BARES

This is a BARES (Basic ARithmetic Expression Evaluator based on Stacks) programming project, that includes a recursive descending parser for EBNF (Extended Backus-Naur Form) grammar.

Compile and Run

In order to generate a BARES executable at the "bin" dir, run:

$ make

To run this project using input and output files:

$ ./bin/bares <input_file> [output_file]

By using std::cin (input) and std::cout (output):

$ ./bin/bares

The Grammar

The EBNF grammar used in this project represents arithmetic expressions that supports scope definition and operations with integers (-32768 to 32767):

• Addition (+)
• Subtraction (-)
• Multiplication (*)
• Division (/)
• Power (^)
• Module (%)

This EBNF grammar is defined by the statements:

<expression>       :=   <term>, { ( "+" | "-" | "*" | "/" | "%" | "^" ), <term> };
<term>             :=   "(", <expression>, ")" | <integer>;
<integer>          :=   0 | [ "-" ], <natural_number>;
<natural_number>   :=   <digit_excl_zero>, {<digit>};
<digit_excl_zero>  :=   "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9";
<digit>            :=   "0" | <digit_excl_zero>;

Error Handling

Syntax and run-time errors are both supported by the program.

1. Integer constant out of range beginning at column (n)!
2. Missing term at column (n)!
3. Extraneous symbol after valid expression found at column (n)!
4. Ill formed integer at column (n)!
5. Missing closing ”)” at column (n)!
6. Unexpected end of expression at column (n)!
7. Division by zero!
8. Numeric overflow error!

Testing and Issues

To test the BARES program, try to run the executable setting "data/expressions" file as input and "data/solve" file as output.

$ ./bin/bares data/expressions data/solve

It is known that this program treats the ill formed integers that appears after a valid operator as a missing term.

Authorship

Developed by Lucas Miguel.