QCborValue: move the toDiagnosticNotation() function to its own file

If we ever need to add QCborValue to the bootstrap library, it's
unlikely that we'll need this part. And by splitting it, I can make the
code handle more cases, that hadn't been properly handled before.

Change-Id: I2f630efbbce54f14bfa9fffd154160c0ad893695
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

1 files changed, 281 insertions, 0 deletions

diff --git a/src/corelib/serialization/qcbordiagnostic.cpp b/src/corelib/serialization/qcbordiagnostic.cpp
new file mode 100644
index 0000000000..8e641ff7cf
--- /dev/null
+++ b/src/corelib/serialization/qcbordiagnostic.cpp
@@ -0,0 +1,281 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 Intel Corporation.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qcborvalue.h"
+#include "qcborvalue_p.h"
+
+#include "qcborarray.h"
+#include "qcbormap.h"
+
+#include <private/qnumeric_p.h>
+#include <qstack.h>
+
+QT_BEGIN_NAMESPACE
+
+namespace  {
+class DiagnosticNotation
+{
+public:
+    static QString create(const QCborValue &v, QCborValue::DiagnosticNotationOptions opts)
+    {
+        DiagnosticNotation dn(opts);
+        dn.appendValue(v);
+        return dn.result;
+    }
+
+private:
+    QStack<int> byteArrayFormatStack;
+    QString separator;
+    QString result;
+    QCborValue::DiagnosticNotationOptions opts;
+    int nestingLevel = 0;
+
+    struct Nest {
+        enum { IndentationWidth = 4 };
+        DiagnosticNotation *dn;
+        Nest(DiagnosticNotation *that) : dn(that)
+        {
+            ++dn->nestingLevel;
+            static const char indent[IndentationWidth + 1] = "    ";
+            if (dn->opts & QCborValue::LineWrapped)
+                dn->separator += QLatin1String(indent, IndentationWidth);
+        }
+        ~Nest()
+        {
+            --dn->nestingLevel;
+            if (dn->opts & QCborValue::LineWrapped)
+                dn->separator.chop(IndentationWidth);
+        }
+    };
+
+    DiagnosticNotation(QCborValue::DiagnosticNotationOptions opts_)
+        : separator(QLatin1String(opts_ & QCborValue::LineWrapped ? "\n" : "")), opts(opts_)
+    {
+        byteArrayFormatStack.push(int(QCborKnownTags::ExpectedBase16));
+    }
+
+    void appendString(const QString &s);
+    void appendArray(const QCborArray &a);
+    void appendMap(const QCborMap &m);
+    void appendValue(const QCborValue &v);
+};
+}
+
+static QString makeFpString(double d)
+{
+    QString s;
+    quint64 v;
+    if (qt_is_inf(d)) {
+        s = (d < 0) ? QStringLiteral("-inf") : QStringLiteral("inf");
+    } else if (qt_is_nan(d)) {
+        s = QStringLiteral("nan");
+    } else if (convertDoubleTo(d, &v)) {
+        s = QString::fromLatin1("%1.0").arg(v);
+        if (d < 0)
+            s.prepend(QLatin1Char('-'));
+    } else {
+        s = QString::number(d, 'g', QLocale::FloatingPointShortest);
+        if (!s.contains(QLatin1Char('.')) && !s.contains('e'))
+            s += QLatin1Char('.');
+    }
+    return s;
+}
+
+static bool isByteArrayEncodingTag(QCborTag tag)
+{
+    switch (quint64(tag)) {
+    case quint64(QCborKnownTags::ExpectedBase16):
+    case quint64(QCborKnownTags::ExpectedBase64):
+    case quint64(QCborKnownTags::ExpectedBase64url):
+        return true;
+    }
+    return false;
+}
+
+void DiagnosticNotation::appendString(const QString &s)
+{
+    result += QLatin1Char('"')
+            + QString(s)
+              .replace(QLatin1Char('\\'), QLatin1String("\\\\"))
+              .replace(QLatin1Char('"'), QLatin1String("\\\""))
+            + QLatin1Char('"');
+}
+
+void DiagnosticNotation::appendArray(const QCborArray &a)
+{
+    result += QLatin1Char('[');
+
+    // length 2 (including the space) when not line wrapping
+    QLatin1String commaValue(", ", opts & QCborValue::LineWrapped ? 1 : 2);
+    {
+        Nest n(this);
+        QLatin1String comma;
+        for (auto v : a) {
+            result += comma + separator;
+            comma = commaValue;
+            appendValue(v);
+        }
+    }
+
+    result += separator + QLatin1Char(']');
+}
+
+void DiagnosticNotation::appendMap(const QCborMap &m)
+{
+    result += QLatin1Char('{');
+
+    // length 2 (including the space) when not line wrapping
+    QLatin1String commaValue(", ", opts & QCborValue::LineWrapped ? 1 : 2);
+    {
+        Nest n(this);
+        QLatin1String comma;
+        for (auto v : m) {
+            result += comma + separator;
+            comma = commaValue;
