Add QByteArray::percentDecoded() as an instance method

Percent-decoding was previously only present as a static method taking
a QBA parameter; it might as well be an instance method of that
parameter. Change most QBA tests to use it rather the static method.

[ChangeLog][QtCore][QByteArray] percentDecoded() is now available as
an instance method of the byte array to be decoded, equivalent to the
static QByteArray::fromPercentEncoding().

Change-Id: I982101c44bdac5cc4041e85598d52ac101d38fa1
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/doc/snippets/code/src_corelib_text_qbytearray.cpp

@@ -490,17 +490,22 @@ macAddress.toHex(0);   // returns "123456abcdef"
 
 //! [51]
 QByteArray text = QByteArray::fromPercentEncoding("Qt%20is%20great%33");
-text.data();            // returns "Qt is great!"
+qDebug("%s", text.data());      // reports "Qt is great!"
 //! [51]
 
 //! [52]
 QByteArray text = "{a fishy string?}";
 QByteArray ba = text.toPercentEncoding("{}", "s");
-qDebug(ba.constData());
+qDebug("%s", ba.constData());
 // prints "{a fi%73hy %73tring%3F}"
 //! [52]
 
 //! [53]
 QByteArray ba = QByteArrayLiteral("byte array contents");
 //! [53]
+
+//! [54]
+QByteArray encoded("Qt%20is%20great%33");
+QByteArray decoded = encoded.percentDecoded(); // Set to "Qt is great!"
+//! [54]
 }

src/corelib/text/qbytearray.cpp

@@ -4494,20 +4494,17 @@ static void q_fromPercentEncoding(QByteArray *ba, char percent)
         ba->truncate(outlen);
 }
 
-void q_fromPercentEncoding(QByteArray *ba)
-{
-    q_fromPercentEncoding(ba, '%');
-}
-
 /*!
-    \since 4.4
+    \since 6.4
 
-    Returns a decoded copy of the URI/URL-style percent-encoded \a input.
-    The \a percent parameter allows you to replace the '%' character for
-    another (for instance, '_' or '=').
+    Decodes URI/URL-style percent-encoding.
+
+    Returns a byte array containing the decoded text. The \a percent parameter
+    allows use of a different character than '%' (for instance, '_' or '=') as
+    the escape character.
 
     For example:
-    \snippet code/src_corelib_text_qbytearray.cpp 51
+    \snippet code/src_corelib_text_qbytearray.cpp 54
 
     \note Given invalid input (such as a string containing the sequence "%G5",
     which is not a valid hexadecimal number) the output will be invalid as
@@ -4515,18 +4512,35 @@ void q_fromPercentEncoding(QByteArray *ba)
 
     \sa toPercentEncoding(), QUrl::fromPercentEncoding()
 */
-QByteArray QByteArray::fromPercentEncoding(const QByteArray &input, char percent)
+QByteArray QByteArray::percentDecoded(char percent) const
 {
-    if (input.isNull())
-        return QByteArray();       // preserve null
-    if (input.isEmpty())
-        return QByteArray(input.data(), 0);
+    if (isEmpty())
+        return *this; // Preserves isNull().
 
-    QByteArray tmp = input;
+    QByteArray tmp = *this;
     q_fromPercentEncoding(&tmp, percent);
     return tmp;
 }
 
+/*!
+    \since 4.4
+
+    Decodes \a input from URI/URL-style percent-encoding.
+
+    Returns a byte array containing the decoded text. The \a percent parameter
+    allows use of a different character than '%' (for instance, '_' or '=') as
+    the escape character. Equivalent to input.percentDecoded(percent).
+
+    For example:
+    \snippet code/src_corelib_text_qbytearray.cpp 51
+
+    \sa percentDecoded()
+*/
+QByteArray QByteArray::fromPercentEncoding(const QByteArray &input, char percent)
+{
+    return input.percentDecoded(percent);
+}
+
 /*! \fn QByteArray QByteArray::fromStdString(const std::string &str)
     \since 5.4
 

