Merge pull request #234 from NeoRaider/userdata

Add public API to use userdata independently of custom serializer

.gitignore

@@ -41,6 +41,7 @@
 /tests/test_parse
 /tests/test_cast
 /tests/test_charcase
+/tests/test_double_serializer
 /tests/test_locale
 /tests/test_null
 /tests/test_printbuf

json_object.c

@@ -54,6 +54,7 @@ static struct json_object* json_object_new(enum json_type o_type);
 
 static json_object_to_json_string_fn json_object_object_to_json_string;
 static json_object_to_json_string_fn json_object_boolean_to_json_string;
+static json_object_to_json_string_fn json_object_double_to_json_string_default;
 static json_object_to_json_string_fn json_object_int_to_json_string;
 static json_object_to_json_string_fn json_object_string_to_json_string;
 static json_object_to_json_string_fn json_object_array_to_json_string;
@@ -234,6 +235,21 @@ enum json_type json_object_get_type(const struct json_object *jso)
 	return jso->o_type;
 }
 
+void* json_object_get_userdata(json_object *jso) {
+	return jso->_userdata;
+}
+
+void json_object_set_userdata(json_object *jso, void *userdata,
+			      json_object_delete_fn *user_delete)
+{
+	// First, clean up any previously existing user info
+	if (jso->_user_delete)
+		jso->_user_delete(jso, jso->_userdata);
+
+	jso->_userdata = userdata;
+	jso->_user_delete = user_delete;
+}
+
 /* set a custom conversion to string */
 
 void json_object_set_serializer(json_object *jso,
@@ -241,13 +257,7 @@ void json_object_set_serializer(json_object *jso,
 	void *userdata,
 	json_object_delete_fn *user_delete)
 {
-	// First, clean up any previously existing user info
-	if (jso->_user_delete)
-	{
-		jso->_user_delete(jso, jso->_userdata);
-	}
-	jso->_userdata = NULL;
-	jso->_user_delete = NULL;
+	json_object_set_userdata(jso, userdata, user_delete);
 
 	if (to_string_func == NULL)
 	{
@@ -261,7 +271,7 @@ void json_object_set_serializer(json_object *jso,
 			jso->_to_json_string = &json_object_boolean_to_json_string;
 			break;
 		case json_type_double:
-			jso->_to_json_string = &json_object_double_to_json_string;
+			jso->_to_json_string = &json_object_double_to_json_string_default;
 			break;
 		case json_type_int:
 			jso->_to_json_string = &json_object_int_to_json_string;
@@ -280,8 +290,6 @@ void json_object_set_serializer(json_object *jso,
 	}
 
 	jso->_to_json_string = to_string_func;
-	jso->_userdata = userdata;
-	jso->_user_delete = user_delete;
 }
 
 
@@ -643,10 +651,11 @@ int64_t json_object_get_int64(const struct json_object *jso)
 
 /* json_object_double */
 
-int json_object_double_to_json_string(struct json_object* jso,
-				      struct printbuf *pb,
-				      int level,
-				      int flags)
+static int json_object_double_to_json_string_format(struct json_object* jso,
+						    struct printbuf *pb,
+						    int level,
+						    int flags,
+						    const char *format)
 {
   char buf[128], *p, *q;
   int size;
@@ -663,7 +672,7 @@ int json_object_double_to_json_string(struct json_object* jso,
       size = snprintf(buf, sizeof(buf), "-Infinity");
   else
     size = snprintf(buf, sizeof(buf),
-        jso->_userdata ? (const char*) jso->_userdata : "%.17g", jso->o.c_double);
+        format ? format : "%.17g", jso->o.c_double);
 
   p = strchr(buf, ',');
   if (p) {
@@ -685,12 +694,30 @@ int json_object_double_to_json_string(struct json_object* jso,
   return size;
 }
 
+static int json_object_double_to_json_string_default(struct json_object* jso,
+						     struct printbuf *pb,
+						     int level,
+						     int flags)
+{
+	return json_object_double_to_json_string_format(jso, pb, level, flags,
+							NULL);
+}
+
+int json_object_double_to_json_string(struct json_object* jso,
+				      struct printbuf *pb,
+				      int level,
+				      int flags)
+{
+	return json_object_double_to_json_string_format(jso, pb, level, flags,
+							jso->_userdata);
+}
+
 struct json_object* json_object_new_double(double d)
 {
 	struct json_object *jso = json_object_new(json_type_double);
 	if (!jso)
 		return NULL;
-	jso->_to_json_string = &json_object_double_to_json_string;
+	jso->_to_json_string = &json_object_double_to_json_string_default;
 	jso->o.c_double = d;
 	return jso;
 }

json_object.h

@@ -223,18 +223,20 @@ extern const char* json_object_to_json_string_ext(struct json_object *obj, int
 flags);
 
