Lab 1: Create a grammar for amount of money

Create a grammar to describe an amount of money:

	currency symbol followed by zero or more spaces, 
	followed by one or more digits, followed by cents 
	(decimal point and two digits).

The currency symbol can be any of these: €, $, ¥, or £

Use ANTLR to generate a parser. Then parse this input: $19.99

Name your start rule: amount

Create a lexer grammar and a parser grammar. Name them MyLexer.g4
and MyParser.g4, respectively. Place them in the current folder 
(in the lab1 folder).

When you've finished your grammars, open a DOS window, change directory
to this folder, and type: run

Note: by default ANTLR works only on ASCII text. €, ¥, and £ are not ASCII
characters. So, you need to specify the character encoding scheme (utf-8).
Here's how to do it:

java org.antlr.v4.Tool -encoding utf-8 MyLexer.g4 -no-listener -no-visitor

java org.antlr.v4.Tool -encoding utf-8 MyParser.g4 -no-listener -no-visitor

This has already been done in run.bat

Hint: you can use these repetition operators:

	* means "zero or more occurrences"
	+ means "one or more occurrences"
	? means "optional" (0 or 1 occurrence)

Thus, the following parser rule means: 

	The input may contain A tokens followed by one
	B token followed by at least one C token.

Parser rule:

	s: A* B C+;