[Qemu-devel] [PATCH 01/10] Introduce qmisc module

[Luiz Capitulino <lcapitulino@redhat.com>]

This module provides miscellania QObject functions.

Currently it exports qobject_from_fmt(), which is somewhat
based on Python's Py_BuildValue() function. It is capable of
creating QObjects from a specified string format.

For example, to create a QDict with mixed data-types one
could do:

QObject *obj = qobject_from_fmt("{ s: [ i, s ], s: i }", ... );

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
---
 Makefile |    2 +-
 qmisc.c  |  222 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 qmisc.h  |   19 +++++
 3 files changed, 242 insertions(+), 1 deletions(-)
 create mode 100644 qmisc.c
 create mode 100644 qmisc.h

diff --git a/Makefile b/Makefile
index d96fb4b..182f176 100644
--- a/Makefile
+++ b/Makefile
@@ -100,7 +100,7 @@ obj-y += buffered_file.o migration.o migration-tcp.o net.o qemu-sockets.o
 obj-y += qemu-char.o aio.o net-checksum.o savevm.o
 obj-y += msmouse.o ps2.o
 obj-y += qdev.o qdev-properties.o ssi.o
-obj-y += qint.o qstring.o qdict.o qlist.o qemu-config.o
+obj-y += qint.o qstring.o qdict.o qlist.o qmisc.o qemu-config.o
 
 obj-$(CONFIG_BRLAPI) += baum.o
 obj-$(CONFIG_WIN32) += tap-win32.o
diff --git a/qmisc.c b/qmisc.c
new file mode 100644
index 0000000..42b6f22
--- /dev/null
+++ b/qmisc.c
@@ -0,0 +1,222 @@
+/*
+ * Misc QObject functions.
+ *
+ * Copyright (C) 2009 Red Hat Inc.
+ *
+ * Authors:
+ *  Luiz Capitulino <lcapitulino@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ */
+#include "qmisc.h"
+#include "qint.h"
+#include "qlist.h"
+#include "qdict.h"
+#include "qstring.h"
+#include "qobject.h"
+#include "qemu-common.h"
+
+/*
+ * qobject_from_fmt() and related functions are based on the Python's
+ * Py_BuildValue() and are subject to the Python Software Foundation
+ * License Version 2.
+ *
+ * Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 Python
+ * Software Foundation.
+ */
+static QObject *build_qobject(const char **fmt, va_list *args);
+
+static QObject *do_mkdict(const char **fmt, va_list *args, int endchar,
+                          int nr_elems)
+{
+    int i;
+    QDict *qdict;
+
+    if (nr_elems < 0)
+        return NULL;
+
+    qdict = qdict_new();
+
+    for (i = 0; i < nr_elems; i += 2) {
+        QString *qs;
+        QObject *obj, *key;
+
+        key = build_qobject(fmt, args);
+        if (!key)
+            goto err;
+
+        obj = build_qobject(fmt, args);
+        if (!obj) {
+            qobject_decref(key);
+            goto err;
+        }
+
+        qs = qobject_to_qstring(key);
+        qdict_put_obj(qdict, qstring_get_str(qs), obj);
+        QDECREF(qs);
+    }
+
+    while (**fmt == ' ')
+        (*fmt)++;
+
+    if (**fmt != endchar)
+        goto err;
+
+    if (endchar)
+        ++*fmt;
+
+    return QOBJECT(qdict);
+
+err:
+    QDECREF(qdict);
+    return NULL;
+}
+
+static QObject *do_mklist(const char **fmt, va_list *args, int endchar,
+                          int nr_elems)
+{
+    int i;
+    QList *qlist;
+
+    if (nr_elems < 0)
+        return NULL;
+
+    qlist = qlist_new();
+
+    for (i = 0; i < nr_elems; i++) {
+        QObject *obj = build_qobject(fmt, args);
+        if (!obj)
+            goto err;
+        qlist_append_obj(qlist, obj);
+    }
+
+    while (**fmt == ' ')
+        (*fmt)++;
+
+    if (**fmt != endchar)
+        goto err;
+
+    if (endchar)
+        ++*fmt;
+
+    return QOBJECT(qlist);
+
+err:
+    QDECREF(qlist);
+    return NULL;
+}
+
+static int
+count_format(const char *format, int endchar)
+{
+    int count = 0;
+    int level = 0;
+
+    while (level > 0 || *format != endchar) {
+        switch (*format) {
+        case '\0':
+            /* Premature end */
+            return -1;
+        case '[':
+        case '{':
+            if (level == 0)
+                count++;
+            level++;
+            break;
+        case ']':
+        case '}':
+            level--;
+            break;
+        case ',':
+        case ':':
+        case ' ':
+        case '\t':
+            break;
+        default:
+            if (level == 0)
+                count++;
+        }
+        format++;
+    }
+    return count;
+}
+
+static QObject *build_qobject(const char **fmt, va_list *args)
+{
+    for (;;) {
+        switch (*(*fmt)++) {
+            case 'i':
+            {
+                QInt *qi = qint_from_int((int64_t) va_arg(*args, int64_t));
+                return QOBJECT(qi);
+            }
+            case 's':
+            {
+                QString *qs = qstring_from_str((char *) va_arg(*args, char *));
+                return QOBJECT(qs);
+            }
+            case '[':
+                return do_mklist(fmt, args, ']', count_format(*fmt, ']'));
+            case '{':
+                return do_mkdict(fmt, args, '}', count_format(*fmt, '}'));
+            case ',':
+            case ':':
+            case ' ':
+            case '\t':
+                break;
+            default:
+                return NULL;
+        }
+    }
+}
+
+/**
+ * qobject_from_fmt(): build QObjects from a specified format.
+ *
+ * Valid characters of the format:
+ *
+ * i   integer, map to QInt
+ * s   string, map to QString
+ * []  list, map to QList
+ * {}  dictionary, map to QDict
+ *
+ * Examples:
+ *
+ * - Create a QInt
+ *
+ *      qobject_from_fmt("i", 42);
+ *
+ * - Create a QList of QStrings
+ *
+ *      qobject_from_fmt("[ i, i, i ]", 0, 1 , 2);
+ *
+ * - Create a QDict with mixed data-types
+ *
+ *      qobject_from_fmt("{ s: [ i, s ], s: i }", ... );
+ *
+ * Return a strong reference to a QObject on success, NULL otherwise.
+ */
+QObject *qobject_from_fmt(const char *fmt, ...)
+{
+    va_list args;
+    QObject *obj;
+
+    va_start(args, fmt);
+    switch (*fmt) {
+        case '[':
+            fmt++;
+            obj = do_mklist(&fmt, &args, ']', count_format(fmt, ']'));
+            break;
+        case '{':
+            fmt++;
+            obj = do_mkdict(&fmt, &args, '}', count_format(fmt, '}'));
+            break;
+        default:
+            obj = build_qobject(&fmt, &args);
+            break;
+    }
+    va_end(args);
+
+    return obj;
+}
diff --git a/qmisc.h b/qmisc.h
new file mode 100644
index 0000000..ac481fe
--- /dev/null
+++ b/qmisc.h
@@ -0,0 +1,19 @@
+/*
+ * QMisc header file.
+ *
+ * Copyright (C) 2009 Red Hat Inc.
+ *
+ * Authors:
+ *  Luiz Capitulino <lcapitulino@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ */
+#ifndef QMISC_H
+#define QMISC_H
+
+#include "qobject.h"
+
+QObject *qobject_from_fmt(const char *fmt, ...);
+
+#endif /* QMISC_H */
-- 
1.6.5.rc2.17.gdbc1b