sed.c

操作系统源代码

	}
}

static int substitute(ipc)
/* Perform s command */
sedcmd *ipc;			/* ptr to s command struct */
{
  int nullmatch;

  if (match(ipc->u.lhs, 0)) {	/* if no match */
	nullmatch = (loc1 == loc2);
	dosub(ipc->rhs);	/* perform it once */
  } else
	return(FALSE);		/* command fails */

  if (ipc->flags.global)	/* if global flag enabled */
	while (*loc2) {		/* cycle through possibles */
		if (nullmatch) loc2++;
		if (match(ipc->u.lhs, 1)) {	/* found another */
			nullmatch = (loc1 == loc2);
			dosub(ipc->rhs);	/* so substitute */
		} else		/* otherwise, */
			break;	/* we're done */
	}
  return(TRUE);			/* we succeeded */
}

static void dosub(rhsbuf)	/* uses linebuf, genbuf, spend */
 /* Generate substituted right-hand side (of s command) */
char *rhsbuf;			/* where to put the result */
{
  register char *lp, *sp, *rp;
  int c;

  /* Copy linebuf to genbuf up to location  1 */
  lp = linebuf;
  sp = genbuf;
  while (lp < loc1) *sp++ = *lp++;

  for (rp = rhsbuf; c = *rp++;) {
	if (c == '&') {
		sp = place(sp, loc1, loc2);
		continue;
	} else if (c & 0200 && (c &= 0177) >= '1' && c < MAXTAGS + '1') {
		sp = place(sp, brastart[c - '1'], bracend[c - '1']);
		continue;
	}
	*sp++ = c & 0177;
	if (sp >= genbuf + MAXBUF) fprintf(stderr, LTLMSG);
  }
  lp = loc2;
  loc2 = sp - genbuf + linebuf;
  while (*sp++ = *lp++)
	if (sp >= genbuf + MAXBUF) fprintf(stderr, LTLMSG);
  lp = linebuf;
  sp = genbuf;
  while (*lp++ = *sp++);
  spend = lp - 1;
}

static char *place(asp, al1, al2)	/* uses genbuf */
 /* Place chars at *al1...*(al1 - 1) at asp... in genbuf[] */
register char *asp, *al1, *al2;
{
  while (al1 < al2) {
	*asp++ = *al1++;
	if (asp >= genbuf + MAXBUF) fprintf(stderr, LTLMSG);
  }
  return(asp);
}

static void listto(p1, fp)
/* Write a hex dump expansion of *p1... to fp */
register char *p1;		/* the source */
FILE *fp;			/* output stream to write to */
{
  p1--;
  while (*p1++)
	if (isprint(*p1))
		putc(*p1, fp);	/* pass it through */
	else {
		putc('\\', fp);	/* emit a backslash */
		switch (*p1) {
		    case '\b':
			putc('b', fp);
			break;	/* BS */
		    case '\t':
			putc('t', fp);
			break;	/* TAB */
		    case '\n':
			putc('n', fp);
			break;	/* NL */
		    case '\r':
			putc('r', fp);
			break;	/* CR */
		    case '\33':
			putc('e', fp);
			break;	/* ESC */
		    default:
			fprintf(fp, "%02x", *p1 & 0xFF);
		}
	}
  putc('\n', fp);
}

static void truncated(h)
int h;
{
  static long last = 0L;

  if (lnum == last) return;
  last = lnum;

  fprintf(stderr, "sed: ");
  fprintf(stderr, h ? "hold space" : "line %ld", lnum);
  fprintf(stderr, " truncated to %d characters\n", MAXBUF);
}

static void command(ipc)
/* Execute compiled command pointed at by ipc */
sedcmd *ipc;
{
  static char holdsp[MAXHOLD + 1];	/* the hold space */
  static char *hspend = holdsp;	/* hold space end pointer */
  register char *p1, *p2;
  char *execp;
  int didsub;			/* true if last s succeeded */

