diff --git a/Makefile.objs b/Makefile.objs
index ec35320..8f9e1fb 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -414,8 +414,9 @@ libcacard-y = cac.o event.o vcard.o vreader.o vcard_emul_nss.o vcard_emul_type.o
 ######################################################################
 # qapi
 
-qapi-nested-y = qapi-visit-core.o qmp-input-visitor.o qmp-output-visitor.o qapi-dealloc-visitor.o
-qapi-nested-y += qmp-registry.o qmp-dispatch.o
+qapi-nested-y = qapi-visit-core.o qapi-dealloc-visitor.o qmp-input-visitor.o
+qapi-nested-y += qmp-output-visitor.o qmp-registry.o qmp-dispatch.o
+qapi-nested-y += string-input-visitor.o string-output-visitor.o
 qapi-obj-y = $(addprefix qapi/, $(qapi-nested-y))
 
 common-obj-y += qmp-marshal.o qapi-visit.o qapi-types.o $(qapi-obj-y)
diff --git a/qapi/string-input-visitor.c b/qapi/string-input-visitor.c
new file mode 100644
index 0000000..9ca4087
--- /dev/null
+++ b/qapi/string-input-visitor.c
@@ -0,0 +1,136 @@
+/*
+ * String parsing visitor
+ *
+ * Copyright Red Hat, Inc. 2012
+ *
+ * Author: Paolo Bonzini <pbonzini@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
+ * See the COPYING.LIB file in the top-level directory.
+ *
+ */
+
+#include "qemu-common.h"
+#include "string-input-visitor.h"
+#include "qapi/qapi-visit-impl.h"
+#include "qerror.h"
+
+struct StringInputVisitor
+{
+    Visitor visitor;
+    const char *string;
+};
+
+static void parse_type_int(Visitor *v, int64_t *obj, const char *name,
+                           Error **errp)
+{
+    StringInputVisitor *siv = DO_UPCAST(StringInputVisitor, visitor, v);
+    char *endp = (char *) siv->string;
+    long long val;
+
+    errno = 0;
+    if (siv->string) {
+        val = strtoll(siv->string, &endp, 0);
+    }
+    if (!siv->string || errno || endp == siv->string || *endp) {
+        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
+                  "integer");
+        return;
+    }
+
+    *obj = val;
+}
+
+static void parse_type_bool(Visitor *v, bool *obj, const char *name,
+                            Error **errp)
+{
+    StringInputVisitor *siv = DO_UPCAST(StringInputVisitor, visitor, v);
+
+    if (siv->string) {
+        if (strcasecmp(siv->string, "on") || strcasecmp(siv->string, "yes") ||
+            strcasecmp(siv->string, "true")) {
+            *obj = true;
+            return;
+        }
+        if (strcasecmp(siv->string, "off") || strcasecmp(siv->string, "no") ||
+            strcasecmp(siv->string, "false")) {
+            *obj = false;
+            return;
+        }
+    }
+
+    error_set(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
+              "boolean");
+}
+
+static void parse_type_str(Visitor *v, char **obj, const char *name,
+                           Error **errp)
+{
+    StringInputVisitor *siv = DO_UPCAST(StringInputVisitor, visitor, v);
+    if (siv->string) {
+        *obj = g_strdup(siv->string);
+    } else {
+        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
+                  "string");
+    }
+}
+
+static void parse_type_number(Visitor *v, double *obj, const char *name,
+                              Error **errp)
+{
+    StringInputVisitor *siv = DO_UPCAST(StringInputVisitor, visitor, v);
+    char *endp = (char *) siv->string;
+    double val;
+
+    errno = 0;
+    if (siv->string) {
+        val = strtod(siv->string, &endp);
+    }
+    if (!siv->string || errno || endp == siv->string || *endp) {
+        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
+                  "number");
+        return;
+    }
+
+    *obj = val;
+}
+
+static void parse_start_optional(Visitor *v, bool *present,
+                                 const char *name, Error **errp)
+{
+    StringInputVisitor *siv = DO_UPCAST(StringInputVisitor, visitor, v);
+
+    if (!siv->string) {
+        *present = false;
+        return;
+    }
+
+    *present = true;
+}
+
+Visitor *string_input_get_visitor(StringInputVisitor *v)
+{
+    return &v->visitor;
+}
+
+void string_input_visitor_cleanup(StringInputVisitor *v)
+{
+    g_free(v);
+}
+
+StringInputVisitor *string_input_visitor_new(const char *str)
+{
+    StringInputVisitor *v;
+
+    v = g_malloc0(sizeof(*v));
+
+    v->visitor.type_enum = input_type_enum;
+    v->visitor.type_int = parse_type_int;
+    v->visitor.type_bool = parse_type_bool;
+    v->visitor.type_str = parse_type_str;
+    v->visitor.type_number = parse_type_number;
+    v->visitor.start_optional = parse_start_optional;
+
+    v->string = str;
+    return v;
+}
diff --git a/qapi/string-input-visitor.h b/qapi/string-input-visitor.h
new file mode 100644
index 0000000..d269d42
--- /dev/null
+++ b/qapi/string-input-visitor.h
@@ -0,0 +1,25 @@
+/*
+ * String parsing Visitor
+ *
+ * Copyright Red Hat, Inc. 2012
+ *
+ * Author: Paolo Bonzini <pbonzini@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
+ * See the COPYING.LIB file in the top-level directory.