+            appendValue(v.first);
+            result += QLatin1String(": ");
+            appendValue(v.second);
+        }
+    }
+
+    result += separator + QLatin1Char('}');
+};
+
+void DiagnosticNotation::appendValue(const QCborValue &v)
+{
+    switch (v.type()) {
+    case QCborValue::Integer:
+        result += QString::number(v.toInteger());
+        return;
+    case QCborValue::ByteArray:
+        switch (byteArrayFormatStack.top()) {
+        case int(QCborKnownTags::ExpectedBase16):
+            result += QString::fromLatin1("h'" +
+                                          v.toByteArray().toHex(opts & QCborValue::ExtendedFormat ? ' ' : '\0') +
+                                          '\'');
+            return;
+        case int(QCborKnownTags::ExpectedBase64):
+            result += QString::fromLatin1("b64'" + v.toByteArray().toBase64() + '\'');
+            return;
+        default:
+        case int(QCborKnownTags::ExpectedBase64url):
+            result += QString::fromLatin1("b64'" +
+                                          v.toByteArray().toBase64(QByteArray::Base64UrlEncoding | QByteArray::OmitTrailingEquals) +
+                                          '\'');
+            return;
+        }
+    case QCborValue::String:
+        return appendString(v.toString());
+    case QCborValue::Array:
+        return appendArray(v.toArray());
+    case QCborValue::Map:
+        return appendMap(v.toMap());
+    case QCborValue::False:
+        result += QLatin1String("false");
+        return;
+    case QCborValue::True:
+        result += QLatin1String("true");
+        return;
+    case QCborValue::Null:
+        result += QLatin1String("null");
+        return;
+    case QCborValue::Undefined:
+        result += QLatin1String("undefined");
+        return;
+    case QCborValue::Double:
+        result += makeFpString(v.toDouble());
+        return;
+    case QCborValue::Invalid:
+        result += QStringLiteral("<invalid>");
+        return;
+
+    default:
+        // Only tags, extended types, and simple types remain; see below.
+        break;
+    }
+
+    if (v.isTag()) {
+        // We handle all extended types as regular tags, so it won't matter
+        // whether we understand that tag or not.
+        bool byteArrayFormat = opts & QCborValue::ExtendedFormat && isByteArrayEncodingTag(v.tag());
+        if (byteArrayFormat)
+            byteArrayFormatStack.push(int(v.tag()));
+        result += QString::number(quint64(v.tag())) + QLatin1Char('(');
+        appendValue(v.taggedValue());
+        result += QLatin1Char(')');
+        if (byteArrayFormat)
+            byteArrayFormatStack.pop();
+    } else {
+        // must be a simple type
+        result += QString::fromLatin1("simple(%1)").arg(quint8(v.toSimpleType()));
+    }
+}
+
+/*!
+    Creates the diagnostic notation equivalent of this CBOR object and returns
+    it. The \a opts parameter controls the dialect of the notation. Diagnostic
+    notation is useful in debugging, to aid the developer in understanding what
+    value is stored in the QCborValue or in a CBOR stream. For that reason, the
+    Qt API provides no support for parsing the diagnostic back into the
+    in-memory format or CBOR stream, though the representation is unique and it
+    would be possible.
+
+    CBOR diagnostic notation is specified by
+    \l{https://tools.ietf.org/html/rfc7049#section-6}{section 6} of RFC 7049.
+    It is a text representation of the CBOR stream and it is very similar to
+    JSON, but it supports the CBOR types not found in JSON. The extended format
+    enabled by the \l{DiagnosticNotationOption}{ExtendedFormat} flag is
+    currently in some IETF drafts and its format is subject to change.
+
+    This function produces the equivalent representation of the stream that
+    toCbor() would produce, without any transformation option provided there.
+    This also implies this function may not produce a representation of the
+    stream that was used to create the object, if it was created using
+    fromCbor(), as that function may have applied transformations. For a
+    high-fidelity notation of a stream, without transformation, see the \c
+    cbordump example.
+
+    \sa toCbor(), toJsonDocument(), QJsonDocument::toJson()
+ */
+QString QCborValue::toDiagnosticNotation(DiagnosticNotationOptions opts) const
+{
+    return DiagnosticNotation::create(*this, opts);
+}
+
+QT_END_NAMESPACE