--  file: calctrace.ads
--  ($Id: calctrace.ads,v 1.1 2005/09/06 11:20:18 baker Exp baker $)

--  a caculator for simple integer expressions based on the following grammar:

--  This version is instrumented with trace output, so that the recursion 
--  pattern is visible.

--  <calc> -> <start> <expr> | <eol> <expr>
--  <expr> -> <term> <term_tail>
--  <term> -> <factor> <factor_tail>
--  <term_tail> -> <add_op> <term> <term_tail> | <empty>
--  <factor> -> '(' <expr> ')' | '-' <factor> | <number>
--  <factor_tail> -> <mult_op> <factor> <factor_tail> | <empty>

--  where:

--    <start> stands for the start of input file/stream.
--    <eol> stands for the end of an input line
--    <number> stands for any integer literal.
--    <empty> stands for the null string

package CalcTrace is
   function Calc return Integer;
   Syntax_Error : exception;
   End_Error : exception;
end CalcTrace;