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sed: rewrite the main loop.

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Rewrite the main loop of the "sed s/..." command, shortening it by ten
lines and simplifying it by removing the switch statement implementing
/g, /1, and /2 separately and repetitively.

This will be needed to bring a fix from OpenBSD later.

Obtained from:	OpenBSD (schwarze CVS Rev. 1.18)
MFC after:	3 weeks
This commit is contained in:
Pedro F. Giffuni 2016-05-07 01:44:22 +00:00
parent dc9643853d
commit b6f5aa5715
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=299211
1 changed files with 43 additions and 49 deletions
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92
usr.bin/sed/process.c
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@ -379,7 +379,7 @@ substitute(struct s_command *cp)
{
SPACE tspace;
regex_t *re;
regoff_t re_off, slen;
regoff_t slen;
int lastempty, n;
char *s;
@ -400,61 +400,55 @@ substitute(struct s_command *cp)
n = cp->u.s->n;
lastempty = 1;
switch (n) {
case 0: /* Global */
do {
if (lastempty || match[0].rm_so != match[0].rm_eo) {
/* Locate start of replaced string. */
re_off = match[0].rm_so;
/* Copy leading retained string. */
cspace(&SS, s, re_off, APPEND);
/* Add in regular expression. */
regsub(&SS, s, cp->u.s->new);
}
do {
/* Copy the leading retained string. */
if (n <= 1 && match[0].rm_so)
cspace(&SS, s, match[0].rm_so, APPEND);
/* Move past this match. */
if (match[0].rm_so != match[0].rm_eo) {
s += match[0].rm_eo;
slen -= match[0].rm_eo;
lastempty = 0;
/* Skip zero-length matches right after other matches. */
if (lastempty || match[0].rm_so ||
match[0].rm_so != match[0].rm_eo) {
if (n <= 1) {
/* Want this match: append replacement. */
regsub(&SS, s, cp->u.s->new);
if (n == 1)
n = -1;
} else {
if (match[0].rm_so < slen)
cspace(&SS, s + match[0].rm_so, 1,
APPEND);
s += match[0].rm_so + 1;
slen -= match[0].rm_so + 1;
lastempty = 1;
/* Want a later match: append original. */
if (match[0].rm_eo)
cspace(&SS, s, match[0].rm_eo, APPEND);
n--;
}
} while (slen >= 0 && regexec_e(re, s, REG_NOTBOL, 0, slen));
/* Copy trailing retained string. */
if (slen > 0)
cspace(&SS, s, slen, APPEND);
break;
default: /* Nth occurrence */
while (--n) {
if (match[0].rm_eo == match[0].rm_so)
match[0].rm_eo = match[0].rm_so + 1;
s += match[0].rm_eo;
slen -= match[0].rm_eo;
if (slen < 0)
return (0);
if (!regexec_e(re, s, REG_NOTBOL, 0, slen))
return (0);
}
/* FALLTHROUGH */
case 1: /* 1st occurrence */
/* Locate start of replaced string. */
re_off = match[0].rm_so + (s - ps);
/* Copy leading retained string. */
cspace(&SS, ps, re_off, APPEND);
/* Add in regular expression. */
regsub(&SS, s, cp->u.s->new);
/* Copy trailing retained string. */
/* Move past this match. */
s += match[0].rm_eo;
slen -= match[0].rm_eo;
/*
* After a zero-length match, advance one byte,
* and at the end of the line, terminate.
*/
if (match[0].rm_so == match[0].rm_eo) {
if (*s == '\0' || *s == '\n')
slen = -1;
else
slen--;
if (*s != '\0')
cspace(&SS, s++, 1, APPEND);
lastempty = 1;
} else
lastempty = 0;
} while (n >= 0 && slen >= 0 && regexec_e(re, s, REG_NOTBOL, 0, slen));
/* Did not find the requested number of matches. */
if (n > 1)
return (0);
/* Copy the trailing retained string. */
if (slen > 0)
cspace(&SS, s, slen, APPEND);
break;
}
/*
* Swap the substitute space and the pattern space, and make sure