qmldom: Start of the Qml Dom library

The goal of the Dom library is to provide a nicer to use basis for the
Qml Code model, to be used by the various QML tools, the designer and
the new compiler.

This commit just adds some common utilities used by the library, to
output strings to a Sink, i.e. a function<void(QStringView).
This allows writing without allocations of extra temporary strings.
The more interesting parts are added in subsequent commits

Task-number: QTBUG-74840
Change-Id: I8fa43d5b622f59c8761b2469551127c0508c23c3
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

1 files changed, 152 insertions, 0 deletions

diff --git a/src/qmldom/qqmldomstringdumper_p.h b/src/qmldom/qqmldomstringdumper_p.h
new file mode 100644
index 0000000000..7669bfc882
--- /dev/null
+++ b/src/qmldom/qqmldomstringdumper_p.h
@@ -0,0 +1,152 @@
+/****************************************************************************
+**
+** Copyright (C) 2020 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQml 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.
+**
+** $QT_END_LICENSE$
+**/
+#ifndef DUMPER_H
+#define DUMPER_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include "qqmldom_global.h"
+#include "qqmldomconstants_p.h"
+
+#include <QtCore/QString>
+#include <QtCore/QStringView>
+#include <QtCore/QDebug>
+
+#include <type_traits>
+
+QT_BEGIN_NAMESPACE
+
+namespace QQmlJS {
+namespace Dom {
+
+using Sink = std::function<void(QStringView)>;
+using DumperFunction = std::function<void(Sink)>;
+
+class Dumper{
+public:
+    DumperFunction dumper;
+private:
+    // We want to avoid the limit of one user conversion:
+    // after doing (* -> QStringView) we cannot have QStringView -> Dumper, as it
+    // would be the second user defined conversion.
+    // For a similar reason we have a template to accept function<void(Sink)> .
+    // The end result is that void f(Dumper) can be called nicely, and avoid overloads:
+    // f(u"bla"), f(QLatin1String("bla")), f(QString()), f([](Sink s){...}),...
+    template <typename T>
+    using if_compatible_dumper = typename
+    std::enable_if<std::is_convertible<T, DumperFunction>::value, bool>::type;
+
+    template<typename T>
+    using if_string_view_convertible = typename
+    std::enable_if<std::is_convertible_v<T, QStringView>, bool>::type;
+
+public:
+    Dumper(QStringView s):
+        dumper([s](Sink sink){ sink(s); }) {}
+
+    Dumper(std::nullptr_t): Dumper(QStringView(nullptr)) {}
+
+    template <typename Stringy, if_string_view_convertible<Stringy> = true>
+    Dumper(Stringy string):
+        Dumper(QStringView(string)) {}
+
+    template <typename U, if_compatible_dumper<U> = true>
+    Dumper(U f): dumper(f) {}
+
+    void operator()(Sink s) { dumper(s); }
+};
+
+template <typename T>
+void sinkInt(Sink s, T i) {
+    const int BUFSIZE = 42; // safe up to 128 bits
+    QChar buf[BUFSIZE];
+    int ibuf = BUFSIZE;
+    buf[--ibuf] = QChar(0);
+    bool neg = false;
+    if (i < 0)
+        neg=true;
+    int digit = i % 10;
+    i = i / 10;
+    if constexpr (std::is_signed_v<T>) {
+        if (neg) { // we change the sign here because -numeric_limits<T>::min() == numeric_limits<T>::min()
+            i = -i;
+            digit = - digit;
+        }
+    }
+    buf[--ibuf] = QChar::fromLatin1('0' + digit);
+    while (i > 0 && ibuf > 0) {
+        digit = i % 10;
+        buf[--ibuf] = QChar::fromLatin1('0' + digit);
+        i = i / 10;
+    }
+    if (neg && ibuf > 0)
+        buf[--ibuf] = QChar::fromLatin1('-');
+    s(QStringView(&buf[ibuf], BUFSIZE - ibuf -1));
+}
+
+QMLDOM_EXPORT QString dumperToString(Dumper writer);
+
+QMLDOM_EXPORT void sinkEscaped(Sink sink, QStringView s,
+                               EscapeOptions options = EscapeOptions::OuterQuotes);
+
+inline void devNull(QStringView) {}
+
+QMLDOM_EXPORT void sinkIndent(Sink s, int indent);
+
+QMLDOM_EXPORT void sinkNewline(Sink s, int indent = 0);
+
+QMLDOM_EXPORT void dumpErrorLevel(Sink s, ErrorLevel level);
+
+QMLDOM_EXPORT void dumperToQDebug(Dumper dumper, QDebug debug);
+
+QMLDOM_EXPORT void dumperToQDebug(Dumper dumper, ErrorLevel level = ErrorLevel::Debug);
+
+} // end namespace Dom
+} // end namespace QQmlJS
+QT_END_NAMESPACE
+
+#endif // DUMPER_H