Tidy up QByteArray::toPercentEncoding()

After inlining the local static void to which it used to delegate most
of the work, the main loop can access *this and we have no need for
yet another copy of it or the variables to iterate it. We can also
access the result array directly, rather than via a (poorly-named)
pointer.

It turns out that wrapping QBA in QBAV each time we call a lambda on
it costs enough to cause a 50% slowdown, so change the lambda to now
take the const refs we have. (Constructing the views only once is as
good, for reference.)

Change-Id: I81c5996d91415d8a933de714177a89462555ff03
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 5 insertions, 10 deletions

diff --git a/src/corelib/text/qbytearray.cpp b/src/corelib/text/qbytearray.cpp
index 1f634fef07..7795fd7f11 100644
--- a/src/corelib/text/qbytearray.cpp
+++ b/src/corelib/text/qbytearray.cpp
@@ -4600,21 +4600,16 @@ QByteArray QByteArray::toPercentEncoding(const QByteArray &exclude, const QByteA
     if (isEmpty())
         return QByteArray(data(), 0);
 
-    const auto contains = [](QByteArrayView view, char c) {
+    const auto contains = [](const QByteArray &view, char c) {
         // As view.contains(c), but optimised to bypass a lot of overhead:
         return view.size() > 0 && memchr(view.data(), c, view.size()) != nullptr;
     };
 
     QByteArray result = *this;
-    QByteArray *ba = &result;
-    QByteArray input = *ba;
-    qsizetype len = input.size();
-    const char *inputData = input.constData();
     char *output = nullptr;
     qsizetype length = 0;
 
-    for (qsizetype i = 0; i < len; ++i) {
-        unsigned char c = *inputData++;
+    for (unsigned char c : *this) {
         if (c != percent
             && ((c >= 0x61 && c <= 0x7A) // ALPHA
                 || (c >= 0x41 && c <= 0x5A) // ALPHA
@@ -4631,8 +4626,8 @@ QByteArray QByteArray::toPercentEncoding(const QByteArray &exclude, const QByteA
         } else {
             if (!output) {
                 // detach now
-                ba->resize(len*3); // worst case
-                output = ba->data();
+                result.resize(size() * 3); // worst case
+                output = result.data();
             }
             output[length++] = percent;
             output[length++] = QtMiscUtils::toHexUpper((c & 0xf0) >> 4);
@@ -4640,7 +4635,7 @@ QByteArray QByteArray::toPercentEncoding(const QByteArray &exclude, const QByteA
         }
     }
     if (output)
-        ba->truncate(length);
+        result.truncate(length);
 
     return result;
 }