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Avoid unnecessary string and list copies

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Change-Id: I78bc4d307be69ce3bbfaa3ca3dd7c85e654af8d6
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>
This commit is contained in:
Yuri Vilmanis
2023-10-30 17:41:50 +10:30
parent 0a3bfc9323
commit 1acf00d3e1
4 changed files with 24 additions and 14 deletions
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22
src/libs/utils/filepath.cpp
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@@ -453,7 +453,7 @@ QStringView FilePath::host() const
QStringView FilePath::pathView() const
{
return QStringView(m_data).left(m_pathLen);
return QStringView(m_data.constData(), m_pathLen);
}
QString FilePath::path() const
@@ -469,7 +469,17 @@ void FilePath::setParts(const QStringView scheme, const QStringView host, QStrin
path = path.mid(3);
m_hash = 0;
m_data = path.toString() + scheme.toString() + host.toString();
// The equivalent of:
// m_data = path.toString() + scheme.toString() + host.toString();
// but with less copying.
// Note: The QStringBuilder optimization does not currently work in this case.
m_data.resize(0);
m_data.reserve(m_schemeLen + m_hostLen + m_pathLen);
m_data.append(path);
m_data.append(scheme);
m_data.append(host);
m_schemeLen = scheme.size();
m_hostLen = host.size();
m_pathLen = path.size();
@@ -1480,7 +1490,7 @@ FilePath FilePath::relativePathFrom(const FilePath &anchor) const
absoluteAnchorPath = anchor.absoluteFilePath();
else
return {};
QString relativeFilePath = calcRelativePath(absPath.path(), absoluteAnchorPath.path());
QString relativeFilePath = calcRelativePath(absPath.pathView(), absoluteAnchorPath.pathView());
if (!filename.isEmpty()) {
if (relativeFilePath == ".")
relativeFilePath.clear();
@@ -1505,14 +1515,14 @@ FilePath FilePath::relativePathFrom(const FilePath &anchor) const
\see FilePath::isRelativePath(), FilePath::relativePathFrom(), FilePath::relativeChildPath()
*/
QString FilePath::calcRelativePath(const QString &absolutePath, const QString &absoluteAnchorPath)
QString FilePath::calcRelativePath(QStringView absolutePath, QStringView absoluteAnchorPath)
{
if (absolutePath.isEmpty() || absoluteAnchorPath.isEmpty())
return QString();
// TODO using split() instead of parsing the strings by char index is slow
// and needs more memory (but the easiest implementation for now)
const QStringList splits1 = absolutePath.split('/');
const QStringList splits2 = absoluteAnchorPath.split('/');
const QList<QStringView> splits1 = absolutePath.split('/');
const QList<QStringView> splits2 = absoluteAnchorPath.split('/');
int i = 0;
while (i < splits1.count() && i < splits2.count() && splits1.at(i) == splits2.at(i))
++i;