[Qemu-devel] [PATCH 7/7] add formatted printing of QObjects

[Paolo Bonzini]

This patch adds a function to format a QDict according to a string
that is printf like but specifies how to navigate the QDict.  All
parts are printed as JSON, but this is fine since this will auto-escape
strings and integers print naturally.

More sophisticated flags can be added later, e.g. %#{foo} would
print a string without escaping.

Cc: Luiz Capitulino <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
---
 Makefile     |    6 +++---
 check-json.c |   39 +++++++++++++++++++++++++++++++++++++++
 qstring.c    |   51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 qstring.h    |    3 +++
 4 files changed, 96 insertions(+), 3 deletions(-)

diff --git a/Makefile b/Makefile
index 2483057..f98b70c 100644
--- a/Makefile
+++ b/Makefile
@@ -211,10 +211,10 @@ qemu-img-cmds.h: $(SRC_PATH)/qemu-img-cmds.hx
        $(call quiet-command,sh $(SRC_PATH)/hxtool -h < $< > $@,"  GEN   $@")
 
 check-json: check-json.o qint.o qstring.o qdict.o qlist.o qemu-malloc.o
-check-qint: check-qint.o qint.o qstring.o qemu-malloc.o
-check-qstring: check-qstring.o qstring.o qemu-malloc.o
+check-qint: check-qint.o qint.o qstring.o qdict.o qemu-malloc.o
+check-qstring: check-qstring.o qint.o qstring.o qdict.o qemu-malloc.o
 check-qdict: check-qdict.o qdict.o qint.o qstring.o qemu-malloc.o
-check-qlist: check-qlist.o qlist.o qint.o qstring.o qemu-malloc.o
+check-qlist: check-qlist.o qlist.o qint.o qstring.o qdict.o qemu-malloc.o
 
 clean:
 # avoid old build problems by removing potentially incorrect old files
diff --git a/check-json.c b/check-json.c
index 9f4cfbe..eaff53b 100644
--- a/check-json.c
+++ b/check-json.c
@@ -21,6 +21,13 @@
     QDECREF(result);                                            \
   } while (0)
 
+#define format_expect(qobj, format, expected)                   \
+  do {                                                          \
+    QString *result = qstring_format (format, qobj);            \
+    fail_unless (!strcmp (qstring_get_str (result), expected)); \
+    QDECREF(result);                                            \
+  } while (0)
+
 START_TEST(qint_json_test)
 {
     QInt *qi;
@@ -88,6 +95,37 @@ START_TEST(nested_json_test)
 }
 END_TEST
 
+START_TEST(format_test)
+{
+    QDict *qdict_in, *qdict_out;
+    QList *qlist;
+
+    format_expect(NULL, "test", "test");
+    format_expect(NULL, "test %%", "test %");
+
+    qdict_in = qdict_new();
+    format_expect(qdict_in, "test %%", "test %");
+    format_expect(qdict_in, "test %{} test", "test {} test");
+    format_expect(qdict_in, "%%%{}%%", "%{}%");
+
+    qdict_put_obj(qdict_in, "in", QOBJECT(qint_from_int(42)));
+    format_expect(qdict_in, "%{}", "{\"in\":42}");
+    format_expect(qdict_in, "test %{in} test", "test 42 test");
+
+    qlist = qlist_new();
+    qlist_append(qlist, qdict_in);
+    QINCREF(qlist);
+
+    qdict_out = qdict_new();
+    qdict_put_obj(qdict_out, "list", QOBJECT(qlist));
+    qdict_put_obj(qdict_out, "in", QOBJECT(qdict_in));
+    format_expect(qdict_out, "%{list}", "[{\"in\":42}]");
+    format_expect(qdict_out, "%{in.in}", "42");
+    format_expect(qdict_out, "%{in.in}%{in.in}", "4242");
+    QDECREF(qdict_out);
+}
+END_TEST
+
 static Suite *QObject_json_suite(void)
 {
     Suite *s;
@@ -102,6 +140,7 @@ static Suite *QObject_json_suite(void)
     tcase_add_test(qobject_json_tcase, qdict_json_test);
     tcase_add_test(qobject_json_tcase, qlist_json_test);
     tcase_add_test(qobject_json_tcase, nested_json_test);
+    tcase_add_test(qobject_json_tcase, format_test);
 
     return s;
 }
diff --git a/qstring.c b/qstring.c
index 10c1952..90d9295 100644
--- a/qstring.c
+++ b/qstring.c
@@ -11,6 +11,7 @@
  */
 #include "qobject.h"
 #include "qstring.h"
+#include "qdict.h"
 #include "qemu-common.h"
 
 static void qstring_destroy_obj(QObject *obj);
@@ -79,6 +80,14 @@ QString *qstring_json_from_qobject_obj(const QObject 
*qobject)
     return qstring;
 }
 
+QString *qstring_format(const char *format, const QDict *root)
+{
+    QString *qstring;
+
+    qstring = qstring_new();
+    qstring_append_format(qstring, format, root);
+    return qstring;
+}
 
 /**
  * qstring_append(): Append a regular C string to a QString
@@ -137,6 +146,48 @@ void qstring_append_escaped(QString *qstring, const char 
*str)
     }
 }
 
+void qstring_append_format(QString *qstring, const char *format,
+                           const struct QDict *root)
+{
+    char buf[256], *p;
+    while (format && *format) {
+        const QObject *next = QOBJECT(root);
+
+        if (*format != '%' || *++format == '%') {
+            qstring_append_ch (qstring, *format++);
+            continue;
+        }
+        if (*format++ != '{')
+            abort ();
+
+        next = QOBJECT(root);
+        if (*format == '}') {
+            format++;
+        } else {
+            do {
+                if (qobject_type(next) != QTYPE_QDICT) {
+                    format = strchr (format, '}');
+                    if (!format) {
+                            return;
+                    }
+                    next = NULL;
+                } else {
+                    p = buf;
+                    while (*format != '.' && *format != '}')
+                        *p++ = *format++;
+                    *p = 0;
+                    next = qdict_get(qobject_to_qdict(next), buf);
+                }
+            } while (*format++ != '}');
+        }
+
+        if (next) {
+            qobject_encode_json(next, qstring);
+        }
+    }
+}
+
+
 /**
  * qstring_append_ch(): Append a character to a QString
  */
diff --git a/qstring.h b/qstring.h
index efc1d7a..2d1fec9 100644
--- a/qstring.h
+++ b/qstring.h
@@ -11,6 +11,7 @@ typedef struct QString {
 
 QString *qstring_new(void);
 QString *qstring_from_str(const char *str);
+QString *qstring_format(const char *format, const struct QDict *qdict);
 QString *qstring_json_from_qobject_obj(const QObject *obj);
 
 #define qstring_json_from_qobject(obj) \
@@ -18,6 +19,8 @@ QString *qstring_json_from_qobject_obj(const QObject *obj);
 
 const char *qstring_get_str(const QString *qstring);
 void qstring_append(QString *qstring, const char *str);
+void qstring_append_format(QString *qstring, const char *format,
+                           const struct QDict *qdict);
 void qstring_append_escaped(QString *qstring, const char *str);
 void qstring_append_ch(QString *qstring, char c);
 QString *qobject_to_qstring(const QObject *obj);
-- 
1.6.2.5