qmllint: Document and cleanup IssueLocationWithContext

Add a few comments to describe IssueLocationWithContext. In addition,
remove useles casts. Also remove uselessly constructing QStrings by
adding a few QStringView overloads.

Change-Id: I3c6e03f38cbe251deda66bd9257462d9ee9cd065
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

3 files changed, 31 insertions, 17 deletions

diff --git a/tools/qmllint/checkidentifiers.cpp b/tools/qmllint/checkidentifiers.cpp
index 7350a1f76e..2c64fd9198 100644
--- a/tools/qmllint/checkidentifiers.cpp
+++ b/tools/qmllint/checkidentifiers.cpp
@@ -33,23 +33,35 @@
 #include <QtCore/qsharedpointer.h>
 #include <stack>
 
+/*!
+    \internal
+    Used to print the the line containing the location of a certain error
+ */
 class IssueLocationWithContext
 {
 public:
-    IssueLocationWithContext(const QString &code, const QQmlJS::SourceLocation &location) {
+    /*!
+       \internal
+       \param code: The whole text of a translation unit
+       \param location: The location where an error occurred.
+     */
+    IssueLocationWithContext(QStringView code, const QQmlJS::SourceLocation &location) {
         int before = qMax(0,code.lastIndexOf(QLatin1Char('\n'), location.offset));
 
         if (before != 0) before++;
 
-        m_beforeText = QStringView{code}.mid(before, int(location.offset - before));
-        m_issueText = QStringView{code}.mid(location.offset, location.length);
-        int after = code.indexOf(QLatin1Char('\n'), int(location.offset + location.length));
-        m_afterText = QStringView{code}.mid(int(location.offset + location.length),
-                                  int(after - (location.offset+location.length)));
+        m_beforeText = code.mid(before, location.offset - before);
+        m_issueText = code.mid(location.offset, location.length);
+        int after = code.indexOf(QLatin1Char('\n'), location.offset + location.length);
+        m_afterText = code.mid(location.offset + location.length,
+                                  after - (location.offset+location.length));
     }
 
+    // returns start of the line till first character of location
     QStringView beforeText() const { return m_beforeText; }
+    // returns the text at location
     QStringView issueText() const { return m_issueText; }
+    // returns any text after location until the end of the line is reached
     QStringView afterText() const { return m_afterText; }
 
 private:
@@ -71,10 +83,10 @@ void CheckIdentifiers::printContext(
         const QString &code, ColorOutput *output, const QQmlJS::SourceLocation &location)
 {
     IssueLocationWithContext issueLocationWithContext { code, location };
-    if (const QString beforeText = issueLocationWithContext.beforeText().toString(); !beforeText.isEmpty())
+    if (const QStringView beforeText = issueLocationWithContext.beforeText(); !beforeText.isEmpty())
         output->write(beforeText, Normal);
-    output->write(issueLocationWithContext.issueText().toString(), Error);
-    if (const QString afterText = issueLocationWithContext.afterText().toString(); !afterText.isEmpty())
+    output->write(issueLocationWithContext.issueText(), Error);
+    if (const QStringView afterText = issueLocationWithContext.afterText(); !afterText.isEmpty())
         output->write(afterText + QLatin1Char('\n'), Normal);
     int tabCount = issueLocationWithContext.beforeText().count(QLatin1Char('\t'));
     output->write(QString::fromLatin1(" ").repeated(
@@ -465,9 +477,9 @@ bool CheckIdentifiers::operator()(
                                 Warning, QStringLiteral("Note"));
                 }
                 IssueLocationWithContext issueLocationWithContext {m_code, location};
-                m_colorOut->write(issueLocationWithContext.beforeText().toString(), Normal);
+                m_colorOut->write(issueLocationWithContext.beforeText(), Normal);
                 m_colorOut->write(rootId + QLatin1Char('.'), Hint);
-                m_colorOut->write(issueLocationWithContext.issueText().toString(), Normal);
+                m_colorOut->write(issueLocationWithContext.issueText(), Normal);
                 m_colorOut->write(issueLocationWithContext.afterText() + QLatin1Char('\n'), Normal);
             } else if (jsId.has_value()
                        && jsId->kind == QQmlJSScope::JavaScriptIdentifier::Injected) {
diff --git a/tools/qmllint/qcoloroutput.cpp b/tools/qmllint/qcoloroutput.cpp
index 22783ef1b9..6e0a483050 100644
--- a/tools/qmllint/qcoloroutput.cpp
+++ b/tools/qmllint/qcoloroutput.cpp
@@ -236,7 +236,7 @@ ColorOutput::~ColorOutput() = default;
 
  \a message will be printed as is. For instance, no line endings will be inserted.
  */
-void ColorOutput::write(const QString &message, int colorID)
+void ColorOutput::write(QStringView message, int colorID)
 {
     if (!d->isSilent())
         d->write(colorify(message, colorID));
@@ -279,7 +279,7 @@ void ColorOutput::writeUncolored(const QString &message)
  This is useful when the colored string is inserted into a translated string(dividing
  the string into several small strings prevents proper translation).
  */
-QString ColorOutput::colorify(const QString &message, int colorID) const
+QString ColorOutput::colorify(QStringView message, int colorID) const
 {
     Q_ASSERT_X(colorID == -1 || d->containsColor(colorID), Q_FUNC_INFO,
                qPrintable(QString::fromLatin1("There is no color registered by id %1")
@@ -295,7 +295,7 @@ QString ColorOutput::colorify(const QString &message, int colorID) const
 
         /* If DefaultColor is set, we don't want to color it. */
         if (color & DefaultColor)
-            return message;
+            return message.toString();
 
         const int foregroundCode = (color & ForegroundMask) >> ForegroundShift;
         const int backgroundCode = (color & BackgroundMask) >> BackgroundShift;
@@ -324,7 +324,7 @@ QString ColorOutput::colorify(const QString &message, int colorID) const
         return finalMessage;
     }
 
-    return message;
+    return message.toString();
 }
 
 /*!
diff --git a/tools/qmllint/qcoloroutput.h b/tools/qmllint/qcoloroutput.h
index 41b8751432..3b171da631 100644
--- a/tools/qmllint/qcoloroutput.h
+++ b/tools/qmllint/qcoloroutput.h
@@ -104,10 +104,12 @@ public:
     void insertMapping(int colorID, ColorCode colorCode);
 
     void writeUncolored(const QString &message);
-    void write(const QString &message, int color = -1);
+    void write(QStringView message, int color = -1);
+    // handle QStringBuilder case
+    Q_WEAK_OVERLOAD void write(const QString &message, int color = -1) { write(QStringView(message), color); }
     void writePrefixedMessage(const QString &message, MessageColors type,
                               const QString &prefix = QString());
-    QString colorify(const QString &message, int color = -1) const;
+    QString colorify(QStringView message, int color = -1) const;
 
 private:
     QScopedPointer<ColorOutputPrivate> d;