minix/external/bsd/flex/dist/examples/manual/eof_rules.lex

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2012-06-06 16:10:32 +02:00
/*
* eof_rules.lex : An example of using multiple buffers
* EOF rules, and start states
*/
%{
#define MAX_NEST 10
YY_BUFFER_STATE include_stack[MAX_NEST];
int include_count = -1;
%}
%x INCLUDE
%%
^"#include"[ \t]*\" BEGIN(INCLUDE);
<INCLUDE>\" BEGIN(INITIAL);
<INCLUDE>[^\"]+ { /* get the include file name */
if ( include_count >= MAX_NEST){
fprintf( stderr, "Too many include files" );
exit( 1 );
}
include_stack[++include_count] = YY_CURRENT_BUFFER;
yyin = fopen( yytext, "r" );
if ( ! yyin ){
fprintf( stderr, "Unable to open \"%s\"\n",yytext);
exit( 1 );
}
yy_switch_to_buffer(yy_create_buffer(yyin,YY_BUF_SIZE));
BEGIN(INITIAL);
}
<INCLUDE><<EOF>>
{
fprintf( stderr, "EOF in include" );
yyterminate();
}
<<EOF>> {
if ( include_count <= 0 ){
yyterminate();
} else {
yy_delete_buffer(include_stack[include_count--] );
yy_switch_to_buffer(include_stack[include_count] );
BEGIN(INCLUDE);
}
}
[a-z]+ ECHO;
.|\n ECHO;