 /**
- * Set a custom serialization function to be used when this particular object
- * is converted to a string by json_object_to_json_string.
+ * Returns the userdata set by json_object_set_userdata() or
+ * json_object_set_serializer()
  *
- * If a custom serializer is already set on this object, any existing
- * user_delete function is called before the new one is set.
+ * @param jso the object to return the userdata for
+ */
+extern void* json_object_get_userdata(json_object *jso);
+
+/**
+ * Set an opaque userdata value for an object
  *
- * If to_string_func is NULL, the other parameters are ignored
- * and the default behaviour is reset.
+ * The userdata can be retrieved using json_object_get_userdata().
  *
- * The userdata parameter is optional and may be passed as NULL.  If provided,
- * it is passed to to_string_func as-is.  This parameter may be NULL even
- * if user_delete is non-NULL.
+ * If custom userdata is already set on this object, any existing user_delete
+ * function is called before the new one is set.
  *
  * The user_delete parameter is optional and may be passed as NULL, even if
  * the userdata parameter is non-NULL.  It will be called just before the
@@ -243,6 +245,44 @@ flags);
  * If this is not provided, it is up to the caller to free the userdata at
  * an appropriate time. (i.e. after the json_object is deleted)
  *
+ * Note: Objects created by parsing strings may have custom serializers set
+ * which expect the userdata to contain specific data (due to use of
+ * json_object_new_double_s()). In this case, json_object_set_serialiser() with
+ * NULL as to_string_func should be used instead to set the userdata and reset
+ * the serializer to its default value.
+ *
+ * @param jso the object to set the userdata for
+ * @param userdata an optional opaque cookie
+ * @param user_delete an optional function from freeing userdata
+ */
+extern void json_object_set_userdata(json_object *jso, void *userdata,
+				     json_object_delete_fn *user_delete);
+
+/**
+ * Set a custom serialization function to be used when this particular object
+ * is converted to a string by json_object_to_json_string.
+ *
+ * If custom userdata is already set on this object, any existing user_delete
+ * function is called before the new one is set.
+ *
+ * If to_string_func is NULL the default behaviour is reset (but the userdata
+ * and user_delete fields are still set).
+ *
+ * The userdata parameter is optional and may be passed as NULL. It can be used
+ * to provide additional data for to_string_func to use. This parameter may
+ * be NULL even if user_delete is non-NULL.
+ *
+ * The user_delete parameter is optional and may be passed as NULL, even if
+ * the userdata parameter is non-NULL.  It will be called just before the
+ * json_object is deleted, after it's reference count goes to zero
+ * (see json_object_put()).
+ * If this is not provided, it is up to the caller to free the userdata at
+ * an appropriate time. (i.e. after the json_object is deleted)
+ *
+ * Note that the userdata is the same as set by json_object_set_userdata(), so
+ * care must be taken not to overwrite the value when both a custom serializer
+ * and json_object_set_userdata() are used.
+ *
  * @param jso the object to customize
  * @param to_string_func the custom serialization function
  * @param userdata an optional opaque cookie
@@ -634,8 +674,13 @@ extern struct json_object* json_object_new_double(double d);
  * inefficiently (e.g. 12.3 => "12.300000000000001") to be
  * serialized with the more convenient form.
  *
- * Note: this is used by json_tokener_parse_ex() to allow for
- *   an exact re-serialization of a parsed object.
+ * Notes:
+ *
+ * This is used by json_tokener_parse_ex() to allow for
+ * an exact re-serialization of a parsed object.
+ *
+ * The userdata field is used to store the string representation, so it
+ * can't be used for other data if this function is used.
  *
  * An equivalent sequence of calls is:
  * @code

tests/Makefile.am

@@ -11,6 +11,7 @@ TESTS+= testReplaceExisting.test
 TESTS+= test_parse_int64.test
 TESTS+= test_null.test
 TESTS+= test_cast.test
+TESTS+= test_double_serializer.test
 TESTS+= test_parse.test
 TESTS+= test_locale.test
 TESTS+= test_charcase.test
@@ -22,7 +23,7 @@ check_PROGRAMS=
 check_PROGRAMS += $(TESTS:.test=)
 
 # Note: handled by test1.test
-check_PROGRAMS += test1Formatted 
+check_PROGRAMS += test1Formatted
 test1Formatted_SOURCES = test1.c parse_flags.c
 test1Formatted_CPPFLAGS = -DTEST_FORMATTED
 

tests/test_double_serializer.c

@@ -0,0 +1,31 @@
+/*
+* Tests if the format string for double serialization is handled correctly
+*/
+
+#include <stdio.h>
+#include "config.h"
+
+#include "json_object.h"
+#include "json_object_private.h"
+
+int main()
+{
+	struct json_object *obj = json_object_new_double(0.5);
+
+	printf("Test default serializer:\n");
+	printf("obj.to_string(standard)=%s\n", json_object_to_json_string(obj));
+
+	printf("Test default serializer with custom userdata:\n");
+	obj->_userdata = "test";
+	printf("obj.to_string(userdata)=%s\n", json_object_to_json_string(obj));
+
+	printf("Test explicit serializer with custom userdata:\n");
+	json_object_set_serializer(obj, json_object_double_to_json_string, "test", NULL);
+	printf("obj.to_string(custom)=%s\n", json_object_to_json_string(obj));
+
+	printf("Test reset serializer:\n");
+	json_object_set_serializer(obj, NULL, NULL, NULL);
+	printf("obj.to_string(reset)=%s\n", json_object_to_json_string(obj));
+
+	json_object_put(obj);
+}

tests/test_double_serializer.expected

@@ -0,0 +1,8 @@
+Test default serializer:
+obj.to_string(standard)=0.5
+Test default serializer with custom userdata:
+obj.to_string(userdata)=0.5
+Test explicit serializer with custom userdata:
+obj.to_string(custom)=test
+Test reset serializer:
+obj.to_string(reset)=0.5

tests/test_double_serializer.test

@@ -0,0 +1,12 @@
+#!/bin/sh
+
+# Common definitions
+if test -z "$srcdir"; then
+    srcdir="${0%/*}"
+    test "$srcdir" = "$0" && srcdir=.
+    test -z "$srcdir" && srcdir=.
+fi
+. "$srcdir/test-defs.sh"
+
+run_output_test test_double_serializer
+exit $?