+ *
+ */
+
+#ifndef STRING_INPUT_VISITOR_H
+#define STRING_INPUT_VISITOR_H
+
+#include "qapi-visit-core.h"
+
+typedef struct StringInputVisitor StringInputVisitor;
+
+StringInputVisitor *string_input_visitor_new(const char *str);
+void string_input_visitor_cleanup(StringInputVisitor *v);
+
+Visitor *string_input_get_visitor(StringInputVisitor *v);
+
+#endif
diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
new file mode 100644
index 0000000..6fa72f3
--- /dev/null
+++ b/qapi/string-output-visitor.c
@@ -0,0 +1,89 @@
+/*
+ * String printing Visitor
+ *
+ * Copyright Red Hat, Inc. 2012
+ *
+ * Author: Paolo Bonzini <pbonzini@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
+ * See the COPYING.LIB file in the top-level directory.
+ *
+ */
+
+#include "qemu-common.h"
+#include "string-output-visitor.h"
+#include "qapi/qapi-visit-impl.h"
+#include "qerror.h"
+
+struct StringOutputVisitor
+{
+    Visitor visitor;
+    char *string;
+};
+
+static void string_output_set(StringOutputVisitor *sov, char *string)
+{
+    g_free(sov->string);
+    sov->string = string;
+}
+
+static void print_type_int(Visitor *v, int64_t *obj, const char *name,
+                           Error **errp)
+{
+    StringOutputVisitor *sov = DO_UPCAST(StringOutputVisitor, visitor, v);
+    string_output_set(sov, g_strdup_printf("%lld", (long long) *obj));
+}
+
+static void print_type_bool(Visitor *v, bool *obj, const char *name,
+                            Error **errp)
+{
+    StringOutputVisitor *sov = DO_UPCAST(StringOutputVisitor, visitor, v);
+    string_output_set(sov, g_strdup(*obj ? "true" : "false"));
+}
+
+static void print_type_str(Visitor *v, char **obj, const char *name,
+                           Error **errp)
+{
+    StringOutputVisitor *sov = DO_UPCAST(StringOutputVisitor, visitor, v);
+    string_output_set(sov, g_strdup(*obj ? *obj : ""));
+}
+
+static void print_type_number(Visitor *v, double *obj, const char *name,
+                              Error **errp)
+{
+    StringOutputVisitor *sov = DO_UPCAST(StringOutputVisitor, visitor, v);
+    string_output_set(sov, g_strdup_printf("%g", *obj));
+}
+
+char *string_output_get_string(StringOutputVisitor *sov)
+{
+    char *string = sov->string;
+    sov->string = NULL;
+    return string;
+}
+
+Visitor *string_output_get_visitor(StringOutputVisitor *sov)
+{
+    return &sov->visitor;
+}
+
+void string_output_visitor_cleanup(StringOutputVisitor *sov)
+{
+    g_free(sov->string);
+    g_free(sov);
+}
+
+StringOutputVisitor *string_output_visitor_new(void)
+{
+    StringOutputVisitor *v;
+
+    v = g_malloc0(sizeof(*v));
+
+    v->visitor.type_enum = output_type_enum;
+    v->visitor.type_int = print_type_int;
+    v->visitor.type_bool = print_type_bool;
+    v->visitor.type_str = print_type_str;
+    v->visitor.type_number = print_type_number;
+
+    return v;
+}
diff --git a/qapi/string-output-visitor.h b/qapi/string-output-visitor.h
new file mode 100644
index 0000000..05b3b29
--- /dev/null
+++ b/qapi/string-output-visitor.h
@@ -0,0 +1,26 @@
+/*
+ * String printing Visitor
+ *
+ * Copyright Red Hat, Inc. 2012
+ *
+ * Author: Paolo Bonzini <pbonzini@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
+ * See the COPYING.LIB file in the top-level directory.
+ *
+ */
+
+#ifndef STRING_OUTPUT_VISITOR_H
+#define STRING_OUTPUT_VISITOR_H
+
+#include "qapi-visit-core.h"
+
+typedef struct StringOutputVisitor StringOutputVisitor;
+
+StringOutputVisitor *string_output_visitor_new(void);
+void string_output_visitor_cleanup(StringOutputVisitor *v);
+
+char *string_output_get_string(StringOutputVisitor *v);
+Visitor *string_output_get_visitor(StringOutputVisitor *v);
+
+#endif
