Dax Studio provides full code completion support
Currently DAX Studio does not support variables in code completion
The code completion is based on the best practice of always prefixing columns with the table name and never prefixing a measure with a table name. So if you type 'table name'[ you will get code completion for all the columns in the ‘table name’ table. But if you just type [ you will be presented with a list of all the measures in the model.
It will list both Functions and Keywords: