Execute some small performance improvements in QProcessEnvironment

If d == 0, then we know we have no items. Therefore, removing or
clearing is an idempotent action. So instead of detaching, leave d == 0.

In the search function, avoid converting the defaultValue to the
internal representation.

2 files changed, 11 insertions, 5 deletions

diff --git a/src/corelib/io/qprocess.cpp b/src/corelib/io/qprocess.cpp
index 7c13bf0..733887a 100644
--- a/src/corelib/io/qprocess.cpp
+++ b/src/corelib/io/qprocess.cpp
@@ -293,7 +293,8 @@ bool QProcessEnvironment::isEmpty() const
 */
 void QProcessEnvironment::clear()
 {
-    d->hash.clear();
+    if (d)
+        d->hash.clear();
 }
 
 /*!
@@ -345,7 +346,8 @@ void QProcessEnvironment::insert(const QString &name, const QString &value)
 */
 void QProcessEnvironment::remove(const QString &name)
 {
-    d->hash.remove(prepareName(name));
+    if (d)
+        d->hash.remove(prepareName(name));
 }
 
 /*!
@@ -364,8 +366,11 @@ QString QProcessEnvironment::value(const QString &name, const QString &defaultVa
     if (!d)
         return defaultValue;
 
-    QProcessEnvironmentPrivate::Unit result = d->hash.value(prepareName(name), prepareValue(defaultValue));
-    return valueToString(result);
+    QProcessEnvironmentPrivate::Hash::ConstIterator it = d->hash.constFind(prepareName(name));
+    if (it == d->hash.constEnd())
+        return defaultValue;
+
+    return valueToString(it.value());
 }
 
 /*!
diff --git a/src/corelib/io/qprocess_p.h b/src/corelib/io/qprocess_p.h
index 1e2979b..b581e91 100644
--- a/src/corelib/io/qprocess_p.h
+++ b/src/corelib/io/qprocess_p.h
@@ -86,7 +86,8 @@ public:
 #else
     typedef QByteArray Unit;
 #endif
-    QHash<Unit, Unit> hash;
+    typedef QHash<Unit, Unit> Hash;
+    Hash hash;
 
     static QProcessEnvironment fromList(const QStringList &list);
     QStringList toList() const;