scan.l

flex编译器的源代码

			}

	^{WS}		/* allow indented rules */

	{WS}		{
			/* This rule is separate from the one below because
			 * otherwise we get variable trailing context, so
			 * we can't build the scanner using -{f,F}.
			 */
			bracelevel = 0;
			continued_action = false;
			BEGIN(ACTION);

			if ( in_rule )
				{
				doing_rule_action = true;
				in_rule = false;
				return '\n';
				}
			}

	{OPTWS}{NL}	{
			bracelevel = 0;
			continued_action = false;
			BEGIN(ACTION);
			unput( '\n' );	/* so <ACTION> sees it */

			if ( in_rule )
				{
				doing_rule_action = true;
				in_rule = false;
				return '\n';
				}
			}

	^{OPTWS}"<<EOF>>"	|
	"<<EOF>>"	return EOF_OP;

	^"%%".*		{
			sectnum = 3;
			BEGIN(SECT3);
			yyterminate(); /* to stop the parser */
			}

	"["({FIRST_CCL_CHAR}|{CCL_EXPR})({CCL_CHAR}|{CCL_EXPR})*	{
			int cclval;

			strcpy( nmstr, yytext );

			/* Check to see if we've already encountered this
			 * ccl.
			 */
			if ( (cclval = ccllookup( (Char *) nmstr )) != 0 )
				{
				if ( input() != ']' )
					synerr( _( "bad character class" ) );

				yylval = cclval;
				++cclreuse;
				return PREVCCL;
				}
			else
				{
				/* We fudge a bit.  We know that this ccl will
				 * soon be numbered as lastccl + 1 by cclinit.
				 */
				cclinstal( (Char *) nmstr, lastccl + 1 );

				/* Push back everything but the leading bracket
				 * so the ccl can be rescanned.
				 */
				yyless( 1 );

				BEGIN(FIRSTCCL);
				return '[';
				}
			}

	"{"{NAME}"}"	{
			register Char *nmdefptr;
			Char *ndlookup();

			strcpy( nmstr, yytext + 1 );
			nmstr[yyleng - 2] = '\0';  /* chop trailing brace */

			if ( (nmdefptr = ndlookup( nmstr )) == 0 )
				format_synerr(
					_( "undefined definition {%s}" ),
						nmstr );

			else
				{ /* push back name surrounded by ()'s */
				int len = strlen( (char *) nmdefptr );

				if ( lex_compat || nmdefptr[0] == '^' ||
				     (len > 0 && nmdefptr[len - 1] == '$') )
					{ /* don't use ()'s after all */
					PUT_BACK_STRING((char *) nmdefptr, 0);

					if ( nmdefptr[0] == '^' )
						BEGIN(CARETISBOL);
					}

				else
					{
					unput(')');
					PUT_BACK_STRING((char *) nmdefptr, 0);
					unput('(');
					}
				}
			}

	[/|*+?.(){}]	return (unsigned char) yytext[0];
	.		RETURNCHAR;
}


<SC>{
	[,*]		return (unsigned char) yytext[0];
	">"		BEGIN(SECT2); return '>';
	">"/^		BEGIN(CARETISBOL); return '>';
	{SCNAME}	RETURNNAME;
	.		{
			format_synerr( _( "bad <start condition>: %s" ),
				yytext );
			}
}

<CARETISBOL>"^"		BEGIN(SECT2); return '^';


<QUOTE>{
	[^"\n]		RETURNCHAR;
	\"		BEGIN(SECT2); return '"';

	{NL}		{
			synerr( _( "missing quote" ) );
			BEGIN(SECT2);
			++linenum;
			return '"';
			}
}


<FIRSTCCL>{
	"^"/[^-\]\n]	BEGIN(CCL); return '^';
	"^"/("-"|"]")	return '^';
	.		BEGIN(CCL); RETURNCHAR;
}

<CCL>{
	-/[^\]\n]	return '-';
	[^\]\n]		RETURNCHAR;
	"]"		BEGIN(SECT2); return ']';
	.|{NL}		{
			synerr( _( "bad character class" ) );
			BEGIN(SECT2);
			return ']';
			}
}

