= Multiple Changes to CIVL Code =

== Model Changes ==

* introduce !LHSExpression, a subtype of !Expression
* rename !ArrayIndexExpression to !SubscriptExpression
* modify !ModelBuilder to get rid of arrow expressions, replacing them with dot of star
* modify !ModelBuilder to get rid of C's pointer-array pun:
** in any subscript expression `a[i]`, make sure `a` has array type.  If it doesn't, translate to `*(a+i)`
** in any place where a pointer is called for, but instead an array `a` is used, replace `a` with `&a[0]`.  Examples include pointer arithmetic (`a+i`, `a-b`), argument to dereference operator `*`, actual arguments in function calls where the corresponding parameter has pointer type.
** make sure the parameter type of a function call is never an array type.   ABC should already be doing this.
* use an enumerated type like ExpressionKind for the different kinds of expressions, so `switch` statements can be used
* add a method to expressions like `SymbolicExpression getConstantValue()` and a corresponding setter, to cache the value of any expression that has a constant value, such as a literal expression


== Semantics Changes ==