  switch (ipc->command) {
      case ACMD:		/* append */
	*aptr++ = ipc;
	if (aptr >= appends + MAXAPPENDS) fprintf(stderr,
			"sed: too many appends after line %ld\n",
			lnum);
	*aptr = 0;
	break;

      case CCMD:		/* change pattern space */
	delete = TRUE;
	if (!ipc->flags.inrange || lastline) printf("%s\n", ipc->u.lhs);
	break;

      case DCMD:		/* delete pattern space */
	delete++;
	break;

      case CDCMD:		/* delete a line in hold space */
	p1 = p2 = linebuf;
	while (*p1 != '\n')
		if (delete = (*p1++ == 0)) return;
	p1++;
	while (*p2++ = *p1++) continue;
	spend = p2 - 1;
	jump++;
	break;

      case EQCMD:		/* show current line number */
	fprintf(stdout, "%ld\n", lnum);
	break;

      case GCMD:		/* copy hold space to pattern space */
	p1 = linebuf;
	p2 = holdsp;
	while (*p1++ = *p2++);
	spend = p1 - 1;
	break;

      case CGCMD:		/* append hold space to pattern space */
	*spend++ = '\n';
	p1 = spend;
	p2 = holdsp;
	do
		if (p1 > linebuf + MAXBUF) {
			truncated(0);
			p1[-1] = 0;
			break;
		}
	while (*p1++ = *p2++);

	spend = p1 - 1;
	break;

      case HCMD:		/* copy pattern space to hold space */
	p1 = holdsp;
	p2 = linebuf;
	while (*p1++ = *p2++);
	hspend = p1 - 1;
	break;

      case CHCMD:		/* append pattern space to hold space */
	*hspend++ = '\n';
	p1 = hspend;
	p2 = linebuf;
	do
		if (p1 > holdsp + MAXBUF) {
			truncated(1);
			p1[-1] = 0;
			break;
		}
	while (*p1++ = *p2++);

	hspend = p1 - 1;
	break;

      case ICMD:		/* insert text */
	printf("%s\n", ipc->u.lhs);
	break;

      case BCMD:		/* branch to label */
	jump = TRUE;
	break;

      case LCMD:		/* list text */
	listto(linebuf, (ipc->fout != NULL) ? ipc->fout : stdout);
	break;

      case NCMD:		/* read next line into pattern space */
	if (!nflag) puts(linebuf);	/* flush out the current line */
	if (aptr > appends) readout();	/* do pending a, r commands */
	if ((execp = getline(linebuf)) == BAD) {
		delete = TRUE;
		break;
	}
	spend = execp;
	anysub = FALSE;
	break;

      case CNCMD:		/* append next line to pattern space */
	if (aptr > appends) readout();
	*spend++ = '\n';
	if ((execp = getline(spend)) == BAD) {
		*--spend = 0;
		break;
	}
	spend = execp;
	anysub = FALSE;
	break;

      case PCMD:		/* print pattern space */
	puts(linebuf);
	break;

      case CPCMD:		/* print one line from pattern space */
cpcom:				/* so s command can jump here */
	for (p1 = linebuf; *p1 != '\n' && *p1 != '\0';) putc(*p1++, stdout);
	putc('\n', stdout);
	break;

      case QCMD:		/* quit the stream editor */
	if (!nflag) puts(linebuf);	/* flush out the current line */
	if (aptr > appends)
		readout();	/* do any pending a and r commands */
	quit(0);

      case RCMD:		/* read a file into the stream */
	*aptr++ = ipc;
	if (aptr >= appends + MAXAPPENDS) fprintf(stderr,
			"sed: too many reads after line %ld\n",
			lnum);
	*aptr = 0;
	break;

