QJson: Move parsing from QJsonDocument to QJsonValue

JSON values are now parsed by QJsonValue instead of QJsonDocument. For
parsing, this removes the need for QJsonDocument entirely.

Fixes: QTBUG-109870
Change-Id: I2f9bae3a53e5d445cc9e8437c63a53a2c7b3593e
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/CMakeLists.txt

@@ -207,6 +207,7 @@ qt_internal_add_module(Core
         serialization/qjsoncbor.cpp
         serialization/qjsondocument.cpp serialization/qjsondocument.h
         serialization/qjsonobject.cpp serialization/qjsonobject.h
+        serialization/qjsonparseerror.h
         serialization/qjsonparser.cpp serialization/qjsonparser_p.h
         serialization/qjsonvalue.cpp serialization/qjsonvalue.h
         serialization/qjsonwriter.cpp serialization/qjsonwriter_p.h

src/corelib/serialization/qjsondocument.h

@@ -5,6 +5,7 @@
 #define QJSONDOCUMENT_H
 
 #include <QtCore/qcompare.h>
+#include <QtCore/qjsonparseerror.h>
 #include <QtCore/qjsonvalue.h>
 #include <QtCore/qscopedpointer.h>
 
@@ -17,32 +18,6 @@ class QCborValue;
 
 namespace QJsonPrivate { class Parser; }
 
-struct Q_CORE_EXPORT QJsonParseError
-{
-    enum ParseError {
-        NoError = 0,
-        UnterminatedObject,
-        MissingNameSeparator,
-        UnterminatedArray,
-        MissingValueSeparator,
-        IllegalValue,
-        TerminationByNumber,
-        IllegalNumber,
-        IllegalEscapeSequence,
-        IllegalUTF8String,
-        UnterminatedString,
-        MissingObject,
-        DeepNesting,
-        DocumentTooLarge,
-        GarbageAtEnd
-    };
-
-    QString    errorString() const;
-
-    int        offset = -1;
-    ParseError error = NoError;
-};
-
 class QJsonDocumentPrivate;
 class Q_CORE_EXPORT QJsonDocument
 {

src/corelib/serialization/qjsonparseerror.h

@@ -0,0 +1,42 @@
+// Copyright (C) 2024 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+#ifndef QJSONPARSEERROR_H
+#define QJSONPARSEERROR_H
+
+#include <QtCore/qtconfigmacros.h>
+#include <QtCore/qtcoreexports.h>
+
+QT_BEGIN_NAMESPACE
+
+class QString;
+
+struct Q_CORE_EXPORT QJsonParseError
+{
+    enum ParseError {
+        NoError = 0,
+        UnterminatedObject,
+        MissingNameSeparator,
+        UnterminatedArray,
+        MissingValueSeparator,
+        IllegalValue,
+        TerminationByNumber,
+        IllegalNumber,
+        IllegalEscapeSequence,
+        IllegalUTF8String,
+        UnterminatedString,
+        MissingObject,
+        DeepNesting,
+        DocumentTooLarge,
+        GarbageAtEnd
+    };
+
+    QString errorString() const;
+
+    int offset = -1;
+    ParseError error = NoError;
+};
+
+QT_END_NAMESPACE
+
+#endif // QJSONPARSEERROR_H

src/corelib/serialization/qjsonvalue.cpp

@@ -14,6 +14,7 @@
 #include <qhash.h>
 #include <qdebug.h>
 #include "qdatastream.h"
+#include "qjsonparser_p.h"
 
 #include <private/qnumeric_p.h>
 #include <private/qcborvalue_p.h>
@@ -593,6 +594,28 @@ QVariant QJsonValue::toVariant() const
 */
 #endif // !QT_NO_VARIANT
 
+/*!
+    \since 6.9
+    Parses \a json as a UTF-8 encoded JSON value, and creates a QJsonValue
+    from it.
+
+    Returns a valid QJsonValue if the parsing succeeds. If it fails, the
+    returned value will be \l {QJsonValue::isUndefined} {undefined}, and
+    the optional \a error variable will contain further details about the
+    error.
+
+    Currently, only objects/maps and arrays/lists can be parsed.
+
+    \sa QJsonParseError, isUndefined()
+ */
+QJsonValue QJsonValue::fromJson(QByteArrayView json, QJsonParseError *error)
+{
+    QJsonPrivate::Parser parser(json.constData(), json.size());
+    QJsonValue result;
+    result.value = parser.parse(error);
+    return result;
+}
+
 /*!
     Returns the type of the value.
 

src/corelib/serialization/qjsonvalue.h

@@ -7,6 +7,7 @@
 #include <QtCore/qcborvalue.h>
 #include <QtCore/qcompare.h>
 #include <QtCore/qglobal.h>
+#include <QtCore/qjsonparseerror.h>
 #include <QtCore/qstring.h>
 #include <QtCore/qshareddata.h>
 
@@ -68,6 +69,8 @@ class Q_CORE_EXPORT QJsonValue
     static QJsonValue fromVariant(const QVariant &variant);
     QVariant toVariant() const;
 
+    static QJsonValue fromJson(QByteArrayView json, QJsonParseError *error = nullptr);
+
     Type type() const;
     inline bool isNull() const { return type() == Null; }
     inline bool isBool() const { return type() == Bool; }