Implicit sharing for QgsFields

Author: nyalldawson

python/core/qgsfield.sip

@@ -1,10 +1,9 @@
-
-/**
-  \class QgsField
-  \brief Class to encapsulate a field in an attribute table or data source.
-
-  QgsField stores metadata about an attribute field, including name, type
-  length, and if applicable, precision.
+/** \class QgsField
+  * \ingroup core
+  * Encapsulate a field in an attribute table or data source.
+  * QgsField stores metadata about an attribute field, including name, type
+  * length, and if applicable, precision.
+  * \note QgsField objects are implicitly shared.
  */
 
 class QgsField
@@ -39,7 +38,7 @@ public:
     QgsField( const QgsField& other );
 
     //! Destructor
-    ~QgsField();
+    virtual ~QgsField();
 
     bool operator==( const QgsField& other ) const;
     bool operator!=( const QgsField& other ) const;
@@ -175,6 +174,15 @@ public:
 }; // class QgsField
 
 
+/** \class QgsFields
+ * \ingroup core
+ * Container of fields for a vector layer.
+ *
+ * In addition to storing a list of QgsField instances, it also:
+ * - allows quick lookups of field names to index in the list
+ *- keeps track of where the field definition comes from (vector data provider, joined layer or newly added from an editing operation)
+ * \note QgsFields objects are implicitly shared.
+ */
 
 class QgsFields
 {
@@ -192,6 +200,16 @@ class QgsFields
       OriginExpression //!< field is calculated from an expression
     };
 
+    /** Constructor for an empty field container
+     */
+    QgsFields();
+
+    /** Copy constructor
+     */
+    QgsFields( const QgsFields& other );
+
+    virtual ~QgsFields();
+
     //! Remove all fields
     void clear();
     //! Append a field. The field must have unique name, otherwise it is rejected (returns false)

src/core/qgsfield.cpp

@@ -178,33 +178,54 @@ bool QgsField::convertCompatible( QVariant& v ) const
 
 ////////////////////////////////////////////////////////////////////////////
 
+QgsFields::QgsFields()
+{
+  d = new QgsFieldsPrivate( );
+}
+
+QgsFields::QgsFields( const QgsFields &other )
+    : d( other.d )
+{
+}
+
+QgsFields &QgsFields::operator =( const QgsFields & other )
+{
+  d = other.d;
+  return *this;
+}
+
+QgsFields::~QgsFields()
+{
+
+}
+
 void QgsFields::clear()
 {
-  mFields.clear();
-  mNameToIndex.clear();
+  d->fields.clear();
+  d->nameToIndex.clear();
 }
 
 bool QgsFields::append( const QgsField& field, FieldOrigin origin, int originIndex )
 {
-  if ( mNameToIndex.contains( field.name() ) )
+  if ( d->nameToIndex.contains( field.name() ) )
     return false;
 
   if ( originIndex == -1 && origin == OriginProvider )
-    originIndex = mFields.count();
-  mFields.append( Field( field, origin, originIndex ) );
+    originIndex = d->fields.count();
+  d->fields.append( Field( field, origin, originIndex ) );
 
-  mNameToIndex.insert( field.name(), mFields.count() - 1 );
+  d->nameToIndex.insert( field.name(), d->fields.count() - 1 );
   return true;
 }
 
 bool QgsFields::appendExpressionField( const QgsField& field, int originIndex )
 {
-  if ( mNameToIndex.contains( field.name() ) )
+  if ( d->nameToIndex.contains( field.name() ) )
     return false;
 
-  mFields.append( Field( field, OriginExpression, originIndex ) );
+  d->fields.append( Field( field, OriginExpression, originIndex ) );
 
-  mNameToIndex.insert( field.name(), mFields.count() - 1 );
+  d->nameToIndex.insert( field.name(), d->fields.count() - 1 );
   return true;
 }
 
@@ -213,8 +234,8 @@ void QgsFields::remove( int fieldIdx )
   if ( !exists( fieldIdx ) )
     return;
 
