public PrgState oneStep(PrgState state)
{
MyIStack <IStmt> stk = state.getStk();
IStmt crtStmt = stk.pop();
return(crtStmt.execute(state));
}
public PrgState execute(PrgState state)
{
MyIStack <IStmt> stk = state.getStk();
stk.push(second);
stk.push(first);
return(null);
}
public PrgState execute(PrgState state)
{
MyIStack <IStmt> stk = state.getStk();
MyIDictionary <string, int> symTable = state.getSymTable();
if (exp.Eval(symTable) != 0)
{
stk.push(thenStatement);
}
else
{
stk.push(elseStatement);
}
return(null);
}
public PrgState execute(PrgState state)
{
MyIStack <IStmt> stack = state.getStk();
MyIDictionary <string, int> symTable = state.getSymTable();
int val = exp.Eval(symTable);
if (symTable.isDefined(id))
{
symTable.update(id, val);
}
else
{
symTable.put(id, val);
}
return(null);
}