PLC Laboratory 7

Interpreter of Arithmetic Expressions Using ANTLR

Using ANTLR, implement an interpreter of arithmetic expressions. These expressions contain +, -, *, / operators (with common priorities and left associativity) and parentheses. To simplify the task, consider we have only binary operators. There are no unary operators in our language.

As a starting point, you can use following ANTLR grammar (it describes different kind of expressions) ANTLR input file

Input specification

In the input, there are expressions, they are written in formatting. Each expression ends with semicolon. Numbers can be written similarly to C language constants. it can be either: decimal , octal (starting with zero) or hexadecimal (starting with characters 0x) number.

Output specification

For each expression write one line containing the result – the computed value of the expression. If there is any error in the input, you can stop the computation.

Example

• Input

012-10; 2 * (0xff+5);
0x23e5-0x201;

• Output

0
520
8676