testxxlexer.l

来自「编译原理（Flex）：生成词法和语法分析程序的源代码的程序。」· L 代码 · 共 59 行

	// An example of using the flex C++ scanner class.

%option C++ noyywrap

%{
int mylineno = 0;
%}

string	\"[^\n"]+\"

ws	[ \t]+

alpha	[A-Za-z]
dig	[0-9]
name	({alpha}|{dig}|\$)({alpha}|{dig}|\_|\.|\-|\/|\$)*
num1	[-+]?{dig}+\.?([eE][-+]?{dig}+)?
num2	[-+]?{dig}*\.{dig}+([eE][-+]?{dig}+)?
number	{num1}|{num2}

%%

{ws}	/* skip blanks and tabs */

"/*"		{
		int c;

		while((c = yyinput()) != 0)
			{
			if(c == '\n')
				++mylineno;

			else if(c == '*')
				{
				if((c = yyinput()) == '/')
					break;
				else
					unput(c);
				}
			}
		}

{number}	cout << "number " << YYText() << '\n';

\n		mylineno++;

{name}		cout << "name " << YYText() << '\n';

{string}	cout << "string " << YYText() << '\n';

%%

int main( int /* argc */, char** /* argv */ )
	{
	FlexLexer* lexer = new yyFlexLexer;
	while(lexer->yylex() != 0)
		;
	return 0;
	}