-  mNameToIndex.remove( mFields[fieldIdx].field.name() );
-  mFields.remove( fieldIdx );
+  d->nameToIndex.remove( d->fields[fieldIdx].field.name() );
+  d->fields.remove( fieldIdx );
 }
 
 void QgsFields::extend( const QgsFields& other )
@@ -225,27 +246,87 @@ void QgsFields::extend( const QgsFields& other )
   }
 }
 
+bool QgsFields::isEmpty() const
+{
+  return d->fields.isEmpty();
+}
+
+int QgsFields::count() const
+{
+  return d->fields.count();
+}
+
+int QgsFields::size() const
+{
+  return d->fields.count();
+}
+
+bool QgsFields::exists( int i ) const
+{
+  return i >= 0 && i < d->fields.count();
+}
+
+QgsField &QgsFields::operator[]( int i )
+{
+  return d->fields[i].field;
+}
+
+const QgsField &QgsFields::at( int i ) const
+{
+  return d->fields[i].field;
+}
+
+const QgsField &QgsFields::field( int fieldIdx ) const
+{
+  return d->fields[fieldIdx].field;
+}
+
+const QgsField &QgsFields::field( const QString &name ) const
+{
+  return d->fields[ indexFromName( name )].field;
+}
+
+const QgsField &QgsFields::operator[]( int i ) const
+{
+  return d->fields[i].field;
+}
+
 QgsFields::FieldOrigin QgsFields::fieldOrigin( int fieldIdx ) const
 {
   if ( !exists( fieldIdx ) )
     return OriginUnknown;
 
-  return mFields[fieldIdx].origin;
+  return d->fields[fieldIdx].origin;
+}
+
+int QgsFields::fieldOriginIndex( int fieldIdx ) const
+{
+  return d->fields[fieldIdx].originIndex;
+}
+
+int QgsFields::indexFromName( const QString &name ) const
+{
+  return d->nameToIndex.value( name, -1 );
 }
 
 QList<QgsField> QgsFields::toList() const
 {
   QList<QgsField> lst;
-  for ( int i = 0; i < mFields.count(); ++i )
-    lst.append( mFields[i].field );
+  for ( int i = 0; i < d->fields.count(); ++i )
+    lst.append( d->fields[i].field );
   return lst;
 }
 
+bool QgsFields::operator==( const QgsFields &other ) const
+{
+  return d->fields == other.d->fields;
+}
+
 int QgsFields::fieldNameIndex( const QString& fieldName ) const
 {
   for ( int idx = 0; idx < count(); ++idx )
   {
-    if ( QString::compare( mFields[idx].field.name(), fieldName, Qt::CaseInsensitive ) == 0 )
+    if ( QString::compare( d->fields[idx].field.name(), fieldName, Qt::CaseInsensitive ) == 0 )
     {
       return idx;
     }
@@ -256,7 +337,7 @@ int QgsFields::fieldNameIndex( const QString& fieldName ) const
 QgsAttributeList QgsFields::allAttributesList() const
 {
   QgsAttributeList lst;
-  for ( int i = 0; i < mFields.count(); ++i )
+  for ( int i = 0; i < d->fields.count(); ++i )
     lst.append( i );
   return lst;
 }

src/core/qgsfield.h

@@ -25,11 +25,14 @@ typedef QList<int> QgsAttributeList;
 
 class QgsExpression;
 class QgsFieldPrivate;
+class QgsFieldsPrivate;
 
-/** \ingroup core
+/** \class QgsField
+  * \ingroup core
   * Encapsulate a field in an attribute table or data source.
   * QgsField stores metadata about an attribute field, including name, type
   * length, and if applicable, precision.
+  * \note QgsField objects are implicitly shared.
  */
 
 class CORE_EXPORT QgsField
@@ -63,7 +66,7 @@ class CORE_EXPORT QgsField
     QgsField& operator =( const QgsField &other );
 
     //! Destructor
-    ~QgsField();
+    virtual ~QgsField();
 
     bool operator==( const QgsField& other ) const;
     bool operator!=( const QgsField& other ) const;
@@ -152,13 +155,14 @@ class CORE_EXPORT QgsField
 }; // class QgsField
 
