class TSelectorDraw: public TSelector

 Default selector constructor.

 Selector destructor.

 Called everytime a loop on the tree(s) starts.

 Delete internal buffers.

 Compile input variables and selection expression.

  varexp is an expression of the general form e1:e2:e3
    where e1,etc is a formula referencing a combination of the columns
  Example:
     varexp = x  simplest case: draw a 1-Dim distribution of column named x
            = sqrt(x)         : draw distribution of sqrt(x)
            = x*y/z
            = y:sqrt(x) 2-Dim dsitribution of y versus sqrt(x)

  selection is an expression with a combination of the columns
  Example:
      selection = "x<y && sqrt(z)>3.2"
       in a selection all the C++ operators are authorized

  Return kFALSE if any of the variable is not compilable.

 Return name corresponding to colindex in varexp.

 varexp is a string of names separated by :
 index is an array with pointers to the start of name[i] in varexp

Get variable buffer.

Get variable formula.

 Initialization of the primitive type arrays if the new size is bigger than the available space.

 Build Index array for names in varexp.

 This function is called at the first entry of a new tree in a chain.

 Called in the entry loop for all entries accepted by Select.

 Called in the entry loop for all entries accepted by Select.
 Complex case with multiplicity.

 Called in the entry loop for all entries accepted by Select.
 Case where the only variable returns an object (or pointer to).

 Set number of entries to estimate variable limits.

 Execute action for object obj fNfill times.

 Estimate limits for 1-D, 2-D or 3-D objects.

 Called at the end of a loop on a TTree.