Add some extension and filter handling functions to QgsFileUtils

python/core/qgsfileutils.sip

@@ -27,6 +27,45 @@ class QgsFileUtils
 Return the human size from bytes
 %End
 
+
+    static QStringList extensionsFromFilter( const QString &filter );
+%Docstring
+Returns a list of the extensions contained within a file ``filter`` string.
+E.g. a ``filter`` of "GeoTIFF Files (*.tiff *.tif)" would return a list
+containing "tiff", "tif". The initial '.' is stripped off the extension.
+
+.. seealso:: :py:func:`ensureFileNameHasExtension()`
+
+.. seealso:: :py:func:`addExtensionFromFilter()`
+%End
+
+    static QString ensureFileNameHasExtension( const QString &fileName, const QStringList &extensions );
+%Docstring
+Ensures that a ``fileName`` ends with an extension from the provided list of
+``extensions``.
+
+E.g. if extensions contains "tif" and "tiff", then a ``fileName`` of
+"d:/my_file" will return "d:/my_file.tif". A ``fileName`` of
+"d:/my_file.TIFF" or "d:/my_file.TIF" will be returned unchanged.
+
+.. seealso:: :py:func:`extensionsFromFilter()`
+
+.. seealso:: :py:func:`addExtensionFromFilter()`
+%End
+
+    static QString addExtensionFromFilter( const QString &fileName, const QString &filter );
+%Docstring
+Ensures that a ``fileName`` ends with an extension from the specified ``filter``
+string.
+
+E.g. a ``fileName`` of "d:/my_file" with a filter of "GeoTIFF Files (*.tiff *.tif)"
+will return "d:/my_file.tif", where as ``fileName`` of "d:/my_file.TIFF" or "d:/my_file.TIF"
+will be returned unchanged.
+
+.. seealso:: :py:func:`extensionsFromFilter()`
+
+.. seealso:: :py:func:`ensureFileNameHasExtension()`
+%End
 };
 
 /************************************************************************

src/core/qgsfileutils.cpp

@@ -1,5 +1,6 @@
 #include "qgsfileutils.h"
 #include <QObject>
+#include <QRegularExpression>
 
 QString QgsFileUtils::representFileSize( qint64 bytes )
 {
@@ -16,3 +17,55 @@ QString QgsFileUtils::representFileSize( qint64 bytes )
   }
   return QString( "%1 %2" ).arg( QString::number( bytes ), unit );
 }
+
+QStringList QgsFileUtils::extensionsFromFilter( const QString &filter )
+{
+  const QRegularExpression rx( QStringLiteral( "\\*\\.([a-zA-Z0-9]+)" ) );
+  QStringList extensions;
+  QRegularExpressionMatchIterator matches = rx.globalMatch( filter );
+
+  while ( matches.hasNext() )
+  {
+    const QRegularExpressionMatch match = matches.next();
+    if ( match.hasMatch() )
+    {
+      QStringList newExtensions = match.capturedTexts();
+      newExtensions.pop_front(); // remove whole match
+      extensions.append( newExtensions );
+    }
+  }
+  return extensions;
+}
+
+QString QgsFileUtils::ensureFileNameHasExtension( const QString &f, const QStringList &extensions )
+{
+  if ( extensions.empty() || f.isEmpty() )
+    return f;
+
+  QString fileName = f;
+  bool hasExt = false;
+  for ( const QString &extension : qgis::as_const( extensions ) )
+  {
+    const QString extWithDot = extension.startsWith( '.' ) ? extension : '.' + extension;
+    if ( fileName.endsWith( extWithDot, Qt::CaseInsensitive ) )
+    {
+      hasExt = true;
+      break;
+    }
+  }
+
+  if ( !hasExt )
+  {
+    const QString extension = extensions.at( 0 );
+    const QString extWithDot = extension.startsWith( '.' ) ? extension : '.' + extension;
+    fileName += extWithDot;
+  }
+
+  return fileName;
+}
+
+QString QgsFileUtils::addExtensionFromFilter( const QString &fileName, const QString &filter )
+{
+  const QStringList extensions = extensionsFromFilter( filter );
+  return ensureFileNameHasExtension( fileName, extensions );
+}

src/core/qgsfileutils.h

@@ -35,6 +35,41 @@ class CORE_EXPORT QgsFileUtils
      */
     static QString representFileSize( qint64 bytes );
 
+
+    /**
+     * Returns a list of the extensions contained within a file \a filter string.
+     * E.g. a \a filter of "GeoTIFF Files (*.tiff *.tif)" would return a list
+     * containing "tiff", "tif". The initial '.' is stripped off the extension.
+     * \see ensureFileNameHasExtension()
+     * \see addExtensionFromFilter()
+     */
+    static QStringList extensionsFromFilter( const QString &filter );
+
+    /**
+     * Ensures that a \a fileName ends with an extension from the provided list of
+     * \a extensions.
+     *
+     * E.g. if extensions contains "tif" and "tiff", then a \a fileName of
+     * "d:/my_file" will return "d:/my_file.tif". A \a fileName of
+     * "d:/my_file.TIFF" or "d:/my_file.TIF" will be returned unchanged.
+     *
+     * \see extensionsFromFilter()
+     * \see addExtensionFromFilter()
+     */
+    static QString ensureFileNameHasExtension( const QString &fileName, const QStringList &extensions );
+
+    /**
+     * Ensures that a \a fileName ends with an extension from the specified \a filter
+     * string.
+     *
+     * E.g. a \a fileName of "d:/my_file" with a filter of "GeoTIFF Files (*.tiff *.tif)"
+     * will return "d:/my_file.tif", where as \a fileName of "d:/my_file.TIFF" or "d:/my_file.TIF"
+     * will be returned unchanged.
+     *
+     * \see extensionsFromFilter()
+     * \see ensureFileNameHasExtension()
+     */
+    static QString addExtensionFromFilter( const QString &fileName, const QString &filter );
 };
 