      case SCMD:		/* substitute RE */
	didsub = substitute(ipc);
	if (didsub) anysub = TRUE;
	if (ipc->flags.print && didsub)
		if (ipc->flags.print == TRUE)
			puts(linebuf);
		else
			goto cpcom;
	if (didsub && ipc->fout) fprintf(ipc->fout, "%s\n", linebuf);
	break;

      case TCMD:		/* branch on any s successful */
      case CTCMD:		/* branch on any s failed */
	if (anysub == (ipc->command == CTCMD))
		break;		/* no branch if any s failed, else */
	anysub = FALSE;
	jump = TRUE;		/* set up to jump to assoc'd label */
	break;

      case CWCMD:		/* write one line from pattern space */
	for (p1 = linebuf; *p1 != '\n' && *p1 != '\0';)
		putc(*p1++, ipc->fout);
	putc('\n', ipc->fout);
	break;

      case WCMD:		/* write pattern space to file */
	fprintf(ipc->fout, "%s\n", linebuf);
	break;

      case XCMD:		/* exchange pattern and hold spaces */
	p1 = linebuf;
	p2 = genbuf;
	while (*p2++ = *p1++) continue;
	p1 = holdsp;
	p2 = linebuf;
	while (*p2++ = *p1++) continue;
	spend = p2 - 1;
	p1 = genbuf;
	p2 = holdsp;
	while (*p2++ = *p1++) continue;
	hspend = p2 - 1;
	break;

      case YCMD:
	p1 = linebuf;
	p2 = ipc->u.lhs;
	while (*p1 = p2[*p1]) p1++;
	break;
  }
}

static void openfile(file)
char *file;
/* Replace stdin by given file */
{
  if (freopen(file, "r", stdin) == NULL) {
	fprintf(stderr, "sed: can't open %s\n", file);
	quit(1);
  }
}

static int c;			/* Will be the next char to read, a kind of
			 * lookahead */

static void get()
/* Read next character into c treating all argument files as run through cat */
{
  while ((c = getchar()) == EOF && --eargc >= 0) openfile(*eargv++);
}

static void initget()
/* Initialise character input */
{
  if (--eargc >= 0) openfile(*eargv++);	/* else input == stdin */
  get();
}

static char *getline(buf)
/* Get next line of text to be edited, return pointer to end */
register char *buf;		/* where to send the input */
{
  if (c == EOF) return BAD;

  lnum++;			/* we can read a new line */

  do {
	if (c == '\n') {
		get();
		break;
	}
	if (buf <= linebuf + MAXBUF) *buf++ = c;
	get();
  } while (c != EOF);

  if (c == EOF) lastline = TRUE;

  if (buf > linebuf + MAXBUF) {
	truncated(0);
	--buf;
  }
  *buf = 0;
  return buf;
}

static int Memcmp(a, b, count)
/* Return TRUE if *a... == *b... for count chars, FALSE otherwise */
register char *a, *b;
int count;
{
  while (count--)		/* look at count characters */
	if (*a++ != *b++)	/* if any are nonequal	 */
		return(FALSE);	/* return FALSE for false */
  return(TRUE);			/* compare succeeded */
}

static void readout()
/* Write file indicated by r command to output */
{
  register int t;		/* hold input char or EOF */
  FILE *fi;			/* ptr to file to be read */

  aptr = appends - 1;		/* arrange for pre-increment to work right */
  while (*++aptr)
	if ((*aptr)->command == ACMD)	/* process "a" cmd */
		printf("%s\n", (*aptr)->u.lhs);
	else {			/* process "r" cmd */
		if ((fi = fopen((*aptr)->u.lhs, "r")) == NULL) {
			fprintf(stderr, "sed: can't open %s\n",
				(*aptr)->u.lhs);
			continue;
		}
		while ((t = getc(fi)) != EOF) putc((char) t, stdout);
		fclose(fi);
	}
  aptr = appends;		/* reset the append ptr */
  *aptr = 0;
}

/* Sedexec.c ends here */