Parses the operator expression and save the operators as a list
of unary or binary operators (i.e. matrix multiplication, see below).
Operation expressions are given in a compact notation and specify
matrices from the operations list.
An operation expression can be a comma-separated list 1, 5, 9,
a dash-delimited range 1-60 or a matrix multiplication involving two
or more lists or ranges. For instance, (X0)(1-20) specifies the
portion of the X174 procapsid crystal asymmetric unit belonging to
the first independent virus particle and corresponds
to the 20 transformations [X0], [X0], ... , [X0].
See C. Lawson, Acta Cryst., D64, 874-882, 2008.
operatorExpression - the operator expression to be parsed
Returns a list of operators for this assembly. The operators
refer to the transformations that should be applied to
the asym ids to generate this macromolecular assembly.
Each ordered pair refers to the multiplication
of the two transformation matrices in the