A (non-empty) stack of summary components.
A stack is used to represent where data is read from (input) or where it
is written to (output). For example, an input stack
[Field f, Argument 0]
means that data is read from field
f from the
0th argument, while an
[Field g, Return] means that data is written to the field
g of the returned object.
Gets the bottom element of this stack.
Holds if this stack contains summary component
Gets the stack obtained by dropping the first
Gets a textual representation of this stack used for MaD models.
Gets the head of this stack.
Gets the length of this stack.
Gets the tail of this stack, if any.
Gets a textual representation of this stack.