 #endif // QGSFILEUTILS_H

tests/src/python/test_qgsfileutils.py

@@ -0,0 +1,60 @@
+# -*- coding: utf-8 -*-
+"""QGIS Unit tests for QgsFileUtils.
+
+.. note:: This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+"""
+__author__ = 'Nyall Dawson'
+__date__ = '18/12/2017'
+__copyright__ = 'Copyright 2017, The QGIS Project'
+# This will get replaced with a git SHA1 when you do a git archive
+__revision__ = '$Format:%H$'
+
+import qgis  # NOQA
+
+from qgis.core import QgsFileUtils
+from qgis.testing import unittest
+
+
+class TestQgsFileUtils(unittest.TestCase):
+
+    def testExtensionsFromFilter(self):
+        self.assertEqual(QgsFileUtils.extensionsFromFilter(''), [])
+        self.assertEqual(QgsFileUtils.extensionsFromFilter('bad'), [])
+        self.assertEqual(QgsFileUtils.extensionsFromFilter('*'), [])
+        self.assertEqual(QgsFileUtils.extensionsFromFilter('*.'), [])
+        self.assertEqual(QgsFileUtils.extensionsFromFilter('Tiff files'), [])
+        self.assertEqual(QgsFileUtils.extensionsFromFilter('(*.)'), [])
+        self.assertEqual(QgsFileUtils.extensionsFromFilter('PNG Files (*.png)'), ['png'])
+        self.assertEqual(QgsFileUtils.extensionsFromFilter('PNG Files (*.PNG)'), ['PNG'])
+        self.assertEqual(QgsFileUtils.extensionsFromFilter('Geotiff Files (*.tiff *.tif)'), ['tiff', 'tif'])
+
+    def testEnsureFileNameHasExtension(self):
+        self.assertEqual(QgsFileUtils.ensureFileNameHasExtension('', ['']), '')
+        self.assertEqual(QgsFileUtils.ensureFileNameHasExtension('', []), '')
+        self.assertEqual(QgsFileUtils.ensureFileNameHasExtension('test', []), 'test')
+        self.assertEqual(QgsFileUtils.ensureFileNameHasExtension('', ['.tif']), '')
+        self.assertEqual(QgsFileUtils.ensureFileNameHasExtension('test', ['.tif']), 'test.tif')
+        self.assertEqual(QgsFileUtils.ensureFileNameHasExtension('test', ['tif']), 'test.tif')
+        self.assertEqual(QgsFileUtils.ensureFileNameHasExtension('test.tif', []), 'test.tif')
+        self.assertEqual(QgsFileUtils.ensureFileNameHasExtension('test.tif', ['bmp']), 'test.tif.bmp')
+        self.assertEqual(QgsFileUtils.ensureFileNameHasExtension('test.tif', ['tiff']), 'test.tif.tiff')
+        self.assertEqual(QgsFileUtils.ensureFileNameHasExtension('test.tif', ['tiff', 'tif']), 'test.tif')
+        self.assertEqual(QgsFileUtils.ensureFileNameHasExtension('test.tif', ['TIFF', 'TIF']), 'test.tif')
+
+    def testAddExtensionFromFilter(self):
+        self.assertEqual(QgsFileUtils.addExtensionFromFilter('test', 'TIFF Files (*.tif)'), 'test.tif')
+        self.assertEqual(QgsFileUtils.addExtensionFromFilter('test', 'TIFF Files (*.tif)'), 'test.tif')
+        self.assertEqual(QgsFileUtils.addExtensionFromFilter('test.tif', ''), 'test.tif')
+        self.assertEqual(QgsFileUtils.addExtensionFromFilter('test.tif', 'BMP Files (*.bmp)'), 'test.tif.bmp')
+        self.assertEqual(QgsFileUtils.addExtensionFromFilter('test.tif', 'TIFF Files (*.tiff)'), 'test.tif.tiff')
+        self.assertEqual(QgsFileUtils.addExtensionFromFilter('test.tif', 'TIFF Files (*.tif *.tiff)'), 'test.tif')
+        self.assertEqual(QgsFileUtils.addExtensionFromFilter('test.tif', 'TIFF Files (*.TIF *.TIFF)'), 'test.tif')
+        self.assertEqual(QgsFileUtils.addExtensionFromFilter('test.tif', 'All Files (*.*)'), 'test.tif')
+        self.assertEqual(QgsFileUtils.addExtensionFromFilter('test', 'All Files (*.*)'), 'test')
+
+
+if __name__ == '__main__':
+    unittest.main()