filterbar: Add support to match case and glob patterns for the filter bar

Currently, Dolphin's filter bar defaults to plain text, but it actually has a hidden regex functionality too: it tries to auto-detect and switch to a regular expression if characters like '*', '?', or '[' are present in the search string.
This approach has a couple of issues. First, the regex/wildcard functionality is completely hidden from the user. Second, the auto-detection is flawed because those are perfectly valid characters in Linux filenames. If a user tries to filter for a file literally named [draft].txt, the auto-switching kicks in and causes unexpected behavior.

This MR fixes this by making the filtering modes explicit through a ComboBox at the side of the filter bar, with the options 'Plain Text', 'Glob' and 'Regular Expression'. It also adds a button to toggle the case sensitive matching. A visual feedback for when the user is inputting an invalid expression has also been implemented by turning the bar background red and making appear an error symbol.

2 files changed, 80 insertions, 18 deletions

diff --git a/src/kitemviews/private/kfileitemmodelfilter.cpp b/src/kitemviews/private/kfileitemmodelfilter.cpp
index 45c62e7ca..48d2f6276 100644
--- a/src/kitemviews/private/kfileitemmodelfilter.cpp
+++ b/src/kitemviews/private/kfileitemmodelfilter.cpp
@@ -13,7 +13,8 @@
 #include <KFileItem>
 
 KFileItemModelFilter::KFileItemModelFilter()
-    : m_useRegExp(false)
+    : m_filterMode(Glob)
+    , m_caseSensitive(false)
     , m_regExp(nullptr)
     , m_lowerCasePattern()
     , m_pattern()
@@ -31,16 +32,29 @@ void KFileItemModelFilter::setPattern(const QString &filter)
     m_pattern = filter;
     m_lowerCasePattern = filter.toLower();
 
-    if (filter.contains(QLatin1Char('*')) || filter.contains(QLatin1Char('?')) || filter.contains(QLatin1Char('['))) {
-        if (!m_regExp) {
-            m_regExp = new QRegularExpression();
-            m_regExp->setPatternOptions(QRegularExpression::CaseInsensitiveOption);
-        }
-        m_regExp->setPattern(QRegularExpression::wildcardToRegularExpression(filter));
-        m_useRegExp = m_regExp->isValid();
-    } else {
-        m_useRegExp = false;
-    }
+    updateFilter();
+}
+
+void KFileItemModelFilter::setFilterMode(FilterMode mode)
+{
+    m_filterMode = mode;
+    updateFilter();
+}
+
+KFileItemModelFilter::FilterMode KFileItemModelFilter::filterMode() const
+{
+    return m_filterMode;
+}
+
+void KFileItemModelFilter::setCaseSensitive(bool caseSensitive)
+{
+    m_caseSensitive = caseSensitive;
+    updateFilter();
+}
+
+bool KFileItemModelFilter::isCaseSensitive() const
+{
+    return m_caseSensitive;
 }
 
 QString KFileItemModelFilter::pattern() const
@@ -48,6 +62,26 @@ QString KFileItemModelFilter::pattern() const
     return m_pattern;
 }
 
+void KFileItemModelFilter::updateFilter()
+{
+    if (m_filterMode == PlainText) {
+        return;
+    }
+
+    if (!m_regExp) {
+        m_regExp = new QRegularExpression();
+    }
+
+    QRegularExpression::PatternOptions options = m_caseSensitive ? QRegularExpression::NoPatternOption : QRegularExpression::CaseInsensitiveOption;
+    if (m_filterMode == Regex) {
+        m_regExp->setPattern(m_pattern);
+        m_regExp->setPatternOptions(options);
+    } else if (m_filterMode == Glob) {
+        m_regExp->setPattern(QRegularExpression::wildcardToRegularExpression(m_pattern, QRegularExpression::UnanchoredWildcardConversion));
+        m_regExp->setPatternOptions(options);
+    }
+}
+
 void KFileItemModelFilter::setMimeTypes(const QStringList &types)
 {
     m_mimeTypes = types;
@@ -98,8 +132,10 @@ bool KFileItemModelFilter::matches(const KFileItem &item) const
 
 bool KFileItemModelFilter::matchesPattern(const KFileItem &item) const
 {
-    if (m_useRegExp) {
-        return m_regExp->match(item.text()).hasMatch();
+    if (m_filterMode == Glob || m_filterMode == Regex) {
+        return m_regExp->isValid() && m_regExp->match(item.text()).hasMatch();
+    } else if (m_caseSensitive) {
+        return item.text().contains(m_pattern);
     } else {
         return item.text().toLower().contains(m_lowerCasePattern);
     }
diff --git a/src/kitemviews/private/kfileitemmodelfilter.h b/src/kitemviews/private/kfileitemmodelfilter.h
index ce6cbeebb..9d93d42cc 100644
--- a/src/kitemviews/private/kfileitemmodelfilter.h
+++ b/src/kitemviews/private/kfileitemmodelfilter.h
@@ -28,16 +28,36 @@ public:
     KFileItemModelFilter();
     virtual ~KFileItemModelFilter();
 
+    /** Filtering modes of KFileItemModelFilter */
+    enum FilterMode {
+        /** Substring matching. */
+        PlainText = 0,
+        /** Matching with glob, default. */
+        Glob,
+        /** Matching with regex. */
+        Regex
+    };
+
     /**
      * Sets the pattern that is used for a comparison with the item
-     * in KFileItemModelFilter::matches(). Per default the pattern
-     * defines a sub-string. As soon as the pattern contains at least
-     * a '*', '?' or '[' the pattern represents a regular expression.
+     * in KFileItemModelFilter::matches().
      */
     void setPattern(const QString &pattern);
     QString pattern() const;
 
     /**
+     * Sets the filtering mode used in KFileItemModelFilter::matches().
+     */
+    void setFilterMode(FilterMode mode);
+    FilterMode filterMode() const;
+
+    /**
+     * Enable or disable the case sensitive filtering.
+     */
+    void setCaseSensitive(bool caseSensitive);
+    bool isCaseSensitive() const;
+
+    /**
      * Set the list of mimetypes that are used for comparison with the
      * item in KFileItemModelFilter::matchesMimeType.
      */
@@ -73,8 +93,14 @@ private:
      */
     bool matchesType(const KFileItem &item) const;
 
-    bool m_useRegExp; // If true, m_regExp is used for filtering,
-                      // otherwise m_lowerCaseFilter is used.
+    /**
+     * Instantiate and configure m_regExp according to m_filterMode and m_caseSensitive.
+     */
+    void updateFilter();
+
+    FilterMode m_filterMode; // The current filtering mode.
+    bool m_caseSensitive; // If true the matching will be case sensitive.
+
     QRegularExpression *m_regExp;
     QString m_lowerCasePattern; // Lowercase version of m_filter for
                                 // faster comparison in matches().