/**
* Enter a nested expression. This is used in interactive mode to control whether to continue past
* end of line, depending on whether the expression is incomplete.
*
* @param promptChar Used in prompt string to indicate type of nesting.
* @return The previous value of promptChar, to be passed to popNesting.
*/
public char pushNesting(char promptChar) {
nesting++;
InPort port = getPort();
char save = port.readState;
port.readState = promptChar;
return save;
}
/**
* Exit a nested expression, reversing pushNesting
*
* @param save Saved values return by prior pushNesting
*/
public void popNesting(char save) {
InPort port = getPort();
port.readState = save;
nesting--;
}