src/corelib/text/qbytearray.h

@@ -373,6 +373,7 @@ public:
     QByteArray toPercentEncoding(const QByteArray &exclude = QByteArray(),
                                  const QByteArray &include = QByteArray(),
                                  char percent = '%') const;
+    [[nodiscard]] QByteArray percentDecoded(char percent = '%') const;
 
     inline QByteArray &setNum(short, int base = 10);
     inline QByteArray &setNum(ushort, int base = 10);

tests/auto/corelib/text/qbytearray/tst_qbytearray.cpp

@@ -1652,15 +1652,15 @@ void tst_QByteArray::toFromPercentEncoding()
 
     QByteArray data = arr.toPercentEncoding();
     QCOMPARE(data, QByteArray("Qt%20is%20great%21"));
-    QCOMPARE(QByteArray::fromPercentEncoding(data), arr);
+    QCOMPARE(data.percentDecoded(), arr);
 
     data = arr.toPercentEncoding("! ", "Qt");
     QCOMPARE(data, QByteArray("%51%74 is grea%74!"));
-    QCOMPARE(QByteArray::fromPercentEncoding(data), arr);
+    QCOMPARE(data.percentDecoded(), arr);
 
     data = arr.toPercentEncoding(QByteArray(), "abcdefghijklmnopqrstuvwxyz", 'Q');
     QCOMPARE(data, QByteArray("Q51Q74Q20Q69Q73Q20Q67Q72Q65Q61Q74Q21"));
-    QCOMPARE(QByteArray::fromPercentEncoding(data, 'Q'), arr);
+    QCOMPARE(data.percentDecoded('Q'), arr);
 
     // verify that to/from percent encoding preserves nullity
     arr = "";
@@ -1676,16 +1676,16 @@ void tst_QByteArray::toFromPercentEncoding()
     QVERIFY(arr.isNull());
     QVERIFY(arr.toPercentEncoding().isEmpty());
     QVERIFY(arr.toPercentEncoding().isNull());
-    QVERIFY(QByteArray::fromPercentEncoding(QByteArray()).isEmpty());
-    QVERIFY(QByteArray::fromPercentEncoding(QByteArray()).isNull());
+    QVERIFY(QByteArray().percentDecoded().isEmpty());
+    QVERIFY(QByteArray().percentDecoded().isNull());
 
     // Verify that literal % in the string to be encoded does round-trip:
     arr = "Qt%20is%20great%21";
     data = arr.toPercentEncoding();
-    QCOMPARE(QByteArray::fromPercentEncoding(data), arr);
+    QCOMPARE(data.percentDecoded(), arr);
     arr = "87% of all statistics are made up!";
     data = arr.toPercentEncoding();
-    QCOMPARE(QByteArray::fromPercentEncoding(data), arr);
+    QCOMPARE(data.percentDecoded(), arr);
 }
 
 void tst_QByteArray::fromPercentEncoding_data()
@@ -1707,7 +1707,7 @@ void tst_QByteArray::fromPercentEncoding()
     QFETCH(QByteArray, encodedString);
     QFETCH(QByteArray, decodedString);
 
-    QCOMPARE(QByteArray::fromPercentEncoding(encodedString), decodedString);
+    QCOMPARE(encodedString.percentDecoded(), decodedString);
 }
 
 void tst_QByteArray::toPercentEncoding_data()
@@ -1768,7 +1768,7 @@ void tst_QByteArray::pecentEncodingRoundTrip()
 
     QByteArray encodedData = original.toPercentEncoding(excludeInEncoding, includeInEncoding);
     QCOMPARE(encodedData, encoded);
-    QCOMPARE(QByteArray::fromPercentEncoding(encodedData), original);
+    QCOMPARE(encodedData.percentDecoded(), original);
 }
 
 struct StringComparisonData