QDebug: pretty-print QStrings and QStringRefs

[ChangeLog][QtCore][QDebug] Printing of QStrings and QStringRefs
whenever "noquote" is not active now prints the strings in a format that
can be copied back to C++ code. All characters that aren't printable in
US-ASCII are escaped (this includes printable Unicode characters outside
of US-ASCII). Pretty-printing will not respect QTextFormat padding or
field widths.

Change-Id: I169a8a0508e24693f5652f0129defe7f709e5d08
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

4 files changed, 109 insertions, 4 deletions

diff --git a/src/corelib/io/qdebug.cpp b/src/corelib/io/qdebug.cpp
index 050a48bd65..d8b77dd603 100644
--- a/src/corelib/io/qdebug.cpp
+++ b/src/corelib/io/qdebug.cpp
@@ -1,6 +1,7 @@
 /****************************************************************************
 **
 ** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
+** Copyright (C) 2014 Intel Corporation.
 ** Contact: http://www.qt-project.org/legal
 **
 ** This file is part of the QtCore module of the Qt Toolkit.
@@ -40,9 +41,12 @@
 
 #include "qdebug.h"
 #include <private/qtextstream_p.h>
+#include <private/qtools_p.h>
 
 QT_BEGIN_NAMESPACE
 
+using QtMiscUtils::toHexUpper;
+
 // This file is needed to force compilation of QDebug into the kernel library.
 
 /*!
@@ -168,6 +172,105 @@ void QDebug::putUcs4(uint ucs4)
     maybeQuote('\'');
 }
 
+template <typename Char>
+static inline void putEscapedString(QTextStreamPrivate *d, const Char *begin, int length)
+{
+    QChar quote(QLatin1Char('"'));
+    d->write(&quote, 1);
+
+    const Char *end = begin + length;
+    for (const Char *p = begin; p != end; ++p) {
+        if (sizeof(Char) == sizeof(QChar)) {
+            int runLength = 0;
+            while (p + runLength != end &&
+                   p[runLength] < 0x7f && p[runLength] >= 0x20 && p[runLength] != '\\' && p[runLength] != '"')
+                ++runLength;
+            if (runLength) {
+                d->write(reinterpret_cast<const QChar *>(p), runLength);
+                p += runLength - 1;
+                continue;
+            }
+        }
+
+        // print as an escape sequence
+        int buflen = 2;
+        ushort buf[sizeof "\\U12345678" - 1];
+        buf[0] = '\\';
+
+        switch (*p) {
+        case '"':
+        case '\\':
+            buf[1] = *p;
+            break;
+        case '\b':
+            buf[1] = 'b';
+            break;
+        case '\f':
+            buf[1] = 'f';
+            break;
+        case '\n':
+            buf[1] = 'n';
+            break;
+        case '\r':
+            buf[1] = 'r';
+            break;
+        case '\t':
+            buf[1] = 't';
+            break;
+        default:
+            if (QChar::isHighSurrogate(*p)) {
+                if ((p + 1) != end && QChar::isLowSurrogate(p[1])) {
+                    // properly-paired surrogates
+                    uint ucs4 = QChar::surrogateToUcs4(*p, p[1]);
+                    ++p;
+                    buf[1] = 'U';
+                    buf[2] = '0'; // toHexUpper(ucs4 >> 32);
+                    buf[3] = '0'; // toHexUpper(ucs4 >> 28);
+                    buf[4] = toHexUpper(ucs4 >> 20);
+                    buf[5] = toHexUpper(ucs4 >> 16);
+                    buf[6] = toHexUpper(ucs4 >> 12);
+                    buf[7] = toHexUpper(ucs4 >> 8);
+                    buf[8] = toHexUpper(ucs4 >> 4);
+                    buf[9] = toHexUpper(ucs4);
+                    buflen = 10;
+                    break;
+                }
+                // improperly-paired surrogates, fall through
+            }
+            buf[1] = 'u';
+            if (sizeof(Char) == 1) {
+                buf[2] = buf[3] = '0';
+            } else {
+                buf[2] = toHexUpper(*p >> 12);
+                buf[3] = toHexUpper(*p >> 8);
+            }
+            buf[4] = toHexUpper(*p >> 4);
+            buf[5] = toHexUpper(*p);
+            buflen = 6;
+        }
+        d->write(reinterpret_cast<QChar *>(buf), buflen);
+    }
+
+    d->write(&quote, 1);
+}
+
+/*!
+    \internal
+    Duplicated from QtTest::toPrettyUnicode().
+*/
+void QDebug::putString(const QChar *begin, size_t length)
+{
+    if (stream->testFlag(Stream::NoQuotes)) {
+        // no quotes, write the string directly too (no pretty-printing)
+        // this respects the QTextStream state, though
+        stream->ts.d_ptr->putString(begin, length);
+    } else {
+        // we'll reset the QTextStream formatting mechanisms, so save the state
+        QDebugStateSaver saver(*this);
+        stream->ts.d_ptr->params.reset();
+        putEscapedString(stream->ts.d_ptr.data(), reinterpret_cast<const ushort *>(begin), length);
+    }
+}
 
