Flex, continuous scanning stream (from socket). Did I miss something using yywrap()?
- by Diederich Kroeske
Working on a socketbased scanner (continuous stream) using Flex for pattern recognition. Flex doesn't find a match that overlaps 'array bounderies'. So I implemented yywrap() to setup new array content as soon yylex() detects < (it will call yywrap). No success so far.
Basically (for pin-pointing my problem) this is my code:
%{
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define BUFFERSIZE 26
/* 0123456789012345678901234 */
char cbuf1[BUFFERSIZE] = "Hello everybody, lex is su"; // Warning, no '\0'
char cbuf2[BUFFERSIZE] = "per cool. Thanks! ";
char recvBuffer[BUFFERSIZE];
int packetCnt = 0;
YY_BUFFER_STATE bufferState1, bufferState2;
%}
%option nounput
%option noinput
%%
"super" { ECHO; }
. { printf( "%c", yytext[0] );}
%%
int yywrap()
{
int retval = 1;
printf(">> yywrap()\n");
if( packetCnt <= 0 ) // Stop after 2
{
// Copy cbuf2 into recvBuffer
memcpy(recvBuffer, cbuf2, BUFFERSIZE);
//
yyrestart(NULL); // ?? has no effect
// Feed new data to flex
bufferState2 = yy_scan_bytes(recvBuffer, BUFFERSIZE);
//
packetCnt++;
// Tell flex to resume scanning
retval = 0;
}
return(retval);
}
int main(void)
{
printf("Lenght: %d\n", (int)sizeof(recvBuffer)) ;
// Copy cbuf1 into recvBuffer
memcpy(recvBuffer, cbuf1, BUFFERSIZE);
//
packetCnt = 0;
//
bufferState1 = yy_scan_bytes(recvBuffer, BUFFERSIZE);
//
yylex();
yy_delete_buffer(bufferState1);
yy_delete_buffer(bufferState2);
return 0;
}
This is my output:
dkmbpro:test dkroeske$ ./text
Lenght: 26
Hello everybody, lex is su>> yywrap()
per cool. Thanks! >> yywrap()
So no match on 'super'. According to the doc the lexxer is not 'reset' between yywrap's. What do I miss? Thanks.