 
-/**
- \ingroup core
- Container of fields for a vector layer.
-
- In addition to storing a list of QgsField instances, it also:
- - allows quick lookups of field names to index in the list
- - keeps track of where the field definition comes from (vector data provider, joined layer or newly added from an editing operation)
+/** \class QgsFields
+ * \ingroup core
+ * Container of fields for a vector layer.
+ *
+ * In addition to storing a list of QgsField instances, it also:
+ * - allows quick lookups of field names to index in the list
+ *- keeps track of where the field definition comes from (vector data provider, joined layer or newly added from an editing operation)
+ * \note QgsFields objects are implicitly shared.
  */
 class CORE_EXPORT QgsFields
 {
@@ -188,6 +192,20 @@ class CORE_EXPORT QgsFields
       int originIndex;     //!< index specific to the origin
     } Field;
 
+    /** Constructor for an empty field container
+     */
+    QgsFields();
+
+    /** Copy constructor
+     */
+    QgsFields( const QgsFields& other );
+
+    /** Assignment operator
+     */
+    QgsFields& operator =( const QgsFields &other );
+
+    virtual ~QgsFields();
+
     //! Remove all fields
     void clear();
     //! Append a field. The field must have unique name, otherwise it is rejected (returns false)
@@ -200,34 +218,34 @@ class CORE_EXPORT QgsFields
     void extend( const QgsFields& other );
 
     //! Check whether the container is empty
-    inline bool isEmpty() const { return mFields.isEmpty(); }
+    bool isEmpty() const;
     //! Return number of items
-    inline int count() const { return mFields.count(); }
+    int count() const;
     //! Return number of items
-    inline int size() const { return mFields.count(); }
+    int size() const;
     //! Return if a field index is valid
     //! @param i  Index of the field which needs to be checked
     //! @return   True if the field exists
-    inline bool exists( int i ) const { return i >= 0 && i < mFields.count(); }
+    bool exists( int i ) const;
 
     //! Get field at particular index (must be in range 0..N-1)
-    inline const QgsField& operator[]( int i ) const { return mFields[i].field; }
+    const QgsField& operator[]( int i ) const;
     //! Get field at particular index (must be in range 0..N-1)
-    inline QgsField& operator[]( int i ) { return mFields[i].field; }
+    QgsField& operator[]( int i );
     //! Get field at particular index (must be in range 0..N-1)
-    const QgsField& at( int i ) const { return mFields[i].field; }
+    const QgsField& at( int i ) const;
     //! Get field at particular index (must be in range 0..N-1)
-    const QgsField& field( int fieldIdx ) const { return mFields[fieldIdx].field; }
+    const QgsField& field( int fieldIdx ) const;
     //! Get field at particular index (must be in range 0..N-1)
-    const QgsField& field( const QString& name ) const { return mFields[ indexFromName( name )].field; }
+    const QgsField& field( const QString& name ) const;
 
     //! Get field's origin (value from an enumeration)
     FieldOrigin fieldOrigin( int fieldIdx ) const;
     //! Get field's origin index (its meaning is specific to each type of origin)
-    int fieldOriginIndex( int fieldIdx ) const { return mFields[fieldIdx].originIndex; }
+    int fieldOriginIndex( int fieldIdx ) const;
 
     //! Look up field's index from name. Returns -1 on error
-    int indexFromName( const QString& name ) const { return mNameToIndex.value( name, -1 ); }
+    int indexFromName( const QString& name ) const;
 
     //! Look up field's index from name - case insensitive
     //! TODO: sort out case sensitive (indexFromName()) vs insensitive (fieldNameIndex()) calls
@@ -242,20 +260,14 @@ class CORE_EXPORT QgsFields
     QList<QgsField> toList() const;
 
     //! @note added in 2.6
-    bool operator==( const QgsFields& other ) const { return mFields == other.mFields; }
+    bool operator==( const QgsFields& other ) const;
     //! @note added in 2.6
     bool operator!=( const QgsFields& other ) const { return !( *this == other ); }
 
-  protected:
-    //! internal storage of the container
-    QVector<Field> mFields;
+  private:
 
-    //! map for quick resolution of name to index
-    QHash<QString, int> mNameToIndex;
+    QSharedDataPointer<QgsFieldsPrivate> d;
 
 };
 
-
-
-
 #endif