Project 2 - Expression Interpreter

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Project 2
The second project involves completing and extending the C++ program that evaluates statements of an
expression language contained in the module 3 case study.
The statements of that expression language consist of an arithmetic expression followed by a list of
assignments. Assignments are separated from the expression and each other by commas. A semicolon
terminates the expression. The arithmetic expressions are fully parenthesized infix expressions
containing integer literals and variables. The valid arithmetic operators are +, –, *, /. Tokens can be
separated by any number of spaces. Variable names begin with an alphabetic character, followed by any
number of alphanumeric characters. Variable names are case sensitive. This syntax is described by BNF
and regular expressions in the case study.
The program reads in the arithmetic expression and encodes the expression as a binary tree. After the
expression has been read in, the variable assignments are read in and the variables and their values of
the variables are placed into the symbol table. Finally the expression is evaluated recursively.
Your first task is to complete the program provided by providing the three missing
classes, Minus, Times and Divide.
Next, you should extend the program so that it supports relational, logical and conditional expression
operators as defined by the following extension to the grammar:
<exp - '(' <operand <op <operand ')' |
'(' <operand ':' <operand '?' <operand ')' |
'(' <operand '!' ')'
<op - '+' | '-' | '*' | '/' | '' | '<' | '=' | '&' | '|'
Note that there are a few differences in the use of these operators compared to their customary use in
the C family of languages. Their differences are:
 In the conditional expression operator, the symbols are reversed and the third operand
represents the condition. The first operand is the value when true and the second the value
when false
 The logical operators use single symbols not double, for example the and operator is & not &&
 The negation operator ! is a postfix operator, not a prefix one
 There are only three relational operators not the usual six and the operator for equality
is = not ==
Like C and C++, any arithmetic expression can be interpreted as a logical value, taking 0 as false and
anything else as true
Your final task is to make the following two modifications to the program:
 The program should accept input from a file, allowing for multiple expressions arranged one per
line.
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 All results should be changed from double to int. In particular the evaluate function should
return an int.
You may assume that all input to the program is syntactically correct.
Deliverables:
Deliverables for this project include the following:
1. Source code correctly implementing all required functionality. Your program must compile with
Microsoft Visual C++ or any modern C/C++ compiler on your O/S.
2. Word or PDF file providing screen shots of successfully compiling and executing the program.
3. Description of the process and lesson learned while completing this project (to be included in
the Word or PDF document).
4. A test plan that contains test cases that test all of the required operators. Each test case should
include the expression and its expected value (to be included in the Word or PDF document).
Grading rubric:
Attribute Meets Does not meet
Functionality 40 points
Completes the program provided in
Module 3 by providing the three
missing Classes:
Minus, Times and Divide.
0 points
Does not complete the program
provided in Module 3 by providing the
three missing Classes:
Minus, Times and Divide.
Extends Functionality 20 points
Extends the program so that it
supports relational, logical and
conditional expression operators.
All results should be changed
from double to int. In particular
the evaluate function should return
an int.
0 points
Does not extend the program so that
it supports relational, logical and
conditional expression operators.
All results should be changed
from double to int. In particular
the evaluate function should return
an int.
Input 20 points
Accepts input from a file, allowing
for multiple expressions arranged
one per line.
0 points
Does not accept input from a file,
allowing for multiple expressions
arranged one per line.
Documentation and
submissions
20 points
Includes source code correctly
implementing all required
functionality.
0 points
Does not Include source code
correctly implementing all required
functionality.
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Program compiles with Microsoft
Visual C++ or any modern C/C++
compiler on your O/S.
Includes Word or PDF file providing
screen shots of successfully
compiling and executing the
program.
Includes a description of the
process and lesson learned while
completing this project (to be
included in the Word or PDF
document).
Includes a test plan that contains
test cases that test all of the
required operators. Each test case
should include the expression and
its expected value (to be included
in the Word or PDF document).
Program does not compile with
Microsoft Visual C++ or any modern
C/C++ compiler on your O/S.
Does not include Word or PDF file
providing screen shots of successfully
compiling and executing the program.
Does not include a description of the
process and lesson learned while
completing this project (to be included
in the Word or PDF document).
Does not include a test plan that
contains test cases that test all of the
required operators. Each test case
should include the expression and its
expected value (to be included in the
Word or PDF document)