Compound variable highlighting

Compound variables are special, in the sense that they have two simultaneous aspects: they are, at the same time, variables, and indexed stem references. The Rexx Parser honors this duality by returning compound variables as single elements that include a number of sub-parts, and the Rexx Highlighter then highlights these parts individually.

  -- An indexed reference
  Say Matrix.1.2A.j..

When highlighting sub-parts, different highlighting attributes will be used for the stem name (a .EL.STEM_VARIABLE or a .EL.EXPOSED_STEM_VARIABLE) and for all the components of its tail. The first dot in a compound variable is part of the stem name. The rest of the symbol, the tail, is an arbitrary sequence of: variables (either local, .EL.SIMPLE_VARIABLE, or exposed, .EL.EXPOSED_SIMPLE_VARIABLE); signless integers (.EL.INTEGER_NUMBER); pure dotless constant symbols (.EL.SYMBOL_LITERAL), and tail separators dots (.EL.TAIL_SEPARATOR).

::Method myMethod
  Expose var stem.
  local = var + 1
  Say stem.12..2E.var.local