 /*!
     \fn QDebug::swap(QDebug &other)
diff --git a/src/corelib/io/qdebug.h b/src/corelib/io/qdebug.h
index 99c2909aa0..a2d6598bce 100644
--- a/src/corelib/io/qdebug.h
+++ b/src/corelib/io/qdebug.h
@@ -78,6 +78,7 @@ class Q_CORE_EXPORT QDebug
     } *stream;
 
     void putUcs4(uint ucs4);
+    void putString(const QChar *begin, size_t length);
 public:
     inline QDebug(QIODevice *device) : stream(new Stream(device)) {}
     inline QDebug(QString *string) : stream(new Stream(string)) {}
@@ -118,8 +119,8 @@ public:
     inline QDebug &operator<<(float t) { stream->ts << t; return maybeSpace(); }
     inline QDebug &operator<<(double t) { stream->ts << t; return maybeSpace(); }
     inline QDebug &operator<<(const char* t) { stream->ts << QString::fromUtf8(t); return maybeSpace(); }
-    inline QDebug &operator<<(const QString & t) { maybeQuote(); stream->ts << t; maybeQuote(); return maybeSpace(); }
-    inline QDebug &operator<<(const QStringRef & t) { return operator<<(t.toString()); }
+    inline QDebug &operator<<(const QString & t) { putString(t.constData(), uint(t.length())); return maybeSpace(); }
+    inline QDebug &operator<<(const QStringRef & t) { putString(t.constData(), uint(t.length())); return maybeSpace(); }
     inline QDebug &operator<<(QLatin1String t) { maybeQuote(); stream->ts << t; maybeQuote(); return maybeSpace(); }
     inline QDebug &operator<<(const QByteArray & t) { maybeQuote(); stream->ts << t; maybeQuote(); return maybeSpace(); }
     inline QDebug &operator<<(const void * t) { stream->ts << t; return maybeSpace(); }
diff --git a/src/corelib/io/qtextstream.cpp b/src/corelib/io/qtextstream.cpp
index 5f3177e58f..771067fa14 100644
--- a/src/corelib/io/qtextstream.cpp
+++ b/src/corelib/io/qtextstream.cpp
@@ -806,7 +806,7 @@ inline void QTextStreamPrivate::restoreToSavedConverterState()
 /*!
     \internal
 */
-inline void QTextStreamPrivate::write(const QChar *data, int len)
+void QTextStreamPrivate::write(const QChar *data, int len)
 {
     if (string) {
         // ### What about seek()??
@@ -885,7 +885,7 @@ inline void QTextStreamPrivate::putChar(QChar ch)
 /*!
     \internal
 */
-inline void QTextStreamPrivate::putString(const QChar *data, int len, bool number)
+void QTextStreamPrivate::putString(const QChar *data, int len, bool number)
 {
     QString pad;
     int padLeft = 0, padRight = 0;
diff --git a/src/corelib/io/qtextstream.h b/src/corelib/io/qtextstream.h
index 5c75a006af..b15e7772e2 100644
--- a/src/corelib/io/qtextstream.h
+++ b/src/corelib/io/qtextstream.h
@@ -185,6 +185,7 @@ public:
 private:
     Q_DISABLE_COPY(QTextStream)
     friend class QDebugStateSaverPrivate;
+    friend class QDebug;
 
     QScopedPointer<QTextStreamPrivate> d_ptr;
 };