[Qemu-devel] [PATCH v6 12/15] qapi: Support pretty printing in JSON output visitor

[Eric Blake <eblake@redhat.com>]

Add pretty printing, where the format intentionally matches that of
qobject_to_json() (a later patch will then rework qobject-json.c to
work on top of the JSON visitor).  The trickiest part is probably
that the testsuite now has to honor parameterization on whether
pretty printing is enabled.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v6: tweak commit message, use of 'bool pretty' in testsuite
[no v5 due to series split]
v4: rebase to earlier changes, defer type_any() to later
v3: rebase to earlier changes
v2: rebase to earlier changes
---
 include/qapi/json-output-visitor.h |   5 +-
 qapi/json-output-visitor.c         |  15 ++++-
 tests/test-json-output-visitor.c   | 124 +++++++++++++++++++++++++------------
 3 files changed, 101 insertions(+), 43 deletions(-)

diff --git a/include/qapi/json-output-visitor.h b/include/qapi/json-output-visitor.h
index 41c79f4..94c9e0f 100644
--- a/include/qapi/json-output-visitor.h
+++ b/include/qapi/json-output-visitor.h
@@ -21,8 +21,11 @@ typedef struct JsonOutputVisitor JsonOutputVisitor;
  * If everything else succeeds, pass @result to visit_complete() to
  * collect the result of the visit.
  *
+ * If @pretty, make the output legible with newlines and indentation;
+ * otherwise the output uses a single line.
+ *
  * For now, this cannot be used to visit the 'any' type.
  */
-Visitor *json_output_visitor_new(char **result);
+Visitor *json_output_visitor_new(bool pretty, char **result);

 #endif
diff --git a/qapi/json-output-visitor.c b/qapi/json-output-visitor.c
index 805154a..7d12879 100644
--- a/qapi/json-output-visitor.c
+++ b/qapi/json-output-visitor.c
@@ -17,6 +17,7 @@
 struct JsonOutputVisitor {
     Visitor visitor;
     QString *str;
+    bool pretty;
     bool comma;
     unsigned int depth;
     char **result;
@@ -30,10 +31,13 @@ static JsonOutputVisitor *to_jov(Visitor *v)
 static void json_output_name(JsonOutputVisitor *jov, const char *name)
 {
     if (jov->comma) {
-        qstring_append(jov->str, ", ");
+        qstring_append(jov->str, jov->pretty ? "," : ", ");
     } else {
         jov->comma = true;
     }
+    if (jov->pretty && jov->depth) {
+        qstring_append_printf(jov->str, "\n%*s", 4 * jov->depth, "");
+    }
     if (name && jov->depth) {
         qstring_append_json_string(jov->str, name);
         qstring_append(jov->str, ": ");
@@ -57,6 +61,9 @@ static void json_output_end_struct(Visitor *v, void **obj)

     assert(jov->depth);
     jov->depth--;
+    if (jov->pretty) {
+        qstring_append_printf(jov->str, "\n%*s", 4 * jov->depth, "");
+    }
     qstring_append(jov->str, "}");
     jov->comma = true;
 }
@@ -85,6 +92,9 @@ static void json_output_end_list(Visitor *v, void **obj)

     assert(jov->depth);
     jov->depth--;
+    if (jov->pretty) {
+        qstring_append_printf(jov->str, "\n%*s", 4 * jov->depth, "");
+    }
     qstring_append(jov->str, "]");
     jov->comma = true;
 }
@@ -165,11 +175,12 @@ static void json_output_free(Visitor *v)
     g_free(jov);
 }

-Visitor *json_output_visitor_new(char **result)
+Visitor *json_output_visitor_new(bool pretty, char **result)
 {
     JsonOutputVisitor *v;

     v = g_malloc0(sizeof(*v));
+    v->pretty = pretty;
     v->result = result;
     *result = NULL;
     v->str = qstring_new();
diff --git a/tests/test-json-output-visitor.c b/tests/test-json-output-visitor.c
index 3c77a61..849cf2b 100644
--- a/tests/test-json-output-visitor.c
+++ b/tests/test-json-output-visitor.c
@@ -24,13 +24,17 @@

 typedef struct TestOutputVisitorData {
     Visitor *ov;
+    bool pretty;
     char *str;
 } TestOutputVisitorData;

 static void visitor_output_setup(TestOutputVisitorData *data,
-                                 const void *unused)
+                                 const void *arg)
 {
-    data->ov = json_output_visitor_new(&data->str);
+    bool pretty = *(bool *)arg;
+
+    data->pretty = pretty;
+    data->ov = json_output_visitor_new(pretty, &data->str);
     g_assert(data->ov);
 }

@@ -52,8 +56,10 @@ static const char *visitor_get(TestOutputVisitorData *data)

 static void visitor_reset(TestOutputVisitorData *data)
 {
+    bool pretty = data->pretty;
+
     visitor_output_teardown(data, NULL);
-    visitor_output_setup(data, NULL);
+    visitor_output_setup(data, &pretty);
 }

 static void test_visitor_out_int(TestOutputVisitorData *data,
@@ -161,8 +167,9 @@ static void test_visitor_out_struct(TestOutputVisitorData *data,
 }

 static void test_visitor_out_struct_nested(TestOutputVisitorData *data,
-                                           const void *unused)
+                                           const void *arg)
 {
+    bool pretty = *(bool *)arg;
     int64_t value = 42;
     UserDefTwo *ud2;
     const char *string = "user def string";
@@ -192,27 +199,51 @@ static void test_visitor_out_struct_nested(TestOutputVisitorData *data,
     visit_type_UserDefTwo(data->ov, "unused", &ud2, &error_abort);