<FIRSTCCL,CCL>{
	"[:alnum:]"	BEGIN(CCL); return CCE_ALNUM;
	"[:alpha:]"	BEGIN(CCL); return CCE_ALPHA;
	"[:blank:]"	BEGIN(CCL); return CCE_BLANK;
	"[:cntrl:]"	BEGIN(CCL); return CCE_CNTRL;
	"[:digit:]"	BEGIN(CCL); return CCE_DIGIT;
	"[:graph:]"	BEGIN(CCL); return CCE_GRAPH;
	"[:lower:]"	BEGIN(CCL); return CCE_LOWER;
	"[:print:]"	BEGIN(CCL); return CCE_PRINT;
	"[:punct:]"	BEGIN(CCL); return CCE_PUNCT;
	"[:space:]"	BEGIN(CCL); return CCE_SPACE;
	"[:upper:]"	BEGIN(CCL); return CCE_UPPER;
	"[:xdigit:]"	BEGIN(CCL); return CCE_XDIGIT;
	{CCL_EXPR}	{
			format_synerr(
				_( "bad character class expression: %s" ),
					yytext );
			BEGIN(CCL); return CCE_ALNUM;
			}
}

<NUM>{
	[[:digit:]]+	{
			yylval = myctoi( yytext );
			return NUMBER;
			}

	","		return ',';
	"}"		BEGIN(SECT2); return '}';

	.		{
			synerr( _( "bad character inside {}'s" ) );
			BEGIN(SECT2);
			return '}';
			}

	{NL}		{
			synerr( _( "missing }" ) );
			BEGIN(SECT2);
			++linenum;
			return '}';
			}
}


<PERCENT_BRACE_ACTION>{
	{OPTWS}"%}".*		bracelevel = 0;

	<ACTION>"/*"		ACTION_ECHO; yy_push_state( COMMENT );

	<CODEBLOCK,ACTION>{
		"reject"	{
			ACTION_ECHO;
			CHECK_REJECT(yytext);
			}
		"yymore"	{
			ACTION_ECHO;
			CHECK_YYMORE(yytext);
			}
	}

	{NAME}|{NOT_NAME}|.	ACTION_ECHO;
	{NL}		{
			++linenum;
			ACTION_ECHO;
			if ( bracelevel == 0 ||
			     (doing_codeblock && indented_code) )
				{
				if ( doing_rule_action )
					add_action( "\tYY_BREAK\n" );

				doing_rule_action = doing_codeblock = false;
				BEGIN(SECT2);
				}
			}
}


	/* Reject and YYmore() are checked for above, in PERCENT_BRACE_ACTION */
<ACTION>{
	"{"		ACTION_ECHO; ++bracelevel;
	"}"		ACTION_ECHO; --bracelevel;
	[^[:alpha:]_{}"'/\n]+	ACTION_ECHO;
	{NAME}		ACTION_ECHO;
	"'"([^'\\\n]|\\.)*"'"	ACTION_ECHO; /* character constant */
	\"		ACTION_ECHO; BEGIN(ACTION_STRING);
	{NL}		{
			++linenum;
			ACTION_ECHO;
			if ( bracelevel == 0 )
				{
				if ( doing_rule_action )
					add_action( "\tYY_BREAK\n" );

				doing_rule_action = false;
				BEGIN(SECT2);
				}
			}
	.		ACTION_ECHO;
}

<ACTION_STRING>{
	[^"\\\n]+	ACTION_ECHO;
	\\.		ACTION_ECHO;
	{NL}		++linenum; ACTION_ECHO;
	\"		ACTION_ECHO; BEGIN(ACTION);
	.		ACTION_ECHO;
}

<COMMENT,ACTION,ACTION_STRING><<EOF>>	{
			synerr( _( "EOF encountered inside an action" ) );
			yyterminate();
			}


<SECT2,QUOTE,FIRSTCCL,CCL>{ESCSEQ}	{
			yylval = myesc( (Char *) yytext );

			if ( YY_START == FIRSTCCL )
				BEGIN(CCL);

			return CHAR;
			}


<SECT3>{
	.*(\n?)		ECHO;
	<<EOF>>		sectnum = 0; yyterminate();
}

<*>.|\n			format_synerr( _( "bad character: %s" ), yytext );

%%


int yywrap()
	{
	if ( --num_input_files > 0 )
		{
		set_input_file( *++input_files );
		return 0;
		}

	else
		return 1;
	}


/* set_input_file - open the given file (if NULL, stdin) for scanning */

void set_input_file( file )
char *file;
	{
	if ( file && strcmp( file, "-" ) )
		{
		infilename = copy_string( file );
		yyin = fopen( infilename, "r" );

		if ( yyin == NULL )
			lerrsf( _( "can't open %s" ), file );
		}

	else
		{
		yyin = stdin;
		infilename = copy_string( "<stdin>" );
		}

	linenum = 1;
	}


/* Wrapper routines for accessing the scanner's malloc routines. */

void *flex_alloc( size )
size_t size;
	{
	return (void *) malloc( size );
	}

void *flex_realloc( ptr, size )
void *ptr;
size_t size;
	{
	return (void *) realloc( ptr, size );
	}

void flex_free( ptr )
void *ptr;
	{
	if ( ptr )
		free( ptr );
	}