Given the following grammar:

expr ::= term [{+ | } term]*

term ::= factor [{* | /} factor]*

factor ::= (expr) | number

In C++, implement lexical analyzer with the following class definition:

class LexicalAnalyzer {

LexicalAnalyzer(String expression); // constructor boolean get_token(Token token); // get next token from expression private boolean scan_number(char c); // scan a real number

}