     out = visitor_get(data);
-    g_assert_cmpstr(out, ==,
-                    "{"
-                     "\"string0\": \"forty two\", "
-                     "\"dict1\": {"
-                      "\"string1\": \"forty three\", "
-                      "\"dict2\": {"
-                       "\"userdef\": {"
-                        "\"integer\": 42, "
-                        "\"string\": \"user def string\""
-                        "}, "
-                       "\"string\": \"forty four\""
-                       "}, "
-                      "\"dict3\": {"
-                       "\"userdef\": {"
-                        "\"integer\": 42, "
-                        "\"string\": \"user def string\""
-                        "}, "
-                      "\"string\": \"forty five\""
-                      "}"
-                     "}"
-                    "}");
+    if (pretty) {
+        g_assert_cmpstr(out, ==,
+                        "{\n"
+                        "    \"string0\": \"forty two\",\n"
+                        "    \"dict1\": {\n"
+                        "        \"string1\": \"forty three\",\n"
+                        "        \"dict2\": {\n"
+                        "            \"userdef\": {\n"
+                        "                \"integer\": 42,\n"
+                        "                \"string\": \"user def string\"\n"
+                        "            },\n"
+                        "            \"string\": \"forty four\"\n"
+                        "        },\n"
+                        "        \"dict3\": {\n"
+                        "            \"userdef\": {\n"
+                        "                \"integer\": 42,\n"
+                        "                \"string\": \"user def string\"\n"
+                        "            },\n"
+                        "            \"string\": \"forty five\"\n"
+                        "        }\n"
+                        "    }\n"
+                        "}");
+    } else {
+        g_assert_cmpstr(out, ==,
+                        "{"
+                         "\"string0\": \"forty two\", "
+                         "\"dict1\": {"
+                          "\"string1\": \"forty three\", "
+                          "\"dict2\": {"
+                           "\"userdef\": {"
+                            "\"integer\": 42, "
+                            "\"string\": \"user def string\""
+                            "}, "
+                           "\"string\": \"forty four\""
+                           "}, "
+                          "\"dict3\": {"
+                           "\"userdef\": {"
+                            "\"integer\": 42, "
+                            "\"string\": \"user def string\""
+                            "}, "
+                          "\"string\": \"forty five\""
+                          "}"
+                         "}"
+                        "}");
+    }
     qapi_free_UserDefTwo(ud2);
 }

@@ -346,36 +377,49 @@ static void test_visitor_out_null(TestOutputVisitorData *data,
     g_assert_cmpstr(out, ==, "null");
 }

-static void output_visitor_test_add(const char *testpath,
+static void output_visitor_test_add(const char *testpath, bool *data,
                                     void (*test_func)(TestOutputVisitorData *,
                                                       const void *))
 {
-    g_test_add(testpath, TestOutputVisitorData, NULL, visitor_output_setup,
+    g_test_add(testpath, TestOutputVisitorData, data, visitor_output_setup,
                test_func, visitor_output_teardown);
 }

 int main(int argc, char **argv)
 {
+    bool plain = false;
+    bool pretty = true;
+
     g_test_init(&argc, &argv, NULL);

-    output_visitor_test_add("/visitor/json/int", test_visitor_out_int);
-    output_visitor_test_add("/visitor/json/bool", test_visitor_out_bool);
-    output_visitor_test_add("/visitor/json/number", test_visitor_out_number);
-    output_visitor_test_add("/visitor/json/string", test_visitor_out_string);
-    output_visitor_test_add("/visitor/json/enum", test_visitor_out_enum);
-    output_visitor_test_add("/visitor/json/enum-errors",
+    output_visitor_test_add("/visitor/json/int", &plain,
+                            test_visitor_out_int);
+    output_visitor_test_add("/visitor/json/bool", &plain,
+                            test_visitor_out_bool);
+    output_visitor_test_add("/visitor/json/number", &plain,
+                            test_visitor_out_number);
+    output_visitor_test_add("/visitor/json/string", &plain,
+                            test_visitor_out_string);
+    output_visitor_test_add("/visitor/json/enum", &plain,
+                            test_visitor_out_enum);
+    output_visitor_test_add("/visitor/json/enum-errors", &plain,
                             test_visitor_out_enum_errors);
-    output_visitor_test_add("/visitor/json/struct", test_visitor_out_struct);
-    output_visitor_test_add("/visitor/json/struct-nested",
+    output_visitor_test_add("/visitor/json/struct", &plain,
+                            test_visitor_out_struct);
+    output_visitor_test_add("/visitor/json/struct-nested", &plain,
                             test_visitor_out_struct_nested);
-    output_visitor_test_add("/visitor/json/struct-errors",
+    output_visitor_test_add("/visitor/json-pretty/struct-nested", &pretty,
+                            test_visitor_out_struct_nested);
+    output_visitor_test_add("/visitor/json/struct-errors", &plain,
                             test_visitor_out_struct_errors);
-    output_visitor_test_add("/visitor/json/list", test_visitor_out_list);
-    output_visitor_test_add("/visitor/json/union-flat",
+    output_visitor_test_add("/visitor/json/list", &plain,
+                            test_visitor_out_list);
+    output_visitor_test_add("/visitor/json/union-flat", &plain,
                             test_visitor_out_union_flat);
-    output_visitor_test_add("/visitor/json/alternate",
+    output_visitor_test_add("/visitor/json/alternate", &plain,
                             test_visitor_out_alternate);
-    output_visitor_test_add("/visitor/json/null", test_visitor_out_null);
+    output_visitor_test_add("/visitor/json/null", &plain,
+                            test_visitor_out_null);

     g_test_run();

-- 
2.7.4