_ARRAY:
+      json_array_add_boolean_element (state->data.array, value);
+      break;
+
+    default:
+      g_assert_not_reached ();
+    }
+
+  return builder;
+}
+
+/**
+ * json_builder_add_string_value:
+ * @builder: a #JsonBuilder
+ * @value: the value of the member or element
+ *
+ * If called after json_builder_set_member_name(), sets @value as member of the
+ * most recent opened object, otherwise @value is added as element of the most
+ * recent opened array.
+ *
+ * See also: json_builder_add_value()
+ *
+ * Return value: the #JsonBuilder, or %NULL if the call was inconsistent
+ */
+JsonBuilder *
+json_builder_add_string_value (JsonBuilder *builder, const gchar *value)
+{
+  JsonBuilderState *state;
+
+  g_return_val_if_fail (JSON_IS_BUILDER (builder), NULL);
+  g_return_val_if_fail (!g_queue_is_empty (builder->priv->stack), NULL);
+  g_return_val_if_fail (json_builder_is_valid_add_mode (builder), NULL);
+
+  state = g_queue_peek_head (builder->priv->stack);
+
+  switch (state->mode)
+    {
+    case JSON_BUILDER_MODE_MEMBER:
+      json_object_set_string_member (state->data.object, state->member_name, value);
+      g_free (state->member_name);
+      state->member_name = NULL;
+      state->mode = JSON_BUILDER_MODE_OBJECT;
+      break;
+
+    case JSON_BUILDER_MODE_ARRAY:
+      json_array_add_string_element (state->data.array, value);
+      break;
+
+    default:
+      g_assert_not_reached ();
+    }
+
+  return builder;
+}
+
+/**
+ * json_builder_add_null_value:
+ * @builder: a #JsonBuilder
+ * @value: the value of the member or element
+ *
+ * If called after json_builder_set_member_name(), sets null as member of the
+ * most recent opened object, otherwise null is added as element of the most
+ * recent opened array.
+ *
+ * See also: json_builder_add_value()
+ *
+ * Return value: the #JsonBuilder, or %NULL if the call was inconsistent
+ */
+JsonBuilder *
+json_builder_add_null_value (JsonBuilder *builder)
+{
+  JsonBuilderState *state;
+
+  g_return_val_if_fail (JSON_IS_BUILDER (builder), NULL);
+  g_return_val_if_fail (!g_queue_is_empty (builder->priv->stack), NULL);
+  g_return_val_if_fail (json_builder_is_valid_add_mode (builder), NULL);
+
+  state = g_queue_peek_head (builder->priv->stack);
+
+  switch (state->mode)
+    {
+    case JSON_BUILDER_MODE_MEMBER:
+      json_object_set_null_member (state->data.object, state->member_name);
+      g_free (state->member_name);
+      state->member_name = NULL;
+      state->mode = JSON_BUILDER_MODE_OBJECT;
+      break;
+
+    case JSON_BUILDER_MODE_ARRAY:
+      json_array_add_null_element (state->data.array);
+      break;
+
+    default:
+      g_assert_not_reached ();
+    }
+
+  return builder;
+}