PLC Laboratory 2

Lexical analyzer

Write a program, that reads an input and converts it into a sequence of lexical symbols – tokens. Each token is a pair, it composes from a type and possibly a value.

The tokens definition depends on you, and it is considered a part of the solution.

Input specification

The input may be containing the following symbols:

• identifiers - consisting of a sequence of letters and numbers starting with a letter
• numbers - formed by a sequence of decimal digits
• operators - symbols '+', '-', '*' and '/',
• delimiters - symbols '(', ')' and ';',
• keywords - div and mod.

Symbols can be separated by a sequence of spaces, tabs, and line breaks.

There can be notes in the input. Notes are preceded by a sequence // and continue to the end of the line.

White spaces and notes does not produce any lexical symbols.

Output specification

Converts the given input into a sequence of tokens and write them on output. Write each token on a separated line.

Example

• Input

    -2 + (245 div 3);  // note
2 mod 3

• Output

Your output can be different, it depends on your definition of tokens.

OP:+
NUM:2
OP:-
LPAR
NUM:245
DIV
NUM:3
PPAR
SEMICOLON
NUM:2
MOD
NUM:3