edf@ROCKY2.ROCKEFELLER.EDU (David MacKenzie) (10/28/88)
Posting-number: Volume 5, Issue 6
Submitted-by: "David MacKenzie" <edf@ROCKY2.ROCKEFELLER.EDU>
Archive-name: ediff
/*
% cc -O ediff.c -o ediff; strip ediff
*
* ediff - translate diff output into plain English
*
* Translates only the normal diff output (not -c or -e/-f).
* Use as a filter. Copies non-diff lines verbatim. Deletes NULs.
*
* The Unix variant that runs on our Charles River Data Systems
* machines, UNOS, comes with, in addition to the standard diff program,
* a program called "difference" that produces more human-readable
* output. Ediff provides the advantages of that program to users of other
* versions of Unix (soon to include us, as we're hoping to get rid of
* the CRDS machines before too long).
*
* Thanks to Mike Haertel for the following information.
* The exact meaning of the normal diff symbols is as follows
* (all line numbers are the ORIGINAL line numbers in each file);
*
* 5,7c8,10
* Change lines 5-7 of file 1 to read as lines 8-10 of file 2 (or, if changing
* file 2 into file 1, change lines 8-10 of file 2 to read as lines 5-7
* of file 1).
*
* 5,7d3
* Delete lines 5-7 of file 1 (alternatively, append lines 5-7 of file 1
* after line 3 of file 2).
*
* 8a12,15
* Append lines 12-15 of file 2 after line 8 of file 1 (alternatively,
* delete lines 12-15 of file 2).
*
* David MacKenzie
* Latest revision: 10/19/88
*/
#include <stdio.h>
#define UNUSED -1L
#ifdef __STDC__
#define P(x) x
#else
#define P(x) ()
#endif
void change P((long, long, long, long));
void delete P((long, long, long));
void append P((long, long, long));
void copylines P((long, int));
int readline P((char *, int, FILE *));
char buf[BUFSIZ]; /* Input line buffer. */
main ()
{
long f1n1, f1n2, f2n1, f2n2; /* File 1, line number 1; etc. */
int res; /* Result of readline. */
while (res = readline (buf, BUFSIZ, stdin))
{
f1n2 = f2n2 = UNUSED;
if
(sscanf (buf, "%ld,%ldc%ld,%ld\n", &f1n1, &f1n2, &f2n1, &f2n2) == 4 ||
sscanf (buf, "%ld,%ldc%ld\n", &f1n1, &f1n2, &f2n1) == 3 ||
sscanf (buf, "%ldc%ld,%ld\n", &f1n1, &f2n1, &f2n2) == 3 ||
sscanf (buf, "%ldc%ld\n", &f1n1, &f2n1) == 2)
change (f1n1, f1n2, f2n1, f2n2);
else if
(sscanf (buf, "%ld,%ldd%ld\n", &f1n1, &f1n2, &f2n1) == 3 ||
sscanf (buf, "%ldd%ld\n", &f1n1, &f2n1) == 2)
delete (f1n1, f1n2, f2n1);
else if
(sscanf (buf, "%lda%ld,%ld\n", &f1n1, &f2n1, &f2n2) == 3 ||
sscanf (buf, "%lda%ld\n", &f1n1, &f2n1) == 2)
append (f1n1, f2n1, f2n2);
else
{
/* The line wasn't the start of a diff. Copy it verbatim. */
fputs (buf, stdout);
/* If it was a long line, copy the remainder. */
while (res == -1)
{
res = readline (buf, BUFSIZ, stdin);
fputs (buf, stdout);
}
}
}
}
void change (f1n1, f1n2, f2n1, f2n2)
long f1n1, f1n2, f2n1, f2n2;
{
printf ("\n-------- ");
if (f1n2 == UNUSED && f2n2 == UNUSED)
printf ("1 line changed at %ld from:\n",
f1n1); /* 1c1 */
else if (f1n2 == UNUSED)
printf ("1 line changed to %ld lines at %ld from:\n",
f2n2 - f2n1 + 1L, f1n1); /* 1c1,2 */
else if (f2n2 == UNUSED)
printf ("%ld lines changed to 1 line at %ld-%ld from:\n",
f1n2 - f1n1 + 1L, f1n1, f1n2); /* 1,2c1 */
else if (f1n2 - f1n1 == f2n2 - f2n1)
printf ("%ld lines changed at %ld-%ld from:\n",
f1n2 - f1n1 + 1L, f1n1, f1n2); /* 1,2c1,2 */
else
printf ("%ld lines changed to %ld lines at %ld-%ld from:\n",
f1n2 - f1n1 + 1L, f2n2 - f2n1 + 1L, f1n1, f1n2); /* 1,2c1,3 */
if (f1n2 == UNUSED)
copylines (1, 2); /* Skip the "< ". */
else
copylines (f1n2 - f1n1 + 1L, 2);
printf ("-------- to:\n");
(void) readline (buf, BUFSIZ, stdin); /* Eat the "---" line. */
if (f2n2 == UNUSED)
copylines (1, 2); /* Skip the "> ". */
else
copylines (f2n2 - f2n1 + 1L, 2);
}
/* ARGSUSED */
void delete (f1n1, f1n2, f2n1)
long f1n1, f1n2, f2n1;
{
printf ("\n-------- ");
if (f1n2 == UNUSED)
{
printf ("1 line deleted at %ld:\n", f1n1); /* 1d1 */
copylines (1, 2); /* Skip the "< ". */
}
else
{
printf ("%ld lines deleted at %ld:\n", f1n2 - f1n1 + 1L, f1n1); /* 1,2d1 */
copylines (f1n2 - f1n1 + 1L, 2);
}
}
void append (f1n1, f2n1, f2n2)
long f1n1, f2n1, f2n2;
{
printf ("\n-------- ");
if (f2n2 == UNUSED)
{
printf ("1 line added at %ld:\n", f1n1); /* 1a1 */
copylines (1, 2); /* Skip the "> ". */
}
else
{
printf ("%ld lines added at %ld:\n", f2n2 - f2n1 + 1L, f1n1); /* 1a1,2 */
copylines (f2n2 - f2n1 + 1L, 2);
}
}
/*
* Copy nlines lines from stdin to stdout; start writing at position skip.
*/
void copylines (nlines, skip)
long nlines;
int skip;
{
int res;
while (nlines-- > 0L)
{
res = readline (buf, BUFSIZ, stdin);
fputs (&buf[skip], stdout);
/* If it was a long line, copy the remainder. */
while (res == -1)
{
res = readline (buf, BUFSIZ, stdin);
fputs (buf, stdout);
}
}
}
/*
* Front end to fgets.
* Exit if EOF; return 1 if end of line read, -1 if partial line read.
*/
int readline (s, len, fp)
char *s;
int len;
FILE *fp;
{
if (!fgets (s, len, fp))
exit (0);
if (s[strlen (s) - 1] == '\n')
return 1;
else
return -1;
}