add basic autocompletion for tables and fields to the sql text input

this does only work on full table names, NOT on aliases
for a full auto completion to work we need a sqlite parser

src/sqltextedit.h

@@ -0,0 +1,47 @@
+#ifndef SQLTEXTEDIT_H
+#define SQLTEXTEDIT_H
+
+#include <QTextEdit>
+
+class QCompleter;
+class QAbstractItemModel;
+
+/**
+ * @brief The SqlTextEdit class
+ * With basic table and fieldname auto completion.
+ * This class is based on the Qt custom completion example.
+ */
+class SqlTextEdit : public QTextEdit
+{
+    Q_OBJECT
+public:
+    explicit SqlTextEdit(QWidget *parent = 0);
+    virtual ~SqlTextEdit();
+
+    void setCompleter(QCompleter* completer);
+    QCompleter* completer() const;
+    void setDefaultCompleterModel(QAbstractItemModel* model);
+
+    // map that associates table -> field model
+    typedef QMap<QString,QAbstractItemModel*> FieldCompleterModelMap;
+
+    void clearFieldCompleterModelMap();
+    QAbstractItemModel* addFieldCompleterModel(const QString& tablename, QAbstractItemModel *model);
+
+protected:
+    void keyPressEvent(QKeyEvent *e);
+    void focusInEvent(QFocusEvent *e);
+
+private:
+    QString identifierUnderCursor() const;
+
+private slots:
+    void insertCompletion(const QString& completion);
+
+private:
+    QCompleter* m_Completer;
+    QAbstractItemModel* m_defaultCompleterModel;
+    FieldCompleterModelMap m_fieldCompleterMap;
+};
+
+#endif // SQLTEXTEDIT_H